mirror of
https://github.com/restic/restic.git
synced 2024-09-08 12:29:39 +02:00
272 lines
7.7 KiB
Go
272 lines
7.7 KiB
Go
// Copyright 2016 Google Inc. All Rights Reserved.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package pubsub
|
|
|
|
import (
|
|
"sync"
|
|
"time"
|
|
|
|
"golang.org/x/net/context"
|
|
pb "google.golang.org/genproto/googleapis/pubsub/v1"
|
|
)
|
|
|
|
// newMessageIterator starts a new streamingMessageIterator. Stop must be called on the messageIterator
|
|
// when it is no longer needed.
|
|
// subName is the full name of the subscription to pull messages from.
|
|
// ctx is the context to use for acking messages and extending message deadlines.
|
|
func newMessageIterator(ctx context.Context, s service, subName string, po *pullOptions) *streamingMessageIterator {
|
|
sp := s.newStreamingPuller(ctx, subName, int32(po.ackDeadline.Seconds()))
|
|
_ = sp.open() // error stored in sp
|
|
return newStreamingMessageIterator(ctx, sp, po)
|
|
}
|
|
|
|
type streamingMessageIterator struct {
|
|
ctx context.Context
|
|
po *pullOptions
|
|
sp *streamingPuller
|
|
kaTicker *time.Ticker // keep-alive (deadline extensions)
|
|
ackTicker *time.Ticker // message acks
|
|
nackTicker *time.Ticker // message nacks (more frequent than acks)
|
|
failed chan struct{} // closed on stream error
|
|
stopped chan struct{} // closed when Stop is called
|
|
drained chan struct{} // closed when stopped && no more pending messages
|
|
wg sync.WaitGroup
|
|
|
|
mu sync.Mutex
|
|
keepAliveDeadlines map[string]time.Time
|
|
pendingReq *pb.StreamingPullRequest
|
|
err error // error from stream failure
|
|
}
|
|
|
|
func newStreamingMessageIterator(ctx context.Context, sp *streamingPuller, po *pullOptions) *streamingMessageIterator {
|
|
// TODO: make kaTicker frequency more configurable. (ackDeadline - 5s) is a
|
|
// reasonable default for now, because the minimum ack period is 10s. This
|
|
// gives us 5s grace.
|
|
keepAlivePeriod := po.ackDeadline - 5*time.Second
|
|
kaTicker := time.NewTicker(keepAlivePeriod)
|
|
|
|
// Ack promptly so users don't lose work if client crashes.
|
|
ackTicker := time.NewTicker(100 * time.Millisecond)
|
|
nackTicker := time.NewTicker(100 * time.Millisecond)
|
|
it := &streamingMessageIterator{
|
|
ctx: ctx,
|
|
sp: sp,
|
|
po: po,
|
|
kaTicker: kaTicker,
|
|
ackTicker: ackTicker,
|
|
nackTicker: nackTicker,
|
|
failed: make(chan struct{}),
|
|
stopped: make(chan struct{}),
|
|
drained: make(chan struct{}),
|
|
keepAliveDeadlines: map[string]time.Time{},
|
|
pendingReq: &pb.StreamingPullRequest{},
|
|
}
|
|
it.wg.Add(1)
|
|
go it.sender()
|
|
return it
|
|
}
|
|
|
|
// Subscription.receive will call stop on its messageIterator when finished with it.
|
|
// Stop will block until Done has been called on all Messages that have been
|
|
// returned by Next, or until the context with which the messageIterator was created
|
|
// is cancelled or exceeds its deadline.
|
|
func (it *streamingMessageIterator) stop() {
|
|
it.mu.Lock()
|
|
select {
|
|
case <-it.stopped:
|
|
default:
|
|
close(it.stopped)
|
|
}
|
|
it.checkDrained()
|
|
it.mu.Unlock()
|
|
it.wg.Wait()
|
|
}
|
|
|
|
// checkDrained closes the drained channel if the iterator has been stopped and all
|
|
// pending messages have either been n/acked or expired.
|
|
//
|
|
// Called with the lock held.
|
|
func (it *streamingMessageIterator) checkDrained() {
|
|
select {
|
|
case <-it.drained:
|
|
return
|
|
default:
|
|
}
|
|
select {
|
|
case <-it.stopped:
|
|
if len(it.keepAliveDeadlines) == 0 {
|
|
close(it.drained)
|
|
}
|
|
default:
|
|
}
|
|
}
|
|
|
|
// Called when a message is acked/nacked.
|
|
func (it *streamingMessageIterator) done(ackID string, ack bool) {
|
|
it.mu.Lock()
|
|
defer it.mu.Unlock()
|
|
delete(it.keepAliveDeadlines, ackID)
|
|
if ack {
|
|
it.pendingReq.AckIds = append(it.pendingReq.AckIds, ackID)
|
|
} else {
|
|
it.addDeadlineMod(ackID, 0) // Nack indicated by modifying the deadline to zero.
|
|
}
|
|
it.checkDrained()
|
|
}
|
|
|
|
// addDeadlineMod adds the ack ID to the pending request with the given deadline.
|
|
//
|
|
// Called with the lock held.
|
|
func (it *streamingMessageIterator) addDeadlineMod(ackID string, deadlineSecs int32) {
|
|
pr := it.pendingReq
|
|
pr.ModifyDeadlineAckIds = append(pr.ModifyDeadlineAckIds, ackID)
|
|
pr.ModifyDeadlineSeconds = append(pr.ModifyDeadlineSeconds, deadlineSecs)
|
|
}
|
|
|
|
// fail is called when a stream method returns a permanent error.
|
|
func (it *streamingMessageIterator) fail(err error) {
|
|
it.mu.Lock()
|
|
if it.err == nil {
|
|
it.err = err
|
|
close(it.failed)
|
|
}
|
|
it.mu.Unlock()
|
|
}
|
|
|
|
// receive makes a call to the stream's Recv method and returns
|
|
// its messages.
|
|
func (it *streamingMessageIterator) receive() ([]*Message, error) {
|
|
// Stop retrieving messages if the context is done, the stream
|
|
// failed, or the iterator's Stop method was called.
|
|
select {
|
|
case <-it.ctx.Done():
|
|
return nil, it.ctx.Err()
|
|
default:
|
|
}
|
|
it.mu.Lock()
|
|
err := it.err
|
|
it.mu.Unlock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
// Receive messages from stream. This may block indefinitely.
|
|
msgs, err := it.sp.fetchMessages()
|
|
// The streamingPuller handles retries, so any error here
|
|
// is fatal.
|
|
if err != nil {
|
|
it.fail(err)
|
|
return nil, err
|
|
}
|
|
// We received some messages. Remember them so we can
|
|
// keep them alive.
|
|
deadline := time.Now().Add(it.po.maxExtension)
|
|
it.mu.Lock()
|
|
for _, m := range msgs {
|
|
m.doneFunc = it.done
|
|
it.keepAliveDeadlines[m.ackID] = deadline
|
|
}
|
|
it.mu.Unlock()
|
|
return msgs, nil
|
|
}
|
|
|
|
// sender runs in a goroutine and handles all sends to the stream.
|
|
func (it *streamingMessageIterator) sender() {
|
|
defer it.wg.Done()
|
|
defer it.kaTicker.Stop()
|
|
defer it.ackTicker.Stop()
|
|
defer it.nackTicker.Stop()
|
|
defer it.sp.closeSend()
|
|
|
|
done := false
|
|
for !done {
|
|
send := false
|
|
select {
|
|
case <-it.ctx.Done():
|
|
// Context canceled or timed out: stop immediately, without
|
|
// another RPC.
|
|
return
|
|
|
|
case <-it.failed:
|
|
// Stream failed: nothing to do, so stop immediately.
|
|
return
|
|
|
|
case <-it.drained:
|
|
// All outstanding messages have been marked done:
|
|
// nothing left to do except send the final request.
|
|
it.mu.Lock()
|
|
send = (len(it.pendingReq.AckIds) > 0 || len(it.pendingReq.ModifyDeadlineAckIds) > 0)
|
|
done = true
|
|
|
|
case <-it.kaTicker.C:
|
|
it.mu.Lock()
|
|
send = it.handleKeepAlives()
|
|
|
|
case <-it.nackTicker.C:
|
|
it.mu.Lock()
|
|
send = (len(it.pendingReq.ModifyDeadlineAckIds) > 0)
|
|
|
|
case <-it.ackTicker.C:
|
|
it.mu.Lock()
|
|
send = (len(it.pendingReq.AckIds) > 0)
|
|
|
|
}
|
|
// Lock is held here.
|
|
if send {
|
|
req := it.pendingReq
|
|
it.pendingReq = &pb.StreamingPullRequest{}
|
|
it.mu.Unlock()
|
|
err := it.sp.send(req)
|
|
if err != nil {
|
|
// The streamingPuller handles retries, so any error here
|
|
// is fatal to the iterator.
|
|
it.fail(err)
|
|
return
|
|
}
|
|
} else {
|
|
it.mu.Unlock()
|
|
}
|
|
}
|
|
}
|
|
|
|
// handleKeepAlives modifies the pending request to include deadline extensions
|
|
// for live messages. It also purges expired messages. It reports whether
|
|
// there were any live messages.
|
|
//
|
|
// Called with the lock held.
|
|
func (it *streamingMessageIterator) handleKeepAlives() bool {
|
|
live, expired := getKeepAliveAckIDs(it.keepAliveDeadlines)
|
|
for _, e := range expired {
|
|
delete(it.keepAliveDeadlines, e)
|
|
}
|
|
dl := trunc32(int64(it.po.ackDeadline.Seconds()))
|
|
for _, m := range live {
|
|
it.addDeadlineMod(m, dl)
|
|
}
|
|
it.checkDrained()
|
|
return len(live) > 0
|
|
}
|
|
|
|
func getKeepAliveAckIDs(items map[string]time.Time) (live, expired []string) {
|
|
now := time.Now()
|
|
for id, expiry := range items {
|
|
if expiry.Before(now) {
|
|
expired = append(expired, id)
|
|
} else {
|
|
live = append(live, id)
|
|
}
|
|
}
|
|
return live, expired
|
|
}
|