db: rename fileBackings to virtualBackings

Rename to clarify that this includes only backings for virtual
sstables.

checkpoint.go

@@ -192,7 +192,7 @@ func (d *DB) Checkpoint(
 	optionsFileNum := d.optionsFileNum
 
 	virtualBackingFiles := make(map[base.DiskFileNum]struct{})
-	d.mu.versions.fileBackings.ForEach(func(backing *fileBacking) {
+	d.mu.versions.virtualBackings.ForEach(func(backing *fileBacking) {
 		virtualBackingFiles[backing.DiskFileNum] = struct{}{}
 	})
 

checkpoint_test.go

@@ -132,7 +132,7 @@ func TestCheckpoint(t *testing.T) {
 			d := dbs[td.CmdArgs[0].String()]
 			d.mu.Lock()
 			d.mu.versions.logLock()
-			fileNums := d.mu.versions.fileBackings.DiskFileNums()
+			fileNums := d.mu.versions.virtualBackings.DiskFileNums()
 			d.mu.versions.logUnlock()
 			d.mu.Unlock()
 

db.go

@@ -2139,7 +2139,7 @@ func (d *DB) Metrics() *Metrics {
 
 	d.mu.versions.logLock()
 	metrics.private.manifestFileSize = uint64(d.mu.versions.manifest.Size())
-	backingCount, backingTotalSize := d.mu.versions.fileBackings.Stats()
+	backingCount, backingTotalSize := d.mu.versions.virtualBackings.Stats()
 	metrics.Table.BackingTableCount = uint64(backingCount)
 	metrics.Table.BackingTableSize = backingTotalSize
 	d.mu.versions.logUnlock()

version_set.go

@@ -84,17 +84,16 @@ type versionSet struct {
 	// still referenced by an inuse iterator.
 	zombieTables map[base.DiskFileNum]uint64 // filenum -> size
 
-	// fileBackings contains the FileBackings with support virtual sstables in the
-	// latest version, sstables in the latest version. Once the file backing is
-	// backing no virtual sstables in the latest version, it is removed from this
-	// map and the corresponding state is added to the zombieTables map. Note that
-	// we don't keep track of file backings which support a virtual sstable which
-	// is not in the latest version.
+	// virtualBackings contains the FileBackings which support virtual sstables in
+	// the latest version. Once the file backing is backing no virtual sstables in
+	// the latest version, it is removed from this map and the corresponding state
+	// is added to the zombieTables map. Note that we don't keep track of file
+	// backings which support a virtual sstable which is not in the latest
+	// version.
 	//
-	// fileBackings is protected by the versionSet.logLock. It's populated
-	// during Open in versionSet.load, but it's not used concurrently during
-	// load.
-	fileBackings manifest.FileBackings
+	// virtualBackings is protected by the versionSet.logLock. It's populated
+	// during Open in versionSet.load, but it's not used concurrently during load.
+	virtualBackings manifest.FileBackings
 
 	// minUnflushedLogNum is the smallest WAL log file number corresponding to
 	// mutations that have not been flushed to an sstable.
@@ -135,7 +134,7 @@ func (vs *versionSet) init(
 	vs.versions.Init(mu)
 	vs.obsoleteFn = vs.addObsoleteLocked
 	vs.zombieTables = make(map[base.DiskFileNum]uint64)
-	vs.fileBackings = manifest.FileBackings{}
+	vs.virtualBackings = manifest.FileBackings{}
 	vs.nextFileNum = 1
 	vs.manifestMarker = marker
 	vs.getFormatMajorVersion = getFMV
@@ -287,11 +286,11 @@ func (vs *versionSet) load(
 	// Populate the fileBackingMap and the FileBacking for virtual sstables since
 	// we have finished version edit accumulation.
 	for _, s := range bve.AddedFileBacking {
-		vs.fileBackings.Add(s)
+		vs.virtualBackings.Add(s)
 	}
 
 	for _, diskFileNum := range bve.RemovedFileBacking {
-		vs.fileBackings.Remove(diskFileNum)
+		vs.virtualBackings.Remove(diskFileNum)
 	}
 
 	newVersion, err := bve.Apply(nil, opts.Comparer, opts.FlushSplitBytes,
@@ -485,7 +484,7 @@ func (vs *versionSet) logAndApply(
 		newVersion, zombies, err = manifest.AccumulateIncompleteAndApplySingleVE(
 			ve, currentVersion, vs.cmp,
 			vs.opts.FlushSplitBytes, vs.opts.Experimental.ReadCompactionRate,
-			&vs.fileBackings,
+			&vs.virtualBackings,
 		)
 		if err != nil {
 			return errors.Wrap(err, "MANIFEST apply failed")

version_set_test.go

@@ -31,7 +31,7 @@ func writeAndIngest(t *testing.T, mem vfs.FS, d *DB, k InternalKey, v []byte, fi
 // d.mu should be help. logLock should not be held.
 func checkBackingSize(t *testing.T, d *DB) {
 	d.mu.versions.logLock()
-	d.mu.versions.fileBackings.Check()
+	d.mu.versions.virtualBackings.Check()
 	d.mu.versions.logUnlock()
 }
 
@@ -156,7 +156,7 @@ func TestLatestRefCounting(t *testing.T) {
 	// to the physical sstable.
 	require.Equal(t, 2, int(m1.LatestRefs()))
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.virtualBackings.DiskFileNums())
 	require.Equal(t, f.Size, m2.FileBacking.VirtualizedSize.Load())
 	checkBackingSize(t, d)
 
@@ -176,7 +176,7 @@ func TestLatestRefCounting(t *testing.T) {
 	require.Equal(t, 1, int(m2.LatestRefs()))
 	require.Equal(t, 0, len(d.mu.versions.zombieTables))
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.virtualBackings.DiskFileNums())
 	require.Equal(t, m2.Size, m2.FileBacking.VirtualizedSize.Load())
 	checkBackingSize(t, d)
 
@@ -193,7 +193,7 @@ func TestLatestRefCounting(t *testing.T) {
 	require.Equal(t, 1, int(m2.LatestRefs()))
 	require.Equal(t, 0, len(d.mu.versions.zombieTables))
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.virtualBackings.DiskFileNums())
 	require.Equal(t, m2.Size, m2.FileBacking.VirtualizedSize.Load())
 
 	// Delete m2 from L6.
@@ -208,7 +208,7 @@ func TestLatestRefCounting(t *testing.T) {
 	require.Equal(t, 0, int(m2.LatestRefs()))
 	require.Equal(t, 1, len(d.mu.versions.zombieTables))
 	require.Equal(t, f.Size, d.mu.versions.zombieTables[f.FileBacking.DiskFileNum])
-	require.Equal(t, []base.DiskFileNum{}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{}, d.mu.versions.virtualBackings.DiskFileNums())
 	require.Equal(t, 0, int(m2.FileBacking.VirtualizedSize.Load()))
 	checkBackingSize(t, d)
 }
@@ -333,7 +333,7 @@ func TestVirtualSSTableManifestReplay(t *testing.T) {
 
 	require.Equal(t, 2, int(m1.LatestRefs()))
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.virtualBackings.DiskFileNums())
 	require.Equal(t, f.Size, m2.FileBacking.VirtualizedSize.Load())
 
 	// Snapshot version edit will be written to a new manifest due to the flush.
@@ -356,7 +356,7 @@ func TestVirtualSSTableManifestReplay(t *testing.T) {
 
 	require.Equal(t, 2, int(virtualFile.LatestRefs()))
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{f.FileBacking.DiskFileNum}, d.mu.versions.virtualBackings.DiskFileNums())
 	require.Equal(t, f.Size, virtualFile.FileBacking.VirtualizedSize.Load())
 	checkBackingSize(t, d)
 	d.mu.Unlock()
@@ -376,7 +376,7 @@ func TestVirtualSSTableManifestReplay(t *testing.T) {
 	}
 	require.Nil(t, virtualFile)
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{}, d.mu.versions.virtualBackings.DiskFileNums())
 	checkBackingSize(t, d)
 	d.mu.Unlock()
 
@@ -397,7 +397,7 @@ func TestVirtualSSTableManifestReplay(t *testing.T) {
 	}
 	require.Nil(t, virtualFile)
 	require.Equal(t, 0, len(d.mu.versions.obsoleteTables))
-	require.Equal(t, []base.DiskFileNum{}, d.mu.versions.fileBackings.DiskFileNums())
+	require.Equal(t, []base.DiskFileNum{}, d.mu.versions.virtualBackings.DiskFileNums())
 	checkBackingSize(t, d)
 	d.mu.Unlock()
 	require.NoError(t, d.Close())