Move code to handle snapshot filenames

This isn't very useful yet, but the next commit will add more code
related to handling the filenames.

pageserver/src/layered_repository.rs

@@ -39,6 +39,7 @@ use zenith_utils::bin_ser::BeSer;
 use zenith_utils::lsn::{AtomicLsn, Lsn};
 use zenith_utils::seqwait::SeqWait;
 
+mod filename;
 mod inmemory_layer;
 mod layer_map;
 mod snapshot_layer;
@@ -893,19 +894,21 @@ impl LayeredTimeline {
             self.timelineid
         );
         let mut layers = self.layers.lock().unwrap();
-        let snapfiles =
-            SnapshotLayer::list_snapshot_files(self.conf, self.timelineid, self.tenantid)?;
+        let snapfilenames =
+            filename::list_snapshot_files(self.conf, self.timelineid, self.tenantid)?;
+
+        for filename in snapfilenames.iter() {
+            let layer = SnapshotLayer::load_snapshot_layer(self.conf, self.timelineid, self.tenantid, filename)?;
 
-        for layer_rc in snapfiles.iter() {
             info!(
                 "found layer {} {}-{} {} on timeline {}",
-                layer_rc.get_seg_tag(),
-                layer_rc.get_start_lsn(),
-                layer_rc.get_end_lsn(),
-                layer_rc.is_dropped(),
+                layer.get_seg_tag(),
+                layer.get_start_lsn(),
+                layer.get_end_lsn(),
+                layer.is_dropped(),
                 self.timelineid
             );
-            layers.insert_historic(Arc::clone(layer_rc));
+            layers.insert_historic(Arc::new(layer));
         }
 
         Ok(())

pageserver/src/layered_repository/filename.rs

@@ -0,0 +1,172 @@
+use crate::layered_repository::storage_layer::{SegmentTag};
+use crate::relish::*;
+use crate::PageServerConf;
+use crate::{ZTenantId, ZTimelineId};
+use std::fmt;
+use std::fs;
+
+use anyhow::Result;
+use log::*;
+use zenith_utils::lsn::Lsn;
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub struct SnapshotFileName {
+    pub seg: SegmentTag,
+    pub start_lsn: Lsn,
+    pub end_lsn: Lsn,
+    pub dropped: bool,
+}
+
+impl SnapshotFileName {
+    fn from_str(fname: &str) -> Option<Self> {
+        // Split the filename into parts
+        //
+        //    <spcnode>_<dbnode>_<relnode>_<forknum>_<seg>_<start LSN>_<end LSN>
+        //
+        // or if it was dropped:
+        //
+        //    <spcnode>_<dbnode>_<relnode>_<forknum>_<seg>_<start LSN>_<end LSN>_DROPPED
+        //
+        let rel;
+        let mut parts;
+        if let Some(rest) = fname.strip_prefix("rel_") {
+            parts = rest.split('_');
+            rel = RelishTag::Relation(RelTag {
+                spcnode: parts.next()?.parse::<u32>().ok()?,
+                dbnode: parts.next()?.parse::<u32>().ok()?,
+                relnode: parts.next()?.parse::<u32>().ok()?,
+                forknum: parts.next()?.parse::<u8>().ok()?,
+            });
+        } else if let Some(rest) = fname.strip_prefix("pg_xact_") {
+            parts = rest.split('_');
+            rel = RelishTag::Slru {
+                slru: SlruKind::Clog,
+                segno: u32::from_str_radix(parts.next()?, 16).ok()?,
+            };
+        } else if let Some(rest) = fname.strip_prefix("pg_multixact_members_") {
+            parts = rest.split('_');
+            rel = RelishTag::Slru {
+                slru: SlruKind::MultiXactMembers,
+                segno: u32::from_str_radix(parts.next()?, 16).ok()?,
+            };
+        } else if let Some(rest) = fname.strip_prefix("pg_multixact_offsets_") {
+            parts = rest.split('_');
+            rel = RelishTag::Slru {
+                slru: SlruKind::MultiXactOffsets,
+                segno: u32::from_str_radix(parts.next()?, 16).ok()?,
+            };
+        } else if let Some(rest) = fname.strip_prefix("pg_filenodemap_") {
+            parts = rest.split('_');
+            rel = RelishTag::FileNodeMap {
+                spcnode: parts.next()?.parse::<u32>().ok()?,
+                dbnode: parts.next()?.parse::<u32>().ok()?,
+            };
+        } else if let Some(rest) = fname.strip_prefix("pg_twophase_") {
+            parts = rest.split('_');
+            rel = RelishTag::TwoPhase {
+                xid: parts.next()?.parse::<u32>().ok()?,
+            };
+        } else if let Some(rest) = fname.strip_prefix("pg_control_checkpoint_") {
+            parts = rest.split('_');
+            rel = RelishTag::Checkpoint;
+        } else if let Some(rest) = fname.strip_prefix("pg_control_") {
+            parts = rest.split('_');
+            rel = RelishTag::ControlFile;
+        } else {
+            return None;
+        }
+
+        let segno = parts.next()?.parse::<u32>().ok()?;
+
+        let seg = SegmentTag { rel, segno };
+
+        let start_lsn = Lsn::from_hex(parts.next()?).ok()?;
+        let end_lsn = Lsn::from_hex(parts.next()?).ok()?;
+
+        let mut dropped = false;
+        if let Some(suffix) = parts.next() {
+            if suffix == "DROPPED" {
+                dropped = true;
+            } else {
+                warn!("unrecognized filename in timeline dir: {}", fname);
+                return None;
+            }
+        }
+        if parts.next().is_some() {
+            warn!("unrecognized filename in timeline dir: {}", fname);
+            return None;
+        }
+
+        Some(SnapshotFileName {
+            seg,
+            start_lsn,
+            end_lsn,
+            dropped,
+        })
+    }
+
+    fn to_string(&self) -> String {
+        let basename = match self.seg.rel {
+            RelishTag::Relation(reltag) => format!(
+                "rel_{}_{}_{}_{}",
+                reltag.spcnode, reltag.dbnode, reltag.relnode, reltag.forknum
+            ),
+            RelishTag::Slru {
+                slru: SlruKind::Clog,
+                segno,
+            } => format!("pg_xact_{:04X}", segno),
+            RelishTag::Slru {
+                slru: SlruKind::MultiXactMembers,
+                segno,
+            } => format!("pg_multixact_members_{:04X}", segno),
+            RelishTag::Slru {
+                slru: SlruKind::MultiXactOffsets,
+                segno,
+            } => format!("pg_multixact_offsets_{:04X}", segno),
+            RelishTag::FileNodeMap { spcnode, dbnode } => {
+                format!("pg_filenodemap_{}_{}", spcnode, dbnode)
+            }
+            RelishTag::TwoPhase { xid } => format!("pg_twophase_{}", xid),
+            RelishTag::Checkpoint => format!("pg_control_checkpoint"),
+            RelishTag::ControlFile => format!("pg_control"),
+        };
+
+        format!(
+            "{}_{}_{:016X}_{:016X}{}",
+            basename,
+            self.seg.segno,
+            u64::from(self.start_lsn),
+            u64::from(self.end_lsn),
+            if self.dropped { "_DROPPED" } else { "" }
+        )
+    }
+}
+
+impl fmt::Display for SnapshotFileName {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.to_string())
+    }
+}
+
+
+/// Create SnapshotFileName structs representing all files on disk
+///
+// TODO: returning an Iterator would be more idiomatic
+pub fn list_snapshot_files(
+    conf: &'static PageServerConf,
+    timelineid: ZTimelineId,
+    tenantid: ZTenantId,
+) -> Result<Vec<SnapshotFileName>> {
+    let path = conf.timeline_path(&timelineid, &tenantid);
+
+    let mut snapfiles: Vec<SnapshotFileName> = Vec::new();
+    for direntry in fs::read_dir(path)? {
+        let fname = direntry?.file_name();
+        let fname = fname.to_str().unwrap();
+
+        if let Some(snapfilename) = SnapshotFileName::from_str(fname) {
+            snapfiles.push(snapfilename);
+        }
+    }
+    return Ok(snapfiles);
+}

pageserver/src/layered_repository/snapshot_layer.rs

@@ -40,19 +40,18 @@
 use crate::layered_repository::storage_layer::{
     Layer, PageReconstructData, PageVersion, SegmentTag,
 };
-use crate::relish::*;
+use crate::layered_repository::filename::{SnapshotFileName};
 use crate::PageServerConf;
 use crate::{ZTenantId, ZTimelineId};
 use anyhow::{bail, Result};
 use log::*;
 use std::collections::BTreeMap;
-use std::fmt;
 use std::fs;
 use std::fs::File;
 use std::io::Write;
 use std::ops::Bound::Included;
 use std::path::PathBuf;
-use std::sync::{Arc, Mutex, MutexGuard};
+use std::sync::{Mutex, MutexGuard};
 
 use bookfile::{Book, BookWriter};
 
@@ -65,145 +64,6 @@ static SNAPSHOT_FILE_MAGIC: u32 = 0x5A616E01;
 static PAGE_VERSIONS_CHAPTER: u64 = 1;
 static REL_SIZES_CHAPTER: u64 = 2;
 
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
-struct SnapshotFileName {
-    seg: SegmentTag,
-    start_lsn: Lsn,
-    end_lsn: Lsn,
-    dropped: bool,
-}
-
-impl SnapshotFileName {
-    fn from_str(fname: &str) -> Option<Self> {
-        // Split the filename into parts
-        //
-        //    <spcnode>_<dbnode>_<relnode>_<forknum>_<seg>_<start LSN>_<end LSN>
-        //
-        // or if it was dropped:
-        //
-        //    <spcnode>_<dbnode>_<relnode>_<forknum>_<seg>_<start LSN>_<end LSN>_DROPPED
-        //
-        let rel;
-        let mut parts;
-        if let Some(rest) = fname.strip_prefix("rel_") {
-            parts = rest.split('_');
-            rel = RelishTag::Relation(RelTag {
-                spcnode: parts.next()?.parse::<u32>().ok()?,
-                dbnode: parts.next()?.parse::<u32>().ok()?,
-                relnode: parts.next()?.parse::<u32>().ok()?,
-                forknum: parts.next()?.parse::<u8>().ok()?,
-            });
-        } else if let Some(rest) = fname.strip_prefix("pg_xact_") {
-            parts = rest.split('_');
-            rel = RelishTag::Slru {
-                slru: SlruKind::Clog,
-                segno: u32::from_str_radix(parts.next()?, 16).ok()?,
-            };
-        } else if let Some(rest) = fname.strip_prefix("pg_multixact_members_") {
-            parts = rest.split('_');
-            rel = RelishTag::Slru {
-                slru: SlruKind::MultiXactMembers,
-                segno: u32::from_str_radix(parts.next()?, 16).ok()?,
-            };
-        } else if let Some(rest) = fname.strip_prefix("pg_multixact_offsets_") {
-            parts = rest.split('_');
-            rel = RelishTag::Slru {
-                slru: SlruKind::MultiXactOffsets,
-                segno: u32::from_str_radix(parts.next()?, 16).ok()?,
-            };
-        } else if let Some(rest) = fname.strip_prefix("pg_filenodemap_") {
-            parts = rest.split('_');
-            rel = RelishTag::FileNodeMap {
-                spcnode: parts.next()?.parse::<u32>().ok()?,
-                dbnode: parts.next()?.parse::<u32>().ok()?,
-            };
-        } else if let Some(rest) = fname.strip_prefix("pg_twophase_") {
-            parts = rest.split('_');
-            rel = RelishTag::TwoPhase {
-                xid: parts.next()?.parse::<u32>().ok()?,
-            };
-        } else if let Some(rest) = fname.strip_prefix("pg_control_checkpoint_") {
-            parts = rest.split('_');
-            rel = RelishTag::Checkpoint;
-        } else if let Some(rest) = fname.strip_prefix("pg_control_") {
-            parts = rest.split('_');
-            rel = RelishTag::ControlFile;
-        } else {
-            return None;
-        }
-
-        let segno = parts.next()?.parse::<u32>().ok()?;
-
-        let seg = SegmentTag { rel, segno };
-
-        let start_lsn = Lsn::from_hex(parts.next()?).ok()?;
-        let end_lsn = Lsn::from_hex(parts.next()?).ok()?;
-
-        let mut dropped = false;
-        if let Some(suffix) = parts.next() {
-            if suffix == "DROPPED" {
-                dropped = true;
-            } else {
-                warn!("unrecognized filename in timeline dir: {}", fname);
-                return None;
-            }
-        }
-        if parts.next().is_some() {
-            warn!("unrecognized filename in timeline dir: {}", fname);
-            return None;
-        }
-
-        Some(SnapshotFileName {
-            seg,
-            start_lsn,
-            end_lsn,
-            dropped,
-        })
-    }
-
-    fn to_string(&self) -> String {
-        let basename = match self.seg.rel {
-            RelishTag::Relation(reltag) => format!(
-                "rel_{}_{}_{}_{}",
-                reltag.spcnode, reltag.dbnode, reltag.relnode, reltag.forknum
-            ),
-            RelishTag::Slru {
-                slru: SlruKind::Clog,
-                segno,
-            } => format!("pg_xact_{:04X}", segno),
-            RelishTag::Slru {
-                slru: SlruKind::MultiXactMembers,
-                segno,
-            } => format!("pg_multixact_members_{:04X}", segno),
-            RelishTag::Slru {
-                slru: SlruKind::MultiXactOffsets,
-                segno,
-            } => format!("pg_multixact_offsets_{:04X}", segno),
-            RelishTag::FileNodeMap { spcnode, dbnode } => {
-                format!("pg_filenodemap_{}_{}", spcnode, dbnode)
-            }
-            RelishTag::TwoPhase { xid } => format!("pg_twophase_{}", xid),
-            RelishTag::Checkpoint => format!("pg_control_checkpoint"),
-            RelishTag::ControlFile => format!("pg_control"),
-        };
-
-        format!(
-            "{}_{}_{:016X}_{:016X}{}",
-            basename,
-            self.seg.segno,
-            u64::from(self.start_lsn),
-            u64::from(self.end_lsn),
-            if self.dropped { "_DROPPED" } else { "" }
-        )
-    }
-}
-
-impl fmt::Display for SnapshotFileName {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", self.to_string())
-    }
-}
-
 ///
 /// SnapshotLayer is the in-memory data structure associated with an
 /// on-disk snapshot file.  We keep a SnapshotLayer in memory for each
@@ -474,38 +334,28 @@ impl SnapshotLayer {
     /// Create SnapshotLayers representing all files on disk
     ///
     // TODO: returning an Iterator would be more idiomatic
-    pub fn list_snapshot_files(
+    pub fn load_snapshot_layer(
         conf: &'static PageServerConf,
         timelineid: ZTimelineId,
         tenantid: ZTenantId,
-    ) -> Result<Vec<Arc<SnapshotLayer>>> {
-        let path = conf.timeline_path(&timelineid, &tenantid);
+        filename: &SnapshotFileName,
+    ) -> Result<SnapshotLayer> {
+        let snapfile = SnapshotLayer {
+            conf,
+            timelineid,
+            tenantid,
+            seg: filename.seg,
+            start_lsn: filename.start_lsn,
+            end_lsn: filename.end_lsn,
+            dropped: filename.dropped,
+            inner: Mutex::new(SnapshotLayerInner {
+                loaded: false,
+                page_versions: BTreeMap::new(),
+                relsizes: BTreeMap::new(),
+            }),
+        };
 
-        let mut snapfiles: Vec<Arc<SnapshotLayer>> = Vec::new();
-        for direntry in fs::read_dir(path)? {
-            let fname = direntry?.file_name();
-            let fname = fname.to_str().unwrap();
-
-            if let Some(snapfilename) = SnapshotFileName::from_str(fname) {
-                let snapfile = SnapshotLayer {
-                    conf,
-                    timelineid,
-                    tenantid,
-                    seg: snapfilename.seg,
-                    start_lsn: snapfilename.start_lsn,
-                    end_lsn: snapfilename.end_lsn,
-                    dropped: snapfilename.dropped,
-                    inner: Mutex::new(SnapshotLayerInner {
-                        loaded: false,
-                        page_versions: BTreeMap::new(),
-                        relsizes: BTreeMap::new(),
-                    }),
-                };
-
-                snapfiles.push(Arc::new(snapfile));
-            }
-        }
-        return Ok(snapfiles);
+        Ok(snapfile)
     }
 
     pub fn delete(&self) -> Result<()> {