| // Copyright 2021 Google LLC |
| // |
| // 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 |
| // |
| // https://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 |
| |
| package wire |
| |
| import ( |
| "sync" |
| "time" |
| ) |
| |
| // minDuration returns the minimum of two durations. |
| func minDuration(a, b time.Duration) time.Duration { |
| if a < b { |
| return a |
| } |
| return b |
| } |
| |
| type timerStatus int |
| |
| const ( |
| timerActive timerStatus = iota |
| timerStopped |
| timerTriggered |
| ) |
| |
| // requestTimer is a one-shot timer used to bound the duration of a request. It |
| // executes `onTimeout` if the timeout expires. |
| type requestTimer struct { |
| onTimeout func() |
| timeoutErr error |
| timer *time.Timer |
| mu sync.Mutex |
| status timerStatus |
| } |
| |
| func newRequestTimer(timeout time.Duration, onTimeout func(), timeoutErr error) *requestTimer { |
| rt := &requestTimer{ |
| onTimeout: onTimeout, |
| timeoutErr: timeoutErr, |
| status: timerActive, |
| } |
| rt.timer = time.AfterFunc(timeout, rt.onTriggered) |
| return rt |
| } |
| |
| func (rt *requestTimer) onTriggered() { |
| rt.mu.Lock() |
| defer rt.mu.Unlock() |
| if rt.status == timerActive { |
| rt.status = timerTriggered |
| rt.onTimeout() |
| } |
| } |
| |
| // Stop should be called upon a successful request to prevent the timer from |
| // expiring. |
| func (rt *requestTimer) Stop() { |
| rt.mu.Lock() |
| defer rt.mu.Unlock() |
| if rt.status == timerActive { |
| rt.status = timerStopped |
| rt.timer.Stop() |
| } |
| } |
| |
| // ResolveError returns `timeoutErr` if the timer triggered, or otherwise |
| // `originalErr`. |
| func (rt *requestTimer) ResolveError(originalErr error) error { |
| rt.mu.Lock() |
| defer rt.mu.Unlock() |
| if rt.status == timerTriggered { |
| return rt.timeoutErr |
| } |
| return originalErr |
| } |
| |
| // streamIdleTimer is an approximate timer used to detect idle streams. |
| // `onTimeout` may be called up to (timeout / pollDivisor) after `timeout` has |
| // expired. |
| type streamIdleTimer struct { |
| timeout time.Duration |
| onTimeout func() |
| task *periodicTask |
| mu sync.Mutex |
| status timerStatus |
| startTime time.Time |
| } |
| |
| const ( |
| pollDivisor = 4 |
| maxPollInterval = time.Minute |
| ) |
| |
| // newStreamIdleTimer creates an unstarted timer. |
| func newStreamIdleTimer(timeout time.Duration, onTimeout func()) *streamIdleTimer { |
| st := &streamIdleTimer{ |
| timeout: timeout, |
| onTimeout: onTimeout, |
| status: timerStopped, |
| } |
| st.task = newPeriodicTask(minDuration(timeout/pollDivisor, maxPollInterval), st.onPoll) |
| st.task.Start() |
| return st |
| } |
| |
| // Restart the timer. Should be called when there is stream activity. |
| func (st *streamIdleTimer) Restart() { |
| st.mu.Lock() |
| defer st.mu.Unlock() |
| st.status = timerActive |
| st.startTime = time.Now() |
| } |
| |
| // Stop the timer to prevent it from expiring. |
| func (st *streamIdleTimer) Stop() { |
| st.mu.Lock() |
| defer st.mu.Unlock() |
| st.status = timerStopped |
| } |
| |
| // Shutdown should be called when the timer is no longer used. |
| func (st *streamIdleTimer) Shutdown() { |
| st.Stop() |
| st.task.Stop() |
| } |
| |
| func (st *streamIdleTimer) onPoll() { |
| timeoutExpired := func() bool { |
| st.mu.Lock() |
| defer st.mu.Unlock() |
| // Note: time.Since() uses monotonic clock readings. |
| if st.status == timerActive && time.Since(st.startTime) > st.timeout { |
| st.status = timerTriggered |
| return true |
| } |
| return false |
| }() |
| if timeoutExpired { |
| st.onTimeout() |
| } |
| } |