Added storage size based retention method and new metrics

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## master / unreleased
  - [CHANGE] New `WALSegmentSize` option to override the `DefaultOptions.WALSegmentSize`. Added to allow using smaller wal files. For example using tmpfs on a RPI to minimise the SD card wear out from the constant WAL writes. As part of this change the `DefaultOptions.WALSegmentSize` constant was also exposed.
+ - [FEATURE]  Size base retention through `Options.MaxBytes`.  As part of this change:
+    - added new metrics - `prometheus_tsdb_storage_blocks_bytes_total`, `prometheus_tsdb_size_retentions_total`, `prometheus_tsdb_time_retentions_total`
+    - new public interface `SizeReader: Size() int64`
+    - `OpenBlock` signature changed to take a logger.
  - [REMOVED] `PrefixMatcher` is considered unused so was removed.
  - [CLEANUP] `Options.WALFlushInterval` is removed as it wasn't used anywhere.
 

block.go

@@ -21,6 +21,8 @@ import (
 	"path/filepath"
 	"sync"
 
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
 	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
 	"github.com/prometheus/tsdb/chunkenc"
@@ -140,6 +142,12 @@ type Appendable interface {
 	Appender() Appender
 }
 
+// SizeReader returns the size of the object in bytes.
+type SizeReader interface {
+	// Size returns the size in bytes.
+	Size() int64
+}
+
 // BlockMeta provides meta information about a block.
 type BlockMeta struct {
 	// Unique identifier for the block and its contents. Changes on compaction.
@@ -166,6 +174,7 @@ type BlockStats struct {
 	NumSeries     uint64 `json:"numSeries,omitempty"`
 	NumChunks     uint64 `json:"numChunks,omitempty"`
 	NumTombstones uint64 `json:"numTombstones,omitempty"`
+	NumBytes      int64  `json:"numBytes,omitempty"`
 }
 
 // BlockDesc describes a block by ULID and time range.
@@ -257,7 +266,10 @@ type Block struct {
 
 // OpenBlock opens the block in the directory. It can be passed a chunk pool, which is used
 // to instantiate chunk structs.
-func OpenBlock(dir string, pool chunkenc.Pool) (*Block, error) {
+func OpenBlock(logger log.Logger, dir string, pool chunkenc.Pool) (*Block, error) {
+	if logger == nil {
+		logger = log.NewNopLogger()
+	}
 	meta, err := readMetaFile(dir)
 	if err != nil {
 		return nil, err
@@ -272,11 +284,20 @@ func OpenBlock(dir string, pool chunkenc.Pool) (*Block, error) {
 		return nil, err
 	}
 
-	tr, err := readTombstones(dir)
+	tr, tsr, err := readTombstones(dir)
 	if err != nil {
 		return nil, err
 	}
 
+	// TODO refactor to set this at block creation time as
+	// that would be the logical place for a block size to be calculated.
+	bs := blockSize(cr, ir, tsr)
+	meta.Stats.NumBytes = bs
+	err = writeMetaFile(dir, meta)
+	if err != nil {
+		level.Warn(logger).Log("msg", "couldn't write the meta file for the block size", "block", dir, "err", err)
+	}
+
 	pb := &Block{
 		dir:             dir,
 		meta:            *meta,
@@ -288,6 +309,16 @@ func OpenBlock(dir string, pool chunkenc.Pool) (*Block, error) {
 	return pb, nil
 }
 
+func blockSize(rr ...SizeReader) int64 {
+	var total int64
+	for _, r := range rr {
+		if r != nil {
+			total += r.Size()
+		}
+	}
+	return total
+}
+
 // Close closes the on-disk block. It blocks as long as there are readers reading from the block.
 func (pb *Block) Close() error {
 	pb.mtx.Lock()
@@ -315,6 +346,9 @@ func (pb *Block) Dir() string { return pb.dir }
 // Meta returns meta information about the block.
 func (pb *Block) Meta() BlockMeta { return pb.meta }
 
+// Size returns the number of bytes that the block takes up.
+func (pb *Block) Size() int64 { return pb.meta.Stats.NumBytes }
+
 // ErrClosing is returned when a block is in the process of being closed.
 var ErrClosing = errors.New("block is closing")
 

block_test.go

@@ -46,14 +46,14 @@ func TestSetCompactionFailed(t *testing.T) {
 	defer os.RemoveAll(tmpdir)
 
 	blockDir := createBlock(t, tmpdir, 0, 0, 0)
-	b, err := OpenBlock(blockDir, nil)
+	b, err := OpenBlock(nil, blockDir, nil)
 	testutil.Ok(t, err)
 	testutil.Equals(t, false, b.meta.Compaction.Failed)
 	testutil.Ok(t, b.setCompactionFailed())
 	testutil.Equals(t, true, b.meta.Compaction.Failed)
 	testutil.Ok(t, b.Close())
 
-	b, err = OpenBlock(blockDir, nil)
+	b, err = OpenBlock(nil, blockDir, nil)
 	testutil.Ok(t, err)
 	testutil.Equals(t, true, b.meta.Compaction.Failed)
 	testutil.Ok(t, b.Close())

chunks/chunks.go

@@ -285,17 +285,15 @@ func (b realByteSlice) Sub(start, end int) ByteSlice {
 // Reader implements a SeriesReader for a serialized byte stream
 // of series data.
 type Reader struct {
-	// The underlying bytes holding the encoded series data.
-	bs []ByteSlice
-
-	// Closers for resources behind the byte slices.
-	cs []io.Closer
-
+	bs   []ByteSlice // The underlying bytes holding the encoded series data.
+	cs   []io.Closer // Closers for resources behind the byte slices.
+	size int64       // The total size of bytes in the reader.
 	pool chunkenc.Pool
 }
 
 func newReader(bs []ByteSlice, cs []io.Closer, pool chunkenc.Pool) (*Reader, error) {
 	cr := Reader{pool: pool, bs: bs, cs: cs}
+	var totalSize int64
 
 	for i, b := range cr.bs {
 		if b.Len() < 4 {
@@ -305,7 +303,9 @@ func newReader(bs []ByteSlice, cs []io.Closer, pool chunkenc.Pool) (*Reader, err
 		if m := binary.BigEndian.Uint32(b.Range(0, 4)); m != MagicChunks {
 			return nil, errors.Errorf("invalid magic number %x", m)
 		}
+		totalSize += int64(b.Len())
 	}
+	cr.size = totalSize
 	return &cr, nil
 }
 
@@ -328,9 +328,10 @@ func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error) {
 		pool = chunkenc.NewPool()
 	}
 
-	var bs []ByteSlice
-	var cs []io.Closer
-
+	var (
+		bs []ByteSlice
+		cs []io.Closer
+	)
 	for _, fn := range files {
 		f, err := fileutil.OpenMmapFile(fn)
 		if err != nil {
@@ -346,6 +347,11 @@ func (s *Reader) Close() error {
 	return closeAll(s.cs...)
 }
 
+// Size returns the size of the chunks.
+func (s *Reader) Size() int64 {
+	return s.size
+}
+
 func (s *Reader) Chunk(ref uint64) (chunkenc.Chunk, error) {
 	var (
 		seq = int(ref >> 32)

compact.go

@@ -347,7 +347,7 @@ func (c *LeveledCompactor) Compact(dest string, dirs []string, open []*Block) (u
 
 		if b == nil {
 			var err error
-			b, err = OpenBlock(d, c.chunkPool)
+			b, err = OpenBlock(c.logger, d, c.chunkPool)
 			if err != nil {
 				return uid, err
 			}