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 {
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// Get returns deletion intervals for the series with the given reference.
Get(ref uint64) (Intervals, error)
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// Iter calls the given function for each encountered interval.
Iter(func(uint64, Intervals) error) error
// Close any underlying resources
Close() error
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}
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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 func() {
if f != nil {
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)
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tr.Iter(func(ref uint64, ivs Intervals) error {
for _, iv := range ivs {
buf.reset()
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buf.putUvarint64(ref)
buf.putVarint64(iv.Mint)
buf.putVarint64(iv.Maxt)
_, err = mw.Write(buf.get())
if err != nil {
return err
}
}
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return nil
})
_, err = f.Write(hash.Sum(nil))
if err != nil {
return err
}
if err = f.Close(); err != nil {
return err
}
f = nil
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
}
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func readTombstones(dir string) (memTombstones, 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")
}
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stonesMap := memTombstones{}
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})
}
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return stonesMap, nil
}
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type memTombstones map[uint64]Intervals
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var emptyTombstoneReader = memTombstones{}
// EmptyTombstoneReader returns a TombstoneReader that is always empty.
func EmptyTombstoneReader() TombstoneReader {
return emptyTombstoneReader
}
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func (t memTombstones) Get(ref uint64) (Intervals, error) {
return t[ref], nil
}
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func (t memTombstones) Iter(f func(uint64, Intervals) error) error {
for ref, ivs := range t {
if err := f(ref, ivs); err != nil {
return err
}
}
return nil
}
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func (t memTombstones) add(ref uint64, itv Interval) {
t[ref] = t[ref].add(itv)
}
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func (memTombstones) 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
}