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package raft
import (
"fmt"
"io"
"sync"
"time"
)
// NewInmemAddr returns a new in-memory addr with
// a randomly generate UUID as the ID.
func NewInmemAddr() ServerAddress {
return ServerAddress(generateUUID())
}
// inmemPipeline is used to pipeline requests for the in-mem transport.
type inmemPipeline struct {
trans *InmemTransport
peer *InmemTransport
peerAddr ServerAddress
doneCh chan AppendFuture
inprogressCh chan *inmemPipelineInflight
shutdown bool
shutdownCh chan struct{}
shutdownLock sync.Mutex
}
type inmemPipelineInflight struct {
future *appendFuture
respCh <-chan RPCResponse
}
// InmemTransport Implements the Transport interface, to allow Raft to be
// tested in-memory without going over a network.
type InmemTransport struct {
sync.RWMutex
consumerCh chan RPC
localAddr ServerAddress
peers map[ServerAddress]*InmemTransport
pipelines []*inmemPipeline
timeout time.Duration
}
// NewInmemTransportWithTimeout is used to initialize a new transport and
// generates a random local address if none is specified. The given timeout
// will be used to decide how long to wait for a connected peer to process the
// RPCs that we're sending it. See also Connect() and Consumer().
func NewInmemTransportWithTimeout(addr ServerAddress, timeout time.Duration) (ServerAddress, *InmemTransport) {
if string(addr) == "" {
addr = NewInmemAddr()
}
trans := &InmemTransport{
consumerCh: make(chan RPC, 16),
localAddr: addr,
peers: make(map[ServerAddress]*InmemTransport),
timeout: timeout,
}
return addr, trans
}
// NewInmemTransport is used to initialize a new transport
// and generates a random local address if none is specified
func NewInmemTransport(addr ServerAddress) (ServerAddress, *InmemTransport) {
return NewInmemTransportWithTimeout(addr, 50*time.Millisecond)
}
// SetHeartbeatHandler is used to set optional fast-path for
// heartbeats, not supported for this transport.
func (i *InmemTransport) SetHeartbeatHandler(cb func(RPC)) {
}
// Consumer implements the Transport interface.
func (i *InmemTransport) Consumer() <-chan RPC {
return i.consumerCh
}
// LocalAddr implements the Transport interface.
func (i *InmemTransport) LocalAddr() ServerAddress {
return i.localAddr
}
// AppendEntriesPipeline returns an interface that can be used to pipeline
// AppendEntries requests.
func (i *InmemTransport) AppendEntriesPipeline(id ServerID, target ServerAddress) (AppendPipeline, error) {
i.Lock()
defer i.Unlock()
peer, ok := i.peers[target]
if !ok {
return nil, fmt.Errorf("failed to connect to peer: %v", target)
}
pipeline := newInmemPipeline(i, peer, target)
i.pipelines = append(i.pipelines, pipeline)
return pipeline, nil
}
// AppendEntries implements the Transport interface.
func (i *InmemTransport) AppendEntries(id ServerID, target ServerAddress, args *AppendEntriesRequest, resp *AppendEntriesResponse) error {
rpcResp, err := i.makeRPC(target, args, nil, i.timeout)
if err != nil {
return err
}
// Copy the result back
out := rpcResp.Response.(*AppendEntriesResponse)
*resp = *out
return nil
}
// RequestVote implements the Transport interface.
func (i *InmemTransport) RequestVote(id ServerID, target ServerAddress, args *RequestVoteRequest, resp *RequestVoteResponse) error {
rpcResp, err := i.makeRPC(target, args, nil, i.timeout)
if err != nil {
return err
}
// Copy the result back
out := rpcResp.Response.(*RequestVoteResponse)
*resp = *out
return nil
}
// InstallSnapshot implements the Transport interface.
func (i *InmemTransport) InstallSnapshot(id ServerID, target ServerAddress, args *InstallSnapshotRequest, resp *InstallSnapshotResponse, data io.Reader) error {
rpcResp, err := i.makeRPC(target, args, data, 10*i.timeout)
if err != nil {
return err
}
// Copy the result back
out := rpcResp.Response.(*InstallSnapshotResponse)
*resp = *out
return nil
}
// TimeoutNow implements the Transport interface.
func (i *InmemTransport) TimeoutNow(id ServerID, target ServerAddress, args *TimeoutNowRequest, resp *TimeoutNowResponse) error {
rpcResp, err := i.makeRPC(target, args, nil, 10*i.timeout)
if err != nil {
return err
}
// Copy the result back
out := rpcResp.Response.(*TimeoutNowResponse)
*resp = *out
return nil
}
func (i *InmemTransport) makeRPC(target ServerAddress, args interface{}, r io.Reader, timeout time.Duration) (rpcResp RPCResponse, err error) {
i.RLock()
peer, ok := i.peers[target]
i.RUnlock()
if !ok {
err = fmt.Errorf("failed to connect to peer: %v", target)
return
}
// Send the RPC over
respCh := make(chan RPCResponse)
req := RPC{
Command: args,
Reader: r,
RespChan: respCh,
}
select {
case peer.consumerCh <- req:
case <-time.After(timeout):
err = fmt.Errorf("send timed out")
return
}
// Wait for a response
select {
case rpcResp = <-respCh:
if rpcResp.Error != nil {
err = rpcResp.Error
}
case <-time.After(timeout):
err = fmt.Errorf("command timed out")
}
return
}
// EncodePeer implements the Transport interface.
func (i *InmemTransport) EncodePeer(id ServerID, p ServerAddress) []byte {
return []byte(p)
}
// DecodePeer implements the Transport interface.
func (i *InmemTransport) DecodePeer(buf []byte) ServerAddress {
return ServerAddress(buf)
}
// Connect is used to connect this transport to another transport for
// a given peer name. This allows for local routing.
func (i *InmemTransport) Connect(peer ServerAddress, t Transport) {
trans := t.(*InmemTransport)
i.Lock()
defer i.Unlock()
i.peers[peer] = trans
}
// Disconnect is used to remove the ability to route to a given peer.
func (i *InmemTransport) Disconnect(peer ServerAddress) {
i.Lock()
defer i.Unlock()
delete(i.peers, peer)
// Disconnect any pipelines
n := len(i.pipelines)
for idx := 0; idx < n; idx++ {
if i.pipelines[idx].peerAddr == peer {
i.pipelines[idx].Close()
i.pipelines[idx], i.pipelines[n-1] = i.pipelines[n-1], nil
idx--
n--
}
}
i.pipelines = i.pipelines[:n]
}
// DisconnectAll is used to remove all routes to peers.
func (i *InmemTransport) DisconnectAll() {
i.Lock()
defer i.Unlock()
i.peers = make(map[ServerAddress]*InmemTransport)
// Handle pipelines
for _, pipeline := range i.pipelines {
pipeline.Close()
}
i.pipelines = nil
}
// Close is used to permanently disable the transport
func (i *InmemTransport) Close() error {
i.DisconnectAll()
return nil
}
func newInmemPipeline(trans *InmemTransport, peer *InmemTransport, addr ServerAddress) *inmemPipeline {
i := &inmemPipeline{
trans: trans,
peer: peer,
peerAddr: addr,
doneCh: make(chan AppendFuture, 16),
inprogressCh: make(chan *inmemPipelineInflight, 16),
shutdownCh: make(chan struct{}),
}
go i.decodeResponses()
return i
}
func (i *inmemPipeline) decodeResponses() {
timeout := i.trans.timeout
for {
select {
case inp := <-i.inprogressCh:
var timeoutCh <-chan time.Time
if timeout > 0 {
timeoutCh = time.After(timeout)
}
select {
case rpcResp := <-inp.respCh:
// Copy the result back
*inp.future.resp = *rpcResp.Response.(*AppendEntriesResponse)
inp.future.respond(rpcResp.Error)
select {
case i.doneCh <- inp.future:
case <-i.shutdownCh:
return
}
case <-timeoutCh:
inp.future.respond(fmt.Errorf("command timed out"))
select {
case i.doneCh <- inp.future:
case <-i.shutdownCh:
return
}
case <-i.shutdownCh:
return
}
case <-i.shutdownCh:
return
}
}
}
func (i *inmemPipeline) AppendEntries(args *AppendEntriesRequest, resp *AppendEntriesResponse) (AppendFuture, error) {
// Create a new future
future := &appendFuture{
start: time.Now(),
args: args,
resp: resp,
}
future.init()
// Handle a timeout
var timeout <-chan time.Time
if i.trans.timeout > 0 {
timeout = time.After(i.trans.timeout)
}
// Send the RPC over
respCh := make(chan RPCResponse, 1)
rpc := RPC{
Command: args,
RespChan: respCh,
}
select {
case i.peer.consumerCh <- rpc:
case <-timeout:
return nil, fmt.Errorf("command enqueue timeout")
case <-i.shutdownCh:
return nil, ErrPipelineShutdown
}
// Send to be decoded
select {
case i.inprogressCh <- &inmemPipelineInflight{future, respCh}:
return future, nil
case <-i.shutdownCh:
return nil, ErrPipelineShutdown
}
}
func (i *inmemPipeline) Consumer() <-chan AppendFuture {
return i.doneCh
}
func (i *inmemPipeline) Close() error {
i.shutdownLock.Lock()
defer i.shutdownLock.Unlock()
if i.shutdown {
return nil
}
i.shutdown = true
close(i.shutdownCh)
return nil
}
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