package fsm import ( "fmt" "time" "github.com/armon/go-metrics" "github.com/hashicorp/consul/agent/consul/state" "github.com/hashicorp/consul/agent/structs" "github.com/hashicorp/go-msgpack/codec" "github.com/hashicorp/raft" ) // snapshot is used to provide a snapshot of the current // state in a way that can be accessed concurrently with operations // that may modify the live state. type snapshot struct { state *state.Snapshot } // snapshotHeader is the first entry in our snapshot type snapshotHeader struct { // LastIndex is the last index that affects the data. // This is used when we do the restore for watchers. LastIndex uint64 } // persister is a function used to help snapshot the FSM state. type persister func(s *snapshot, sink raft.SnapshotSink, encoder *codec.Encoder) error // persisters is a list of snapshot functions. var persisters []persister // registerPersister adds a new helper. This should be called at package // init() time. func registerPersister(fn persister) { persisters = append(persisters, fn) } // restorer is a function used to load back a snapshot of the FSM state. type restorer func(header *snapshotHeader, restore *state.Restore, decoder *codec.Decoder) error // restorers is a map of restore functions by message type. var restorers map[structs.MessageType]restorer // registerRestorer adds a new helper. This should be called at package // init() time. func registerRestorer(msg structs.MessageType, fn restorer) { if restorers == nil { restorers = make(map[structs.MessageType]restorer) } if restorers[msg] != nil { panic(fmt.Errorf("Message %d is already registered", msg)) } restorers[msg] = fn } // Persist saves the FSM snapshot out to the given sink. func (s *snapshot) Persist(sink raft.SnapshotSink) error { defer metrics.MeasureSince([]string{"consul", "fsm", "persist"}, time.Now()) defer metrics.MeasureSince([]string{"fsm", "persist"}, time.Now()) // Write the header header := snapshotHeader{ LastIndex: s.state.LastIndex(), } encoder := codec.NewEncoder(sink, msgpackHandle) if err := encoder.Encode(&header); err != nil { sink.Cancel() return err } // Run all the persisters to write the FSM state. for _, fn := range persisters { if err := fn(s, sink, encoder); err != nil { sink.Cancel() return err } } return nil } func (s *snapshot) Release() { s.state.Close() }