TermInfo contain the end_offset of the postings.

We slice the ReadOnlySource tightly.

CHANGELOG.md

@@ -1,8 +1,6 @@
 Tantivy 0.14.0
 =========================
-- Remove dependency to atomicwrites #833. Implemented by @pmasurel upon suggestion and research from @asafigan). 
-- Migrated tantivy error from the now deprecated `failure` crate to `thiserror` #760. (@hirevo)
-- Switched to structure logging (via the `slog` crate). (@pmasurel)
+- Remove dependency to atomicwrites #833 .Implemented by @pmasurel upon suggestion and research from @asafigan). 
 
 Tantivy 0.13.1
 ===================

Cargo.toml

@@ -23,8 +23,7 @@ memmap = {version = "0.7", optional=true}
 lz4 = {version="1", optional=true}
 snap = "1"
 tempfile = {version="3", optional=true}
-slog = "2.5"
-slog-stdlog = "4"
+log = "0.4"
 serde = {version="1", features=["derive"]}
 serde_json = "1"
 num_cpus = "1"
@@ -43,7 +42,7 @@ bitpacking = {version="0.8", default-features = false, features=["bitpacker4x"]}
 census = "0.4"
 fnv = "1"
 owned-read = "0.4"
-thiserror = "1.0"
+failure = "0.1"
 htmlescape = "0.3"
 fail = "0.4"
 murmurhash32 = "0.2"

doc/src/index-format.md

@@ -0,0 +1,50 @@
+
+# Managed files 
++----------+-----------+-------------------+
+| content  |  footer   |  footer_len: u32  |
++----------+-----------+-------------------+
+
+# Term Dictionary (Composite File)
+
++---------+---------------------------+------------------------+
+|   fst   | term_info_store           |   footer_len:  u64     |
++---------+---------------------------+------------------------+
+
+During a merge the term info store need to fit in memory.
+It has a cost of n bytes per term.
+
+# term_info_store
++-------------------+---------------------------+------------------------+
+|  len_block_meta   |  block_meta               |  term_infos            |
++-------------------+---------------------------+------------------------+
+
+# inverted_index
++------------------------+---------------------------+------------------------+
+|  total_num_tokens: u64 |  posting_lists.. |  term_infos            |
++------------------------+---------------------------+------------------------+
+
+# postings lists
++------------------------+---------------------------+------------------------+
+|    
++
+
+# composite file
++----------------+-----+----------------+----------------------+----------------+
+| field file 1   | ... | field field n  |composite file footer | footer len: u32| 
++----------------+-----+----------------+----------------------+----------------+
+
+# composite file footer
+
++-----------------+---------------------------------------+
+|num fields: vint | (file_addr, offset_delta: vint) []... |
++-----------------+---------------------------------------+
+
+# FileAddr 
++--------------+--------------+
+|  field: u32  |  idx: VInt   |
++--------------+--------------+
+
+# Posting lists 
++-----------------------------------------+
+| skip_reader 
++-----------------------------------------+

src/core/executor.rs

@@ -1,6 +1,5 @@
 use crossbeam::channel;
 use rayon::{ThreadPool, ThreadPoolBuilder};
-use slog::{error, Logger};
 
 /// Search executor whether search request are single thread or multithread.
 ///
@@ -44,7 +43,6 @@ impl Executor {
         &self,
         f: F,
         args: AIterator,
-        logger: Logger,
     ) -> crate::Result<Vec<R>> {
         match self {
             Executor::SingleThread => args.map(f).collect::<crate::Result<_>>(),
@@ -59,7 +57,7 @@ impl Executor {
                                 let (idx, arg) = arg_with_idx;
                                 let fruit = f(arg);
                                 if let Err(err) = fruit_sender.send((idx, fruit)) {
-                                    error!(logger, "Failed to send search task. It probably means all search threads have panicked. {:?}", err);
+                                    error!("Failed to send search task. It probably means all search threads have panicked. {:?}", err);
                                 }
                             });
                         }
@@ -89,21 +87,17 @@ impl Executor {
 #[cfg(test)]
 mod tests {
 
-    use slog::{o, Discard, Logger};
-
     use super::Executor;
 
     #[test]
     #[should_panic(expected = "panic should propagate")]
     fn test_panic_propagates_single_thread() {
-        let logger = Logger::root(Discard, o!());
         let _result: Vec<usize> = Executor::single_thread()
             .map(
                 |_| {
                     panic!("panic should propagate");
                 },
                 vec![0].into_iter(),
-                logger,
             )
             .unwrap();
     }
@@ -111,7 +105,6 @@ mod tests {
     #[test]
     #[should_panic] //< unfortunately the panic message is not propagated
     fn test_panic_propagates_multi_thread() {
-        let logger = Logger::root(Discard, o!());
         let _result: Vec<usize> = Executor::multi_thread(1, "search-test")
             .unwrap()
             .map(
@@ -119,16 +112,14 @@ mod tests {
                     panic!("panic should propagate");
                 },
                 vec![0].into_iter(),
-                logger,
             )
             .unwrap();
     }
 
     #[test]
     fn test_map_singlethread() {
-        let logger = Logger::root(Discard, o!());
         let result: Vec<usize> = Executor::single_thread()
-            .map(|i| Ok(i * 2), 0..1_000, logger)
+            .map(|i| Ok(i * 2), 0..1_000)
             .unwrap();
         assert_eq!(result.len(), 1_000);
         for i in 0..1_000 {
@@ -138,10 +129,9 @@ mod tests {
 
     #[test]
     fn test_map_multithread() {
-        let logger = Logger::root(Discard, o!());
         let result: Vec<usize> = Executor::multi_thread(3, "search-test")
             .unwrap()
-            .map(|i| Ok(i * 2), 0..10, logger)
+            .map(|i| Ok(i * 2), 0..10)
             .unwrap();
         assert_eq!(result.len(), 10);
         for i in 0..10 {

src/core/index.rs

@@ -21,7 +21,6 @@ use crate::schema::FieldType;
 use crate::schema::Schema;
 use crate::tokenizer::{TextAnalyzer, TokenizerManager};
 use crate::IndexWriter;
-use slog::Logger;
 use std::borrow::BorrowMut;
 use std::collections::HashSet;
 use std::fmt;
@@ -58,14 +57,7 @@ pub struct Index {
 }
 
 impl Index {
-
-    pub(crate) fn logger(&self) -> &Logger {
-        self.directory.logger()
-    }
-
-    /// Examines the directory to see if it contains an index.
-    ///
-    /// Effectively, it only checks for the presence of the `meta.json` file.
+    /// Examines the director to see if it contains an index
     pub fn exists<Dir: Directory>(dir: &Dir) -> bool {
         dir.exists(&META_FILEPATH)
     }
@@ -148,18 +140,16 @@ impl Index {
         Index::create(mmap_directory, schema)
     }
 
-    /// Creates a new index given an implementation of the trait `Directory`.
-    ///
-    /// If a directory previously existed, it will be erased.
+    /// Creates a new index given an implementation of the trait `Directory`
     pub fn create<Dir: Directory>(dir: Dir, schema: Schema) -> crate::Result<Index> {
         let directory = ManagedDirectory::wrap(dir)?;
-        Index::new_from_directory(directory, schema)
+        Index::from_directory(directory, schema)
     }
 
     /// Create a new index from a directory.
     ///
     /// This will overwrite existing meta.json
-    fn new_from_directory(mut directory: ManagedDirectory, schema: Schema) -> crate::Result<Index> {
+    fn from_directory(mut directory: ManagedDirectory, schema: Schema) -> crate::Result<Index> {
         save_new_metas(schema.clone(), directory.borrow_mut())?;
         let metas = IndexMeta::with_schema(schema);
         Index::create_from_metas(directory, &metas, SegmentMetaInventory::default())
@@ -250,8 +240,6 @@ impl Index {
 
     /// Open the index using the provided directory
     pub fn open<D: Directory>(directory: D) -> crate::Result<Index> {
-        let logger: &Logger = directory.logger();
-        slog::info!(logger, "index-open"; "directory" => format!("{:?}", directory));
         let directory = ManagedDirectory::wrap(directory)?;
         let inventory = SegmentMetaInventory::default();
         let metas = load_metas(&directory, &inventory)?;

src/core/index_meta.rs

@@ -116,6 +116,7 @@ impl SegmentMeta {
             SegmentComponent::FASTFIELDS => ".fast".to_string(),
             SegmentComponent::FIELDNORMS => ".fieldnorm".to_string(),
             SegmentComponent::DELETE => format!(".{}.del", self.delete_opstamp().unwrap_or(0)),
+            SegmentComponent::FIELDSTATS => ".fieldstats".to_string(),
         });
         PathBuf::from(path)
     }

src/core/inverted_index_reader.rs

@@ -1,4 +1,3 @@
-use crate::common::BinarySerializable;
 use crate::directory::ReadOnlySource;
 use crate::positions::PositionReader;
 use crate::postings::TermInfo;
@@ -36,14 +35,12 @@ impl InvertedIndexReader {
         postings_source: ReadOnlySource,
         positions_source: ReadOnlySource,
         positions_idx_source: ReadOnlySource,
+        total_num_tokens: u64,
         record_option: IndexRecordOption,
     ) -> InvertedIndexReader {
-        let total_num_tokens_data = postings_source.slice(0, 8);
-        let mut total_num_tokens_cursor = total_num_tokens_data.as_slice();
-        let total_num_tokens = u64::deserialize(&mut total_num_tokens_cursor).unwrap_or(0u64);
         InvertedIndexReader {
             termdict,
-            postings_source: postings_source.slice_from(8),
+            postings_source,
             positions_source,
             positions_idx_source,
             record_option,
@@ -89,7 +86,7 @@ impl InvertedIndexReader {
         term_info: &TermInfo,
         block_postings: &mut BlockSegmentPostings,
     ) {
-        let offset = term_info.postings_offset as usize;
+        let offset = term_info.postings_start_offset as usize;
         let end_source = self.postings_source.len();
         let postings_slice = self.postings_source.slice(offset, end_source);
         block_postings.reset(term_info.doc_freq, postings_slice);
@@ -117,8 +114,10 @@ impl InvertedIndexReader {
         term_info: &TermInfo,
         requested_option: IndexRecordOption,
     ) -> BlockSegmentPostings {
-        let offset = term_info.postings_offset as usize;
-        let postings_data = self.postings_source.slice_from(offset);
+        let postings_data = self.postings_source.slice(
+            term_info.postings_start_offset as usize,
+            term_info.postings_end_offset as usize,
+        );
         BlockSegmentPostings::from_data(
             term_info.doc_freq,
             postings_data,

src/core/searcher.rs

@@ -143,7 +143,6 @@ impl Searcher {
                 collector.collect_segment(weight.as_ref(), segment_ord as u32, segment_reader)
             },
             segment_readers.iter().enumerate(),
-            self.index.logger().clone(),
         )?;
         collector.merge_fruits(fruits)
     }

src/core/segment_component.rs

@@ -24,14 +24,17 @@ pub enum SegmentComponent {
     /// Accessing a document from the store is relatively slow, as it
     /// requires to decompress the entire block it belongs to.
     STORE,
+
     /// Bitset describing which document of the segment is deleted.
     DELETE,
+
+    FIELDSTATS,
 }
 
 impl SegmentComponent {
     /// Iterates through the components.
     pub fn iterator() -> slice::Iter<'static, SegmentComponent> {
-        static SEGMENT_COMPONENTS: [SegmentComponent; 8] = [
+        static SEGMENT_COMPONENTS: [SegmentComponent; 9] = [
             SegmentComponent::POSTINGS,
             SegmentComponent::POSITIONS,
             SegmentComponent::POSITIONSSKIP,
@@ -40,6 +43,7 @@ impl SegmentComponent {
             SegmentComponent::TERMS,
             SegmentComponent::STORE,
             SegmentComponent::DELETE,
+            SegmentComponent::FIELDSTATS,
         ];
         SEGMENT_COMPONENTS.iter()
     }

src/core/segment_id.rs

@@ -21,12 +21,6 @@ use std::sync::atomic;
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub struct SegmentId(Uuid);
 
-impl ToString for SegmentId {
-    fn to_string(&self) -> String {
-        self.short_uuid_string()
-    }
-}
-
 #[cfg(test)]
 static AUTO_INC_COUNTER: Lazy<atomic::AtomicUsize> = Lazy::new(|| atomic::AtomicUsize::default());
 

src/core/segment_reader.rs

@@ -1,4 +1,3 @@
-use crate::common::CompositeFile;
 use crate::common::HasLen;
 use crate::core::InvertedIndexReader;
 use crate::core::Segment;
@@ -16,8 +15,8 @@ use crate::space_usage::SegmentSpaceUsage;
 use crate::store::StoreReader;
 use crate::termdict::TermDictionary;
 use crate::DocId;
+use crate::{common::CompositeFile, postings::FieldStats};
 use fail::fail_point;
-use slog::{warn, Logger};
 use std::collections::HashMap;
 use std::fmt;
 use std::sync::Arc;
@@ -50,11 +49,11 @@ pub struct SegmentReader {
     positions_idx_composite: CompositeFile,
     fast_fields_readers: Arc<FastFieldReaders>,
     fieldnorm_readers: FieldNormReaders,
+    field_stats: FieldStats,
 
     store_source: ReadOnlySource,
     delete_bitset_opt: Option<DeleteBitSet>,
     schema: Schema,
-    logger: Logger,
 }
 
 impl SegmentReader {
@@ -181,6 +180,9 @@ impl SegmentReader {
         let fieldnorm_data = segment.open_read(SegmentComponent::FIELDNORMS)?;
         let fieldnorm_readers = FieldNormReaders::open(fieldnorm_data)?;
 
+        let field_stats_data = segment.open_read(SegmentComponent::FIELDSTATS)?;
+        let field_stats = FieldStats::from_source(field_stats_data.as_slice())?;
+
         let delete_bitset_opt = if segment.meta().has_deletes() {
             let delete_data = segment.open_read(SegmentComponent::DELETE)?;
             Some(DeleteBitSet::open(delete_data))
@@ -196,13 +198,13 @@ impl SegmentReader {
             postings_composite,
             fast_fields_readers: fast_field_readers,
             fieldnorm_readers,
+            field_stats,
             segment_id: segment.id(),
             store_source,
             delete_bitset_opt,
             positions_composite,
             positions_idx_composite,
             schema,
-            logger: segment.index().logger().clone(),
         })
     }
 
@@ -232,11 +234,7 @@ impl SegmentReader {
         let record_option_opt = field_type.get_index_record_option();
 
         if record_option_opt.is_none() {
-            warn!(
-                self.logger,
-                "Field {:?} does not seem indexed.",
-                field_entry.name()
-            );
+            warn!("Field {:?} does not seem indexed.", field_entry.name());
         }
 
         let postings_source_opt = self.postings_composite.open_read(field);
@@ -267,11 +265,17 @@ impl SegmentReader {
             .open_read(field)
             .expect("Index corrupted. Failed to open field positions in composite file.");
 
+        let total_num_tokens = self
+            .field_stats
+            .get(field)
+            .map(|field_stat| field_stat.num_tokens())
+            .unwrap_or(0u64);
         let inv_idx_reader = Arc::new(InvertedIndexReader::new(
             TermDictionary::from_source(&termdict_source),
             postings_source,
             positions_source,
             positions_idx_source,
+            total_num_tokens,
             record_option,
         ));
 

src/directory/directory.rs

@@ -1,5 +1,3 @@
-use slog::{error, Logger};
-
 use crate::directory::directory_lock::Lock;
 use crate::directory::error::LockError;
 use crate::directory::error::{DeleteError, OpenReadError, OpenWriteError};
@@ -66,10 +64,7 @@ impl<T: Send + Sync + 'static> From<Box<T>> for DirectoryLock {
 impl Drop for DirectoryLockGuard {
     fn drop(&mut self) {
         if let Err(e) = self.directory.delete(&*self.path) {
-            error!(
-                self.directory.logger(),
-                "Failed to remove the lock file. {:?}", e
-            );
+            error!("Failed to remove the lock file. {:?}", e);
         }
     }
 }
@@ -85,7 +80,7 @@ fn try_acquire_lock(
 ) -> Result<DirectoryLock, TryAcquireLockError> {
     let mut write = directory.open_write(filepath).map_err(|e| match e {
         OpenWriteError::FileAlreadyExists(_) => TryAcquireLockError::FileExists,
-        OpenWriteError::IOError { io_error, .. } => TryAcquireLockError::IOError(io_error),
+        OpenWriteError::IOError(io_error) => TryAcquireLockError::IOError(io_error.into()),
     })?;
     write.flush().map_err(TryAcquireLockError::IOError)?;
     Ok(DirectoryLock::from(Box::new(DirectoryLockGuard {
@@ -214,9 +209,6 @@ pub trait Directory: DirectoryClone + fmt::Debug + Send + Sync + 'static {
     /// `OnCommit` `ReloadPolicy`. Not implementing watch in a `Directory` only prevents the
     /// `OnCommit` `ReloadPolicy` to work properly.
     fn watch(&self, watch_callback: WatchCallback) -> crate::Result<WatchHandle>;
-
-    /// Returns the `slog::Logger` configured for the `Directory`.
-    fn logger(&self) -> &Logger;
 }
 
 /// DirectoryClone

src/directory/error.rs

@@ -1,60 +1,160 @@
 use crate::Version;
+use std::error::Error as StdError;
 use std::fmt;
 use std::io;
 use std::path::PathBuf;
 
 /// Error while trying to acquire a directory lock.
-#[derive(Debug, Error)]
+#[derive(Debug, Fail)]
 pub enum LockError {
     /// Failed to acquired a lock as it is already held by another
     /// client.
     /// - In the context of a blocking lock, this means the lock was not released within some `timeout` period.
     /// - In the context of a non-blocking lock, this means the lock was busy at the moment of the call.
-    #[error("Could not acquire lock as it is already held, possibly by a different process.")]
+    #[fail(
+        display = "Could not acquire lock as it is already held, possibly by a different process."
+    )]
     LockBusy,
     /// Trying to acquire a lock failed with an `IOError`
-    #[error("Failed to acquire the lock due to an io:Error.")]
+    #[fail(display = "Failed to acquire the lock due to an io:Error.")]
     IOError(io::Error),
 }
 
+/// General IO error with an optional path to the offending file.
+#[derive(Debug)]
+pub struct IOError {
+    path: Option<PathBuf>,
+    err: io::Error,
+}
+
+impl Into<io::Error> for IOError {
+    fn into(self) -> io::Error {
+        self.err
+    }
+}
+
+impl fmt::Display for IOError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.path {
+            Some(ref path) => write!(f, "io error occurred on path '{:?}': '{}'", path, self.err),
+            None => write!(f, "io error occurred: '{}'", self.err),
+        }
+    }
+}
+
+impl StdError for IOError {
+    fn description(&self) -> &str {
+        "io error occurred"
+    }
+
+    fn cause(&self) -> Option<&dyn StdError> {
+        Some(&self.err)
+    }
+}
+
+impl IOError {
+    pub(crate) fn with_path(path: PathBuf, err: io::Error) -> Self {
+        IOError {
+            path: Some(path),
+            err,
+        }
+    }
+}
+
+impl From<io::Error> for IOError {
+    fn from(err: io::Error) -> IOError {
+        IOError { path: None, err }
+    }
+}
+
 /// Error that may occur when opening a directory
-#[derive(Debug, Error)]
+#[derive(Debug)]
 pub enum OpenDirectoryError {
     /// The underlying directory does not exists.
-    #[error("Directory does not exist: '{0}'.")]
     DoesNotExist(PathBuf),
     /// The path exists but is not a directory.
-    #[error("Path exists but is not a directory: '{0}'.")]
     NotADirectory(PathBuf),
-    /// Failed to create a temp directory.
-    #[error("Failed to create a temporary directory: '{0}'.")]
-    FailedToCreateTempDir(io::Error),
     /// IoError
-    #[error("IOError '{io_error:?}' while create directory in: '{directory_path:?}'.")]
-    IoError {
-        /// underlying io Error.
-        io_error: io::Error,
-        /// directory we tried to open.
-        directory_path: PathBuf,
-    },
+    IoError(io::Error),
+}
+
+impl From<io::Error> for OpenDirectoryError {
+    fn from(io_err: io::Error) -> Self {
+        OpenDirectoryError::IoError(io_err)
+    }
+}
+
+impl fmt::Display for OpenDirectoryError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            OpenDirectoryError::DoesNotExist(ref path) => {
+                write!(f, "the underlying directory '{:?}' does not exist", path)
+            }
+            OpenDirectoryError::NotADirectory(ref path) => {
+                write!(f, "the path '{:?}' exists but is not a directory", path)
+            }
+            OpenDirectoryError::IoError(ref err) => write!(
+                f,
+                "IOError while trying to open/create the directory. {:?}",
+                err
+            ),
+        }
+    }
+}
+
+impl StdError for OpenDirectoryError {
+    fn description(&self) -> &str {
+        "error occurred while opening a directory"
+    }
+
+    fn cause(&self) -> Option<&dyn StdError> {
+        None
+    }
 }
 
 /// Error that may occur when starting to write in a file
-#[derive(Debug, Error)]
+#[derive(Debug)]
 pub enum OpenWriteError {
     /// Our directory is WORM, writing an existing file is forbidden.
     /// Checkout the `Directory` documentation.
-    #[error("File already exists: '{0}'")]
     FileAlreadyExists(PathBuf),
     /// Any kind of IO error that happens when
     /// writing in the underlying IO device.
-    #[error("IOError '{io_error:?}' while opening file for write: '{filepath}'.")]
-    IOError {
-        /// The underlying `io::Error`.
-        io_error: io::Error,
-        /// File path of the file that tantivy failed to open for write.
-        filepath: PathBuf,
-    },
+    IOError(IOError),
+}
+
+impl From<IOError> for OpenWriteError {
+    fn from(err: IOError) -> OpenWriteError {
+        OpenWriteError::IOError(err)
+    }
+}
+
+impl fmt::Display for OpenWriteError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            OpenWriteError::FileAlreadyExists(ref path) => {
+                write!(f, "the file '{:?}' already exists", path)
+            }
+            OpenWriteError::IOError(ref err) => write!(
+                f,
+                "an io error occurred while opening a file for writing: '{}'",
+                err
+            ),
+        }
+    }
+}
+
+impl StdError for OpenWriteError {
+    fn description(&self) -> &str {
+        "error occurred while opening a file for writing"
+    }
+
+    fn cause(&self) -> Option<&dyn StdError> {
+        match *self {
+            OpenWriteError::FileAlreadyExists(_) => None,
+            OpenWriteError::IOError(ref err) => Some(err),
+        }
+    }
 }
 
 /// Type of index incompatibility between the library and the index found on disk
@@ -117,41 +217,55 @@ impl fmt::Debug for Incompatibility {
 }
 
 /// Error that may occur when accessing a file read
-#[derive(Debug, Error)]
+#[derive(Debug)]
 pub enum OpenReadError {
     /// The file does not exists.
-    #[error("Files does not exists: {0:?}")]
-    FileDoesNotExist(PathBuf),
-    /// Any kind of io::Error.
-    #[error(
-        "IOError: '{io_error:?}' happened while opening the following file for Read: {filepath}."
-    )]
-    IOError {
-        /// The underlying `io::Error`.
-        io_error: io::Error,
-        /// File path of the file that tantivy failed to open for read.
-        filepath: PathBuf,
-    },
-    /// This library does not support the index version found in file footer.
-    #[error("Index version unsupported: {0:?}")]
-    IncompatibleIndex(Incompatibility),
-}
-
-/// Error that may occur when trying to delete a file
-#[derive(Debug, Error)]
-pub enum DeleteError {
-    /// The file does not exists.
-    #[error("File does not exists: '{0}'.")]
     FileDoesNotExist(PathBuf),
     /// Any kind of IO error that happens when
     /// interacting with the underlying IO device.
-    #[error("The following IO error happened while deleting file '{filepath}': '{io_error:?}'.")]
-    IOError {
-        /// The underlying `io::Error`.
-        io_error: io::Error,
-        /// File path of the file that tantivy failed to delete.
-        filepath: PathBuf,
-    },
+    IOError(IOError),
+    /// This library doesn't support the index version found on disk
+    IncompatibleIndex(Incompatibility),
+}
+
+impl From<IOError> for OpenReadError {
+    fn from(err: IOError) -> OpenReadError {
+        OpenReadError::IOError(err)
+    }
+}
+
+impl fmt::Display for OpenReadError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            OpenReadError::FileDoesNotExist(ref path) => {
+                write!(f, "the file '{:?}' does not exist", path)
+            }
+            OpenReadError::IOError(ref err) => write!(
+                f,
+                "an io error occurred while opening a file for reading: '{}'",
+                err
+            ),
+            OpenReadError::IncompatibleIndex(ref footer) => {
+                write!(f, "Incompatible index format: {:?}", footer)
+            }
+        }
+    }
+}
+
+/// Error that may occur when trying to delete a file
+#[derive(Debug)]
+pub enum DeleteError {
+    /// The file does not exists.
+    FileDoesNotExist(PathBuf),
+    /// Any kind of IO error that happens when
+    /// interacting with the underlying IO device.
+    IOError(IOError),
+}
+
+impl From<IOError> for DeleteError {
+    fn from(err: IOError) -> DeleteError {
+        DeleteError::IOError(err)
+    }
 }
 
 impl From<Incompatibility> for OpenReadError {
@@ -159,3 +273,29 @@ impl From<Incompatibility> for OpenReadError {
         OpenReadError::IncompatibleIndex(incompatibility)
     }
 }
+
+impl fmt::Display for DeleteError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            DeleteError::FileDoesNotExist(ref path) => {
+                write!(f, "the file '{:?}' does not exist", path)
+            }
+            DeleteError::IOError(ref err) => {
+                write!(f, "an io error occurred while deleting a file: '{}'", err)
+            }
+        }
+    }
+}
+
+impl StdError for DeleteError {
+    fn description(&self) -> &str {
+        "error occurred while deleting a file"
+    }
+
+    fn cause(&self) -> Option<&dyn StdError> {
+        match *self {
+            DeleteError::FileDoesNotExist(_) => None,
+            DeleteError::IOError(ref err) => Some(err),
+        }
+    }
+}

src/directory/managed_directory.rs

@@ -1,5 +1,5 @@
 use crate::core::{MANAGED_FILEPATH, META_FILEPATH};
-use crate::directory::error::{DeleteError, LockError, OpenReadError, OpenWriteError};
+use crate::directory::error::{DeleteError, IOError, LockError, OpenReadError, OpenWriteError};
 use crate::directory::footer::{Footer, FooterProxy};
 use crate::directory::DirectoryLock;
 use crate::directory::GarbageCollectionResult;
@@ -11,9 +11,9 @@ use crate::error::DataCorruption;
 use crate::Directory;
 
 use crc32fast::Hasher;
-use slog::{debug, error, info};
 use std::collections::HashSet;
 use std::io;
+use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::result;
 use std::sync::RwLockWriteGuard;
@@ -56,9 +56,9 @@ fn save_managed_paths(
     directory: &mut dyn Directory,
     wlock: &RwLockWriteGuard<'_, MetaInformation>,
 ) -> io::Result<()> {
-    let mut managed_json = serde_json::to_string_pretty(&wlock.managed_paths)?;
-    managed_json.push_str("\n");
-    directory.atomic_write(&MANAGED_FILEPATH, managed_json.as_bytes())?;
+    let mut w = serde_json::to_vec(&wlock.managed_paths)?;
+    writeln!(&mut w)?;
+    directory.atomic_write(&MANAGED_FILEPATH, &w[..])?;
     Ok(())
 }
 
@@ -86,12 +86,7 @@ impl ManagedDirectory {
                 directory: Box::new(directory),
                 meta_informations: Arc::default(),
             }),
-            Err(OpenReadError::IOError { io_error, filepath }) => {
-                Err(crate::TantivyError::OpenReadError(OpenReadError::IOError {
-                    io_error,
-                    filepath,
-                }))
-            }
+            Err(OpenReadError::IOError(e)) => Err(From::from(e)),
             Err(OpenReadError::IncompatibleIndex(incompatibility)) => {
                 // For the moment, this should never happen  `meta.json`
                 // do not have any footer and cannot detect incompatibility.
@@ -118,7 +113,7 @@ impl ManagedDirectory {
         &mut self,
         get_living_files: L,
     ) -> crate::Result<GarbageCollectionResult> {
-        info!(self.directory.logger(), "gc"; "stage"=>"start");
+        info!("Garbage collect");
         let mut files_to_delete = vec![];
 
         // It is crucial to get the living files after acquiring the
@@ -153,7 +148,7 @@ impl ManagedDirectory {
                     }
                 }
                 Err(err) => {
-                    error!(self.logger(), "Failed to acquire lock for GC");
+                    error!("Failed to acquire lock for GC");
                     return Err(crate::TantivyError::from(err));
                 }
             }
@@ -165,7 +160,7 @@ impl ManagedDirectory {
         for file_to_delete in files_to_delete {
             match self.delete(&file_to_delete) {
                 Ok(_) => {
-                    debug!(self.logger(), "deleted-success"; "file"=>format!("{:?}", file_to_delete));
+                    info!("Deleted {:?}", file_to_delete);
                     deleted_files.push(file_to_delete);
                 }
                 Err(file_error) => {
@@ -173,12 +168,12 @@ impl ManagedDirectory {
                         DeleteError::FileDoesNotExist(_) => {
                             deleted_files.push(file_to_delete.clone());
                         }
-                        DeleteError::IOError { .. } => {
+                        DeleteError::IOError(_) => {
                             failed_to_delete_files.push(file_to_delete.clone());
                             if !cfg!(target_os = "windows") {
                                 // On windows, delete is expected to fail if the file
                                 // is mmapped.
-                                error!(self.logger(), "delete-file-fail"; "path"=>file_to_delete.to_str().unwrap_or("<invalid-utf8>"));
+                                error!("Failed to delete {:?}", file_to_delete);
                             }
                         }
                     }
@@ -200,10 +195,6 @@ impl ManagedDirectory {
             save_managed_paths(self.directory.as_mut(), &meta_informations_wlock)?;
         }
 
-        info!(self.directory.logger(), "gc"; "stage"=>"end", 
-                "num-sucess-file-deletes"=>deleted_files.len(), 
-                "num-failed-file-deletes"=>failed_to_delete_files.len());
-
         Ok(GarbageCollectionResult {
             deleted_files,
             failed_to_delete_files,
@@ -240,11 +231,8 @@ impl ManagedDirectory {
     /// Verify checksum of a managed file
     pub fn validate_checksum(&self, path: &Path) -> result::Result<bool, OpenReadError> {
         let reader = self.directory.open_read(path)?;
-        let (footer, data) =
-            Footer::extract_footer(reader).map_err(|io_error| OpenReadError::IOError {
-                io_error,
-                filepath: path.to_path_buf(),
-            })?;
+        let (footer, data) = Footer::extract_footer(reader)
+            .map_err(|err| IOError::with_path(path.to_path_buf(), err))?;
         let mut hasher = Hasher::new();
         hasher.update(data.as_slice());
         let crc = hasher.finalize();
@@ -257,6 +245,7 @@ impl ManagedDirectory {
 
     /// List files for which checksum does not match content
     pub fn list_damaged(&self) -> result::Result<HashSet<PathBuf>, OpenReadError> {
+        let mut hashset = HashSet::new();
         let mut managed_paths = self
             .meta_informations
             .read()
@@ -266,37 +255,27 @@ impl ManagedDirectory {
 
         managed_paths.remove(*META_FILEPATH);
 
-        let mut damaged_files = HashSet::new();
-        for path in managed_paths {
+        for path in managed_paths.into_iter() {
             if !self.validate_checksum(&path)? {
-                damaged_files.insert(path);
+                hashset.insert(path);
             }
         }
-        Ok(damaged_files)
+        Ok(hashset)
     }
 }
 
 impl Directory for ManagedDirectory {
     fn open_read(&self, path: &Path) -> result::Result<ReadOnlySource, OpenReadError> {
-        slog::debug!(self.logger(), "open-read"; "path" => path.to_str().unwrap_or("<invalid-utf8>"));
         let read_only_source = self.directory.open_read(path)?;
-        let (footer, reader) = Footer::extract_footer(read_only_source).map_err(|io_error| {
-            OpenReadError::IOError {
-                io_error,
-                filepath: path.to_path_buf(),
-            }
-        })?;
+        let (footer, reader) = Footer::extract_footer(read_only_source)
+            .map_err(|err| IOError::with_path(path.to_path_buf(), err))?;
         footer.is_compatible()?;
         Ok(reader)
     }
 
     fn open_write(&mut self, path: &Path) -> result::Result<WritePtr, OpenWriteError> {
-        slog::debug!(self.logger(), "open-write"; "path" => path.to_str().unwrap_or("<invalid-utf8>"));
         self.register_file_as_managed(path)
-            .map_err(|io_error| OpenWriteError::IOError {
-                io_error,
-                filepath: path.to_path_buf(),
-            })?;
+            .map_err(|e| IOError::with_path(path.to_owned(), e))?;
         Ok(io::BufWriter::new(Box::new(FooterProxy::new(
             self.directory
                 .open_write(path)?
@@ -306,11 +285,9 @@ impl Directory for ManagedDirectory {
         ))))
     }
 
-    fn atomic_write(&mut self, path: &Path, content: &[u8]) -> io::Result<()> {
-        let content_str = std::str::from_utf8(content).unwrap_or("<content-not-utf-8>");
-        slog::debug!(self.logger(), "Atomic write"; "path" => format!("{:?}", path), "content_length"=>content_str);
+    fn atomic_write(&mut self, path: &Path, data: &[u8]) -> io::Result<()> {
         self.register_file_as_managed(path)?;
-        self.directory.atomic_write(path, content)
+        self.directory.atomic_write(path, data)
     }
 
     fn atomic_read(&self, path: &Path) -> result::Result<Vec<u8>, OpenReadError> {
@@ -332,10 +309,6 @@ impl Directory for ManagedDirectory {
     fn watch(&self, watch_callback: WatchCallback) -> crate::Result<WatchHandle> {
         self.directory.watch(watch_callback)
     }
-
-    fn logger(&self) -> &slog::Logger {
-        self.directory.logger()
-    }
 }
 
 impl Clone for ManagedDirectory {

src/directory/mmap_directory.rs

@@ -1,6 +1,8 @@
 use crate::core::META_FILEPATH;
 use crate::directory::error::LockError;
-use crate::directory::error::{DeleteError, OpenDirectoryError, OpenReadError, OpenWriteError};
+use crate::directory::error::{
+    DeleteError, IOError, OpenDirectoryError, OpenReadError, OpenWriteError,
+};
 use crate::directory::read_only_source::BoxedData;
 use crate::directory::AntiCallToken;
 use crate::directory::Directory;
@@ -17,8 +19,6 @@ use notify::RawEvent;
 use notify::RecursiveMode;
 use notify::Watcher;
 use serde::{Deserialize, Serialize};
-use slog::{debug, o, Drain, Logger};
-use slog_stdlog::StdLog;
 use std::collections::HashMap;
 use std::convert::From;
 use std::fmt;
@@ -36,6 +36,11 @@ use std::sync::Weak;
 use std::thread;
 use tempfile::TempDir;
 
+/// Create a default io error given a string.
+pub(crate) fn make_io_err(msg: String) -> io::Error {
+    io::Error::new(io::ErrorKind::Other, msg)
+}
+
 /// Returns None iff the file exists, can be read, but is empty (and hence
 /// cannot be mmapped)
 fn open_mmap(full_path: &Path) -> result::Result<Option<Mmap>, OpenReadError> {
@@ -43,17 +48,13 @@ fn open_mmap(full_path: &Path) -> result::Result<Option<Mmap>, OpenReadError> {
         if e.kind() == io::ErrorKind::NotFound {
             OpenReadError::FileDoesNotExist(full_path.to_owned())
         } else {
-            OpenReadError::IOError {
-                io_error: e,
-                filepath: full_path.to_owned(),
-            }
+            OpenReadError::IOError(IOError::with_path(full_path.to_owned(), e))
         }
     })?;
 
-    let meta_data = file.metadata().map_err(|e| OpenReadError::IOError {
-        io_error: e,
-        filepath: full_path.to_owned(),
-    })?;
+    let meta_data = file
+        .metadata()
+        .map_err(|e| IOError::with_path(full_path.to_owned(), e))?;
     if meta_data.len() == 0 {
         // if the file size is 0, it will not be possible
         // to mmap the file, so we return None
@@ -63,10 +64,7 @@ fn open_mmap(full_path: &Path) -> result::Result<Option<Mmap>, OpenReadError> {
     unsafe {
         memmap::Mmap::map(&file)
             .map(Some)
-            .map_err(|e| OpenReadError::IOError {
-                io_error: e,
-                filepath: full_path.to_owned(),
-            })
+            .map_err(|e| From::from(IOError::with_path(full_path.to_owned(), e)))
     }
 }
 
@@ -146,7 +144,7 @@ struct WatcherWrapper {
 }
 
 impl WatcherWrapper {
-    pub(crate) fn new(path: &Path, logger: Logger) -> Result<Self, OpenDirectoryError> {
+    pub fn new(path: &Path) -> Result<Self, OpenDirectoryError> {
         let (tx, watcher_recv): (Sender<RawEvent>, Receiver<RawEvent>) = channel();
         // We need to initialize the
         let watcher = notify::raw_watcher(tx)
@@ -160,8 +158,7 @@ impl WatcherWrapper {
                     panic!("Unknown error while starting watching directory {:?}", path);
                 }
             })?;
-        let watcher_router: Arc<WatchCallbackList> =
-            Arc::new(WatchCallbackList::with_logger(logger));
+        let watcher_router: Arc<WatchCallbackList> = Default::default();
         let watcher_router_clone = watcher_router.clone();
         thread::Builder::new()
             .name("meta-file-watch-thread".to_string())
@@ -186,10 +183,6 @@ impl WatcherWrapper {
                         }
                     }
                 }
-            })
-            .map_err(|io_error| OpenDirectoryError::IoError {
-                io_error,
-                directory_path: path.to_path_buf(),
             })?;
         Ok(WatcherWrapper {
             _watcher: Mutex::new(watcher),
@@ -224,21 +217,15 @@ struct MmapDirectoryInner {
     mmap_cache: RwLock<MmapCache>,
     _temp_directory: Option<TempDir>,
     watcher: RwLock<Option<WatcherWrapper>>,
-    logger: Logger,
 }
 
 impl MmapDirectoryInner {
-    fn new(
-        root_path: PathBuf,
-        temp_directory: Option<TempDir>,
-        logger: Logger,
-    ) -> MmapDirectoryInner {
+    fn new(root_path: PathBuf, temp_directory: Option<TempDir>) -> MmapDirectoryInner {
         MmapDirectoryInner {
             root_path,
             mmap_cache: Default::default(),
             _temp_directory: temp_directory,
             watcher: RwLock::new(None),
-            logger,
         }
     }
 
@@ -250,7 +237,7 @@ impl MmapDirectoryInner {
         // The downside is that we might create a watch wrapper that is not useful.
         let need_initialization = self.watcher.read().unwrap().is_none();
         if need_initialization {
-            let watch_wrapper = WatcherWrapper::new(&self.root_path, self.logger.clone())?;
+            let watch_wrapper = WatcherWrapper::new(&self.root_path)?;
             let mut watch_wlock = self.watcher.write().unwrap();
             // the watcher could have been initialized when we released the lock, and
             // we do not want to lose the watched files that were set.
@@ -273,8 +260,8 @@ impl fmt::Debug for MmapDirectory {
 }
 
 impl MmapDirectory {
-    fn new(root_path: PathBuf, temp_directory: Option<TempDir>, logger: Logger) -> MmapDirectory {
-        let inner = MmapDirectoryInner::new(root_path, temp_directory, logger);
+    fn new(root_path: PathBuf, temp_directory: Option<TempDir>) -> MmapDirectory {
+        let inner = MmapDirectoryInner::new(root_path, temp_directory);
         MmapDirectory {
             inner: Arc::new(inner),
         }
@@ -285,19 +272,16 @@ impl MmapDirectory {
     /// This is mostly useful to test the MmapDirectory itself.
     /// For your unit tests, prefer the RAMDirectory.
     pub fn create_from_tempdir() -> Result<MmapDirectory, OpenDirectoryError> {
-        let tempdir = TempDir::new().map_err(OpenDirectoryError::FailedToCreateTempDir)?;
-        let logger = Logger::root(StdLog.fuse(), o!());
-        Ok(MmapDirectory::new(tempdir.path().to_owned(), Some(tempdir), logger))
+        let tempdir = TempDir::new().map_err(OpenDirectoryError::IoError)?;
+        let tempdir_path = PathBuf::from(tempdir.path());
+        Ok(MmapDirectory::new(tempdir_path, Some(tempdir)))
     }
 
     /// Opens a MmapDirectory in a directory.
     ///
     /// Returns an error if the `directory_path` does not
     /// exist or if it is not a directory.
-    pub fn open_with_logger<P: AsRef<Path>>(
-        directory_path: P,
-        logger: Logger,
-    ) -> Result<MmapDirectory, OpenDirectoryError> {
+    pub fn open<P: AsRef<Path>>(directory_path: P) -> Result<MmapDirectory, OpenDirectoryError> {
         let directory_path: &Path = directory_path.as_ref();
         if !directory_path.exists() {
             Err(OpenDirectoryError::DoesNotExist(PathBuf::from(
@@ -308,20 +292,10 @@ impl MmapDirectory {
                 directory_path,
             )))
         } else {
-            Ok(MmapDirectory::new(
-                PathBuf::from(directory_path),
-                None,
-                logger,
-            ))
+            Ok(MmapDirectory::new(PathBuf::from(directory_path), None))
         }
     }
 
-    /// Creates an `MmapDirectory` at the given path.
-    pub fn open<P: AsRef<Path>>(directory_path: P) -> Result<MmapDirectory, OpenDirectoryError> {
-        let logger = Logger::root(StdLog.fuse(), o!());
-        Self::open_with_logger(directory_path, logger)
-    }
-
     /// Joins a relative_path to the directory `root_path`
     /// to create a proper complete `filepath`.
     fn resolve_path(&self, relative_path: &Path) -> PathBuf {
@@ -381,12 +355,11 @@ impl MmapDirectory {
 struct ReleaseLockFile {
     _file: File,
     path: PathBuf,
-    logger: Logger,
 }
 
 impl Drop for ReleaseLockFile {
     fn drop(&mut self) {
-        debug!(self.logger, "Releasing lock {:?}", self.path);
+        debug!("Releasing lock {:?}", self.path);
     }
 }
 
@@ -425,18 +398,16 @@ impl TerminatingWrite for SafeFileWriter {
 
 impl Directory for MmapDirectory {
     fn open_read(&self, path: &Path) -> result::Result<ReadOnlySource, OpenReadError> {
+        debug!("Open Read {:?}", path);
         let full_path = self.resolve_path(path);
+
         let mut mmap_cache = self.inner.mmap_cache.write().map_err(|_| {
             let msg = format!(
                 "Failed to acquired write lock \
                  on mmap cache while reading {:?}",
                 path
             );
-            let io_error = io::Error::new(io::ErrorKind::Other, msg);
-            OpenReadError::IOError {
-                io_error,
-                filepath: path.to_owned(),
-            }
+            IOError::with_path(path.to_owned(), make_io_err(msg))
         })?;
         Ok(mmap_cache
             .get_mmap(&full_path)?
@@ -449,18 +420,14 @@ impl Directory for MmapDirectory {
     fn delete(&self, path: &Path) -> result::Result<(), DeleteError> {
         let full_path = self.resolve_path(path);
         match fs::remove_file(&full_path) {
-            Ok(_) => self.sync_directory().map_err(|e| DeleteError::IOError {
-                io_error: e,
-                filepath: path.to_path_buf(),
-            }),
+            Ok(_) => self
+                .sync_directory()
+                .map_err(|e| IOError::with_path(path.to_owned(), e).into()),
             Err(e) => {
                 if e.kind() == io::ErrorKind::NotFound {
                     Err(DeleteError::FileDoesNotExist(path.to_owned()))
                 } else {
-                    Err(DeleteError::IOError {
-                        io_error: e,
-                        filepath: path.to_path_buf(),
-                    })
+                    Err(IOError::with_path(path.to_owned(), e).into())
                 }
             }
         }
@@ -472,7 +439,9 @@ impl Directory for MmapDirectory {
     }
 
     fn open_write(&mut self, path: &Path) -> Result<WritePtr, OpenWriteError> {
+        debug!("Open Write {:?}", path);
         let full_path = self.resolve_path(path);
+
         let open_res = OpenOptions::new()
             .write(true)
             .create_new(true)
@@ -482,25 +451,18 @@ impl Directory for MmapDirectory {
             if err.kind() == io::ErrorKind::AlreadyExists {
                 OpenWriteError::FileAlreadyExists(path.to_owned())
             } else {
-                OpenWriteError::IOError {
-                    io_error: err,
-                    filepath: path.to_owned(),
-                }
+                IOError::with_path(path.to_owned(), err).into()
             }
         })?;
 
         // making sure the file is created.
-        file.flush().map_err(|io_error| OpenWriteError::IOError {
-            io_error,
-            filepath: path.to_owned(),
-        })?;
+        file.flush()
+            .map_err(|e| IOError::with_path(path.to_owned(), e))?;
 
         // Apparetntly, on some filesystem syncing the parent
         // directory is required.
-        self.sync_directory().map_err(|e| OpenWriteError::IOError {
-            io_error: e,
-            filepath: path.to_owned(),
-        })?;
+        self.sync_directory()
+            .map_err(|e| IOError::with_path(path.to_owned(), e))?;
 
         let writer = SafeFileWriter::new(file);
         Ok(BufWriter::new(Box::new(writer)))
@@ -512,26 +474,21 @@ impl Directory for MmapDirectory {
         match File::open(&full_path) {
             Ok(mut file) => {
                 file.read_to_end(&mut buffer)
-                    .map_err(|io_error| OpenReadError::IOError {
-                        io_error,
-                        filepath: path.to_owned(),
-                    })?;
+                    .map_err(|e| IOError::with_path(path.to_owned(), e))?;
                 Ok(buffer)
             }
-            Err(io_error) => {
-                if io_error.kind() == io::ErrorKind::NotFound {
+            Err(e) => {
+                if e.kind() == io::ErrorKind::NotFound {
                     Err(OpenReadError::FileDoesNotExist(path.to_owned()))
                 } else {
-                    Err(OpenReadError::IOError {
-                        io_error,
-                        filepath: path.to_owned(),
-                    })
+                    Err(IOError::with_path(path.to_owned(), e).into())
                 }
             }
         }
     }
 
     fn atomic_write(&mut self, path: &Path, content: &[u8]) -> io::Result<()> {
+        debug!("Atomic Write {:?}", path);
         let mut tempfile = tempfile::Builder::new().tempfile_in(&self.inner.root_path)?;
         tempfile.write_all(content)?;
         tempfile.flush()?;
@@ -553,22 +510,16 @@ impl Directory for MmapDirectory {
         } else {
             file.try_lock_exclusive().map_err(|_| LockError::LockBusy)?
         }
-        let logger = self.inner.logger.clone();
         // dropping the file handle will release the lock.
         Ok(DirectoryLock::from(Box::new(ReleaseLockFile {
             path: lock.filepath.clone(),
             _file: file,
-            logger,
         })))
     }
 
     fn watch(&self, watch_callback: WatchCallback) -> crate::Result<WatchHandle> {
         self.inner.watch(watch_callback)
     }
-
-    fn logger(&self) -> &Logger {
-        &self.inner.logger
-    }
 }
 
 #[cfg(test)]
@@ -678,8 +629,7 @@ mod tests {
         let counter_clone = counter.clone();
         let tmp_dir = tempfile::TempDir::new().unwrap();
         let tmp_dirpath = tmp_dir.path().to_owned();
-        let logger = Logger::root(slog::Discard, o!());
-        let mut watch_wrapper = WatcherWrapper::new(&tmp_dirpath, logger).unwrap();
+        let mut watch_wrapper = WatcherWrapper::new(&tmp_dirpath).unwrap();
         let tmp_file = tmp_dirpath.join(*META_FILEPATH);
         let _handle = watch_wrapper.watch(Box::new(move || {
             counter_clone.fetch_add(1, Ordering::SeqCst);

src/directory/mod.rs

@@ -23,8 +23,7 @@ pub use self::directory::{Directory, DirectoryClone};
 pub use self::directory_lock::{Lock, INDEX_WRITER_LOCK, META_LOCK};
 pub use self::ram_directory::RAMDirectory;
 pub use self::read_only_source::ReadOnlySource;
-pub(crate) use self::watch_event_router::WatchCallbackList;
-pub use self::watch_event_router::{WatchCallback, WatchHandle};
+pub use self::watch_event_router::{WatchCallback, WatchCallbackList, WatchHandle};
 use std::io::{self, BufWriter, Write};
 use std::path::PathBuf;
 /// Outcome of the Garbage collection

src/directory/ram_directory.rs

@@ -5,8 +5,6 @@ use crate::directory::WatchCallbackList;
 use crate::directory::{Directory, ReadOnlySource, WatchCallback, WatchHandle};
 use crate::directory::{TerminatingWrite, WritePtr};
 use fail::fail_point;
-use slog::{o, Drain, Logger};
-use slog_stdlog::StdLog;
 use std::collections::HashMap;
 use std::fmt;
 use std::io::{self, BufWriter, Cursor, Seek, SeekFrom, Write};
@@ -68,7 +66,7 @@ impl Write for VecWriter {
 
     fn flush(&mut self) -> io::Result<()> {
         self.is_flushed = true;
-        let mut fs = self.shared_directory.fs.inner_directory.write().unwrap();
+        let mut fs = self.shared_directory.fs.write().unwrap();
         fs.write(self.path.clone(), self.data.get_ref());
         Ok(())
     }
@@ -80,19 +78,13 @@ impl TerminatingWrite for VecWriter {
     }
 }
 
+#[derive(Default)]
 struct InnerDirectory {
     fs: HashMap<PathBuf, ReadOnlySource>,
     watch_router: WatchCallbackList,
 }
 
 impl InnerDirectory {
-    fn with_logger(logger: Logger) -> Self {
-        InnerDirectory {
-            fs: Default::default(),
-            watch_router: WatchCallbackList::with_logger(logger.clone()),
-        }
-    }
-
     fn write(&mut self, path: PathBuf, data: &[u8]) -> bool {
         let data = ReadOnlySource::new(Vec::from(data));
         self.fs.insert(path, data).is_some()
@@ -125,32 +117,20 @@ impl InnerDirectory {
     }
 }
 
-impl Default for RAMDirectory {
-    fn default() -> RAMDirectory {
-        let logger = Logger::root(StdLog.fuse(), o!());
-        Self::with_logger(logger)
-    }
-}
-
 impl fmt::Debug for RAMDirectory {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "RAMDirectory")
     }
 }
 
-struct Inner {
-    inner_directory: RwLock<InnerDirectory>,
-    logger: Logger,
-}
-
 /// A Directory storing everything in anonymous memory.
 ///
 /// It is mainly meant for unit testing.
 /// Writes are only made visible upon flushing.
 ///
-#[derive(Clone)]
+#[derive(Clone, Default)]
 pub struct RAMDirectory {
-    fs: Arc<Inner>,
+    fs: Arc<RwLock<InnerDirectory>>,
 }
 
 impl RAMDirectory {
@@ -159,21 +139,10 @@ impl RAMDirectory {
         Self::default()
     }
 
-    /// Create a `RAMDirectory` with a custom logger.
-    pub fn with_logger(logger: Logger) -> RAMDirectory {
-        let inner_directory = InnerDirectory::with_logger(logger.clone()).into();
-        RAMDirectory {
-            fs: Arc::new(Inner {
-                inner_directory,
-                logger,
-            }),
-        }
-    }
-
     /// Returns the sum of the size of the different files
     /// in the RAMDirectory.
     pub fn total_mem_usage(&self) -> usize {
-        self.fs.inner_directory.read().unwrap().total_mem_usage()
+        self.fs.read().unwrap().total_mem_usage()
     }
 
     /// Write a copy of all of the files saved in the RAMDirectory in the target `Directory`.
@@ -183,7 +152,7 @@ impl RAMDirectory {
     ///
     /// If an error is encounterred, files may be persisted partially.
     pub fn persist(&self, dest: &mut dyn Directory) -> crate::Result<()> {
-        let wlock = self.fs.inner_directory.write().unwrap();
+        let wlock = self.fs.write().unwrap();
         for (path, source) in wlock.fs.iter() {
             let mut dest_wrt = dest.open_write(path)?;
             dest_wrt.write_all(source.as_slice())?;
@@ -195,25 +164,24 @@ impl RAMDirectory {
 
 impl Directory for RAMDirectory {
     fn open_read(&self, path: &Path) -> result::Result<ReadOnlySource, OpenReadError> {
-        self.fs.inner_directory.read().unwrap().open_read(path)
+        self.fs.read().unwrap().open_read(path)
     }
 
     fn delete(&self, path: &Path) -> result::Result<(), DeleteError> {
         fail_point!("RAMDirectory::delete", |_| {
-            Err(DeleteError::IOError {
-                io_error: io::Error::from(io::ErrorKind::Other),
-                filepath: path.to_path_buf(),
-            })
+            use crate::directory::error::IOError;
+            let io_error = IOError::from(io::Error::from(io::ErrorKind::Other));
+            Err(DeleteError::from(io_error))
         });
-        self.fs.inner_directory.write().unwrap().delete(path)
+        self.fs.write().unwrap().delete(path)
     }
 
     fn exists(&self, path: &Path) -> bool {
-        self.fs.inner_directory.read().unwrap().exists(path)
+        self.fs.read().unwrap().exists(path)
     }
 
     fn open_write(&mut self, path: &Path) -> Result<WritePtr, OpenWriteError> {
-        let mut fs = self.fs.inner_directory.write().unwrap();
+        let mut fs = self.fs.write().unwrap();
         let path_buf = PathBuf::from(path);
         let vec_writer = VecWriter::new(path_buf.clone(), self.clone());
         let exists = fs.write(path_buf.clone(), &[]);
@@ -237,38 +205,19 @@ impl Directory for RAMDirectory {
         let path_buf = PathBuf::from(path);
 
         // Reserve the path to prevent calls to .write() to succeed.
-        self.fs
-            .inner_directory
-            .write()
-            .unwrap()
-            .write(path_buf.clone(), &[]);
+        self.fs.write().unwrap().write(path_buf.clone(), &[]);
 
         let mut vec_writer = VecWriter::new(path_buf, self.clone());
         vec_writer.write_all(data)?;
         vec_writer.flush()?;
         if path == Path::new(&*META_FILEPATH) {
-            let _ = self
-                .fs
-                .inner_directory
-                .write()
-                .unwrap()
-                .watch_router
-                .broadcast();
+            let _ = self.fs.write().unwrap().watch_router.broadcast();
         }
         Ok(())
     }
 
     fn watch(&self, watch_callback: WatchCallback) -> crate::Result<WatchHandle> {
-        Ok(self
-            .fs
-            .inner_directory
-            .write()
-            .unwrap()
-            .watch(watch_callback))
-    }
-
-    fn logger(&self) -> &Logger {
-        &self.fs.logger
+        Ok(self.fs.write().unwrap().watch(watch_callback))
     }
 }
 

src/directory/watch_event_router.rs

@@ -1,6 +1,5 @@
 use futures::channel::oneshot;
 use futures::{Future, TryFutureExt};
-use slog::{error, Logger};
 use std::sync::Arc;
 use std::sync::RwLock;
 use std::sync::Weak;
@@ -12,9 +11,9 @@ pub type WatchCallback = Box<dyn Fn() + Sync + Send>;
 ///
 /// It registers callbacks (See `.subscribe(...)`) and
 /// calls them upon calls to `.broadcast(...)`.
-pub(crate) struct WatchCallbackList {
+#[derive(Default)]
+pub struct WatchCallbackList {
     router: RwLock<Vec<Weak<WatchCallback>>>,
-    logger: Logger,
 }
 
 /// Controls how long a directory should watch for a file change.
@@ -33,13 +32,6 @@ impl WatchHandle {
 }
 
 impl WatchCallbackList {
-    pub fn with_logger(logger: Logger) -> Self {
-        WatchCallbackList {
-            logger,
-            router: Default::default(),
-        }
-    }
-
     /// Subscribes a new callback and returns a handle that controls the lifetime of the callback.
     pub fn subscribe(&self, watch_callback: WatchCallback) -> WatchHandle {
         let watch_callback_arc = Arc::new(watch_callback);
@@ -82,8 +74,8 @@ impl WatchCallbackList {
             });
         if let Err(err) = spawn_res {
             error!(
-                self.logger,
-                "Failed to spawn thread to call watch callbacks. Cause: {:?}", err
+                "Failed to spawn thread to call watch callbacks. Cause: {:?}",
+                err
             );
         }
         result
@@ -94,18 +86,13 @@ impl WatchCallbackList {
 mod tests {
     use crate::directory::WatchCallbackList;
     use futures::executor::block_on;
-    use slog::{o, Discard, Logger};
     use std::mem;
     use std::sync::atomic::{AtomicUsize, Ordering};
     use std::sync::Arc;
 
-    fn default_watch_callback_list() -> WatchCallbackList {
-        WatchCallbackList::with_logger(Logger::root(Discard, o!()))
-    }
-
     #[test]
     fn test_watch_event_router_simple() {
-        let watch_event_router = default_watch_callback_list();
+        let watch_event_router = WatchCallbackList::default();
         let counter: Arc<AtomicUsize> = Default::default();
         let counter_clone = counter.clone();
         let inc_callback = Box::new(move || {
@@ -132,7 +119,7 @@ mod tests {
 
     #[test]
     fn test_watch_event_router_multiple_callback_same_key() {
-        let watch_event_router = default_watch_callback_list();
+        let watch_event_router = WatchCallbackList::default();
         let counter: Arc<AtomicUsize> = Default::default();
         let inc_callback = |inc: usize| {
             let counter_clone = counter.clone();
@@ -161,7 +148,7 @@ mod tests {
 
     #[test]
     fn test_watch_event_router_multiple_callback_different_key() {
-        let watch_event_router = default_watch_callback_list();
+        let watch_event_router = WatchCallbackList::default();
         let counter: Arc<AtomicUsize> = Default::default();
         let counter_clone = counter.clone();
         let inc_callback = Box::new(move || {

src/error.rs

@@ -2,13 +2,11 @@
 
 use std::io;
 
+use crate::directory::error::{IOError, OpenDirectoryError, OpenReadError, OpenWriteError};
 use crate::directory::error::{Incompatibility, LockError};
 use crate::fastfield::FastFieldNotAvailableError;
 use crate::query;
-use crate::{
-    directory::error::{OpenDirectoryError, OpenReadError, OpenWriteError},
-    schema,
-};
+use crate::schema;
 use std::fmt;
 use std::path::PathBuf;
 use std::sync::PoisonError;
@@ -45,47 +43,44 @@ impl fmt::Debug for DataCorruption {
     }
 }
 
-/// The library's error enum
-#[derive(Debug, Error)]
+/// The library's failure based error enum
+#[derive(Debug, Fail)]
 pub enum TantivyError {
-    /// Failed to open the directory.
-    #[error("Failed to open the directory: '{0:?}'")]
-    OpenDirectoryError(#[from] OpenDirectoryError),
-    /// Failed to open a file for read.
-    #[error("Failed to open file for read: '{0:?}'")]
-    OpenReadError(#[from] OpenReadError),
-    /// Failed to open a file for write.
-    #[error("Failed to open file for write: '{0:?}'")]
-    OpenWriteError(#[from] OpenWriteError),
+    /// Path does not exist.
+    #[fail(display = "Path does not exist: '{:?}'", _0)]
+    PathDoesNotExist(PathBuf),
+    /// File already exists, this is a problem when we try to write into a new file.
+    #[fail(display = "File already exists: '{:?}'", _0)]
+    FileAlreadyExists(PathBuf),
     /// Index already exists in this directory
-    #[error("Index already exists")]
+    #[fail(display = "Index already exists")]
     IndexAlreadyExists,
     /// Failed to acquire file lock
-    #[error("Failed to acquire Lockfile: {0:?}. {1:?}")]
+    #[fail(display = "Failed to acquire Lockfile: {:?}. {:?}", _0, _1)]
     LockFailure(LockError, Option<String>),
     /// IO Error.
-    #[error("An IO error occurred: '{0}'")]
-    IOError(#[from] io::Error),
+    #[fail(display = "An IO error occurred: '{}'", _0)]
+    IOError(#[cause] IOError),
     /// Data corruption.
-    #[error("Data corrupted: '{0:?}'")]
+    #[fail(display = "{:?}", _0)]
     DataCorruption(DataCorruption),
     /// A thread holding the locked panicked and poisoned the lock.
-    #[error("A thread holding the locked panicked and poisoned the lock")]
+    #[fail(display = "A thread holding the locked panicked and poisoned the lock")]
     Poisoned,
     /// Invalid argument was passed by the user.
-    #[error("An invalid argument was passed: '{0}'")]
+    #[fail(display = "An invalid argument was passed: '{}'", _0)]
     InvalidArgument(String),
     /// An Error happened in one of the thread.
-    #[error("An error occurred in a thread: '{0}'")]
+    #[fail(display = "An error occurred in a thread: '{}'", _0)]
     ErrorInThread(String),
     /// An Error appeared related to the schema.
-    #[error("Schema error: '{0}'")]
+    #[fail(display = "Schema error: '{}'", _0)]
     SchemaError(String),
     /// System error. (e.g.: We failed spawning a new thread)
-    #[error("System error.'{0}'")]
+    #[fail(display = "System error.'{}'", _0)]
     SystemError(String),
     /// Index incompatible with current version of tantivy
-    #[error("{0:?}")]
+    #[fail(display = "{:?}", _0)]
     IncompatibleIndex(Incompatibility),
 }
 
@@ -94,17 +89,31 @@ impl From<DataCorruption> for TantivyError {
         TantivyError::DataCorruption(data_corruption)
     }
 }
+
 impl From<FastFieldNotAvailableError> for TantivyError {
     fn from(fastfield_error: FastFieldNotAvailableError) -> TantivyError {
         TantivyError::SchemaError(format!("{}", fastfield_error))
     }
 }
+
 impl From<LockError> for TantivyError {
     fn from(lock_error: LockError) -> TantivyError {
         TantivyError::LockFailure(lock_error, None)
     }
 }
 
+impl From<IOError> for TantivyError {
+    fn from(io_error: IOError) -> TantivyError {
+        TantivyError::IOError(io_error)
+    }
+}
+
+impl From<io::Error> for TantivyError {
+    fn from(io_error: io::Error) -> TantivyError {
+        TantivyError::IOError(io_error.into())
+    }
+}
+
 impl From<query::QueryParserError> for TantivyError {
     fn from(parsing_error: query::QueryParserError) -> TantivyError {
         TantivyError::InvalidArgument(format!("Query is invalid. {:?}", parsing_error))
@@ -117,12 +126,49 @@ impl<Guard> From<PoisonError<Guard>> for TantivyError {
     }
 }
 
+impl From<OpenReadError> for TantivyError {
+    fn from(error: OpenReadError) -> TantivyError {
+        match error {
+            OpenReadError::FileDoesNotExist(filepath) => TantivyError::PathDoesNotExist(filepath),
+            OpenReadError::IOError(io_error) => TantivyError::IOError(io_error),
+            OpenReadError::IncompatibleIndex(incompatibility) => {
+                TantivyError::IncompatibleIndex(incompatibility)
+            }
+        }
+    }
+}
+
 impl From<schema::DocParsingError> for TantivyError {
     fn from(error: schema::DocParsingError) -> TantivyError {
         TantivyError::InvalidArgument(format!("Failed to parse document {:?}", error))
     }
 }
 
+impl From<OpenWriteError> for TantivyError {
+    fn from(error: OpenWriteError) -> TantivyError {
+        match error {
+            OpenWriteError::FileAlreadyExists(filepath) => {
+                TantivyError::FileAlreadyExists(filepath)
+            }
+            OpenWriteError::IOError(io_error) => TantivyError::IOError(io_error),
+        }
+    }
+}
+
+impl From<OpenDirectoryError> for TantivyError {
+    fn from(error: OpenDirectoryError) -> TantivyError {
+        match error {
+            OpenDirectoryError::DoesNotExist(directory_path) => {
+                TantivyError::PathDoesNotExist(directory_path)
+            }
+            OpenDirectoryError::NotADirectory(directory_path) => {
+                TantivyError::InvalidArgument(format!("{:?} is not a directory", directory_path))
+            }
+            OpenDirectoryError::IoError(err) => TantivyError::IOError(IOError::from(err)),
+        }
+    }
+}
+
 impl From<serde_json::Error> for TantivyError {
     fn from(error: serde_json::Error) -> TantivyError {
         let io_err = io::Error::from(error);

src/fastfield/error.rs

@@ -4,8 +4,8 @@ use std::result;
 /// `FastFieldNotAvailableError` is returned when the
 /// user requested for a fast field reader, and the field was not
 /// defined in the schema as a fast field.
-#[derive(Debug, Error)]
-#[error("Fast field not available: '{field_name:?}'")]
+#[derive(Debug, Fail)]
+#[fail(display = "Fast field not available: '{:?}'", field_name)]
 pub struct FastFieldNotAvailableError {
     field_name: String,
 }

src/indexer/index_writer.rs

@@ -27,7 +27,6 @@ use crate::Opstamp;
 use crossbeam::channel;
 use futures::executor::block_on;
 use futures::future::Future;
-use slog::{error, info, Logger};
 use smallvec::smallvec;
 use smallvec::SmallVec;
 use std::mem;
@@ -196,21 +195,20 @@ fn index_documents(
     grouped_document_iterator: &mut dyn Iterator<Item = OperationGroup>,
     segment_updater: &mut SegmentUpdater,
     mut delete_cursor: DeleteCursor,
-    logger: &Logger,
 ) -> crate::Result<bool> {
     let schema = segment.schema();
 
-    info!(logger, "segment-index"; "stage"=>"start");
     let mut segment_writer = SegmentWriter::for_segment(memory_budget, segment.clone(), &schema)?;
-    let mut buffer_limit_reached = false;
     for document_group in grouped_document_iterator {
         for doc in document_group {
             segment_writer.add_document(doc, &schema)?;
         }
         let mem_usage = segment_writer.mem_usage();
         if mem_usage >= memory_budget - MARGIN_IN_BYTES {
-            buffer_limit_reached = true;
-
+            info!(
+                "Buffer limit reached, flushing segment with maxdoc={}.",
+                segment_writer.max_doc()
+            );
             break;
         }
     }
@@ -230,14 +228,6 @@ fn index_documents(
     let segment_with_max_doc = segment.with_max_doc(max_doc);
 
     let last_docstamp: Opstamp = *(doc_opstamps.last().unwrap());
-    info!(
-        logger,
-        "segment-index";
-        "stage" => "serialize",
-        "cause" => if buffer_limit_reached { "buffer-limit" } else { "commit" },
-        "maxdoc" => max_doc,
-        "last_docstamp" => last_docstamp
-    );
 
     let delete_bitset_opt = apply_deletes(
         &segment_with_max_doc,
@@ -251,18 +241,7 @@ fn index_documents(
         delete_cursor,
         delete_bitset_opt,
     );
-
-    info!(
-        logger,
-        "segment-index";
-        "stage" => "publish",
-    );
     block_on(segment_updater.schedule_add_segment(segment_entry))?;
-    info!(
-        logger,
-        "segment-index";
-        "stage" => "end",
-    );
     Ok(true)
 }
 
@@ -365,10 +344,6 @@ impl IndexWriter {
         Ok(index_writer)
     }
 
-    pub(crate) fn logger(&self) -> &Logger {
-        self.index.logger()
-    }
-
     fn drop_sender(&mut self) {
         let (sender, _receiver) = channel::bounded(1);
         self.operation_sender = sender;
@@ -377,8 +352,6 @@ impl IndexWriter {
     /// If there are some merging threads, blocks until they all finish their work and
     /// then drop the `IndexWriter`.
     pub fn wait_merging_threads(mut self) -> crate::Result<()> {
-        info!(self.logger(), "wait-merge-threads"; "stage"=>"start");
-
         // this will stop the indexing thread,
         // dropping the last reference to the segment_updater.
         self.drop_sender();
@@ -399,9 +372,9 @@ impl IndexWriter {
             .map_err(|_| TantivyError::ErrorInThread("Failed to join merging thread.".into()));
 
         if let Err(ref e) = result {
-            error!(self.logger(), "some merge thread failed"; "cause"=>e.to_string());
+            error!("Some merging thread failed {:?}", e);
         }
-        info!(self.logger(), "wait-merge-threads"; "stage"=>"stop");
+
         result
     }
 
@@ -461,16 +434,12 @@ impl IndexWriter {
                         return Ok(());
                     }
                     let segment = index.new_segment();
-                    let segment_id = segment.id();
                     index_documents(
                         mem_budget,
                         segment,
                         &mut document_iterator,
                         &mut segment_updater,
                         delete_cursor.clone(),
-                        &index
-                            .logger()
-                            .new(slog::o!("segment"=>segment_id.to_string())),
                     )?;
                 }
             })?;
@@ -584,10 +553,7 @@ impl IndexWriter {
     ///
     /// The opstamp at the last commit is returned.
     pub fn rollback(&mut self) -> crate::Result<Opstamp> {
-        info!(
-            self.logger(),
-            "Rolling back to opstamp {}", self.committed_opstamp
-        );
+        info!("Rolling back to opstamp {}", self.committed_opstamp);
         // marks the segment updater as killed. From now on, all
         // segment updates will be ignored.
         self.segment_updater.kill();
@@ -644,8 +610,6 @@ impl IndexWriter {
     /// using this API.
     /// See [`PreparedCommit::set_payload()`](PreparedCommit.html)
     pub fn prepare_commit(&mut self) -> crate::Result<PreparedCommit> {
-        let logger = self.logger().clone();
-
         // Here, because we join all of the worker threads,
         // all of the segment update for this commit have been
         // sent.
@@ -656,10 +620,7 @@ impl IndexWriter {
         //
         // This will move uncommitted segments to the state of
         // committed segments.
-
-        let commit_opstamp = self.stamper.stamp();
-
-        info!(logger, "prepare-commit"; "opstamp" => commit_opstamp);
+        info!("Preparing commit");
 
         // this will drop the current document channel
         // and recreate a new one.
@@ -675,8 +636,9 @@ impl IndexWriter {
             self.add_indexing_worker()?;
         }
 
+        let commit_opstamp = self.stamper.stamp();
         let prepared_commit = PreparedCommit::new(self, commit_opstamp);
-        info!(logger, "Prepared commit {}", commit_opstamp);
+        info!("Prepared commit {}", commit_opstamp);
         Ok(prepared_commit)
     }
 

src/indexer/prepared_commit.rs

@@ -1,7 +1,6 @@
 use super::IndexWriter;
 use crate::Opstamp;
 use futures::executor::block_on;
-use slog::info;
 
 /// A prepared commit
 pub struct PreparedCommit<'a> {
@@ -32,7 +31,7 @@ impl<'a> PreparedCommit<'a> {
     }
 
     pub fn commit(self) -> crate::Result<Opstamp> {
-        info!(self.index_writer.logger(), "committing {}", self.opstamp);
+        info!("committing {}", self.opstamp);
         let _ = block_on(
             self.index_writer
                 .segment_updater()

src/indexer/segment_manager.rs

@@ -1,5 +1,3 @@
-use slog::{warn, Logger};
-
 use super::segment_register::SegmentRegister;
 use crate::core::SegmentId;
 use crate::core::SegmentMeta;
@@ -44,9 +42,9 @@ impl SegmentRegisters {
 ///
 /// It guarantees the atomicity of the
 /// changes (merges especially)
+#[derive(Default)]
 pub struct SegmentManager {
     registers: RwLock<SegmentRegisters>,
-    logger: Logger,
 }
 
 impl Debug for SegmentManager {
@@ -79,14 +77,12 @@ impl SegmentManager {
     pub fn from_segments(
         segment_metas: Vec<SegmentMeta>,
         delete_cursor: &DeleteCursor,
-        logger: Logger,
     ) -> SegmentManager {
         SegmentManager {
             registers: RwLock::new(SegmentRegisters {
                 uncommitted: SegmentRegister::default(),
                 committed: SegmentRegister::new(segment_metas, delete_cursor),
             }),
-            logger,
         }
     }
 
@@ -190,7 +186,7 @@ impl SegmentManager {
         let segments_status = registers_lock
             .segments_status(before_merge_segment_ids)
             .ok_or_else(|| {
-                warn!(self.logger, "couldn't find segment in SegmentManager");
+                warn!("couldn't find segment in SegmentManager");
                 crate::TantivyError::InvalidArgument(
                     "The segments that were merged could not be found in the SegmentManager. \
                      This is not necessarily a bug, and can happen after a rollback for instance."

src/indexer/segment_updater.rs

@@ -23,9 +23,9 @@ use futures::channel::oneshot;
 use futures::executor::{ThreadPool, ThreadPoolBuilder};
 use futures::future::Future;
 use futures::future::TryFutureExt;
-use slog::{debug, error, info, warn};
 use std::borrow::BorrowMut;
 use std::collections::HashSet;
+use std::io::Write;
 use std::ops::Deref;
 use std::path::PathBuf;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -65,11 +65,12 @@ pub fn save_new_metas(schema: Schema, directory: &mut dyn Directory) -> crate::R
 ///
 /// This method is not part of tantivy's public API
 fn save_metas(metas: &IndexMeta, directory: &mut dyn Directory) -> crate::Result<()> {
-    let mut meta_json = serde_json::to_string_pretty(metas)?;
+    info!("save metas");
+    let mut buffer = serde_json::to_vec_pretty(metas)?;
     // Just adding a new line at the end of the buffer.
-    meta_json.push_str("\n");
-    debug!(directory.logger(), "save meta"; "content"=>&meta_json);
-    directory.atomic_write(&META_FILEPATH, meta_json.as_bytes())?;
+    writeln!(&mut buffer)?;
+    directory.atomic_write(&META_FILEPATH, &buffer[..])?;
+    debug!("Saved metas {:?}", serde_json::to_string_pretty(&metas));
     Ok(())
 }
 
@@ -96,6 +97,7 @@ impl Deref for SegmentUpdater {
 async fn garbage_collect_files(
     segment_updater: SegmentUpdater,
 ) -> crate::Result<GarbageCollectionResult> {
+    info!("Running garbage collection");
     let mut index = segment_updater.index.clone();
     index
         .directory_mut()
@@ -105,12 +107,14 @@ async fn garbage_collect_files(
 /// Merges a list of segments the list of segment givens in the `segment_entries`.
 /// This function happens in the calling thread and is computationally expensive.
 fn merge(
-    merged_segment: Segment,
     index: &Index,
     mut segment_entries: Vec<SegmentEntry>,
     target_opstamp: Opstamp,
 ) -> crate::Result<SegmentEntry> {
-    // First we apply all of the delete to the merged segment, up to the target opstamp.
+    // first we need to apply deletes to our segment.
+    let merged_segment = index.new_segment();
+
+    // First we apply all of the delet to the merged segment, up to the target opstamp.
     for segment_entry in &mut segment_entries {
         let segment = index.segment(segment_entry.meta().clone());
         advance_deletes(segment, segment_entry, target_opstamp)?;
@@ -163,8 +167,7 @@ impl SegmentUpdater {
         delete_cursor: &DeleteCursor,
     ) -> crate::Result<SegmentUpdater> {
         let segments = index.searchable_segment_metas()?;
-        let segment_manager =
-            SegmentManager::from_segments(segments, delete_cursor, index.logger().clone());
+        let segment_manager = SegmentManager::from_segments(segments, delete_cursor);
         let pool = ThreadPoolBuilder::new()
             .name_prefix("segment_updater")
             .pool_size(1)
@@ -384,18 +387,7 @@ impl SegmentUpdater {
             .segment_manager
             .start_merge(merge_operation.segment_ids())?;
 
-        let segment_ids_str: String = merge_operation
-            .segment_ids()
-            .iter()
-            .map(|segment_id| segment_id.to_string())
-            .collect::<Vec<String>>()
-            .join(",");
-
-        let merged_segment = self.index.new_segment();
-        let logger = self.index.logger().new(slog::o!("segments"=>segment_ids_str, "merged-segment"=>merged_segment.id().to_string()));
-
-        let num_merges: usize = self.merge_operations.list().len();
-        slog::info!(&logger, "merge"; "stage"=>"start", "num-merges" => num_merges);
+        info!("Starting merge  - {:?}", merge_operation.segment_ids());
 
         let (merging_future_send, merging_future_recv) =
             oneshot::channel::<crate::Result<SegmentMeta>>();
@@ -406,20 +398,22 @@ impl SegmentUpdater {
             // as well as which segment is currently in merge and therefore should not be
             // candidate for another merge.
             match merge(
-                merged_segment,
                 &segment_updater.index,
                 segment_entries,
                 merge_operation.target_opstamp(),
             ) {
                 Ok(after_merge_segment_entry) => {
-                    info!(&logger, "merge"; "stage" => "end");
                     let segment_meta = segment_updater
                         .end_merge(merge_operation, after_merge_segment_entry)
                         .await;
                     let _send_result = merging_future_send.send(segment_meta);
                 }
                 Err(e) => {
-                    error!(&logger, "merge"; "stage" => "fail", "cause"=>e.to_string());
+                    warn!(
+                        "Merge of {:?} was cancelled: {:?}",
+                        merge_operation.segment_ids().to_vec(),
+                        e
+                    );
                     // ... cancel merge
                     if cfg!(test) {
                         panic!("Merge failed.");
@@ -460,12 +454,11 @@ impl SegmentUpdater {
             .collect::<Vec<_>>();
         merge_candidates.extend(committed_merge_candidates.into_iter());
 
-        let logger = self.index.logger();
         for merge_operation in merge_candidates {
             if let Err(err) = self.start_merge(merge_operation) {
                 warn!(
-                    logger,
-                    "merge-start-fail (not fatal, not necessarily a problem)"; "reason" => format!("{}", err),
+                    "Starting the merge failed for the following reason. This is not fatal. {}",
+                    err
                 );
             }
         }
@@ -478,11 +471,8 @@ impl SegmentUpdater {
     ) -> impl Future<Output = crate::Result<SegmentMeta>> {
         let segment_updater = self.clone();
         let after_merge_segment_meta = after_merge_segment_entry.meta().clone();
-        let logger = self.index.logger().new(
-            slog::o!("segment"=>after_merge_segment_meta.id().to_string(),
-            "delete-opstamp"=>after_merge_segment_meta.delete_opstamp()),
-        );
         let end_merge_future = self.schedule_future(async move {
+            info!("End merge {:?}", after_merge_segment_entry.meta());
             {
                 let mut delete_cursor = after_merge_segment_entry.delete_cursor().clone();
                 if let Some(delete_operation) = delete_cursor.get() {
@@ -496,7 +486,6 @@ impl SegmentUpdater {
                             committed_opstamp,
                         ) {
                             error!(
-                                logger,
                                 "Merge of {:?} was cancelled (advancing deletes failed): {:?}",
                                 merge_operation.segment_ids(),
                                 e

src/indexer/segment_writer.rs

@@ -1,4 +1,5 @@
 use super::operation::AddOperation;
+use crate::core::Segment;
 use crate::core::SerializableSegment;
 use crate::fastfield::FastFieldsWriter;
 use crate::fieldnorm::{FieldNormReaders, FieldNormsWriter};
@@ -14,7 +15,6 @@ use crate::tokenizer::{BoxTokenStream, PreTokenizedStream};
 use crate::tokenizer::{FacetTokenizer, TextAnalyzer};
 use crate::tokenizer::{TokenStreamChain, Tokenizer};
 use crate::Opstamp;
-use crate::{core::Segment, tokenizer::MAX_TOKEN_LEN};
 use crate::{DocId, SegmentComponent};
 use std::io;
 
@@ -146,9 +146,6 @@ impl SegmentWriter {
                     for fake_str in facets {
                         let mut unordered_term_id_opt = None;
                         FacetTokenizer.token_stream(fake_str).process(&mut |token| {
-                            if token.text.len() > MAX_TOKEN_LEN {
-                                return;
-                            }
                             term_buffer.set_text(&token.text);
                             let unordered_term_id =
                                 multifield_postings.subscribe(doc_id, &term_buffer);

src/lib.rs

@@ -102,7 +102,10 @@
 extern crate serde_json;
 
 #[macro_use]
-extern crate thiserror;
+extern crate log;
+
+#[macro_use]
+extern crate failure;
 
 #[cfg(all(test, feature = "unstable"))]
 extern crate test;
@@ -145,7 +148,6 @@ pub mod schema;
 pub mod space_usage;
 pub mod store;
 pub mod termdict;
-pub use slog;
 
 mod reader;
 

src/postings/mod.rs

@@ -5,6 +5,7 @@ Postings module (also called inverted index)
 mod block_search;
 mod block_segment_postings;
 pub(crate) mod compression;
+mod field_stats;
 mod postings;
 mod postings_writer;
 mod recorder;
@@ -15,6 +16,7 @@ mod stacker;
 mod term_info;
 
 pub(crate) use self::block_search::BlockSearcher;
+pub(crate) use self::field_stats::{FieldStat, FieldStats};
 
 pub(crate) use self::postings_writer::MultiFieldPostingsWriter;
 pub use self::serializer::{FieldSerializer, InvertedIndexSerializer};

src/postings/postings_writer.rs

@@ -227,17 +227,23 @@ pub trait PostingsWriter {
         term_buffer.set_field(field);
         let mut sink = |token: &Token| {
             // We skip all tokens with a len greater than u16.
-            if token.text.len() > MAX_TOKEN_LEN {
-                return;
+            if token.text.len() <= MAX_TOKEN_LEN {
+                term_buffer.set_text(token.text.as_str());
+                self.subscribe(
+                    term_index,
+                    doc_id,
+                    token.position as u32,
+                    &term_buffer,
+                    heap,
+                );
+            } else {
+                info!(
+                    "A token exceeding MAX_TOKEN_LEN ({}>{}) was dropped. Search for \
+                     MAX_TOKEN_LEN in the documentation for more information.",
+                    token.text.len(),
+                    MAX_TOKEN_LEN
+                );
             }
-            term_buffer.set_text(token.text.as_str());
-            self.subscribe(
-                term_index,
-                doc_id,
-                token.position as u32,
-                &term_buffer,
-                heap,
-            );
         };
         token_stream.process(&mut sink)
     }

src/postings/serializer.rs

@@ -1,5 +1,4 @@
-use super::TermInfo;
-use crate::common::{BinarySerializable, VInt};
+use super::{FieldStat, FieldStats, TermInfo};
 use crate::common::{CompositeWrite, CountingWriter};
 use crate::core::Segment;
 use crate::directory::WritePtr;
@@ -11,6 +10,10 @@ use crate::query::BM25Weight;
 use crate::schema::Schema;
 use crate::schema::{Field, FieldEntry, FieldType};
 use crate::termdict::{TermDictionaryBuilder, TermOrdinal};
+use crate::{
+    common::{BinarySerializable, VInt},
+    directory::TerminatingWrite,
+};
 use crate::{DocId, Score};
 use std::cmp::Ordering;
 use std::io::{self, Write};
@@ -51,6 +54,8 @@ pub struct InvertedIndexSerializer {
     postings_write: CompositeWrite<WritePtr>,
     positions_write: CompositeWrite<WritePtr>,
     positionsidx_write: CompositeWrite<WritePtr>,
+    field_stats: FieldStats,
+    field_stats_write: WritePtr,
     schema: Schema,
 }
 
@@ -61,6 +66,7 @@ impl InvertedIndexSerializer {
         postings_write: CompositeWrite<WritePtr>,
         positions_write: CompositeWrite<WritePtr>,
         positionsidx_write: CompositeWrite<WritePtr>,
+        field_stats_write: WritePtr,
         schema: Schema,
     ) -> crate::Result<InvertedIndexSerializer> {
         Ok(InvertedIndexSerializer {
@@ -68,18 +74,21 @@ impl InvertedIndexSerializer {
             postings_write,
             positions_write,
             positionsidx_write,
+            field_stats: FieldStats::default(),
+            field_stats_write,
             schema,
         })
     }
 
     /// Open a new `PostingsSerializer` for the given segment
     pub fn open(segment: &mut Segment) -> crate::Result<InvertedIndexSerializer> {
-        use crate::SegmentComponent::{POSITIONS, POSITIONSSKIP, POSTINGS, TERMS};
+        use crate::SegmentComponent::{FIELDSTATS, POSITIONS, POSITIONSSKIP, POSTINGS, TERMS};
         InvertedIndexSerializer::create(
             CompositeWrite::wrap(segment.open_write(TERMS)?),
             CompositeWrite::wrap(segment.open_write(POSTINGS)?),
             CompositeWrite::wrap(segment.open_write(POSITIONS)?),
             CompositeWrite::wrap(segment.open_write(POSITIONSSKIP)?),
+            segment.open_write(FIELDSTATS)?,
             segment.schema(),
         )
     }
@@ -94,6 +103,8 @@ impl InvertedIndexSerializer {
         total_num_tokens: u64,
         fieldnorm_reader: Option<FieldNormReader>,
     ) -> io::Result<FieldSerializer<'_>> {
+        self.field_stats
+            .insert(field, FieldStat::new(total_num_tokens));
         let field_entry: &FieldEntry = self.schema.get_field_entry(field);
         let term_dictionary_write = self.terms_write.for_field(field);
         let postings_write = self.postings_write.for_field(field);
@@ -112,7 +123,10 @@ impl InvertedIndexSerializer {
     }
 
     /// Closes the serializer.
-    pub fn close(self) -> io::Result<()> {
+    pub fn close(mut self) -> io::Result<()> {
+        self.field_stats
+            .serialize(self.field_stats_write.get_mut())?;
+        self.field_stats_write.terminate()?;
         self.terms_write.close()?;
         self.postings_write.close()?;
         self.positions_write.close()?;
@@ -142,7 +156,6 @@ impl<'a> FieldSerializer<'a> {
         positionsidx_write: &'a mut CountingWriter<WritePtr>,
         fieldnorm_reader: Option<FieldNormReader>,
     ) -> io::Result<FieldSerializer<'a>> {
-        total_num_tokens.serialize(postings_write)?;
         let (term_freq_enabled, position_enabled): (bool, bool) = match field_type {
             FieldType::Str(ref text_options) => {
                 if let Some(text_indexing_options) = text_options.get_indexing_options() {
@@ -190,7 +203,8 @@ impl<'a> FieldSerializer<'a> {
             .unwrap_or(0u64);
         TermInfo {
             doc_freq: 0,
-            postings_offset: self.postings_serializer.addr(),
+            postings_start_offset: self.postings_serializer.addr(),
+            postings_end_offset: 0u64,
             positions_idx,
         }
     }
@@ -244,10 +258,12 @@ impl<'a> FieldSerializer<'a> {
     /// using `VInt` encoding.
     pub fn close_term(&mut self) -> io::Result<()> {
         if self.term_open {
-            self.term_dictionary_builder
-                .insert_value(&self.current_term_info)?;
             self.postings_serializer
                 .close_term(self.current_term_info.doc_freq)?;
+            let end_offset = self.postings_serializer.addr();
+            self.current_term_info.postings_end_offset = end_offset;
+            self.term_dictionary_builder
+                .insert_value(&self.current_term_info)?;
             self.term_open = false;
         }
         Ok(())

src/postings/term_info.rs

@@ -7,35 +7,49 @@ use std::io;
 pub struct TermInfo {
     /// Number of documents in the segment containing the term
     pub doc_freq: u32,
-    /// Start offset within the postings (`.idx`) file.
-    pub postings_offset: u64,
+    /// Start offset of the posting list within the postings (`.idx`) file.
+    pub postings_start_offset: u64,
+    /// End offset of the posting list within the postings (`.idx`) file.
+    pub postings_end_offset: u64,
     /// Start offset of the first block within the position (`.pos`) file.
     pub positions_idx: u64,
 }
 
+impl TermInfo {
+    pub(crate) fn posting_num_bytes(&self) -> u32 {
+        let num_bytes = self.postings_end_offset - self.postings_start_offset;
+        assert!(num_bytes <= std::u32::MAX as u64);
+        num_bytes as u32
+    }
+}
+
 impl FixedSize for TermInfo {
     /// Size required for the binary serialization of a `TermInfo` object.
     /// This is large, but in practise, `TermInfo` are encoded in blocks and
     /// only the first `TermInfo` of a block is serialized uncompressed.
     /// The subsequent `TermInfo` are delta encoded and bitpacked.
-    const SIZE_IN_BYTES: usize = u32::SIZE_IN_BYTES + 2 * u64::SIZE_IN_BYTES;
+    const SIZE_IN_BYTES: usize = 2 * u32::SIZE_IN_BYTES + 2 * u64::SIZE_IN_BYTES;
 }
 
 impl BinarySerializable for TermInfo {
     fn serialize<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
         self.doc_freq.serialize(writer)?;
-        self.postings_offset.serialize(writer)?;
+        self.postings_start_offset.serialize(writer)?;
+        self.posting_num_bytes().serialize(writer)?;
         self.positions_idx.serialize(writer)?;
         Ok(())
     }
 
     fn deserialize<R: io::Read>(reader: &mut R) -> io::Result<Self> {
         let doc_freq = u32::deserialize(reader)?;
-        let postings_offset = u64::deserialize(reader)?;
+        let postings_start_offset = u64::deserialize(reader)?;
+        let postings_num_bytes = u32::deserialize(reader)?;
+        let postings_end_offset = postings_start_offset + u64::from(postings_num_bytes);
         let positions_idx = u64::deserialize(reader)?;
         Ok(TermInfo {
             doc_freq,
-            postings_offset,
+            postings_start_offset,
+            postings_end_offset,
             positions_idx,
         })
     }

src/query/query_parser/query_parser.rs

@@ -21,48 +21,51 @@ use std::str::FromStr;
 use tantivy_query_grammar::{UserInputAST, UserInputBound, UserInputLeaf};
 
 /// Possible error that may happen when parsing a query.
-#[derive(Debug, PartialEq, Eq, Error)]
+#[derive(Debug, PartialEq, Eq, Fail)]
 pub enum QueryParserError {
     /// Error in the query syntax
-    #[error("Syntax Error")]
+    #[fail(display = "Syntax Error")]
     SyntaxError,
     /// `FieldDoesNotExist(field_name: String)`
     /// The query references a field that is not in the schema
-    #[error("File does not exists: '{0:?}'")]
+    #[fail(display = "File does not exists: '{:?}'", _0)]
     FieldDoesNotExist(String),
     /// The query contains a term for a `u64` or `i64`-field, but the value
     /// is neither.
-    #[error("Expected a valid integer: '{0:?}'")]
+    #[fail(display = "Expected a valid integer: '{:?}'", _0)]
     ExpectedInt(ParseIntError),
     /// The query contains a term for a `f64`-field, but the value
     /// is not a f64.
-    #[error("Invalid query: Only excluding terms given")]
+    #[fail(display = "Invalid query: Only excluding terms given")]
     ExpectedFloat(ParseFloatError),
     /// It is forbidden queries that are only "excluding". (e.g. -title:pop)
-    #[error("Invalid query: Only excluding terms given")]
+    #[fail(display = "Invalid query: Only excluding terms given")]
     AllButQueryForbidden,
     /// If no default field is declared, running a query without any
     /// field specified is forbbidden.
-    #[error("No default field declared and no field specified in query")]
+    #[fail(display = "No default field declared and no field specified in query")]
     NoDefaultFieldDeclared,
     /// The field searched for is not declared
     /// as indexed in the schema.
-    #[error("The field '{0:?}' is not declared as indexed")]
+    #[fail(display = "The field '{:?}' is not declared as indexed", _0)]
     FieldNotIndexed(String),
     /// A phrase query was requested for a field that does not
     /// have any positions indexed.
-    #[error("The field '{0:?}' does not have positions indexed")]
+    #[fail(display = "The field '{:?}' does not have positions indexed", _0)]
     FieldDoesNotHavePositionsIndexed(String),
     /// The tokenizer for the given field is unknown
     /// The two argument strings are the name of the field, the name of the tokenizer
-    #[error("The tokenizer '{0:?}' for the field '{1:?}' is unknown")]
+    #[fail(
+        display = "The tokenizer '{:?}' for the field '{:?}' is unknown",
+        _0, _1
+    )]
     UnknownTokenizer(String, String),
     /// The query contains a range query with a phrase as one of the bounds.
     /// Only terms can be used as bounds.
-    #[error("A range query cannot have a phrase as one of the bounds")]
+    #[fail(display = "A range query cannot have a phrase as one of the bounds")]
     RangeMustNotHavePhrase,
     /// The format for the date field is not RFC 3339 compliant.
-    #[error("The date field has an invalid format")]
+    #[fail(display = "The date field has an invalid format")]
     DateFormatError(chrono::ParseError),
 }
 

src/reader/mod.rs

@@ -1,7 +1,5 @@
 mod pool;
 
-use slog::error;
-
 pub use self::pool::LeasedItem;
 use self::pool::Pool;
 use crate::core::Segment;
@@ -64,7 +62,6 @@ impl IndexReaderBuilder {
     /// to open different segment readers. It may take hundreds of milliseconds
     /// of time and it may return an error.
     pub fn try_into(self) -> crate::Result<IndexReader> {
-        let logger = self.index.logger().clone();
         let inner_reader = InnerIndexReader {
             index: self.index,
             num_searchers: self.num_searchers,
@@ -83,8 +80,8 @@ impl IndexReaderBuilder {
                 let callback = move || {
                     if let Err(err) = inner_reader_arc_clone.reload() {
                         error!(
-                            logger,
-                            "Error while loading searcher after commit was detected. {:?}", err
+                            "Error while loading searcher after commit was detected. {:?}",
+                            err
                         );
                     }
                 };

src/schema/schema.rs

@@ -381,16 +381,19 @@ impl<'de> Deserialize<'de> for Schema {
 
 /// Error that may happen when deserializing
 /// a document from JSON.
-#[derive(Debug, Error, PartialEq)]
+#[derive(Debug, Fail, PartialEq)]
 pub enum DocParsingError {
     /// The payload given is not valid JSON.
-    #[error("The provided string is not valid JSON")]
+    #[fail(display = "The provided string is not valid JSON")]
     NotJSON(String),
     /// One of the value node could not be parsed.
-    #[error("The field '{0:?}' could not be parsed: {1:?}")]
+    #[fail(display = "The field '{:?}' could not be parsed: {:?}", _0, _1)]
     ValueError(String, ValueParsingError),
     /// The json-document contains a field that is not declared in the schema.
-    #[error("The document contains a field that is not declared in the schema: {0:?}")]
+    #[fail(
+        display = "The document contains a field that is not declared in the schema: {:?}",
+        _0
+    )]
     NoSuchFieldInSchema(String),
 }
 

src/space_usage/mod.rs

@@ -25,6 +25,8 @@ pub enum ComponentSpaceUsage {
     Store(StoreSpaceUsage),
     /// Some sort of raw byte count
     Basic(ByteCount),
+    ///
+    Unimplemented,
 }
 
 /// Represents combined space usage of an entire searcher and its component segments.
@@ -119,7 +121,7 @@ impl SegmentSpaceUsage {
     /// Clones the underlying data.
     /// Use the components directly if this is somehow in performance critical code.
     pub fn component(&self, component: SegmentComponent) -> ComponentSpaceUsage {
-        use self::ComponentSpaceUsage::*;
+        use self::ComponentSpaceUsage::{Basic, PerField, Store, Unimplemented};
         use crate::SegmentComponent::*;
         match component {
             POSTINGS => PerField(self.postings().clone()),
@@ -130,6 +132,7 @@ impl SegmentSpaceUsage {
             TERMS => PerField(self.termdict().clone()),
             STORE => Store(self.store().clone()),
             DELETE => Basic(self.deletes()),
+            FIELDSTATS => Unimplemented,
         }
     }
 

src/store/skiplist/skiplist_builder.rs

@@ -68,17 +68,19 @@ impl<T: BinarySerializable> SkipListBuilder<T> {
     }
 
     pub fn insert(&mut self, key: u64, dest: &T) -> io::Result<()> {
+        let mut layer_id = 0;
         let mut skip_pointer = self.data_layer.insert(key, dest)?;
-        for layer_id in 0.. {
-            if let Some((skip_doc_id, skip_offset)) = skip_pointer {
-                skip_pointer = self
+        loop {
+            skip_pointer = match skip_pointer {
+                Some((skip_doc_id, skip_offset)) => self
                     .get_skip_layer(layer_id)
-                    .insert(skip_doc_id, &skip_offset)?;
-            } else {
-                break;
-            }
+                    .insert(skip_doc_id, &skip_offset)?,
+                None => {
+                    return Ok(());
+                }
+            };
+            layer_id += 1;
         }
-        Ok(())
     }
 
     pub fn write<W: Write>(self, output: &mut W) -> io::Result<()> {

src/termdict/mod.rs

@@ -44,11 +44,13 @@ mod tests {
 
     const BLOCK_SIZE: usize = 1_500;
 
-    fn make_term_info(val: u64) -> TermInfo {
+    fn make_term_info(term_ord: u64) -> TermInfo {
+        let offset = |term_ord: u64| term_ord * 100 + term_ord * term_ord;
         TermInfo {
-            doc_freq: val as u32,
-            positions_idx: val * 2u64,
-            postings_offset: val * 3u64,
+            doc_freq: term_ord as u32,
+            postings_start_offset: offset(term_ord),
+            postings_end_offset: offset(term_ord + 1),
+            positions_idx: offset(term_ord) * 2u64,
         }
     }
 
@@ -208,20 +210,14 @@ mod tests {
     }
 
     #[test]
-    fn test_stream_high_range_prefix_suffix() {
+    fn test_stream_high_range_prefix_suffix() -> std::io::Result<()> {
         let buffer: Vec<u8> = {
             let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
             // term requires more than 16bits
-            term_dictionary_builder
-                .insert("abcdefghijklmnopqrstuvwxy", &make_term_info(1))
-                .unwrap();
-            term_dictionary_builder
-                .insert("abcdefghijklmnopqrstuvwxyz", &make_term_info(2))
-                .unwrap();
-            term_dictionary_builder
-                .insert("abr", &make_term_info(2))
-                .unwrap();
-            term_dictionary_builder.finish().unwrap()
+            term_dictionary_builder.insert("abcdefghijklmnopqrstuvwxy", &make_term_info(1))?;
+            term_dictionary_builder.insert("abcdefghijklmnopqrstuvwxyz", &make_term_info(2))?;
+            term_dictionary_builder.insert("abr", &make_term_info(3))?;
+            term_dictionary_builder.finish()?
         };
         let source = ReadOnlySource::from(buffer);
         let term_dictionary: TermDictionary = TermDictionary::from_source(&source);
@@ -229,12 +225,15 @@ mod tests {
         assert!(kv_stream.advance());
         assert_eq!(kv_stream.key(), "abcdefghijklmnopqrstuvwxy".as_bytes());
         assert_eq!(kv_stream.value(), &make_term_info(1));
+        dbg!(make_term_info(1));
         assert!(kv_stream.advance());
         assert_eq!(kv_stream.key(), "abcdefghijklmnopqrstuvwxyz".as_bytes());
         assert_eq!(kv_stream.value(), &make_term_info(2));
         assert!(kv_stream.advance());
         assert_eq!(kv_stream.key(), "abr".as_bytes());
+        assert_eq!(kv_stream.value(), &make_term_info(3));
         assert!(!kv_stream.advance());
+        Ok(())
     }
 
     #[test]

src/termdict/term_info_store.rs

@@ -57,21 +57,28 @@ impl TermInfoBlockMeta {
         self.doc_freq_nbits + self.postings_offset_nbits + self.positions_idx_nbits
     }
 
+    // Here inner_offset is the offset within the block, WITHOUT the first term_info.
+    // In other word, term_info #1,#2,#3 gets inner_offset 0,1,2... While term_info #0
+    // is encoded without bitpacking.
     fn deserialize_term_info(&self, data: &[u8], inner_offset: usize) -> TermInfo {
+        assert!(inner_offset < BLOCK_LEN - 1);
         let num_bits = self.num_bits() as usize;
         let mut cursor = num_bits * inner_offset;
 
+        let postings_start_offset = extract_bits(data, cursor, self.postings_offset_nbits);
+        let postings_end_offset = self.ref_term_info.postings_start_offset
+            + extract_bits(data, cursor + num_bits, self.postings_offset_nbits);
+        cursor += self.postings_offset_nbits as usize;
+
         let doc_freq = extract_bits(data, cursor, self.doc_freq_nbits) as u32;
         cursor += self.doc_freq_nbits as usize;
 
-        let postings_offset = extract_bits(data, cursor, self.postings_offset_nbits);
-        cursor += self.postings_offset_nbits as usize;
-
         let positions_idx = extract_bits(data, cursor, self.positions_idx_nbits);
 
         TermInfo {
             doc_freq,
-            postings_offset: postings_offset + self.ref_term_info.postings_offset,
+            postings_start_offset: postings_start_offset + self.ref_term_info.postings_start_offset,
+            postings_end_offset,
             positions_idx: positions_idx + self.ref_term_info.positions_idx,
         }
     }
@@ -126,14 +133,13 @@ impl TermInfoStore {
             .expect("Failed to deserialize terminfoblockmeta");
         let inner_offset = (term_ord as usize) % BLOCK_LEN;
         if inner_offset == 0 {
-            term_info_block_data.ref_term_info
-        } else {
-            let term_info_data = self.term_info_source.as_slice();
-            term_info_block_data.deserialize_term_info(
-                &term_info_data[term_info_block_data.offset as usize..],
-                inner_offset - 1,
-            )
+            return term_info_block_data.ref_term_info;
         }
+        let term_info_data = self.term_info_source.as_slice();
+        term_info_block_data.deserialize_term_info(
+            &term_info_data[term_info_block_data.offset as usize..],
+            inner_offset - 1,
+        )
     }
 
     pub fn num_terms(&self) -> usize {
@@ -154,16 +160,17 @@ fn bitpack_serialize<W: Write>(
     term_info_block_meta: &TermInfoBlockMeta,
     term_info: &TermInfo,
 ) -> io::Result<()> {
+    bit_packer.write(
+        term_info.postings_start_offset,
+        term_info_block_meta.postings_offset_nbits,
+        write,
+    )?;
     bit_packer.write(
         u64::from(term_info.doc_freq),
         term_info_block_meta.doc_freq_nbits,
         write,
     )?;
-    bit_packer.write(
-        term_info.postings_offset,
-        term_info_block_meta.postings_offset_nbits,
-        write,
-    )?;
+
     bit_packer.write(
         term_info.positions_idx,
         term_info_block_meta.positions_idx_nbits,
@@ -183,23 +190,27 @@ impl TermInfoStoreWriter {
     }
 
     fn flush_block(&mut self) -> io::Result<()> {
-        if self.term_infos.is_empty() {
-            return Ok(());
-        }
         let mut bit_packer = BitPacker::new();
         let ref_term_info = self.term_infos[0].clone();
+
+        let last_term_info = if let Some(last_term_info) = self.term_infos.last().cloned() {
+            last_term_info
+        } else {
+            return Ok(());
+        };
+        let postings_end_offset =
+            last_term_info.postings_end_offset - ref_term_info.postings_start_offset;
         for term_info in &mut self.term_infos[1..] {
-            term_info.postings_offset -= ref_term_info.postings_offset;
+            term_info.postings_start_offset -= ref_term_info.postings_start_offset;
             term_info.positions_idx -= ref_term_info.positions_idx;
         }
 
         let mut max_doc_freq: u32 = 0u32;
-        let mut max_postings_offset: u64 = 0u64;
-        let mut max_positions_idx: u64 = 0u64;
+        let max_postings_offset: u64 = postings_end_offset;
+        let max_positions_idx: u64 = last_term_info.positions_idx;
+
         for term_info in &self.term_infos[1..] {
             max_doc_freq = cmp::max(max_doc_freq, term_info.doc_freq);
-            max_postings_offset = cmp::max(max_postings_offset, term_info.postings_offset);
-            max_positions_idx = cmp::max(max_positions_idx, term_info.positions_idx);
         }
 
         let max_doc_freq_nbits: u8 = compute_num_bits(u64::from(max_doc_freq));
@@ -224,6 +235,12 @@ impl TermInfoStoreWriter {
             )?;
         }
 
+        bit_packer.write(
+            postings_end_offset,
+            term_info_block_meta.postings_offset_nbits,
+            &mut self.buffer_term_infos,
+        )?;
+
         // Block need end up at the end of a byte.
         bit_packer.flush(&mut self.buffer_term_infos)?;
         self.term_infos.clear();
@@ -232,6 +249,7 @@ impl TermInfoStoreWriter {
     }
 
     pub fn write_term_info(&mut self, term_info: &TermInfo) -> io::Result<()> {
+        assert!(term_info.postings_end_offset >= term_info.postings_start_offset);
         self.num_terms += 1u64;
         self.term_infos.push(term_info.clone());
         if self.term_infos.len() >= BLOCK_LEN {
@@ -291,10 +309,11 @@ mod tests {
     #[test]
     fn test_term_info_block_meta_serialization() {
         let term_info_block_meta = TermInfoBlockMeta {
-            offset: 2009,
+            offset: 2009u64,
             ref_term_info: TermInfo {
                 doc_freq: 512,
-                postings_offset: 51,
+                postings_start_offset: 51,
+                postings_end_offset: 57u64,
                 positions_idx: 3584,
             },
             doc_freq_nbits: 10,
@@ -312,10 +331,12 @@ mod tests {
     fn test_pack() {
         let mut store_writer = TermInfoStoreWriter::new();
         let mut term_infos = vec![];
+        let offset = |i| (i * 13 + i * i) as u64;
         for i in 0..1000 {
             let term_info = TermInfo {
                 doc_freq: i as u32,
-                postings_offset: (i / 10) as u64,
+                postings_start_offset: offset(i),
+                postings_end_offset: offset(i + 1),
                 positions_idx: (i * 7) as u64,
             };
             store_writer.write_term_info(&term_info).unwrap();
@@ -325,7 +346,12 @@ mod tests {
         store_writer.serialize(&mut buffer).unwrap();
         let term_info_store = TermInfoStore::open(&ReadOnlySource::from(buffer));
         for i in 0..1000 {
-            assert_eq!(term_info_store.get(i as u64), term_infos[i]);
+            assert_eq!(
+                term_info_store.get(i as u64),
+                term_infos[i],
+                "term info {}",
+                i
+            );
         }
     }
 }