Add Chunk.Utilization() methods

When using the chunking code in other projects (both Weave Prism and ChronixDB ingester), you sometimes want to know how well you are utilizing your chunks when closing/storing them.
sman591 · Oct 6, 2016 · c212ef0 · c212ef0
1 parent 0dbcf55
commit c212ef0
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Showing 4 changed files with 17 additions and 0 deletions.
diff --git a/storage/local/chunk/chunk.go b/storage/local/chunk/chunk.go
@@ -273,6 +273,7 @@ type Chunk interface {
 	Unmarshal(io.Reader) error
 	UnmarshalFromBuf([]byte) error
 	Encoding() Encoding
+	Utilization() float64
 }
 
 // Iterator enables efficient access to the content of a chunk. It is

diff --git a/storage/local/chunk/delta.go b/storage/local/chunk/delta.go
@@ -267,6 +267,11 @@ func (c *deltaEncodedChunk) UnmarshalFromBuf(buf []byte) error {
 // encoding implements chunk.
 func (c deltaEncodedChunk) Encoding() Encoding { return Delta }
 
+// Utilization implements chunk.
+func (c deltaEncodedChunk) Utilization() float64 {
+	return float64(len(c)) / float64(cap(c))
+}
+
 func (c deltaEncodedChunk) timeBytes() deltaBytes {
 	return deltaBytes(c[deltaHeaderTimeBytesOffset])
 }

diff --git a/storage/local/chunk/doubledelta.go b/storage/local/chunk/doubledelta.go
@@ -277,6 +277,11 @@ func (c *doubleDeltaEncodedChunk) UnmarshalFromBuf(buf []byte) error {
 // encoding implements chunk.
 func (c doubleDeltaEncodedChunk) Encoding() Encoding { return DoubleDelta }
 
+// Utilization implements chunk.
+func (c doubleDeltaEncodedChunk) Utilization() float64 {
+	return float64(len(c)) / float64(cap(c))
+}
+
 func (c doubleDeltaEncodedChunk) baseTime() model.Time {
 	return model.Time(
 		binary.LittleEndian.Uint64(

diff --git a/storage/local/chunk/varbit.go b/storage/local/chunk/varbit.go
@@ -322,6 +322,12 @@ func (c varbitChunk) UnmarshalFromBuf(buf []byte) error {
 // encoding implements chunk.
 func (c varbitChunk) Encoding() Encoding { return Varbit }
 
+// Utilization implements chunk.
+func (c varbitChunk) Utilization() float64 {
+	// 15 bytes is the length of the chunk footer.
+	return math.Min(float64(c.nextSampleOffset()/8+15)/float64(cap(c)), 1)
+}
+
 // FirstTime implements chunk.
 func (c varbitChunk) FirstTime() model.Time {
 	return model.Time(