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package storage
import (
"fmt"
"os"
"path/filepath"
"sync"
"github.com/seaweedfs/seaweedfs/weed/glog"
"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
"github.com/seaweedfs/seaweedfs/weed/util"
"google.golang.org/protobuf/proto"
)
const (
StateFileName = "state.pb"
StateFileMode = 0644
)
type State struct {
filePath string
pb *volume_server_pb.VolumeServerState
mu sync.Mutex
}
func NewState(dir string) (*State, error) {
state := &State{
filePath: filepath.Join(dir, StateFileName),
pb: nil,
}
err := state.Load()
return state, err
}
func NewStateFromProto(filePath string, state *volume_server_pb.VolumeServerState) *State {
pb := &volume_server_pb.VolumeServerState{}
proto.Merge(pb, state)
return &State{
filePath: filePath,
pb: pb,
}
}
func (st *State) Proto() *volume_server_pb.VolumeServerState {
st.mu.Lock()
defer st.mu.Unlock()
return st.pb
}
func (st *State) Load() error {
st.mu.Lock()
defer st.mu.Unlock()
st.pb = &volume_server_pb.VolumeServerState{}
if !util.FileExists(st.filePath) {
glog.V(1).Infof("No preexisting store state at %s", st.filePath)
return nil
}
binPb, err := os.ReadFile(st.filePath)
if err != nil {
st.pb = nil
return fmt.Errorf("failed to read store state from %s : %v", st.filePath, err)
}
if err := proto.Unmarshal(binPb, st.pb); err != nil {
st.pb = nil
return fmt.Errorf("failed to parse store state from %s : %v", st.filePath, err)
}
glog.V(1).Infof("Got store state from %s: %v", st.filePath, st.pb)
return nil
}
func (st *State) save(locking bool) error {
if locking {
st.mu.Lock()
defer st.mu.Unlock()
}
if st.pb == nil {
st.pb = &volume_server_pb.VolumeServerState{}
}
binPb, err := proto.Marshal(st.pb)
if err != nil {
return fmt.Errorf("failed to serialize store state %v: %s", st.pb, err)
}
if err := util.WriteFile(st.filePath, binPb, StateFileMode); err != nil {
return fmt.Errorf("failed to write store state to %s : %v", st.filePath, err)
}
glog.V(1).Infof("Saved store state %v to %s", st.pb, st.filePath)
return nil
}
func (st *State) Save() error {
return st.save(true)
}
func (st *State) Update(state *volume_server_pb.VolumeServerState) error {
st.mu.Lock()
defer st.mu.Unlock()
if state == nil {
return nil
}
if got, want := st.pb.GetVersion(), state.GetVersion(); got != want {
return fmt.Errorf("version mismatch for VolumeServerState (got %d, want %d)", got, want)
}
origState := st.pb
st.pb = &volume_server_pb.VolumeServerState{}
proto.Merge(st.pb, state)
st.pb.Version = st.pb.GetVersion() + 1
err := st.save(false)
if err != nil {
// restore the original state upon save failures, to avoid skew between in-memory and disk state protos.
st.pb = origState
}
return err
}