[#754] blobstor: Estimate compressability

Now it is possible to enable compressability estimation.
If data is likely uncompressable, it should reduce CPU time and memory.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

cmd/frostfs-node/config.go

@@ -105,7 +105,10 @@ type applicationConfiguration struct {
 }
 
 type shardCfg struct {
-	compress                  bool
+	compress                         bool
+	estimateCompressibility          bool
+	estimateCompressibilityThreshold float64
+
 	smallSizeObjectLimit      uint64
 	uncompressableContentType []string
 	refillMetabase            bool
@@ -217,6 +220,8 @@ func (a *applicationConfiguration) updateShardConfig(c *config.Config, oldConfig
 	newConfig.refillMetabase = oldConfig.RefillMetabase()
 	newConfig.mode = oldConfig.Mode()
 	newConfig.compress = oldConfig.Compress()
+	newConfig.estimateCompressibility = oldConfig.EstimateCompressibility()
+	newConfig.estimateCompressibilityThreshold = oldConfig.EstimateCompressibilityThreshold()
 	newConfig.uncompressableContentType = oldConfig.UncompressableContentTypes()
 	newConfig.smallSizeObjectLimit = oldConfig.SmallSizeLimit()
 
@@ -830,6 +835,8 @@ func (c *cfg) getShardOpts(shCfg shardCfg) shardOptsWithID {
 	blobstoreOpts := []blobstor.Option{
 		blobstor.WithCompressObjects(shCfg.compress),
 		blobstor.WithUncompressableContentTypes(shCfg.uncompressableContentType),
+		blobstor.WithCompressibilityEstimate(shCfg.estimateCompressibility),
+		blobstor.WithCompressibilityEstimateThreshold(shCfg.estimateCompressibilityThreshold),
 		blobstor.WithStorages(ss),
 		blobstor.WithLogger(c.log),
 	}

cmd/frostfs-node/config/cast.go

@@ -223,3 +223,15 @@ func parseSizeInBytes(sizeStr string) uint64 {
 	size := cast.ToFloat64(sizeStr)
 	return safeMul(size, multiplier)
 }
+
+// FloatOrDefault reads a configuration value
+// from c by name and casts it to float64.
+//
+// Returns defaultValue if the value can not be casted.
+func FloatOrDefault(c *Config, name string, defaultValue float64) float64 {
+	v, err := cast.ToFloat64E(c.Value(name))
+	if err != nil {
+		return defaultValue
+	}
+	return v
+}

cmd/frostfs-node/config/engine/config_test.go

@@ -84,6 +84,8 @@ func TestEngineSection(t *testing.T) {
 
 				require.Equal(t, true, sc.Compress())
 				require.Equal(t, []string{"audio/*", "video/*"}, sc.UncompressableContentTypes())
+				require.Equal(t, true, sc.EstimateCompressibility())
+				require.Equal(t, float64(0.7), sc.EstimateCompressibilityThreshold())
 				require.EqualValues(t, 102400, sc.SmallSizeLimit())
 
 				require.Equal(t, 2, len(ss))

cmd/frostfs-node/config/engine/shard/config.go

@@ -16,8 +16,11 @@ import (
 // which provides access to Shard configurations.
 type Config config.Config
 
-// SmallSizeLimitDefault is a default limit of small objects payload in bytes.
-const SmallSizeLimitDefault = 1 << 20
+const (
+	// SmallSizeLimitDefault is a default limit of small objects payload in bytes.
+	SmallSizeLimitDefault                   = 1 << 20
+	EstimateCompressibilityThresholdDefault = 0.1
+)
 
 // From wraps config section into Config.
 func From(c *config.Config) *Config {
@@ -43,6 +46,30 @@ func (x *Config) UncompressableContentTypes() []string {
 		"compression_exclude_content_types")
 }
 
+// EstimateCompressibility returns the value of "estimate_compressibility" config parameter.
+//
+// Returns false if the value is not a valid bool.
+func (x *Config) EstimateCompressibility() bool {
+	return config.BoolSafe(
+		(*config.Config)(x),
+		"compression_estimate_compressibility",
+	)
+}
+
+// EstimateCompressibilityThreshold returns the value of "estimate_compressibility_threshold" config parameter.
+//
+// Returns EstimateCompressibilityThresholdDefault if the value is not defined, not valid float or not in range [0.0; 1.0].
+func (x *Config) EstimateCompressibilityThreshold() float64 {
+	v := config.FloatOrDefault(
+		(*config.Config)(x),
+		"compression_estimate_compressibility_threshold",
+		EstimateCompressibilityThresholdDefault)
+	if v < 0.0 || v > 1.0 {
+		return EstimateCompressibilityThresholdDefault
+	}
+	return v
+}
+
 // SmallSizeLimit returns the value of "small_object_size" config parameter.
 //
 // Returns SmallSizeLimitDefault if the value is not a positive number.