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storage.go
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storage.go
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package raft
import (
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"sort"
"strings"
"github.com/coreos/etcd/raft"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/snap"
"github.com/coreos/etcd/wal"
"github.com/coreos/etcd/wal/walpb"
"github.com/docker/swarmkit/api"
"github.com/docker/swarmkit/log"
"github.com/docker/swarmkit/manager/state/raft/membership"
"github.com/docker/swarmkit/manager/state/store"
"golang.org/x/net/context"
)
var errNoWAL = errors.New("no WAL present")
func (n *Node) walDir() string {
return filepath.Join(n.StateDir, "wal")
}
func (n *Node) snapDir() string {
return filepath.Join(n.StateDir, "snap")
}
func (n *Node) loadAndStart(ctx context.Context, forceNewCluster bool) error {
walDir := n.walDir()
snapDir := n.snapDir()
if err := os.MkdirAll(snapDir, 0700); err != nil {
return fmt.Errorf("create snapshot directory error: %v", err)
}
// Create a snapshotter
n.snapshotter = snap.New(snapDir)
if !wal.Exist(walDir) {
return errNoWAL
}
// Load snapshot data
snapshot, err := n.snapshotter.Load()
if err != nil && err != snap.ErrNoSnapshot {
return err
}
if snapshot != nil {
// Load the snapshot data into the store
if err := n.restoreFromSnapshot(snapshot.Data, forceNewCluster); err != nil {
return err
}
}
// Read logs to fully catch up store
if err := n.readWAL(ctx, snapshot, forceNewCluster); err != nil {
return err
}
return nil
}
func (n *Node) createWAL(nodeID string) (raft.Peer, error) {
raftNode := &api.RaftMember{
RaftID: n.Config.ID,
NodeID: nodeID,
Addr: n.Address,
}
metadata, err := raftNode.Marshal()
if err != nil {
return raft.Peer{}, fmt.Errorf("error marshalling raft node: %v", err)
}
n.wal, err = wal.Create(n.walDir(), metadata)
if err != nil {
return raft.Peer{}, fmt.Errorf("create wal error: %v", err)
}
n.cluster.AddMember(&membership.Member{RaftMember: raftNode})
return raft.Peer{ID: n.Config.ID, Context: metadata}, nil
}
// moveWALAndSnap moves away the WAL and snapshot because we were removed
// from the cluster and will need to recreate them if we are readded.
func (n *Node) moveWALAndSnap() error {
newWALDir, err := ioutil.TempDir(n.StateDir, "wal.")
if err != nil {
return err
}
err = os.Rename(n.walDir(), newWALDir)
if err != nil {
return err
}
newSnapDir, err := ioutil.TempDir(n.StateDir, "snap.")
if err != nil {
return err
}
err = os.Rename(n.snapDir(), newSnapDir)
if err != nil {
return err
}
return nil
}
func (n *Node) readWAL(ctx context.Context, snapshot *raftpb.Snapshot, forceNewCluster bool) (err error) {
var (
walsnap walpb.Snapshot
metadata []byte
st raftpb.HardState
ents []raftpb.Entry
)
if snapshot != nil {
walsnap.Index = snapshot.Metadata.Index
walsnap.Term = snapshot.Metadata.Term
}
repaired := false
for {
if n.wal, err = wal.Open(n.walDir(), walsnap); err != nil {
return fmt.Errorf("open wal error: %v", err)
}
if metadata, st, ents, err = n.wal.ReadAll(); err != nil {
if err := n.wal.Close(); err != nil {
return err
}
// we can only repair ErrUnexpectedEOF and we never repair twice.
if repaired || err != io.ErrUnexpectedEOF {
return fmt.Errorf("read wal error (%v) and cannot be repaired", err)
}
if !wal.Repair(n.walDir()) {
return fmt.Errorf("WAL error (%v) cannot be repaired", err)
}
log.G(ctx).Infof("repaired WAL error (%v)", err)
repaired = true
continue
}
break
}
defer func() {
if err != nil {
if walErr := n.wal.Close(); walErr != nil {
n.Config.Logger.Errorf("error closing raft WAL: %v", walErr)
}
}
}()
var raftNode api.RaftMember
if err := raftNode.Unmarshal(metadata); err != nil {
return fmt.Errorf("error unmarshalling wal metadata: %v", err)
}
n.Config.ID = raftNode.RaftID
// All members that are no longer part of the cluster must be added to
// the removed list right away, so that we don't try to connect to them
// before processing the configuration change entries, which could make
// us get stuck.
for _, ent := range ents {
if ent.Index <= st.Commit && ent.Type == raftpb.EntryConfChange {
var cc raftpb.ConfChange
if err := cc.Unmarshal(ent.Data); err != nil {
return fmt.Errorf("error unmarshalling config change: %v", err)
}
if cc.Type == raftpb.ConfChangeRemoveNode {
n.cluster.RemoveMember(cc.NodeID)
}
}
}
if forceNewCluster {
// discard the previously uncommitted entries
for i, ent := range ents {
if ent.Index > st.Commit {
log.G(context.Background()).Infof("discarding %d uncommitted WAL entries ", len(ents)-i)
ents = ents[:i]
break
}
}
// force append the configuration change entries
toAppEnts := createConfigChangeEnts(getIDs(snapshot, ents), uint64(n.Config.ID), st.Term, st.Commit)
// All members that are being removed as part of the
// force-new-cluster process must be added to the
// removed list right away, so that we don't try to
// connect to them before processing the configuration
// change entries, which could make us get stuck.
for _, ccEnt := range toAppEnts {
if ccEnt.Type == raftpb.EntryConfChange {
var cc raftpb.ConfChange
if err := cc.Unmarshal(ccEnt.Data); err != nil {
return fmt.Errorf("error unmarshalling force-new-cluster config change: %v", err)
}
if cc.Type == raftpb.ConfChangeRemoveNode {
n.cluster.RemoveMember(cc.NodeID)
}
}
}
ents = append(ents, toAppEnts...)
// force commit newly appended entries
err := n.wal.Save(st, toAppEnts)
if err != nil {
log.G(context.Background()).Fatalf("%v", err)
}
if len(toAppEnts) != 0 {
st.Commit = toAppEnts[len(toAppEnts)-1].Index
}
}
if snapshot != nil {
if err := n.raftStore.ApplySnapshot(*snapshot); err != nil {
return err
}
}
if err := n.raftStore.SetHardState(st); err != nil {
return err
}
if err := n.raftStore.Append(ents); err != nil {
return err
}
return nil
}
func (n *Node) saveSnapshot(snapshot raftpb.Snapshot, keepOldSnapshots uint64) error {
err := n.wal.SaveSnapshot(walpb.Snapshot{
Index: snapshot.Metadata.Index,
Term: snapshot.Metadata.Term,
})
if err != nil {
return err
}
err = n.snapshotter.SaveSnap(snapshot)
if err != nil {
return err
}
err = n.wal.ReleaseLockTo(snapshot.Metadata.Index)
if err != nil {
return err
}
// Delete any older snapshots
curSnapshot := fmt.Sprintf("%016x-%016x%s", snapshot.Metadata.Term, snapshot.Metadata.Index, ".snap")
dirents, err := ioutil.ReadDir(n.snapDir())
if err != nil {
return err
}
var snapshots []string
for _, dirent := range dirents {
if strings.HasSuffix(dirent.Name(), ".snap") {
snapshots = append(snapshots, dirent.Name())
}
}
// Sort snapshot filenames in reverse lexical order
sort.Sort(sort.Reverse(sort.StringSlice(snapshots)))
// Ignore any snapshots that are older than the current snapshot.
// Delete the others. Rather than doing lexical comparisons, we look
// at what exists before/after the current snapshot in the slice.
// This means that if the current snapshot doesn't appear in the
// directory for some strange reason, we won't delete anything, which
// is the safe behavior.
var (
afterCurSnapshot bool
removeErr error
)
for i, snapFile := range snapshots {
if afterCurSnapshot {
if uint64(len(snapshots)-i) <= keepOldSnapshots {
return removeErr
}
err := os.Remove(filepath.Join(n.snapDir(), snapFile))
if err != nil && removeErr == nil {
removeErr = err
}
} else if snapFile == curSnapshot {
afterCurSnapshot = true
}
}
return removeErr
}
func (n *Node) doSnapshot(raftConfig *api.RaftConfig) {
snapshot := api.Snapshot{Version: api.Snapshot_V0}
for _, member := range n.cluster.Members() {
snapshot.Membership.Members = append(snapshot.Membership.Members,
&api.RaftMember{
NodeID: member.NodeID,
RaftID: member.RaftID,
Addr: member.Addr,
})
}
snapshot.Membership.Removed = n.cluster.Removed()
viewStarted := make(chan struct{})
n.asyncTasks.Add(1)
n.snapshotInProgress = make(chan uint64, 1) // buffered in case Shutdown is called during the snapshot
go func(appliedIndex, snapshotIndex uint64) {
defer func() {
n.asyncTasks.Done()
n.snapshotInProgress <- snapshotIndex
}()
var err error
n.memoryStore.View(func(tx store.ReadTx) {
close(viewStarted)
var storeSnapshot *api.StoreSnapshot
storeSnapshot, err = n.memoryStore.Save(tx)
snapshot.Store = *storeSnapshot
})
if err != nil {
n.Config.Logger.Error(err)
return
}
d, err := snapshot.Marshal()
if err != nil {
n.Config.Logger.Error(err)
return
}
snap, err := n.raftStore.CreateSnapshot(appliedIndex, &n.confState, d)
if err == nil {
if err := n.saveSnapshot(snap, raftConfig.KeepOldSnapshots); err != nil {
n.Config.Logger.Error(err)
return
}
snapshotIndex = appliedIndex
if appliedIndex > raftConfig.LogEntriesForSlowFollowers {
err := n.raftStore.Compact(appliedIndex - raftConfig.LogEntriesForSlowFollowers)
if err != nil && err != raft.ErrCompacted {
n.Config.Logger.Error(err)
}
}
} else if err != raft.ErrSnapOutOfDate {
n.Config.Logger.Error(err)
}
}(n.appliedIndex, n.snapshotIndex)
// Wait for the goroutine to establish a read transaction, to make
// sure it sees the state as of this moment.
<-viewStarted
}
func (n *Node) restoreFromSnapshot(data []byte, forceNewCluster bool) error {
var snapshot api.Snapshot
if err := snapshot.Unmarshal(data); err != nil {
return err
}
if snapshot.Version != api.Snapshot_V0 {
return fmt.Errorf("unrecognized snapshot version %d", snapshot.Version)
}
if err := n.memoryStore.Restore(&snapshot.Store); err != nil {
return err
}
n.cluster.Clear()
if !forceNewCluster {
for _, member := range snapshot.Membership.Members {
if err := n.registerNode(&api.RaftMember{RaftID: member.RaftID, NodeID: member.NodeID, Addr: member.Addr}); err != nil {
return err
}
}
}
for _, removedMember := range snapshot.Membership.Removed {
n.cluster.RemoveMember(removedMember)
}
return nil
}