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