Addressed code review

moved Opstamp to top-level namespace, added a docstring

Corrected minor typos/whitespace

src/core/index_meta.rs

@@ -1,8 +1,8 @@
 use core::SegmentMeta;
-use indexer::Opstamp;
 use schema::Schema;
 use serde_json;
 use std::fmt;
+use Opstamp;
 
 /// Meta information about the `Index`.
 ///

src/core/segment.rs

@@ -6,11 +6,11 @@ use directory::error::{OpenReadError, OpenWriteError};
 use directory::Directory;
 use directory::{ReadOnlySource, WritePtr};
 use indexer::segment_serializer::SegmentSerializer;
-use indexer::Opstamp;
 use schema::Schema;
 use std::fmt;
 use std::path::PathBuf;
 use std::result;
+use Opstamp;
 use Result;
 
 /// A segment is a piece of the index.

src/core/segment_meta.rs

@@ -1,11 +1,11 @@
 use super::SegmentComponent;
 use census::{Inventory, TrackedObject};
 use core::SegmentId;
-use indexer::Opstamp;
 use serde;
 use std::collections::HashSet;
 use std::fmt;
 use std::path::PathBuf;
+use Opstamp;
 
 lazy_static! {
     static ref INVENTORY: Inventory<InnerSegmentMeta> = { Inventory::new() };
@@ -137,7 +137,7 @@ impl SegmentMeta {
         self.max_doc() - self.num_deleted_docs()
     }
 
-    /// Returns the opstamp of the last delete operation
+    /// Returns the `Opstamp` of the last delete operation
     /// taken in account in this segment.
     pub fn delete_opstamp(&self) -> Option<Opstamp> {
         self.tracked

src/indexer/delete_queue.rs

@@ -1,8 +1,8 @@
 use super::operation::DeleteOperation;
-use indexer::Opstamp;
 use std::mem;
 use std::ops::DerefMut;
 use std::sync::{Arc, RwLock};
+use Opstamp;
 
 // The DeleteQueue is similar in conceptually to a multiple
 // consumer single producer broadcast channel.

src/indexer/doc_opstamp_mapping.rs

@@ -1,5 +1,6 @@
 use std::sync::Arc;
 use DocId;
+use Opstamp;
 
 // Doc to opstamp is used to identify which
 // document should be deleted.
@@ -22,8 +23,6 @@ pub enum DocToOpstampMapping {
     None,
 }
 
-use super::Opstamp;
-
 impl From<Vec<u64>> for DocToOpstampMapping {
     fn from(opstamps: Vec<Opstamp>) -> DocToOpstampMapping {
         DocToOpstampMapping::WithMap(Arc::new(opstamps))

src/indexer/index_writer.rs

@@ -19,7 +19,6 @@ use indexer::doc_opstamp_mapping::DocToOpstampMapping;
 use indexer::operation::DeleteOperation;
 use indexer::stamper::Stamper;
 use indexer::MergePolicy;
-use indexer::Opstamp;
 use indexer::SegmentEntry;
 use indexer::SegmentWriter;
 use postings::compute_table_size;
@@ -31,6 +30,7 @@ use std::ops::Range;
 use std::sync::Arc;
 use std::thread;
 use std::thread::JoinHandle;
+use Opstamp;
 use Result;
 
 // Size of the margin for the heap. A segment is closed when the remaining memory

src/indexer/merge_operation.rs

@@ -1,6 +1,6 @@
 use census::{Inventory, TrackedObject};
-use indexer::Opstamp;
 use std::collections::HashSet;
+use Opstamp;
 use SegmentId;
 
 #[derive(Default)]
@@ -18,8 +18,8 @@ impl MergeOperationInventory {
     }
 }
 
-/// A `MergeOperation` has two role.
-/// It carries all of the information required to describe a merge :
+/// A `MergeOperation` has two roles.
+/// It carries all of the information required to describe a merge:
 /// - `target_opstamp` is the opstamp up to which we want to consume the
 /// delete queue and reflect their deletes.
 /// - `segment_ids` is the list of segment to be merged.

src/indexer/mod.rs

@@ -25,7 +25,6 @@ pub use self::segment_entry::SegmentEntry;
 pub use self::segment_manager::SegmentManager;
 pub use self::segment_serializer::SegmentSerializer;
 pub use self::segment_writer::SegmentWriter;
-pub use self::stamper::Opstamp;
 
 /// Alias for the default merge policy, which is the `LogMergePolicy`.
 pub type DefaultMergePolicy = LogMergePolicy;

src/indexer/operation.rs

@@ -1,6 +1,6 @@
-use indexer::Opstamp;
 use schema::Document;
 use schema::Term;
+use Opstamp;
 
 /// Timestamped Delete operation.
 #[derive(Clone, Eq, PartialEq, Debug)]

src/indexer/prepared_commit.rs

@@ -1,5 +1,5 @@
 use super::IndexWriter;
-use indexer::Opstamp;
+use Opstamp;
 use Result;
 
 /// A prepared commit

src/indexer/segment_updater.rs

@@ -20,7 +20,6 @@ use indexer::merge_operation::MergeOperationInventory;
 use indexer::merger::IndexMerger;
 use indexer::stamper::Stamper;
 use indexer::MergeOperation;
-use indexer::Opstamp;
 use indexer::SegmentEntry;
 use indexer::SegmentSerializer;
 use indexer::{DefaultMergePolicy, MergePolicy};
@@ -37,6 +36,7 @@ use std::sync::Arc;
 use std::sync::RwLock;
 use std::thread;
 use std::thread::JoinHandle;
+use Opstamp;
 use Result;
 
 /// Save the index meta file.

src/indexer/segment_writer.rs

@@ -4,7 +4,6 @@ use core::SerializableSegment;
 use fastfield::FastFieldsWriter;
 use fieldnorm::FieldNormsWriter;
 use indexer::segment_serializer::SegmentSerializer;
-use indexer::Opstamp;
 use postings::MultiFieldPostingsWriter;
 use schema::FieldType;
 use schema::Schema;
@@ -16,6 +15,7 @@ use tokenizer::BoxedTokenizer;
 use tokenizer::FacetTokenizer;
 use tokenizer::{TokenStream, Tokenizer};
 use DocId;
+use Opstamp;
 use Result;
 
 /// A `SegmentWriter` is in charge of creating segment index from a

src/indexer/stamper.rs

@@ -1,8 +1,7 @@
 use std::ops::Range;
 use std::sync::atomic::Ordering;
 use std::sync::Arc;
-
-pub type Opstamp = u64;
+use Opstamp;
 
 // AtomicU64 have not landed in stable.
 // For the moment let's just use AtomicUsize on
@@ -10,8 +9,8 @@ pub type Opstamp = u64;
 #[cfg(target_arch = "x86_64")]
 mod archicture_impl {
 
-    use indexer::stamper::Opstamp;
     use std::sync::atomic::{AtomicU64, Ordering};
+    use Opstamp;
 
     #[derive(Default)]
     pub struct AtomicU64Ersatz(AtomicU64);
@@ -35,10 +34,10 @@ mod archicture_impl {
 #[cfg(not(target_arch = "x86_64"))]
 mod archicture_impl {
 
-    use indexer::stamper::Opstamp;
     use std::sync::atomic::Ordering;
     /// Under other architecture, we rely on a mutex.
     use std::sync::RwLock;
+    use Opstamp;
 
     #[derive(Default)]
     pub struct AtomicU64Ersatz(RwLock<u64>);

src/lib.rs

@@ -254,6 +254,14 @@ pub mod merge_policy {
 /// as they are added in the segment.
 pub type DocId = u32;
 
+/// A u64 assigned to every operation incrementally
+///
+/// Used to sequence operations in the correct order during
+/// asynchronous processing of adding documents, merging segments or rollback
+/// Modelled by an AtomicU64 or a u64 under a RW-lock
+/// on platforms without atomic integer support.
+pub type Opstamp = u64;
+
 /// A f32 that represents the relevance of the document to the query
 ///
 /// This is modelled internally as a `f32`. The