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persister.go
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persister.go
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package raft
//
// support for Raft and kvraft to save persistent
// Raft state (log &c) and k/v server snapshots.
//
// we will use the original persister.go to test your code for grading.
// so, while you can modify this code to help you debug, please
// test with the original before submitting.
//
import (
"encoding/binary"
"fmt"
"io"
"log"
"os"
"sync"
"sync/atomic"
"time"
"github.com/edsrzf/mmap-go"
)
type Persister struct {
mu sync.RWMutex
raftstate []byte
snapshot []byte
killed int32
me int
f *os.File
snapshotF *os.File
mmap mmap.MMap
needsave int32
needsaveLog int32
manageSN bool
}
func MakePersister() *Persister {
persister := &Persister{
me: -1,
manageSN: true,
}
return persister
}
func MakrRealPersister(me int, managgSnapshot bool) *Persister {
persister := &Persister{
manageSN: managgSnapshot,
}
os.MkdirAll("data", os.ModePerm)
f, err := os.OpenFile(fmt.Sprintf("data/%d.rast", me), os.O_RDWR|os.O_APPEND|os.O_CREATE, os.FileMode(0777))
if err != nil {
log.Fatal(err)
}
info, _ := f.Stat()
f.Seek(0, 0)
err = f.Truncate(20000 * 1024)
if err != nil {
panic(err)
}
err = f.Sync()
if err != nil {
panic(err)
}
persister.mmap, _ = mmap.MapRegion(f, -1, mmap.RDWR, 0, 0)
if info.Size() == 20000*1024 {
l := int64(binary.LittleEndian.Uint64(persister.mmap[:8]))
if l > 0 {
persister.raftstate = persister.mmap[8 : 8+l]
}
} else {
binary.LittleEndian.PutUint64(persister.mmap[:8], uint64(0))
}
f1, err := os.OpenFile(fmt.Sprintf("data/%d-sn.rast", me), os.O_RDWR|os.O_APPEND|os.O_CREATE, os.FileMode(0777))
if err == nil {
persister.snapshot, _ = io.ReadAll(f1)
} else {
log.Fatal(err)
}
persister.f = f
persister.snapshotF = f1
persister.me = me
go func() {
for {
time.Sleep(time.Second)
if atomic.LoadInt32(&persister.killed) == 1 {
return
}
if atomic.CompareAndSwapInt32(&persister.needsave, 1, 0) {
// fmt.Println("persist")
save(persister)
}
}
}()
return persister
}
func save(persister *Persister) {
if persister.me == -1 {
return
}
wg := sync.WaitGroup{}
wg.Add(1)
go func() {
if persister.manageSN {
persister.snapshotF.Truncate(0)
persister.snapshotF.Seek(0, 0)
persister.snapshotF.Write(persister.snapshot)
}
wg.Done()
}()
wg.Wait()
}
func (ps *Persister) Kill() {
i := atomic.AddInt32(&ps.killed, 1)
if i == 1 {
save(ps)
ps.mmap.Flush()
ps.mmap.Unmap()
ps.f.Sync()
ps.f.Close()
ps.snapshotF.Close()
}
}
func (ps *Persister) ManageSnapshot() bool {
return ps.manageSN
}
func (ps *Persister) Copy() *Persister {
ps.mu.Lock()
defer ps.mu.Unlock()
np := MakePersister()
np.raftstate = ps.raftstate
np.snapshot = ps.snapshot
return np
}
func (ps *Persister) SaveRaftState(state []byte) {
// _, _, line, _ := runtime.Caller(2)
// fmt.Println(line)
atomic.StoreInt32(&ps.needsaveLog, 1)
ps.mu.Lock()
defer ps.mu.Unlock()
ps.raftstate = state
if ps.mmap != nil {
binary.LittleEndian.PutUint64(ps.mmap[:8], uint64(len(state)))
copy(ps.mmap[8:len(state)+8], state)
}
}
func (ps *Persister) ReadRaftState() []byte {
ps.mu.RLock()
defer ps.mu.RUnlock()
return ps.raftstate
}
func (ps *Persister) RaftStateSize() int {
ps.mu.RLock()
defer ps.mu.RUnlock()
return len(ps.raftstate)
}
// Save both Raft state and K/V snapshot as a single atomic action,
// to help avoid them getting out of sync.
func (ps *Persister) SaveStateAndSnapshot(state []byte, snapshot []byte) {
atomic.StoreInt32(&ps.needsave, 1)
ps.mu.Lock()
defer ps.mu.Unlock()
ps.raftstate = state
ps.snapshot = snapshot
}
func (ps *Persister) ReadSnapshot() []byte {
ps.mu.RLock()
defer ps.mu.RUnlock()
return ps.snapshot
}
func (ps *Persister) SnapshotSize() int {
ps.mu.RLock()
defer ps.mu.RUnlock()
return len(ps.snapshot)
}