compression: improve compression stats string

Improve the compression stats string to be shorter and more readable:
 - `None` instead of `NoCompression`;
 - remove redundant second number for `None`;
 - order algorithms according to the definition.

We also rename some of the compression constants.

We still support the previous format. The previous format is written
out by v25.3, but is never read back/parsed by that version.

Author: RaduBerinde

internal/compression/adaptive_test.go

@@ -37,7 +37,7 @@ func TestAdaptiveCompressorCompressible(t *testing.T) {
 	// Test the adaptive compressor with compressible data and make sure it uses
 	// the slow algorithm.
 	ac := NewAdaptiveCompressor(AdaptiveCompressorParams{
-		Fast:            None,
+		Fast:            NoCompression,
 		Slow:            ZstdLevel1,
 		ReductionCutoff: 0.6,
 		SampleEvery:     10,

internal/compression/compression.go

@@ -19,10 +19,10 @@ import (
 type Algorithm uint8
 
 const (
-	NoCompression Algorithm = iota
-	SnappyAlgorithm
-	Zstd
+	NoAlgorithm Algorithm = iota
+	Snappy
 	MinLZ
+	Zstd
 
 	NumAlgorithms
 
@@ -33,9 +33,9 @@ const (
 // compression algorithm.
 func (a Algorithm) String() string {
 	switch a {
-	case NoCompression:
-		return "NoCompression"
-	case SnappyAlgorithm:
+	case NoAlgorithm:
+		return "None"
+	case Snappy:
 		return "Snappy"
 	case Zstd:
 		return "ZSTD"
@@ -86,8 +86,8 @@ func ParseSetting(s string) (_ Setting, ok bool) {
 
 // Setting presets.
 var (
-	None          = makePreset(NoCompression, 0)
-	Snappy        = makePreset(SnappyAlgorithm, 0)
+	NoCompression = makePreset(NoAlgorithm, 0)
+	SnappySetting = makePreset(Snappy, 0)
 	MinLZFastest  = makePreset(MinLZ, minlz.LevelFastest)
 	MinLZBalanced = makePreset(MinLZ, minlz.LevelBalanced)
 	ZstdLevel1    = makePreset(Zstd, 1)
@@ -110,9 +110,9 @@ type Compressor interface {
 
 func GetCompressor(s Setting) Compressor {
 	switch s.Algorithm {
-	case NoCompression:
+	case NoAlgorithm:
 		return noopCompressor{}
-	case SnappyAlgorithm:
+	case Snappy:
 		return snappyCompressor{}
 	case Zstd:
 		return getZstdCompressor(int(s.Level))
@@ -143,9 +143,9 @@ type Decompressor interface {
 
 func GetDecompressor(a Algorithm) Decompressor {
 	switch a {
-	case NoCompression:
+	case NoAlgorithm:
 		return noopDecompressor{}
-	case SnappyAlgorithm:
+	case Snappy:
 		return snappyDecompressor{}
 	case Zstd:
 		return getZstdDecompressor()

internal/compression/noop.go

@@ -9,7 +9,7 @@ type noopCompressor struct{}
 var _ Compressor = noopCompressor{}
 
 func (noopCompressor) Compress(dst, src []byte) ([]byte, Setting) {
-	return append(dst[:0], src...), None
+	return append(dst[:0], src...), NoCompression
 }
 func (noopCompressor) Close() {}
 

internal/compression/snappy.go

@@ -14,11 +14,11 @@ type snappyCompressor struct{}
 
 var _ Compressor = snappyCompressor{}
 
-func (snappyCompressor) Algorithm() Algorithm { return SnappyAlgorithm }
+func (snappyCompressor) Algorithm() Algorithm { return Snappy }
 
 func (snappyCompressor) Compress(dst, src []byte) ([]byte, Setting) {
 	dst = dst[:cap(dst):cap(dst)]
-	return snappy.Encode(dst, src), Snappy
+	return snappy.Encode(dst, src), SnappySetting
 }
 
 func (snappyCompressor) Close() {}

metrics.go

@@ -509,9 +509,9 @@ type CompressionStatsForSetting = block.CompressionStatsForSetting
 func (cm *CompressionMetrics) Add(stats *block.CompressionStats) {
 	for s, cs := range stats.All() {
 		switch s.Algorithm {
-		case compression.NoCompression:
+		case compression.NoAlgorithm:
 			cm.NoCompressionBytes += cs.UncompressedBytes
-		case compression.SnappyAlgorithm:
+		case compression.Snappy:
 			cm.Snappy.Add(cs)
 		case compression.MinLZ:
 			cm.MinLZ.Add(cs)

replay/testdata/corpus/simple_ingest

@@ -101,6 +101,6 @@ simple_ingest/MANIFEST-000008:
   size: 209
 simple_ingest/MANIFEST-000010: stat simple_ingest/MANIFEST-000010: file does not exist
 simple_ingest/000007.sst:
-  size: 770
-simple_ingest/000009.sst:
   size: 765
+simple_ingest/000009.sst:
+  size: 759

replay/testdata/corpus/simple_val_sep

@@ -103,6 +103,6 @@ stat simple_val_sep/MANIFEST-000013 simple_val_sep/000015.sst simple_val_sep/000
 simple_val_sep/MANIFEST-000013:
   size: 250
 simple_val_sep/000015.sst:
-  size: 878
+  size: 873
 simple_val_sep/000016.blob:
   size: 97

replay/testdata/replay_ingest

@@ -6,24 +6,24 @@ tree
           /
             build/
       36      000002.log
-     770      000005.sst
-     770      000007.sst
-     765      000009.sst
+     765      000005.sst
+     765      000007.sst
+     759      000009.sst
        0      LOCK
      172      MANIFEST-000001
      209      MANIFEST-000008
     2800      OPTIONS-000003
        0      marker.format-version.000012.025
        0      marker.manifest.000002.MANIFEST-000008
             simple_ingest/
-     770      000007.sst
-     765      000009.sst
+     765      000007.sst
+     759      000009.sst
      172      MANIFEST-000001
      209      MANIFEST-000008
               checkpoint/
       25        000002.log
-     787        000004.sst
-     770        000005.sst
+     782        000004.sst
+     765        000005.sst
      172        MANIFEST-000001
     2800        OPTIONS-000003
        0        marker.format-version.000001.025

replay/testdata/replay_val_sep

@@ -5,14 +5,14 @@ tree
 ----
           /
             build/
-     906      000005.sst
+     900      000005.sst
      101      000006.blob
-     884      000008.sst
+     879      000008.sst
       97      000009.blob
       92      000011.log
-     769      000012.sst
+     764      000012.sst
       63      000014.log
-     878      000015.sst
+     873      000015.sst
       97      000016.blob
        0      LOCK
      152      MANIFEST-000010
@@ -21,16 +21,16 @@ tree
        0      marker.format-version.000011.024
        0      marker.manifest.000003.MANIFEST-000013
             simple_val_sep/
-     878      000015.sst
+     873      000015.sst
       97      000016.blob
      250      MANIFEST-000013
               checkpoint/
-     906        000005.sst
+     900        000005.sst
      101        000006.blob
-     884        000008.sst
+     879        000008.sst
       97        000009.blob
       64        000011.log
-     769        000012.sst
+     764        000012.sst
      187        MANIFEST-000013
     2936        OPTIONS-000003
        0        marker.format-version.000001.024

sstable/block/compression.go

@@ -55,8 +55,8 @@ func (p *CompressionProfile) UsesMinLZ() bool {
 }
 
 var (
-	NoCompression     = simpleCompressionProfile("NoCompression", compression.None)
-	SnappyCompression = simpleCompressionProfile("Snappy", compression.Snappy)
+	NoCompression     = simpleCompressionProfile("NoCompression", compression.NoCompression)
+	SnappyCompression = simpleCompressionProfile("Snappy", compression.SnappySetting)
 	ZstdCompression   = simpleCompressionProfile("ZSTD", compression.ZstdLevel3)
 	MinLZCompression  = simpleCompressionProfile("MinLZ", compression.MinLZFastest)
 
@@ -95,7 +95,7 @@ var fastestCompression = func() compression.Setting {
 	if runtime.GOARCH == "arm64" {
 		// MinLZ is generally faster and better than Snappy except for arm64: Snappy
 		// has an arm64 assembly implementation and MinLZ does not.
-		return compression.Snappy
+		return compression.SnappySetting
 	}
 	return compression.MinLZFastest
 }()
@@ -190,9 +190,9 @@ func (i CompressionIndicator) String() string {
 func (i CompressionIndicator) Algorithm() compression.Algorithm {
 	switch i {
 	case NoCompressionIndicator:
-		return compression.NoCompression
+		return compression.NoAlgorithm
 	case SnappyCompressionIndicator:
-		return compression.SnappyAlgorithm
+		return compression.Snappy
 	case ZstdCompressionIndicator:
 		return compression.Zstd
 	case MinLZCompressionIndicator:
@@ -204,9 +204,9 @@ func (i CompressionIndicator) Algorithm() compression.Algorithm {
 
 func compressionIndicatorFromAlgorithm(algo compression.Algorithm) CompressionIndicator {
 	switch algo {
-	case compression.NoCompression:
+	case compression.NoAlgorithm:
 		return NoCompressionIndicator
-	case compression.SnappyAlgorithm:
+	case compression.Snappy:
 		return SnappyCompressionIndicator
 	case compression.Zstd:
 		return ZstdCompressionIndicator