prometheus/tombstones.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 tsdb
import (
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"github.com/pkg/errors"
)
const tombstoneFilename = "tombstones"
const (
// MagicTombstone is 4 bytes at the head of a tombstone file.
MagicTombstone = 0x130BA30
tombstoneFormatV1 = 1
)
// TombstoneReader gives access to tombstone intervals by series reference.
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type TombstoneReader interface {
Get(ref uint64) Intervals
Close() error
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}
func writeTombstoneFile(dir string, tr tombstoneReader) error {
path := filepath.Join(dir, tombstoneFilename)
tmp := path + ".tmp"
hash := newCRC32()
f, err := os.Create(tmp)
if err != nil {
return err
}
defer f.Close()
buf := encbuf{b: make([]byte, 3*binary.MaxVarintLen64)}
buf.reset()
// Write the meta.
buf.putBE32(MagicTombstone)
buf.putByte(tombstoneFormatV1)
_, err = f.Write(buf.get())
if err != nil {
return err
}
mw := io.MultiWriter(f, hash)
for k, v := range tr {
for _, itv := range v {
buf.reset()
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buf.putUvarint64(k)
buf.putVarint64(itv.Mint)
buf.putVarint64(itv.Maxt)
_, err = mw.Write(buf.get())
if err != nil {
return err
}
}
}
_, err = f.Write(hash.Sum(nil))
if err != nil {
return err
}
return renameFile(tmp, path)
}
// Stone holds the information on the posting and time-range
// that is deleted.
type Stone struct {
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ref uint64
intervals Intervals
}
func readTombstones(dir string) (tombstoneReader, error) {
b, err := ioutil.ReadFile(filepath.Join(dir, tombstoneFilename))
if err != nil {
return nil, err
}
if len(b) < 5 {
return nil, errors.Wrap(errInvalidSize, "tombstones header")
}
d := &decbuf{b: b[:len(b)-4]} // 4 for the checksum.
if mg := d.be32(); mg != MagicTombstone {
return nil, fmt.Errorf("invalid magic number %x", mg)
}
if flag := d.byte(); flag != tombstoneFormatV1 {
return nil, fmt.Errorf("invalid tombstone format %x", flag)
}
if d.err() != nil {
return nil, d.err()
}
// Verify checksum
hash := newCRC32()
if _, err := hash.Write(d.get()); err != nil {
return nil, errors.Wrap(err, "write to hash")
}
if binary.BigEndian.Uint32(b[len(b)-4:]) != hash.Sum32() {
return nil, errors.New("checksum did not match")
}
stonesMap := newEmptyTombstoneReader()
for d.len() > 0 {
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k := d.uvarint64()
mint := d.varint64()
maxt := d.varint64()
if d.err() != nil {
return nil, d.err()
}
stonesMap.add(k, Interval{mint, maxt})
}
return newTombstoneReader(stonesMap), nil
}
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type tombstoneReader map[uint64]Intervals
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func newTombstoneReader(ts map[uint64]Intervals) tombstoneReader {
return tombstoneReader(ts)
}
func newEmptyTombstoneReader() tombstoneReader {
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return tombstoneReader(make(map[uint64]Intervals))
}
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func (t tombstoneReader) Get(ref uint64) Intervals {
return t[ref]
}
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func (t tombstoneReader) add(ref uint64, itv Interval) {
t[ref] = t[ref].add(itv)
}
func (tombstoneReader) Close() error {
return nil
}
// Interval represents a single time-interval.
type Interval struct {
Mint, Maxt int64
}
func (tr Interval) inBounds(t int64) bool {
return t >= tr.Mint && t <= tr.Maxt
}
func (tr Interval) isSubrange(dranges Intervals) bool {
for _, r := range dranges {
if r.inBounds(tr.Mint) && r.inBounds(tr.Maxt) {
return true
}
}
return false
}
// Intervals represents a set of increasing and non-overlapping time-intervals.
type Intervals []Interval
// This adds the new time-range to the existing ones.
// The existing ones must be sorted.
func (itvs Intervals) add(n Interval) Intervals {
for i, r := range itvs {
// TODO(gouthamve): Make this codepath easier to digest.
if r.inBounds(n.Mint-1) || r.inBounds(n.Mint) {
if n.Maxt > r.Maxt {
itvs[i].Maxt = n.Maxt
}
j := 0
for _, r2 := range itvs[i+1:] {
if n.Maxt < r2.Mint {
break
}
j++
}
if j != 0 {
if itvs[i+j].Maxt > n.Maxt {
itvs[i].Maxt = itvs[i+j].Maxt
}
itvs = append(itvs[:i+1], itvs[i+j+1:]...)
}
return itvs
}
if r.inBounds(n.Maxt+1) || r.inBounds(n.Maxt) {
if n.Mint < r.Maxt {
itvs[i].Mint = n.Mint
}
return itvs
}
if n.Mint < r.Mint {
newRange := make(Intervals, i, len(itvs[:i])+1)
copy(newRange, itvs[:i])
newRange = append(newRange, n)
newRange = append(newRange, itvs[i:]...)
return newRange
}
}
itvs = append(itvs, n)
return itvs
}