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checkpoint.go
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checkpoint.go
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/*
* Copyright 2017 Dgraph Labs, Inc.
*
* 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 client
import (
"encoding/binary"
"fmt"
"path/filepath"
"sync"
"time"
"github.com/dgraph-io/badger"
"gopkg.in/adibiarsotp/dgraph.v82/x"
)
type waterMark struct {
last uint64 // Last line number that was written to Badger.
mark *x.WaterMark
wg *sync.WaitGroup
}
// A watermark for each file.
type syncMarks map[string]waterMark
// Create syncmarks for files and store them in dgraphClient.
func (d *Dgraph) NewSyncMarks(files []string) error {
if len(files) == 0 {
return nil
}
if len(d.marks) > 0 {
return fmt.Errorf("NewSyncMarks should only be called once.")
}
for _, file := range files {
ap, err := filepath.Abs(file)
if err != nil {
return err
}
if _, ok := d.marks[ap]; ok {
return fmt.Errorf("Found duplicate file: %+v\n", ap)
}
d.marks.create(ap)
}
t := time.NewTicker(10 * time.Second)
d.checkpointTicker = t
go func(t *time.Ticker) {
for range t.C {
d.writeCheckpoint()
}
}(t)
return nil
}
// Get checkpoint for file from Badger.
func (d *Dgraph) Checkpoint(file string) (uint64, error) {
return d.alloc.getFromKV(fmt.Sprintf("checkpoint-%s", file))
}
// Used to write checkpoints to Badger.
func (d *Dgraph) writeCheckpoint() {
wb := make([]*badger.Entry, 0, len(d.marks))
for file, wm := range d.marks {
doneUntil := wm.mark.DoneUntil()
if doneUntil == 0 || doneUntil == wm.last {
continue
}
wm.last = doneUntil
d.marks[file] = wm
var buf [10]byte
n := binary.PutUvarint(buf[:], doneUntil)
wb = badger.EntriesSet(wb, []byte(fmt.Sprintf("checkpoint-%s", file)), buf[:n])
}
if err := d.alloc.kv.BatchSet(wb); err != nil {
fmt.Printf("Error while writing to disk %v\n", err)
}
for _, wbe := range wb {
if err := wbe.Error; err != nil {
fmt.Printf("Error while writing to disk %v\n", err)
}
}
}
func (g syncMarks) create(file string) waterMark {
x.AssertTrue(g != nil)
if prev, present := g[file]; present {
return prev
}
m := &x.WaterMark{Name: file}
m.Init()
wm := waterMark{mark: m, wg: new(sync.WaitGroup)}
g[file] = wm
return wm
}