forked from prometheus-junkyard/tsdb
/
chunks.go
498 lines (433 loc) · 11.4 KB
/
chunks.go
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// Copyright 2017 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package chunks
import (
"bufio"
"encoding/binary"
"fmt"
"hash"
"hash/crc32"
"io"
"io/ioutil"
"os"
"path/filepath"
"strconv"
"github.com/pkg/errors"
"github.com/prometheus/tsdb/chunkenc"
"github.com/prometheus/tsdb/fileutil"
)
const (
// MagicChunks is 4 bytes at the head of a series file.
MagicChunks = 0x85BD40DD
)
// Meta holds information about a chunk of data.
type Meta struct {
// Ref and Chunk hold either a reference that can be used to retrieve
// chunk data or the data itself.
// Generally, only one of them is set.
Ref uint64
Chunk chunkenc.Chunk
MinTime, MaxTime int64 // time range the data covers
}
// writeHash writes the chunk encoding and raw data into the provided hash.
func (cm *Meta) writeHash(h hash.Hash) error {
if _, err := h.Write([]byte{byte(cm.Chunk.Encoding())}); err != nil {
return err
}
if _, err := h.Write(cm.Chunk.Bytes()); err != nil {
return err
}
return nil
}
// Returns true if the chunk overlaps [mint, maxt].
func (cm *Meta) OverlapsClosedInterval(mint, maxt int64) bool {
// The chunk itself is a closed interval [cm.MinTime, cm.MaxTime].
return cm.MinTime <= maxt && mint <= cm.MaxTime
}
var (
errInvalidSize = fmt.Errorf("invalid size")
)
var castagnoliTable *crc32.Table
func init() {
castagnoliTable = crc32.MakeTable(crc32.Castagnoli)
}
// newCRC32 initializes a CRC32 hash with a preconfigured polynomial, so the
// polynomial may be easily changed in one location at a later time, if necessary.
func newCRC32() hash.Hash32 {
return crc32.New(castagnoliTable)
}
// Writer implements the ChunkWriter interface for the standard
// serialization format.
type Writer struct {
dirFile *os.File
files []*os.File
wbuf *bufio.Writer
n int64
crc32 hash.Hash
segmentSize int64
}
const (
defaultChunkSegmentSize = 512 * 1024 * 1024
chunksFormatV1 = 1
)
// NewWriter returns a new writer against the given directory.
func NewWriter(dir string) (*Writer, error) {
if err := os.MkdirAll(dir, 0777); err != nil {
return nil, err
}
dirFile, err := fileutil.OpenDir(dir)
if err != nil {
return nil, err
}
cw := &Writer{
dirFile: dirFile,
n: 0,
crc32: newCRC32(),
segmentSize: defaultChunkSegmentSize,
}
return cw, nil
}
func (w *Writer) tail() *os.File {
if len(w.files) == 0 {
return nil
}
return w.files[len(w.files)-1]
}
// finalizeTail writes all pending data to the current tail file,
// truncates its size, and closes it.
func (w *Writer) finalizeTail() error {
tf := w.tail()
if tf == nil {
return nil
}
if err := w.wbuf.Flush(); err != nil {
return err
}
if err := fileutil.Fsync(tf); err != nil {
return err
}
// As the file was pre-allocated, we truncate any superfluous zero bytes.
off, err := tf.Seek(0, io.SeekCurrent)
if err != nil {
return err
}
if err := tf.Truncate(off); err != nil {
return err
}
return tf.Close()
}
func (w *Writer) cut() error {
// Sync current tail to disk and close.
if err := w.finalizeTail(); err != nil {
return err
}
p, _, err := nextSequenceFile(w.dirFile.Name())
if err != nil {
return err
}
f, err := os.OpenFile(p, os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
return err
}
if err = fileutil.Preallocate(f, w.segmentSize, true); err != nil {
return err
}
if err = w.dirFile.Sync(); err != nil {
return err
}
// Write header metadata for new file.
metab := make([]byte, 8)
binary.BigEndian.PutUint32(metab[:4], MagicChunks)
metab[4] = chunksFormatV1
if _, err := f.Write(metab); err != nil {
return err
}
w.files = append(w.files, f)
if w.wbuf != nil {
w.wbuf.Reset(f)
} else {
w.wbuf = bufio.NewWriterSize(f, 8*1024*1024)
}
w.n = 8
return nil
}
func (w *Writer) write(b []byte) error {
n, err := w.wbuf.Write(b)
w.n += int64(n)
return err
}
// MergeOverlappingChunks removes the samples whose timestamp is overlapping.
// The last appearing sample is retained in case there is overlapping.
// This assumes that `chks []Meta` is sorted w.r.t. MinTime.
func MergeOverlappingChunks(chks []Meta) ([]Meta, error) {
if len(chks) < 2 {
return chks, nil
}
newChks := make([]Meta, 0, len(chks)) // Will contain the merged chunks.
newChks = append(newChks, chks[0])
last := 0
for _, c := range chks[1:] {
// We need to check only the last chunk in newChks.
// Reason: (1) newChks[last-1].MaxTime < newChks[last].MinTime (non overlapping)
// (2) As chks are sorted w.r.t. MinTime, newChks[last].MinTime < c.MinTime.
// So never overlaps with newChks[last-1] or anything before that.
if c.MinTime > newChks[last].MaxTime {
newChks = append(newChks, c)
continue
}
nc := &newChks[last]
if c.MaxTime > nc.MaxTime {
nc.MaxTime = c.MaxTime
}
chk, err := MergeChunks(nc.Chunk, c.Chunk)
if err != nil {
return nil, err
}
nc.Chunk = chk
}
return newChks, nil
}
// MergeChunks vertically merges a and b, i.e., if there is any sample
// with same timestamp in both a and b, the sample in a is discarded.
func MergeChunks(a, b chunkenc.Chunk) (*chunkenc.XORChunk, error) {
newChunk := chunkenc.NewXORChunk()
app, err := newChunk.Appender()
if err != nil {
return nil, err
}
ait := a.Iterator()
bit := b.Iterator()
aok, bok := ait.Next(), bit.Next()
for aok && bok {
at, av := ait.At()
bt, bv := bit.At()
if at < bt {
app.Append(at, av)
aok = ait.Next()
} else if bt < at {
app.Append(bt, bv)
bok = bit.Next()
} else {
app.Append(bt, bv)
aok = ait.Next()
bok = bit.Next()
}
}
for aok {
at, av := ait.At()
app.Append(at, av)
aok = ait.Next()
}
for bok {
bt, bv := bit.At()
app.Append(bt, bv)
bok = bit.Next()
}
if ait.Err() != nil {
return nil, ait.Err()
}
if bit.Err() != nil {
return nil, bit.Err()
}
return newChunk, nil
}
func (w *Writer) WriteChunks(chks ...Meta) error {
// Calculate maximum space we need and cut a new segment in case
// we don't fit into the current one.
maxLen := int64(binary.MaxVarintLen32) // The number of chunks.
for _, c := range chks {
maxLen += binary.MaxVarintLen32 + 1 // The number of bytes in the chunk and its encoding.
maxLen += int64(len(c.Chunk.Bytes()))
maxLen += 4 // The 4 bytes of crc32
}
newsz := w.n + maxLen
if w.wbuf == nil || w.n > w.segmentSize || newsz > w.segmentSize && maxLen <= w.segmentSize {
if err := w.cut(); err != nil {
return err
}
}
var (
b = [binary.MaxVarintLen32]byte{}
seq = uint64(w.seq()) << 32
)
for i := range chks {
chk := &chks[i]
chk.Ref = seq | uint64(w.n)
n := binary.PutUvarint(b[:], uint64(len(chk.Chunk.Bytes())))
if err := w.write(b[:n]); err != nil {
return err
}
b[0] = byte(chk.Chunk.Encoding())
if err := w.write(b[:1]); err != nil {
return err
}
if err := w.write(chk.Chunk.Bytes()); err != nil {
return err
}
w.crc32.Reset()
if err := chk.writeHash(w.crc32); err != nil {
return err
}
if err := w.write(w.crc32.Sum(b[:0])); err != nil {
return err
}
}
return nil
}
func (w *Writer) seq() int {
return len(w.files) - 1
}
func (w *Writer) Close() error {
if err := w.finalizeTail(); err != nil {
return err
}
// close dir file (if not windows platform will fail on rename)
return w.dirFile.Close()
}
// ByteSlice abstracts a byte slice.
type ByteSlice interface {
Len() int
Range(start, end int) []byte
}
type realByteSlice []byte
func (b realByteSlice) Len() int {
return len(b)
}
func (b realByteSlice) Range(start, end int) []byte {
return b[start:end]
}
func (b realByteSlice) Sub(start, end int) ByteSlice {
return b[start:end]
}
// Reader implements a SeriesReader for a serialized byte stream
// of series data.
type Reader struct {
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 {
return nil, errors.Wrapf(errInvalidSize, "validate magic in segment %d", i)
}
// Verify magic number.
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
}
// NewReader returns a new chunk reader against the given byte slices.
func NewReader(bs []ByteSlice, pool chunkenc.Pool) (*Reader, error) {
if pool == nil {
pool = chunkenc.NewPool()
}
return newReader(bs, nil, pool)
}
// NewDirReader returns a new Reader against sequentially numbered files in the
// given directory.
func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error) {
files, err := sequenceFiles(dir)
if err != nil {
return nil, err
}
if pool == nil {
pool = chunkenc.NewPool()
}
var (
bs []ByteSlice
cs []io.Closer
)
for _, fn := range files {
f, err := fileutil.OpenMmapFile(fn)
if err != nil {
return nil, errors.Wrapf(err, "mmap files")
}
cs = append(cs, f)
bs = append(bs, realByteSlice(f.Bytes()))
}
return newReader(bs, cs, pool)
}
func (s *Reader) Close() error {
return closeAll(s.cs)
}
// Size returns the size of the chunks.
func (s *Reader) Size() int64 {
return s.size
}
// Chunk returns a chunk from a given reference.
func (s *Reader) Chunk(ref uint64) (chunkenc.Chunk, error) {
var (
sgmSeq = int(ref >> 32)
sgmOffset = int((ref << 32) >> 32)
)
if sgmSeq >= len(s.bs) {
return nil, errors.Errorf("reference sequence %d out of range", sgmSeq)
}
chkS := s.bs[sgmSeq]
if sgmOffset >= chkS.Len() {
return nil, errors.Errorf("offset %d beyond data size %d", sgmOffset, chkS.Len())
}
// With the minimum chunk length this should never cause us reading
// over the end of the slice.
chk := chkS.Range(sgmOffset, sgmOffset+binary.MaxVarintLen32)
chkLen, n := binary.Uvarint(chk)
if n <= 0 {
return nil, errors.Errorf("reading chunk length failed with %d", n)
}
chk = chkS.Range(sgmOffset+n, sgmOffset+n+1+int(chkLen))
return s.pool.Get(chunkenc.Encoding(chk[0]), chk[1:1+chkLen])
}
func nextSequenceFile(dir string) (string, int, error) {
names, err := fileutil.ReadDir(dir)
if err != nil {
return "", 0, err
}
i := uint64(0)
for _, n := range names {
j, err := strconv.ParseUint(n, 10, 64)
if err != nil {
continue
}
i = j
}
return filepath.Join(dir, fmt.Sprintf("%0.6d", i+1)), int(i + 1), nil
}
func sequenceFiles(dir string) ([]string, error) {
files, err := ioutil.ReadDir(dir)
if err != nil {
return nil, err
}
var res []string
for _, fi := range files {
if _, err := strconv.ParseUint(fi.Name(), 10, 64); err != nil {
continue
}
res = append(res, filepath.Join(dir, fi.Name()))
}
return res, nil
}
func closeAll(cs []io.Closer) (err error) {
for _, c := range cs {
if e := c.Close(); e != nil {
err = e
}
}
return err
}