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fsm.go
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fsm.go
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package consul
import (
"fmt"
"github.com/hashicorp/consul/consul/structs"
"github.com/hashicorp/raft"
"github.com/ugorji/go/codec"
"io"
"log"
"time"
)
// consulFSM implements a finite state machine that is used
// along with Raft to provide strong consistency. We implement
// this outside the Server to avoid exposing this outside the package.
type consulFSM struct {
logOutput io.Writer
logger *log.Logger
state *StateStore
}
// consulSnapshot 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 consulSnapshot struct {
state *StateSnapshot
}
// 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
}
// NewFSM is used to construct a new FSM with a blank state
func NewFSM(logOutput io.Writer) (*consulFSM, error) {
state, err := NewStateStore(logOutput)
if err != nil {
return nil, err
}
fsm := &consulFSM{
logOutput: logOutput,
logger: log.New(logOutput, "", log.LstdFlags),
state: state,
}
return fsm, nil
}
// Close is used to cleanup resources associated with the FSM
func (c *consulFSM) Close() error {
return c.state.Close()
}
// State is used to return a handle to the current state
func (c *consulFSM) State() *StateStore {
return c.state
}
func (c *consulFSM) Apply(log *raft.Log) interface{} {
buf := log.Data
switch structs.MessageType(buf[0]) {
case structs.RegisterRequestType:
return c.decodeRegister(buf[1:], log.Index)
case structs.DeregisterRequestType:
return c.applyDeregister(buf[1:], log.Index)
case structs.KVSRequestType:
return c.applyKVSOperation(buf[1:], log.Index)
default:
panic(fmt.Errorf("failed to apply request: %#v", buf))
}
}
func (c *consulFSM) decodeRegister(buf []byte, index uint64) interface{} {
var req structs.RegisterRequest
if err := structs.Decode(buf, &req); err != nil {
panic(fmt.Errorf("failed to decode request: %v", err))
}
return c.applyRegister(&req, index)
}
func (c *consulFSM) applyRegister(req *structs.RegisterRequest, index uint64) interface{} {
// Ensure the node
node := structs.Node{req.Node, req.Address}
if err := c.state.EnsureNode(index, node); err != nil {
c.logger.Printf("[INFO] consul.fsm: EnsureNode failed: %v", err)
return err
}
// Ensure the service if provided
if req.Service != nil {
if err := c.state.EnsureService(index, req.Node, req.Service); err != nil {
c.logger.Printf("[INFO] consul.fsm: EnsureService failed: %v", err)
return err
}
}
// Ensure the check if provided
if req.Check != nil {
if err := c.state.EnsureCheck(index, req.Check); err != nil {
c.logger.Printf("[INFO] consul.fsm: EnsureCheck failed: %v", err)
return err
}
}
return nil
}
func (c *consulFSM) applyDeregister(buf []byte, index uint64) interface{} {
var req structs.DeregisterRequest
if err := structs.Decode(buf, &req); err != nil {
panic(fmt.Errorf("failed to decode request: %v", err))
}
// Either remove the service entry or the whole node
if req.ServiceID != "" {
if err := c.state.DeleteNodeService(index, req.Node, req.ServiceID); err != nil {
c.logger.Printf("[INFO] consul.fsm: DeleteNodeService failed: %v", err)
return err
}
} else if req.CheckID != "" {
if err := c.state.DeleteNodeCheck(index, req.Node, req.CheckID); err != nil {
c.logger.Printf("[INFO] consul.fsm: DeleteNodeCheck failed: %v", err)
return err
}
} else {
if err := c.state.DeleteNode(index, req.Node); err != nil {
c.logger.Printf("[INFO] consul.fsm: DeleteNode failed: %v", err)
return err
}
}
return nil
}
func (c *consulFSM) applyKVSOperation(buf []byte, index uint64) interface{} {
var req structs.KVSRequest
if err := structs.Decode(buf, &req); err != nil {
panic(fmt.Errorf("failed to decode request: %v", err))
}
switch req.Op {
case structs.KVSSet:
return c.state.KVSSet(index, &req.DirEnt)
case structs.KVSDelete:
return c.state.KVSDelete(index, req.DirEnt.Key)
case structs.KVSDeleteTree:
return c.state.KVSDeleteTree(index, req.DirEnt.Key)
case structs.KVSCAS:
act, err := c.state.KVSCheckAndSet(index, &req.DirEnt)
if err != nil {
return err
} else {
return act
}
default:
c.logger.Printf("[WARN] consul.fsm: Invalid KVS operation '%s'", req.Op)
return fmt.Errorf("Invalid KVS operation '%s'", req.Op)
}
return nil
}
func (c *consulFSM) Snapshot() (raft.FSMSnapshot, error) {
defer func(start time.Time) {
c.logger.Printf("[INFO] consul.fsm: snapshot created in %v", time.Now().Sub(start))
}(time.Now())
// Create a new snapshot
snap, err := c.state.Snapshot()
if err != nil {
return nil, err
}
return &consulSnapshot{snap}, nil
}
func (c *consulFSM) Restore(old io.ReadCloser) error {
defer old.Close()
// Create a new state store
state, err := NewStateStore(c.logOutput)
if err != nil {
return err
}
c.state.Close()
c.state = state
// Create a decoder
var handle codec.MsgpackHandle
dec := codec.NewDecoder(old, &handle)
// Read in the header
var header snapshotHeader
if err := dec.Decode(&header); err != nil {
return err
}
// Populate the new state
msgType := make([]byte, 1)
for {
// Read the message type
_, err := old.Read(msgType)
if err == io.EOF {
break
} else if err != nil {
return err
}
// Decode
switch structs.MessageType(msgType[0]) {
case structs.RegisterRequestType:
var req structs.RegisterRequest
if err := dec.Decode(&req); err != nil {
return err
}
c.applyRegister(&req, header.LastIndex)
case structs.KVSRequestType:
var req structs.DirEntry
if err := dec.Decode(&req); err != nil {
return err
}
if err := c.state.KVSRestore(&req); err != nil {
return err
}
default:
return fmt.Errorf("Unrecognized msg type: %v", msgType)
}
}
return nil
}
func (s *consulSnapshot) Persist(sink raft.SnapshotSink) error {
// Register the nodes
handle := codec.MsgpackHandle{}
encoder := codec.NewEncoder(sink, &handle)
// Write the header
header := snapshotHeader{
LastIndex: s.state.LastIndex(),
}
if err := encoder.Encode(&header); err != nil {
sink.Cancel()
return err
}
// Get all the nodes
nodes := s.state.Nodes()
// Register each node
var req structs.RegisterRequest
for i := 0; i < len(nodes); i++ {
req = structs.RegisterRequest{
Node: nodes[i].Node,
Address: nodes[i].Address,
}
// Register the node itself
sink.Write([]byte{byte(structs.RegisterRequestType)})
if err := encoder.Encode(&req); err != nil {
sink.Cancel()
return err
}
// Register each service this node has
services := s.state.NodeServices(nodes[i].Node)
for _, srv := range services.Services {
req.Service = srv
sink.Write([]byte{byte(structs.RegisterRequestType)})
if err := encoder.Encode(&req); err != nil {
sink.Cancel()
return err
}
}
// Register each check this node has
req.Service = nil
checks := s.state.NodeChecks(nodes[i].Node)
for _, check := range checks {
req.Check = check
sink.Write([]byte{byte(structs.RegisterRequestType)})
if err := encoder.Encode(&req); err != nil {
sink.Cancel()
return err
}
}
}
// Enable GC of the ndoes
nodes = nil
// Dump the KVS entries
streamCh := make(chan interface{}, 256)
errorCh := make(chan error)
go func() {
if err := s.state.KVSDump(streamCh); err != nil {
errorCh <- err
}
}()
OUTER:
for {
select {
case raw := <-streamCh:
if raw == nil {
break OUTER
}
sink.Write([]byte{byte(structs.KVSRequestType)})
if err := encoder.Encode(raw); err != nil {
sink.Cancel()
return err
}
case err := <-errorCh:
sink.Cancel()
return err
}
}
return nil
}
func (s *consulSnapshot) Release() {
s.state.Close()
}