LCOV - code coverage report
Current view: top level - pebble - version_set.go (source / functions) Hit Total Coverage
Test: 2025-01-02 08:16Z f87b4ded - tests only.lcov Lines: 648 732 88.5 %
Date: 2025-01-02 08:18:00 Functions: 0 0 -

          Line data    Source code
       1             : // Copyright 2012 The LevelDB-Go and Pebble Authors. All rights reserved. Use
       2             : // of this source code is governed by a BSD-style license that can be found in
       3             : // the LICENSE file.
       4             : 
       5             : package pebble
       6             : 
       7             : import (
       8             :         "fmt"
       9             :         "io"
      10             :         "sync"
      11             :         "sync/atomic"
      12             : 
      13             :         "github.com/cockroachdb/errors"
      14             :         "github.com/cockroachdb/pebble/internal/base"
      15             :         "github.com/cockroachdb/pebble/internal/invariants"
      16             :         "github.com/cockroachdb/pebble/internal/manifest"
      17             :         "github.com/cockroachdb/pebble/objstorage"
      18             :         "github.com/cockroachdb/pebble/record"
      19             :         "github.com/cockroachdb/pebble/vfs"
      20             :         "github.com/cockroachdb/pebble/vfs/atomicfs"
      21             : )
      22             : 
      23             : const numLevels = manifest.NumLevels
      24             : 
      25             : const manifestMarkerName = `manifest`
      26             : 
      27             : // Provide type aliases for the various manifest structs.
      28             : type bulkVersionEdit = manifest.BulkVersionEdit
      29             : type deletedFileEntry = manifest.DeletedFileEntry
      30             : type fileMetadata = manifest.FileMetadata
      31             : type physicalMeta = manifest.PhysicalFileMeta
      32             : type virtualMeta = manifest.VirtualFileMeta
      33             : type fileBacking = manifest.FileBacking
      34             : type newFileEntry = manifest.NewFileEntry
      35             : type version = manifest.Version
      36             : type versionEdit = manifest.VersionEdit
      37             : type versionList = manifest.VersionList
      38             : 
      39             : // versionSet manages a collection of immutable versions, and manages the
      40             : // creation of a new version from the most recent version. A new version is
      41             : // created from an existing version by applying a version edit which is just
      42             : // like it sounds: a delta from the previous version. Version edits are logged
      43             : // to the MANIFEST file, which is replayed at startup.
      44             : type versionSet struct {
      45             :         // Next seqNum to use for WAL writes.
      46             :         logSeqNum base.AtomicSeqNum
      47             : 
      48             :         // The upper bound on sequence numbers that have been assigned so far. A
      49             :         // suffix of these sequence numbers may not have been written to a WAL. Both
      50             :         // logSeqNum and visibleSeqNum are atomically updated by the commitPipeline.
      51             :         // visibleSeqNum is <= logSeqNum.
      52             :         visibleSeqNum base.AtomicSeqNum
      53             : 
      54             :         // Number of bytes present in sstables being written by in-progress
      55             :         // compactions. This value will be zero if there are no in-progress
      56             :         // compactions. Updated and read atomically.
      57             :         atomicInProgressBytes atomic.Int64
      58             : 
      59             :         // Immutable fields.
      60             :         dirname  string
      61             :         provider objstorage.Provider
      62             :         // Set to DB.mu.
      63             :         mu   *sync.Mutex
      64             :         opts *Options
      65             :         fs   vfs.FS
      66             :         cmp  *base.Comparer
      67             :         // Dynamic base level allows the dynamic base level computation to be
      68             :         // disabled. Used by tests which want to create specific LSM structures.
      69             :         dynamicBaseLevel bool
      70             : 
      71             :         // Mutable fields.
      72             :         versions versionList
      73             :         picker   compactionPicker
      74             : 
      75             :         // Not all metrics are kept here. See DB.Metrics().
      76             :         metrics Metrics
      77             : 
      78             :         // A pointer to versionSet.addObsoleteLocked. Avoids allocating a new closure
      79             :         // on the creation of every version.
      80             :         obsoleteFn        func(obsolete []*fileBacking)
      81             :         obsoleteTables    []tableInfo
      82             :         obsoleteManifests []fileInfo
      83             :         obsoleteOptions   []fileInfo
      84             : 
      85             :         // Zombie tables which have been removed from the current version but are
      86             :         // still referenced by an inuse iterator.
      87             :         zombieTables map[base.DiskFileNum]tableInfo
      88             : 
      89             :         // virtualBackings contains information about the FileBackings which support
      90             :         // virtual sstables in the latest version. It is mainly used to determine when
      91             :         // a backing is no longer in use by the tables in the latest version; this is
      92             :         // not a trivial problem because compactions and other operations can happen
      93             :         // in parallel (and they can finish in unpredictable order).
      94             :         //
      95             :         // This mechanism is complementary to the backing Ref/Unref mechanism, which
      96             :         // determines when a backing is no longer used by *any* live version and can
      97             :         // be removed.
      98             :         //
      99             :         // In principle this should have been a copy-on-write structure, with each
     100             :         // Version having its own record of its virtual backings (similar to the
     101             :         // B-tree that holds the tables). However, in practice we only need it for the
     102             :         // latest version, so we use a simpler structure and store it in the
     103             :         // versionSet instead.
     104             :         //
     105             :         // virtualBackings is modified under DB.mu and the log lock. If it is accessed
     106             :         // under DB.mu and a version update is in progress, it reflects the state of
     107             :         // the next version.
     108             :         virtualBackings manifest.VirtualBackings
     109             : 
     110             :         // minUnflushedLogNum is the smallest WAL log file number corresponding to
     111             :         // mutations that have not been flushed to an sstable.
     112             :         minUnflushedLogNum base.DiskFileNum
     113             : 
     114             :         // The next file number. A single counter is used to assign file
     115             :         // numbers for the WAL, MANIFEST, sstable, and OPTIONS files.
     116             :         nextFileNum atomic.Uint64
     117             : 
     118             :         // The current manifest file number.
     119             :         manifestFileNum base.DiskFileNum
     120             :         manifestMarker  *atomicfs.Marker
     121             : 
     122             :         manifestFile          vfs.File
     123             :         manifest              *record.Writer
     124             :         getFormatMajorVersion func() FormatMajorVersion
     125             : 
     126             :         writing    bool
     127             :         writerCond sync.Cond
     128             :         // State for deciding when to write a snapshot. Protected by mu.
     129             :         rotationHelper record.RotationHelper
     130             : }
     131             : 
     132             : type tableInfo struct {
     133             :         fileInfo
     134             :         isLocal bool
     135             : }
     136             : 
     137             : func (vs *versionSet) init(
     138             :         dirname string,
     139             :         provider objstorage.Provider,
     140             :         opts *Options,
     141             :         marker *atomicfs.Marker,
     142             :         getFMV func() FormatMajorVersion,
     143             :         mu *sync.Mutex,
     144           1 : ) {
     145           1 :         vs.dirname = dirname
     146           1 :         vs.provider = provider
     147           1 :         vs.mu = mu
     148           1 :         vs.writerCond.L = mu
     149           1 :         vs.opts = opts
     150           1 :         vs.fs = opts.FS
     151           1 :         vs.cmp = opts.Comparer
     152           1 :         vs.dynamicBaseLevel = true
     153           1 :         vs.versions.Init(mu)
     154           1 :         vs.obsoleteFn = vs.addObsoleteLocked
     155           1 :         vs.zombieTables = make(map[base.DiskFileNum]tableInfo)
     156           1 :         vs.virtualBackings = manifest.MakeVirtualBackings()
     157           1 :         vs.nextFileNum.Store(1)
     158           1 :         vs.manifestMarker = marker
     159           1 :         vs.getFormatMajorVersion = getFMV
     160           1 : }
     161             : 
     162             : // create creates a version set for a fresh DB.
     163             : func (vs *versionSet) create(
     164             :         jobID JobID,
     165             :         dirname string,
     166             :         provider objstorage.Provider,
     167             :         opts *Options,
     168             :         marker *atomicfs.Marker,
     169             :         getFormatMajorVersion func() FormatMajorVersion,
     170             :         mu *sync.Mutex,
     171           1 : ) error {
     172           1 :         vs.init(dirname, provider, opts, marker, getFormatMajorVersion, mu)
     173           1 :         var bve bulkVersionEdit
     174           1 :         newVersion, err := bve.Apply(nil /* curr */, opts.Comparer, opts.FlushSplitBytes, opts.Experimental.ReadCompactionRate)
     175           1 :         if err != nil {
     176           0 :                 return err
     177           0 :         }
     178           1 :         vs.append(newVersion)
     179           1 : 
     180           1 :         vs.picker = newCompactionPickerByScore(newVersion, &vs.virtualBackings, vs.opts, nil)
     181           1 :         // Note that a "snapshot" version edit is written to the manifest when it is
     182           1 :         // created.
     183           1 :         vs.manifestFileNum = vs.getNextDiskFileNum()
     184           1 :         err = vs.createManifest(vs.dirname, vs.manifestFileNum, vs.minUnflushedLogNum, vs.nextFileNum.Load(), nil /* virtualBackings */)
     185           1 :         if err == nil {
     186           1 :                 if err = vs.manifest.Flush(); err != nil {
     187           1 :                         vs.opts.Logger.Fatalf("MANIFEST flush failed: %v", err)
     188           1 :                 }
     189             :         }
     190           1 :         if err == nil {
     191           1 :                 if err = vs.manifestFile.Sync(); err != nil {
     192           1 :                         vs.opts.Logger.Fatalf("MANIFEST sync failed: %v", err)
     193           1 :                 }
     194             :         }
     195           1 :         if err == nil {
     196           1 :                 // NB: Move() is responsible for syncing the data directory.
     197           1 :                 if err = vs.manifestMarker.Move(base.MakeFilename(fileTypeManifest, vs.manifestFileNum)); err != nil {
     198           1 :                         vs.opts.Logger.Fatalf("MANIFEST set current failed: %v", err)
     199           1 :                 }
     200             :         }
     201             : 
     202           1 :         vs.opts.EventListener.ManifestCreated(ManifestCreateInfo{
     203           1 :                 JobID:   int(jobID),
     204           1 :                 Path:    base.MakeFilepath(vs.fs, vs.dirname, fileTypeManifest, vs.manifestFileNum),
     205           1 :                 FileNum: vs.manifestFileNum,
     206           1 :                 Err:     err,
     207           1 :         })
     208           1 :         if err != nil {
     209           1 :                 return err
     210           1 :         }
     211           1 :         return nil
     212             : }
     213             : 
     214             : // load loads the version set from the manifest file.
     215             : func (vs *versionSet) load(
     216             :         dirname string,
     217             :         provider objstorage.Provider,
     218             :         opts *Options,
     219             :         manifestFileNum base.DiskFileNum,
     220             :         marker *atomicfs.Marker,
     221             :         getFormatMajorVersion func() FormatMajorVersion,
     222             :         mu *sync.Mutex,
     223           1 : ) error {
     224           1 :         vs.init(dirname, provider, opts, marker, getFormatMajorVersion, mu)
     225           1 : 
     226           1 :         vs.manifestFileNum = manifestFileNum
     227           1 :         manifestPath := base.MakeFilepath(opts.FS, dirname, fileTypeManifest, vs.manifestFileNum)
     228           1 :         manifestFilename := opts.FS.PathBase(manifestPath)
     229           1 : 
     230           1 :         // Read the versionEdits in the manifest file.
     231           1 :         var bve bulkVersionEdit
     232           1 :         bve.AddedByFileNum = make(map[base.FileNum]*fileMetadata)
     233           1 :         manifest, err := vs.fs.Open(manifestPath)
     234           1 :         if err != nil {
     235           0 :                 return errors.Wrapf(err, "pebble: could not open manifest file %q for DB %q",
     236           0 :                         errors.Safe(manifestFilename), dirname)
     237           0 :         }
     238           1 :         defer manifest.Close()
     239           1 :         rr := record.NewReader(manifest, 0 /* logNum */)
     240           1 :         for {
     241           1 :                 r, err := rr.Next()
     242           1 :                 if err == io.EOF || record.IsInvalidRecord(err) {
     243           1 :                         break
     244             :                 }
     245           1 :                 if err != nil {
     246           0 :                         return errors.Wrapf(err, "pebble: error when loading manifest file %q",
     247           0 :                                 errors.Safe(manifestFilename))
     248           0 :                 }
     249           1 :                 var ve versionEdit
     250           1 :                 err = ve.Decode(r)
     251           1 :                 if err != nil {
     252           0 :                         // Break instead of returning an error if the record is corrupted
     253           0 :                         // or invalid.
     254           0 :                         if err == io.EOF || record.IsInvalidRecord(err) {
     255           0 :                                 break
     256             :                         }
     257           0 :                         return err
     258             :                 }
     259           1 :                 if ve.ComparerName != "" {
     260           1 :                         if ve.ComparerName != vs.cmp.Name {
     261           1 :                                 return errors.Errorf("pebble: manifest file %q for DB %q: "+
     262           1 :                                         "comparer name from file %q != comparer name from Options %q",
     263           1 :                                         errors.Safe(manifestFilename), dirname, errors.Safe(ve.ComparerName), errors.Safe(vs.cmp.Name))
     264           1 :                         }
     265             :                 }
     266           1 :                 if err := bve.Accumulate(&ve); err != nil {
     267           0 :                         return err
     268           0 :                 }
     269           1 :                 if ve.MinUnflushedLogNum != 0 {
     270           1 :                         vs.minUnflushedLogNum = ve.MinUnflushedLogNum
     271           1 :                 }
     272           1 :                 if ve.NextFileNum != 0 {
     273           1 :                         vs.nextFileNum.Store(ve.NextFileNum)
     274           1 :                 }
     275           1 :                 if ve.LastSeqNum != 0 {
     276           1 :                         // logSeqNum is the _next_ sequence number that will be assigned,
     277           1 :                         // while LastSeqNum is the last assigned sequence number. Note that
     278           1 :                         // this behaviour mimics that in RocksDB; the first sequence number
     279           1 :                         // assigned is one greater than the one present in the manifest
     280           1 :                         // (assuming no WALs contain higher sequence numbers than the
     281           1 :                         // manifest's LastSeqNum). Increment LastSeqNum by 1 to get the
     282           1 :                         // next sequence number that will be assigned.
     283           1 :                         //
     284           1 :                         // If LastSeqNum is less than SeqNumStart, increase it to at least
     285           1 :                         // SeqNumStart to leave ample room for reserved sequence numbers.
     286           1 :                         if ve.LastSeqNum+1 < base.SeqNumStart {
     287           0 :                                 vs.logSeqNum.Store(base.SeqNumStart)
     288           1 :                         } else {
     289           1 :                                 vs.logSeqNum.Store(ve.LastSeqNum + 1)
     290           1 :                         }
     291             :                 }
     292             :         }
     293             :         // We have already set vs.nextFileNum = 2 at the beginning of the
     294             :         // function and could have only updated it to some other non-zero value,
     295             :         // so it cannot be 0 here.
     296           1 :         if vs.minUnflushedLogNum == 0 {
     297           1 :                 if vs.nextFileNum.Load() >= 2 {
     298           1 :                         // We either have a freshly created DB, or a DB created by RocksDB
     299           1 :                         // that has not had a single flushed SSTable yet. This is because
     300           1 :                         // RocksDB bumps up nextFileNum in this case without bumping up
     301           1 :                         // minUnflushedLogNum, even if WALs with non-zero file numbers are
     302           1 :                         // present in the directory.
     303           1 :                 } else {
     304           0 :                         return base.CorruptionErrorf("pebble: malformed manifest file %q for DB %q",
     305           0 :                                 errors.Safe(manifestFilename), dirname)
     306           0 :                 }
     307             :         }
     308           1 :         vs.markFileNumUsed(vs.minUnflushedLogNum)
     309           1 : 
     310           1 :         // Populate the fileBackingMap and the FileBacking for virtual sstables since
     311           1 :         // we have finished version edit accumulation.
     312           1 :         for _, b := range bve.AddedFileBacking {
     313           1 :                 vs.virtualBackings.AddAndRef(b)
     314           1 :         }
     315             : 
     316           1 :         for _, addedLevel := range bve.Added {
     317           1 :                 for _, m := range addedLevel {
     318           1 :                         if m.Virtual {
     319           1 :                                 vs.virtualBackings.AddTable(m)
     320           1 :                         }
     321             :                 }
     322             :         }
     323             : 
     324           1 :         if invariants.Enabled {
     325           1 :                 // There should be no deleted tables or backings, since we're starting from
     326           1 :                 // an empty state.
     327           1 :                 for _, deletedLevel := range bve.Deleted {
     328           1 :                         if len(deletedLevel) != 0 {
     329           0 :                                 panic("deleted files after manifest replay")
     330             :                         }
     331             :                 }
     332           1 :                 if len(bve.RemovedFileBacking) > 0 {
     333           0 :                         panic("deleted backings after manifest replay")
     334             :                 }
     335             :         }
     336             : 
     337           1 :         newVersion, err := bve.Apply(nil, opts.Comparer, opts.FlushSplitBytes, opts.Experimental.ReadCompactionRate)
     338           1 :         if err != nil {
     339           0 :                 return err
     340           0 :         }
     341           1 :         newVersion.L0Sublevels.InitCompactingFileInfo(nil /* in-progress compactions */)
     342           1 :         vs.append(newVersion)
     343           1 : 
     344           1 :         for i := range vs.metrics.Levels {
     345           1 :                 l := &vs.metrics.Levels[i]
     346           1 :                 l.NumFiles = int64(newVersion.Levels[i].Len())
     347           1 :                 files := newVersion.Levels[i].Slice()
     348           1 :                 l.Size = int64(files.SizeSum())
     349           1 :         }
     350           1 :         for _, l := range newVersion.Levels {
     351           1 :                 iter := l.Iter()
     352           1 :                 for f := iter.First(); f != nil; f = iter.Next() {
     353           1 :                         if !f.Virtual {
     354           1 :                                 _, localSize := sizeIfLocal(f.FileBacking, vs.provider)
     355           1 :                                 vs.metrics.Table.Local.LiveSize = uint64(int64(vs.metrics.Table.Local.LiveSize) + localSize)
     356           1 :                         }
     357             :                 }
     358             :         }
     359           1 :         vs.virtualBackings.ForEach(func(backing *fileBacking) {
     360           1 :                 _, localSize := sizeIfLocal(backing, vs.provider)
     361           1 :                 vs.metrics.Table.Local.LiveSize = uint64(int64(vs.metrics.Table.Local.LiveSize) + localSize)
     362           1 :         })
     363             : 
     364           1 :         vs.picker = newCompactionPickerByScore(newVersion, &vs.virtualBackings, vs.opts, nil)
     365           1 :         return nil
     366             : }
     367             : 
     368           1 : func (vs *versionSet) close() error {
     369           1 :         if vs.manifestFile != nil {
     370           1 :                 if err := vs.manifestFile.Close(); err != nil {
     371           0 :                         return err
     372           0 :                 }
     373             :         }
     374           1 :         if vs.manifestMarker != nil {
     375           1 :                 if err := vs.manifestMarker.Close(); err != nil {
     376           0 :                         return err
     377           0 :                 }
     378             :         }
     379           1 :         return nil
     380             : }
     381             : 
     382             : // logLock locks the manifest for writing. The lock must be released by either
     383             : // a call to logUnlock or logAndApply.
     384             : //
     385             : // DB.mu must be held when calling this method, but the mutex may be dropped and
     386             : // re-acquired during the course of this method.
     387           1 : func (vs *versionSet) logLock() {
     388           1 :         // Wait for any existing writing to the manifest to complete, then mark the
     389           1 :         // manifest as busy.
     390           1 :         for vs.writing {
     391           1 :                 // Note: writerCond.L is DB.mu, so we unlock it while we wait.
     392           1 :                 vs.writerCond.Wait()
     393           1 :         }
     394           1 :         vs.writing = true
     395             : }
     396             : 
     397             : // logUnlock releases the lock for manifest writing.
     398             : //
     399             : // DB.mu must be held when calling this method.
     400           1 : func (vs *versionSet) logUnlock() {
     401           1 :         if !vs.writing {
     402           0 :                 vs.opts.Logger.Fatalf("MANIFEST not locked for writing")
     403           0 :         }
     404           1 :         vs.writing = false
     405           1 :         vs.writerCond.Signal()
     406             : }
     407             : 
     408             : // logAndApply logs the version edit to the manifest, applies the version edit
     409             : // to the current version, and installs the new version.
     410             : //
     411             : // logAndApply fills in the following fields of the VersionEdit: NextFileNum,
     412             : // LastSeqNum, RemovedBackingTables. The removed backing tables are those
     413             : // backings that are no longer used (in the new version) after applying the edit
     414             : // (as per vs.virtualBackings). Other than these fields, the VersionEdit must be
     415             : // complete.
     416             : //
     417             : // New table backing references (FileBacking.Ref) are taken as part of applying
     418             : // the version edit. The state of the virtual backings (vs.virtualBackings) is
     419             : // updated before logging to the manifest and installing the latest version;
     420             : // this is ok because any failure in those steps is fatal.
     421             : // TODO(radu): remove the error return.
     422             : //
     423             : // DB.mu must be held when calling this method and will be released temporarily
     424             : // while performing file I/O. Requires that the manifest is locked for writing
     425             : // (see logLock). Will unconditionally release the manifest lock (via
     426             : // logUnlock) even if an error occurs.
     427             : //
     428             : // inProgressCompactions is called while DB.mu is held, to get the list of
     429             : // in-progress compactions.
     430             : func (vs *versionSet) logAndApply(
     431             :         jobID JobID,
     432             :         ve *versionEdit,
     433             :         metrics map[int]*LevelMetrics,
     434             :         forceRotation bool,
     435             :         inProgressCompactions func() []compactionInfo,
     436           1 : ) error {
     437           1 :         if !vs.writing {
     438           0 :                 vs.opts.Logger.Fatalf("MANIFEST not locked for writing")
     439           0 :         }
     440           1 :         defer vs.logUnlock()
     441           1 : 
     442           1 :         if ve.MinUnflushedLogNum != 0 {
     443           1 :                 if ve.MinUnflushedLogNum < vs.minUnflushedLogNum ||
     444           1 :                         vs.nextFileNum.Load() <= uint64(ve.MinUnflushedLogNum) {
     445           0 :                         panic(fmt.Sprintf("pebble: inconsistent versionEdit minUnflushedLogNum %d",
     446           0 :                                 ve.MinUnflushedLogNum))
     447             :                 }
     448             :         }
     449             : 
     450             :         // This is the next manifest filenum, but if the current file is too big we
     451             :         // will write this ve to the next file which means what ve encodes is the
     452             :         // current filenum and not the next one.
     453             :         //
     454             :         // TODO(sbhola): figure out why this is correct and update comment.
     455           1 :         ve.NextFileNum = vs.nextFileNum.Load()
     456           1 : 
     457           1 :         // LastSeqNum is set to the current upper bound on the assigned sequence
     458           1 :         // numbers. Note that this is exactly the behavior of RocksDB. LastSeqNum is
     459           1 :         // used to initialize versionSet.logSeqNum and versionSet.visibleSeqNum on
     460           1 :         // replay. It must be higher than or equal to any than any sequence number
     461           1 :         // written to an sstable, including sequence numbers in ingested files.
     462           1 :         // Note that LastSeqNum is not (and cannot be) the minimum unflushed sequence
     463           1 :         // number. This is fallout from ingestion which allows a sequence number X to
     464           1 :         // be assigned to an ingested sstable even though sequence number X-1 resides
     465           1 :         // in an unflushed memtable. logSeqNum is the _next_ sequence number that
     466           1 :         // will be assigned, so subtract that by 1 to get the upper bound on the
     467           1 :         // last assigned sequence number.
     468           1 :         logSeqNum := vs.logSeqNum.Load()
     469           1 :         ve.LastSeqNum = logSeqNum - 1
     470           1 :         if logSeqNum == 0 {
     471           0 :                 // logSeqNum is initialized to 1 in Open() if there are no previous WAL
     472           0 :                 // or manifest records, so this case should never happen.
     473           0 :                 vs.opts.Logger.Fatalf("logSeqNum must be a positive integer: %d", logSeqNum)
     474           0 :         }
     475             : 
     476           1 :         currentVersion := vs.currentVersion()
     477           1 :         var newVersion *version
     478           1 : 
     479           1 :         // Generate a new manifest if we don't currently have one, or forceRotation
     480           1 :         // is true, or the current one is too large.
     481           1 :         //
     482           1 :         // For largeness, we do not exclusively use MaxManifestFileSize size
     483           1 :         // threshold since we have had incidents where due to either large keys or
     484           1 :         // large numbers of files, each edit results in a snapshot + write of the
     485           1 :         // edit. This slows the system down since each flush or compaction is
     486           1 :         // writing a new manifest snapshot. The primary goal of the size-based
     487           1 :         // rollover logic is to ensure that when reopening a DB, the number of edits
     488           1 :         // that need to be replayed on top of the snapshot is "sane". Rolling over
     489           1 :         // to a new manifest after each edit is not relevant to that goal.
     490           1 :         //
     491           1 :         // Consider the following cases:
     492           1 :         // - The number of live files F in the DB is roughly stable: after writing
     493           1 :         //   the snapshot (with F files), say we require that there be enough edits
     494           1 :         //   such that the cumulative number of files in those edits, E, be greater
     495           1 :         //   than F. This will ensure that the total amount of time in logAndApply
     496           1 :         //   that is spent in snapshot writing is ~50%.
     497           1 :         //
     498           1 :         // - The number of live files F in the DB is shrinking drastically, say from
     499           1 :         //   F to F/10: This can happen for various reasons, like wide range
     500           1 :         //   tombstones, or large numbers of smaller than usual files that are being
     501           1 :         //   merged together into larger files. And say the new files generated
     502           1 :         //   during this shrinkage is insignificant compared to F/10, and so for
     503           1 :         //   this example we will assume it is effectively 0. After this shrinking,
     504           1 :         //   E = 0.9F, and so if we used the previous snapshot file count, F, as the
     505           1 :         //   threshold that needs to be exceeded, we will further delay the snapshot
     506           1 :         //   writing. Which means on DB reopen we will need to replay 0.9F edits to
     507           1 :         //   get to a version with 0.1F files. It would be better to create a new
     508           1 :         //   snapshot when E exceeds the number of files in the current version.
     509           1 :         //
     510           1 :         // - The number of live files F in the DB is growing via perfect ingests
     511           1 :         //   into L6: Say we wrote the snapshot when there were F files and now we
     512           1 :         //   have 10F files, so E = 9F. We will further delay writing a new
     513           1 :         //   snapshot. This case can be critiqued as contrived, but we consider it
     514           1 :         //   nonetheless.
     515           1 :         //
     516           1 :         // The logic below uses the min of the last snapshot file count and the file
     517           1 :         // count in the current version.
     518           1 :         vs.rotationHelper.AddRecord(int64(len(ve.DeletedFiles) + len(ve.NewFiles)))
     519           1 :         sizeExceeded := vs.manifest.Size() >= vs.opts.MaxManifestFileSize
     520           1 :         requireRotation := forceRotation || vs.manifest == nil
     521           1 : 
     522           1 :         var nextSnapshotFilecount int64
     523           1 :         for i := range vs.metrics.Levels {
     524           1 :                 nextSnapshotFilecount += vs.metrics.Levels[i].NumFiles
     525           1 :         }
     526           1 :         if sizeExceeded && !requireRotation {
     527           1 :                 requireRotation = vs.rotationHelper.ShouldRotate(nextSnapshotFilecount)
     528           1 :         }
     529           1 :         var newManifestFileNum base.DiskFileNum
     530           1 :         var prevManifestFileSize uint64
     531           1 :         var newManifestVirtualBackings []*fileBacking
     532           1 :         if requireRotation {
     533           1 :                 newManifestFileNum = vs.getNextDiskFileNum()
     534           1 :                 prevManifestFileSize = uint64(vs.manifest.Size())
     535           1 : 
     536           1 :                 // We want the virtual backings *before* applying the version edit, because
     537           1 :                 // the new manifest will contain the pre-apply version plus the last version
     538           1 :                 // edit.
     539           1 :                 newManifestVirtualBackings = vs.virtualBackings.Backings()
     540           1 :         }
     541             : 
     542             :         // Grab certain values before releasing vs.mu, in case createManifest() needs
     543             :         // to be called.
     544           1 :         minUnflushedLogNum := vs.minUnflushedLogNum
     545           1 :         nextFileNum := vs.nextFileNum.Load()
     546           1 : 
     547           1 :         // Note: this call populates ve.RemovedBackingTables.
     548           1 :         zombieBackings, removedVirtualBackings, localLiveSizeDelta :=
     549           1 :                 getZombiesAndUpdateVirtualBackings(ve, &vs.virtualBackings, vs.provider)
     550           1 : 
     551           1 :         if err := func() error {
     552           1 :                 vs.mu.Unlock()
     553           1 :                 defer vs.mu.Lock()
     554           1 : 
     555           1 :                 if vs.getFormatMajorVersion() < FormatVirtualSSTables && len(ve.CreatedBackingTables) > 0 {
     556           0 :                         return base.AssertionFailedf("MANIFEST cannot contain virtual sstable records due to format major version")
     557           0 :                 }
     558           1 :                 var b bulkVersionEdit
     559           1 :                 err := b.Accumulate(ve)
     560           1 :                 if err != nil {
     561           0 :                         return errors.Wrap(err, "MANIFEST accumulate failed")
     562           0 :                 }
     563           1 :                 newVersion, err = b.Apply(
     564           1 :                         currentVersion, vs.cmp, vs.opts.FlushSplitBytes, vs.opts.Experimental.ReadCompactionRate,
     565           1 :                 )
     566           1 :                 if err != nil {
     567           0 :                         return errors.Wrap(err, "MANIFEST apply failed")
     568           0 :                 }
     569             : 
     570           1 :                 if newManifestFileNum != 0 {
     571           1 :                         if err := vs.createManifest(vs.dirname, newManifestFileNum, minUnflushedLogNum, nextFileNum, newManifestVirtualBackings); err != nil {
     572           1 :                                 vs.opts.EventListener.ManifestCreated(ManifestCreateInfo{
     573           1 :                                         JobID:   int(jobID),
     574           1 :                                         Path:    base.MakeFilepath(vs.fs, vs.dirname, fileTypeManifest, newManifestFileNum),
     575           1 :                                         FileNum: newManifestFileNum,
     576           1 :                                         Err:     err,
     577           1 :                                 })
     578           1 :                                 return errors.Wrap(err, "MANIFEST create failed")
     579           1 :                         }
     580             :                 }
     581             : 
     582           1 :                 w, err := vs.manifest.Next()
     583           1 :                 if err != nil {
     584           0 :                         return errors.Wrap(err, "MANIFEST next record write failed")
     585           0 :                 }
     586             : 
     587             :                 // NB: Any error from this point on is considered fatal as we don't know if
     588             :                 // the MANIFEST write occurred or not. Trying to determine that is
     589             :                 // fraught. Instead we rely on the standard recovery mechanism run when a
     590             :                 // database is open. In particular, that mechanism generates a new MANIFEST
     591             :                 // and ensures it is synced.
     592           1 :                 if err := ve.Encode(w); err != nil {
     593           0 :                         return errors.Wrap(err, "MANIFEST write failed")
     594           0 :                 }
     595           1 :                 if err := vs.manifest.Flush(); err != nil {
     596           1 :                         return errors.Wrap(err, "MANIFEST flush failed")
     597           1 :                 }
     598           1 :                 if err := vs.manifestFile.Sync(); err != nil {
     599           1 :                         return errors.Wrap(err, "MANIFEST sync failed")
     600           1 :                 }
     601           1 :                 if newManifestFileNum != 0 {
     602           1 :                         // NB: Move() is responsible for syncing the data directory.
     603           1 :                         if err := vs.manifestMarker.Move(base.MakeFilename(fileTypeManifest, newManifestFileNum)); err != nil {
     604           0 :                                 return errors.Wrap(err, "MANIFEST set current failed")
     605           0 :                         }
     606           1 :                         vs.opts.EventListener.ManifestCreated(ManifestCreateInfo{
     607           1 :                                 JobID:   int(jobID),
     608           1 :                                 Path:    base.MakeFilepath(vs.fs, vs.dirname, fileTypeManifest, newManifestFileNum),
     609           1 :                                 FileNum: newManifestFileNum,
     610           1 :                         })
     611             :                 }
     612           1 :                 return nil
     613           1 :         }(); err != nil {
     614           1 :                 // Any error encountered during any of the operations in the previous
     615           1 :                 // closure are considered fatal. Treating such errors as fatal is preferred
     616           1 :                 // to attempting to unwind various file and b-tree reference counts, and
     617           1 :                 // re-generating L0 sublevel metadata. This may change in the future, if
     618           1 :                 // certain manifest / WAL operations become retryable. For more context, see
     619           1 :                 // #1159 and #1792.
     620           1 :                 vs.opts.Logger.Fatalf("%s", err)
     621           1 :                 return err
     622           1 :         }
     623             : 
     624           1 :         if requireRotation {
     625           1 :                 // Successfully rotated.
     626           1 :                 vs.rotationHelper.Rotate(nextSnapshotFilecount)
     627           1 :         }
     628             :         // Now that DB.mu is held again, initialize compacting file info in
     629             :         // L0Sublevels.
     630           1 :         inProgress := inProgressCompactions()
     631           1 : 
     632           1 :         newVersion.L0Sublevels.InitCompactingFileInfo(inProgressL0Compactions(inProgress))
     633           1 : 
     634           1 :         // Update the zombie tables set first, as installation of the new version
     635           1 :         // will unref the previous version which could result in addObsoleteLocked
     636           1 :         // being called.
     637           1 :         for _, b := range zombieBackings {
     638           1 :                 vs.zombieTables[b.backing.DiskFileNum] = tableInfo{
     639           1 :                         fileInfo: fileInfo{
     640           1 :                                 FileNum:  b.backing.DiskFileNum,
     641           1 :                                 FileSize: b.backing.Size,
     642           1 :                         },
     643           1 :                         isLocal: b.isLocal,
     644           1 :                 }
     645           1 :         }
     646             : 
     647             :         // Unref the removed backings and report those that already became obsolete.
     648             :         // Note that the only case where we report obsolete tables here is when
     649             :         // VirtualBackings.Protect/Unprotect was used to keep a backing alive without
     650             :         // it being used in the current version.
     651           1 :         var obsoleteVirtualBackings []*fileBacking
     652           1 :         for _, b := range removedVirtualBackings {
     653           1 :                 if b.backing.Unref() == 0 {
     654           1 :                         obsoleteVirtualBackings = append(obsoleteVirtualBackings, b.backing)
     655           1 :                 }
     656             :         }
     657           1 :         vs.addObsoleteLocked(obsoleteVirtualBackings)
     658           1 : 
     659           1 :         // Install the new version.
     660           1 :         vs.append(newVersion)
     661           1 : 
     662           1 :         if ve.MinUnflushedLogNum != 0 {
     663           1 :                 vs.minUnflushedLogNum = ve.MinUnflushedLogNum
     664           1 :         }
     665           1 :         if newManifestFileNum != 0 {
     666           1 :                 if vs.manifestFileNum != 0 {
     667           1 :                         vs.obsoleteManifests = append(vs.obsoleteManifests, fileInfo{
     668           1 :                                 FileNum:  vs.manifestFileNum,
     669           1 :                                 FileSize: prevManifestFileSize,
     670           1 :                         })
     671           1 :                 }
     672           1 :                 vs.manifestFileNum = newManifestFileNum
     673             :         }
     674             : 
     675           1 :         for level, update := range metrics {
     676           1 :                 vs.metrics.Levels[level].Add(update)
     677           1 :         }
     678           1 :         for i := range vs.metrics.Levels {
     679           1 :                 l := &vs.metrics.Levels[i]
     680           1 :                 l.NumFiles = int64(newVersion.Levels[i].Len())
     681           1 :                 l.NumVirtualFiles = newVersion.Levels[i].NumVirtual
     682           1 :                 l.VirtualSize = newVersion.Levels[i].VirtualSize
     683           1 :                 l.Size = int64(newVersion.Levels[i].Size())
     684           1 : 
     685           1 :                 l.Sublevels = 0
     686           1 :                 if l.NumFiles > 0 {
     687           1 :                         l.Sublevels = 1
     688           1 :                 }
     689           1 :                 if invariants.Enabled {
     690           1 :                         levelFiles := newVersion.Levels[i].Slice()
     691           1 :                         if size := int64(levelFiles.SizeSum()); l.Size != size {
     692           0 :                                 vs.opts.Logger.Fatalf("versionSet metrics L%d Size = %d, actual size = %d", i, l.Size, size)
     693           0 :                         }
     694           1 :                         if nVirtual := levelFiles.NumVirtual(); nVirtual != l.NumVirtualFiles {
     695           0 :                                 vs.opts.Logger.Fatalf(
     696           0 :                                         "versionSet metrics L%d NumVirtual = %d, actual NumVirtual = %d",
     697           0 :                                         i, l.NumVirtualFiles, nVirtual,
     698           0 :                                 )
     699           0 :                         }
     700           1 :                         if vSize := levelFiles.VirtualSizeSum(); vSize != l.VirtualSize {
     701           0 :                                 vs.opts.Logger.Fatalf(
     702           0 :                                         "versionSet metrics L%d Virtual size = %d, actual size = %d",
     703           0 :                                         i, l.VirtualSize, vSize,
     704           0 :                                 )
     705           0 :                         }
     706             :                 }
     707             :         }
     708           1 :         vs.metrics.Levels[0].Sublevels = int32(len(newVersion.L0SublevelFiles))
     709           1 :         vs.metrics.Table.Local.LiveSize = uint64(int64(vs.metrics.Table.Local.LiveSize) + localLiveSizeDelta)
     710           1 : 
     711           1 :         vs.picker = newCompactionPickerByScore(newVersion, &vs.virtualBackings, vs.opts, inProgress)
     712           1 :         if !vs.dynamicBaseLevel {
     713           1 :                 vs.picker.forceBaseLevel1()
     714           1 :         }
     715           1 :         return nil
     716             : }
     717             : 
     718             : type fileBackingInfo struct {
     719             :         backing *fileBacking
     720             :         isLocal bool
     721             : }
     722             : 
     723             : // getZombiesAndUpdateVirtualBackings updates the virtual backings with the
     724             : // changes in the versionEdit and populates ve.RemovedBackingTables.
     725             : // Returns:
     726             : //   - zombieBackings: all backings (physical and virtual) that will no longer be
     727             : //     needed when we apply ve.
     728             : //   - removedVirtualBackings: the virtual backings that will be removed by the
     729             : //     VersionEdit and which must be Unref()ed by the caller. These backings
     730             : //     match ve.RemovedBackingTables.
     731             : //   - localLiveSizeDelta: the delta in local live bytes.
     732             : func getZombiesAndUpdateVirtualBackings(
     733             :         ve *versionEdit, virtualBackings *manifest.VirtualBackings, provider objstorage.Provider,
     734           1 : ) (zombieBackings, removedVirtualBackings []fileBackingInfo, localLiveSizeDelta int64) {
     735           1 :         // First, deal with the physical tables.
     736           1 :         //
     737           1 :         // A physical backing has become unused if it is in DeletedFiles but not in
     738           1 :         // NewFiles or CreatedBackingTables.
     739           1 :         //
     740           1 :         // Note that for the common case where there are very few elements, the map
     741           1 :         // will stay on the stack.
     742           1 :         stillUsed := make(map[base.DiskFileNum]struct{})
     743           1 :         for _, nf := range ve.NewFiles {
     744           1 :                 if !nf.Meta.Virtual {
     745           1 :                         stillUsed[nf.Meta.FileBacking.DiskFileNum] = struct{}{}
     746           1 :                         _, localFileDelta := sizeIfLocal(nf.Meta.FileBacking, provider)
     747           1 :                         localLiveSizeDelta += localFileDelta
     748           1 :                 }
     749             :         }
     750           1 :         for _, b := range ve.CreatedBackingTables {
     751           1 :                 stillUsed[b.DiskFileNum] = struct{}{}
     752           1 :         }
     753           1 :         for _, m := range ve.DeletedFiles {
     754           1 :                 if !m.Virtual {
     755           1 :                         // NB: this deleted file may also be in NewFiles or
     756           1 :                         // CreatedBackingTables, due to a file moving between levels, or
     757           1 :                         // becoming virtualized. In which case there is no change due to this
     758           1 :                         // file in the localLiveSizeDelta -- the subtraction below compensates
     759           1 :                         // for the addition.
     760           1 :                         isLocal, localFileDelta := sizeIfLocal(m.FileBacking, provider)
     761           1 :                         localLiveSizeDelta -= localFileDelta
     762           1 :                         if _, ok := stillUsed[m.FileBacking.DiskFileNum]; !ok {
     763           1 :                                 zombieBackings = append(zombieBackings, fileBackingInfo{
     764           1 :                                         backing: m.FileBacking,
     765           1 :                                         isLocal: isLocal,
     766           1 :                                 })
     767           1 :                         }
     768             :                 }
     769             :         }
     770             : 
     771             :         // Now deal with virtual tables.
     772             :         //
     773             :         // When a virtual table moves between levels we AddTable() then RemoveTable(),
     774             :         // which works out.
     775           1 :         for _, b := range ve.CreatedBackingTables {
     776           1 :                 virtualBackings.AddAndRef(b)
     777           1 :                 _, localFileDelta := sizeIfLocal(b, provider)
     778           1 :                 localLiveSizeDelta += localFileDelta
     779           1 :         }
     780           1 :         for _, nf := range ve.NewFiles {
     781           1 :                 if nf.Meta.Virtual {
     782           1 :                         virtualBackings.AddTable(nf.Meta)
     783           1 :                 }
     784             :         }
     785           1 :         for _, m := range ve.DeletedFiles {
     786           1 :                 if m.Virtual {
     787           1 :                         virtualBackings.RemoveTable(m)
     788           1 :                 }
     789             :         }
     790             : 
     791           1 :         if unused := virtualBackings.Unused(); len(unused) > 0 {
     792           1 :                 // Virtual backings that are no longer used are zombies and are also added
     793           1 :                 // to RemovedBackingTables (before the version edit is written to disk).
     794           1 :                 ve.RemovedBackingTables = make([]base.DiskFileNum, len(unused))
     795           1 :                 for i, b := range unused {
     796           1 :                         isLocal, localFileDelta := sizeIfLocal(b, provider)
     797           1 :                         localLiveSizeDelta -= localFileDelta
     798           1 :                         ve.RemovedBackingTables[i] = b.DiskFileNum
     799           1 :                         zombieBackings = append(zombieBackings, fileBackingInfo{
     800           1 :                                 backing: b,
     801           1 :                                 isLocal: isLocal,
     802           1 :                         })
     803           1 :                         virtualBackings.Remove(b.DiskFileNum)
     804           1 :                 }
     805           1 :                 removedVirtualBackings = zombieBackings[len(zombieBackings)-len(unused):]
     806             :         }
     807           1 :         return zombieBackings, removedVirtualBackings, localLiveSizeDelta
     808             : }
     809             : 
     810             : // sizeIfLocal returns backing.Size if the backing is a local file, else 0.
     811             : func sizeIfLocal(
     812             :         backing *fileBacking, provider objstorage.Provider,
     813           1 : ) (isLocal bool, localSize int64) {
     814           1 :         isLocal = objstorage.IsLocalTable(provider, backing.DiskFileNum)
     815           1 :         if isLocal {
     816           1 :                 return true, int64(backing.Size)
     817           1 :         }
     818           1 :         return false, 0
     819             : }
     820             : 
     821             : func (vs *versionSet) incrementCompactions(
     822             :         kind compactionKind, extraLevels []*compactionLevel, pickerMetrics compactionPickerMetrics,
     823           1 : ) {
     824           1 :         switch kind {
     825           1 :         case compactionKindDefault:
     826           1 :                 vs.metrics.Compact.Count++
     827           1 :                 vs.metrics.Compact.DefaultCount++
     828             : 
     829           1 :         case compactionKindFlush, compactionKindIngestedFlushable:
     830           1 :                 vs.metrics.Flush.Count++
     831             : 
     832           1 :         case compactionKindMove:
     833           1 :                 vs.metrics.Compact.Count++
     834           1 :                 vs.metrics.Compact.MoveCount++
     835             : 
     836           1 :         case compactionKindDeleteOnly:
     837           1 :                 vs.metrics.Compact.Count++
     838           1 :                 vs.metrics.Compact.DeleteOnlyCount++
     839             : 
     840           1 :         case compactionKindElisionOnly:
     841           1 :                 vs.metrics.Compact.Count++
     842           1 :                 vs.metrics.Compact.ElisionOnlyCount++
     843             : 
     844           1 :         case compactionKindRead:
     845           1 :                 vs.metrics.Compact.Count++
     846           1 :                 vs.metrics.Compact.ReadCount++
     847             : 
     848           0 :         case compactionKindTombstoneDensity:
     849           0 :                 vs.metrics.Compact.Count++
     850           0 :                 vs.metrics.Compact.TombstoneDensityCount++
     851             : 
     852           1 :         case compactionKindRewrite:
     853           1 :                 vs.metrics.Compact.Count++
     854           1 :                 vs.metrics.Compact.RewriteCount++
     855             : 
     856           1 :         case compactionKindCopy:
     857           1 :                 vs.metrics.Compact.Count++
     858           1 :                 vs.metrics.Compact.CopyCount++
     859             : 
     860           0 :         default:
     861           0 :                 if invariants.Enabled {
     862           0 :                         panic("unhandled compaction kind")
     863             :                 }
     864             :         }
     865           1 :         if len(extraLevels) > 0 {
     866           1 :                 vs.metrics.Compact.MultiLevelCount++
     867           1 :         }
     868             : }
     869             : 
     870           1 : func (vs *versionSet) incrementCompactionBytes(numBytes int64) {
     871           1 :         vs.atomicInProgressBytes.Add(numBytes)
     872           1 : }
     873             : 
     874             : // createManifest creates a manifest file that contains a snapshot of vs.
     875             : func (vs *versionSet) createManifest(
     876             :         dirname string,
     877             :         fileNum, minUnflushedLogNum base.DiskFileNum,
     878             :         nextFileNum uint64,
     879             :         virtualBackings []*fileBacking,
     880           1 : ) (err error) {
     881           1 :         var (
     882           1 :                 filename     = base.MakeFilepath(vs.fs, dirname, fileTypeManifest, fileNum)
     883           1 :                 manifestFile vfs.File
     884           1 :                 manifest     *record.Writer
     885           1 :         )
     886           1 :         defer func() {
     887           1 :                 if manifest != nil {
     888           0 :                         manifest.Close()
     889           0 :                 }
     890           1 :                 if manifestFile != nil {
     891           0 :                         manifestFile.Close()
     892           0 :                 }
     893           1 :                 if err != nil {
     894           1 :                         vs.fs.Remove(filename)
     895           1 :                 }
     896             :         }()
     897           1 :         manifestFile, err = vs.fs.Create(filename, "pebble-manifest")
     898           1 :         if err != nil {
     899           1 :                 return err
     900           1 :         }
     901           1 :         manifest = record.NewWriter(manifestFile)
     902           1 : 
     903           1 :         snapshot := versionEdit{
     904           1 :                 ComparerName: vs.cmp.Name,
     905           1 :         }
     906           1 : 
     907           1 :         for level, levelMetadata := range vs.currentVersion().Levels {
     908           1 :                 iter := levelMetadata.Iter()
     909           1 :                 for meta := iter.First(); meta != nil; meta = iter.Next() {
     910           1 :                         snapshot.NewFiles = append(snapshot.NewFiles, newFileEntry{
     911           1 :                                 Level: level,
     912           1 :                                 Meta:  meta,
     913           1 :                         })
     914           1 :                 }
     915             :         }
     916             : 
     917           1 :         snapshot.CreatedBackingTables = virtualBackings
     918           1 : 
     919           1 :         // When creating a version snapshot for an existing DB, this snapshot VersionEdit will be
     920           1 :         // immediately followed by another VersionEdit (being written in logAndApply()). That
     921           1 :         // VersionEdit always contains a LastSeqNum, so we don't need to include that in the snapshot.
     922           1 :         // But it does not necessarily include MinUnflushedLogNum, NextFileNum, so we initialize those
     923           1 :         // using the corresponding fields in the versionSet (which came from the latest preceding
     924           1 :         // VersionEdit that had those fields).
     925           1 :         snapshot.MinUnflushedLogNum = minUnflushedLogNum
     926           1 :         snapshot.NextFileNum = nextFileNum
     927           1 : 
     928           1 :         w, err1 := manifest.Next()
     929           1 :         if err1 != nil {
     930           0 :                 return err1
     931           0 :         }
     932           1 :         if err := snapshot.Encode(w); err != nil {
     933           0 :                 return err
     934           0 :         }
     935             : 
     936           1 :         if vs.manifest != nil {
     937           1 :                 vs.manifest.Close()
     938           1 :                 vs.manifest = nil
     939           1 :         }
     940           1 :         if vs.manifestFile != nil {
     941           1 :                 if err := vs.manifestFile.Close(); err != nil {
     942           0 :                         return err
     943           0 :                 }
     944           1 :                 vs.manifestFile = nil
     945             :         }
     946             : 
     947           1 :         vs.manifest, manifest = manifest, nil
     948           1 :         vs.manifestFile, manifestFile = manifestFile, nil
     949           1 :         return nil
     950             : }
     951             : 
     952             : // NB: This method is not safe for concurrent use. It is only safe
     953             : // to be called when concurrent changes to nextFileNum are not expected.
     954           1 : func (vs *versionSet) markFileNumUsed(fileNum base.DiskFileNum) {
     955           1 :         if vs.nextFileNum.Load() <= uint64(fileNum) {
     956           1 :                 vs.nextFileNum.Store(uint64(fileNum + 1))
     957           1 :         }
     958             : }
     959             : 
     960             : // getNextFileNum returns the next file number to be used.
     961             : //
     962             : // Can be called without the versionSet's mutex being held.
     963           1 : func (vs *versionSet) getNextFileNum() base.FileNum {
     964           1 :         x := vs.nextFileNum.Add(1) - 1
     965           1 :         return base.FileNum(x)
     966           1 : }
     967             : 
     968             : // Can be called without the versionSet's mutex being held.
     969           1 : func (vs *versionSet) getNextDiskFileNum() base.DiskFileNum {
     970           1 :         x := vs.nextFileNum.Add(1) - 1
     971           1 :         return base.DiskFileNum(x)
     972           1 : }
     973             : 
     974           1 : func (vs *versionSet) append(v *version) {
     975           1 :         if v.Refs() != 0 {
     976           0 :                 panic("pebble: version should be unreferenced")
     977             :         }
     978           1 :         if !vs.versions.Empty() {
     979           1 :                 vs.versions.Back().UnrefLocked()
     980           1 :         }
     981           1 :         v.Deleted = vs.obsoleteFn
     982           1 :         v.Ref()
     983           1 :         vs.versions.PushBack(v)
     984           1 :         if invariants.Enabled {
     985           1 :                 // Verify that the virtualBackings contains all the backings referenced by
     986           1 :                 // the version.
     987           1 :                 for _, l := range v.Levels {
     988           1 :                         iter := l.Iter()
     989           1 :                         for f := iter.First(); f != nil; f = iter.Next() {
     990           1 :                                 if f.Virtual {
     991           1 :                                         if _, ok := vs.virtualBackings.Get(f.FileBacking.DiskFileNum); !ok {
     992           0 :                                                 panic(fmt.Sprintf("%s is not in virtualBackings", f.FileBacking.DiskFileNum))
     993             :                                         }
     994             :                                 }
     995             :                         }
     996             :                 }
     997             :         }
     998             : }
     999             : 
    1000           1 : func (vs *versionSet) currentVersion() *version {
    1001           1 :         return vs.versions.Back()
    1002           1 : }
    1003             : 
    1004           1 : func (vs *versionSet) addLiveFileNums(m map[base.DiskFileNum]struct{}) {
    1005           1 :         current := vs.currentVersion()
    1006           1 :         for v := vs.versions.Front(); true; v = v.Next() {
    1007           1 :                 for _, lm := range v.Levels {
    1008           1 :                         iter := lm.Iter()
    1009           1 :                         for f := iter.First(); f != nil; f = iter.Next() {
    1010           1 :                                 m[f.FileBacking.DiskFileNum] = struct{}{}
    1011           1 :                         }
    1012             :                 }
    1013           1 :                 if v == current {
    1014           1 :                         break
    1015             :                 }
    1016             :         }
    1017             :         // virtualBackings contains backings that are referenced by some virtual
    1018             :         // tables in the latest version (which are handled above), and backings that
    1019             :         // are not but are still alive because of the protection mechanism (see
    1020             :         // manifset.VirtualBackings). This loop ensures the latter get added to the
    1021             :         // map.
    1022           1 :         vs.virtualBackings.ForEach(func(b *fileBacking) {
    1023           1 :                 m[b.DiskFileNum] = struct{}{}
    1024           1 :         })
    1025             : }
    1026             : 
    1027             : // addObsoleteLocked will add the fileInfo associated with obsolete backing
    1028             : // sstables to the obsolete tables list.
    1029             : //
    1030             : // The file backings in the obsolete list must not appear more than once.
    1031             : //
    1032             : // DB.mu must be held when addObsoleteLocked is called.
    1033           1 : func (vs *versionSet) addObsoleteLocked(obsolete []*fileBacking) {
    1034           1 :         if len(obsolete) == 0 {
    1035           1 :                 return
    1036           1 :         }
    1037             : 
    1038           1 :         obsoleteFileInfo := make([]tableInfo, len(obsolete))
    1039           1 :         for i, bs := range obsolete {
    1040           1 :                 obsoleteFileInfo[i].FileNum = bs.DiskFileNum
    1041           1 :                 obsoleteFileInfo[i].FileSize = bs.Size
    1042           1 :         }
    1043             : 
    1044           1 :         if invariants.Enabled {
    1045           1 :                 dedup := make(map[base.DiskFileNum]struct{})
    1046           1 :                 for _, fi := range obsoleteFileInfo {
    1047           1 :                         dedup[fi.FileNum] = struct{}{}
    1048           1 :                 }
    1049           1 :                 if len(dedup) != len(obsoleteFileInfo) {
    1050           0 :                         panic("pebble: duplicate FileBacking present in obsolete list")
    1051             :                 }
    1052             :         }
    1053             : 
    1054           1 :         for i, fi := range obsoleteFileInfo {
    1055           1 :                 // Note that the obsolete tables are no longer zombie by the definition of
    1056           1 :                 // zombie, but we leave them in the zombie tables map until they are
    1057           1 :                 // deleted from disk.
    1058           1 :                 //
    1059           1 :                 // TODO(sumeer): this means that the zombie metrics, like ZombieSize,
    1060           1 :                 // computed in DB.Metrics are also being counted in the obsolete metrics.
    1061           1 :                 // Was this intentional?
    1062           1 :                 info, ok := vs.zombieTables[fi.FileNum]
    1063           1 :                 if !ok {
    1064           0 :                         vs.opts.Logger.Fatalf("MANIFEST obsolete table %s not marked as zombie", fi.FileNum)
    1065           0 :                 }
    1066           1 :                 obsoleteFileInfo[i].isLocal = info.isLocal
    1067             :         }
    1068             : 
    1069           1 :         vs.obsoleteTables = append(vs.obsoleteTables, obsoleteFileInfo...)
    1070           1 :         vs.updateObsoleteTableMetricsLocked()
    1071             : }
    1072             : 
    1073             : // addObsolete will acquire DB.mu, so DB.mu must not be held when this is
    1074             : // called.
    1075           1 : func (vs *versionSet) addObsolete(obsolete []*fileBacking) {
    1076           1 :         vs.mu.Lock()
    1077           1 :         defer vs.mu.Unlock()
    1078           1 :         vs.addObsoleteLocked(obsolete)
    1079           1 : }
    1080             : 
    1081           1 : func (vs *versionSet) updateObsoleteTableMetricsLocked() {
    1082           1 :         vs.metrics.Table.ObsoleteCount = int64(len(vs.obsoleteTables))
    1083           1 :         vs.metrics.Table.ObsoleteSize = 0
    1084           1 :         vs.metrics.Table.Local.ObsoleteSize = 0
    1085           1 :         for _, fi := range vs.obsoleteTables {
    1086           1 :                 vs.metrics.Table.ObsoleteSize += fi.FileSize
    1087           1 :                 if fi.isLocal {
    1088           1 :                         vs.metrics.Table.Local.ObsoleteSize += fi.FileSize
    1089           1 :                 }
    1090             :         }
    1091             : }
    1092             : 
    1093             : func findCurrentManifest(
    1094             :         fs vfs.FS, dirname string, ls []string,
    1095           1 : ) (marker *atomicfs.Marker, manifestNum base.DiskFileNum, exists bool, err error) {
    1096           1 :         // Locating a marker should succeed even if the marker has never been placed.
    1097           1 :         var filename string
    1098           1 :         marker, filename, err = atomicfs.LocateMarkerInListing(fs, dirname, manifestMarkerName, ls)
    1099           1 :         if err != nil {
    1100           1 :                 return nil, 0, false, err
    1101           1 :         }
    1102             : 
    1103           1 :         if filename == "" {
    1104           1 :                 // The marker hasn't been set yet. This database doesn't exist.
    1105           1 :                 return marker, 0, false, nil
    1106           1 :         }
    1107             : 
    1108           1 :         var ok bool
    1109           1 :         _, manifestNum, ok = base.ParseFilename(fs, filename)
    1110           1 :         if !ok {
    1111           0 :                 return marker, 0, false, base.CorruptionErrorf("pebble: MANIFEST name %q is malformed", errors.Safe(filename))
    1112           0 :         }
    1113           1 :         return marker, manifestNum, true, nil
    1114             : }
    1115             : 
    1116           1 : func newFileMetrics(newFiles []manifest.NewFileEntry) map[int]*LevelMetrics {
    1117           1 :         m := map[int]*LevelMetrics{}
    1118           1 :         for _, nf := range newFiles {
    1119           1 :                 lm := m[nf.Level]
    1120           1 :                 if lm == nil {
    1121           1 :                         lm = &LevelMetrics{}
    1122           1 :                         m[nf.Level] = lm
    1123           1 :                 }
    1124           1 :                 lm.NumFiles++
    1125           1 :                 lm.Size += int64(nf.Meta.Size)
    1126             :         }
    1127           1 :         return m
    1128             : }

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