README
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contextcond
This library provides a sync.Cond that has a WaitContext() method.
WaitContext(context.Context) waits for either the condvar to wake it, or the context to be cancelled.
It returns nil if the condvar woke it, or ctx.Err() if the context was cancelled.
Benchmark
contextcond is slower than sync.Cond, so you should only use it if you need WaitContext().
$ go test -bench .
goos: linux
goarch: amd64
pkg: github.com/Jille/contextcond
cpu: Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz
BenchmarkCond1-8 560541 1968 ns/op
BenchmarkCond2-8 196060 7049 ns/op
BenchmarkCond4-8 95750 12685 ns/op
BenchmarkCond8-8 49628 25710 ns/op
BenchmarkCond16-8 34155 37504 ns/op
BenchmarkCond32-8 14602 82923 ns/op
Compared to sync.Cond:
$ go test -bench . /usr/lib/go-1.19/src/sync/cond_test.go
goos: linux
goarch: amd64
cpu: Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz
BenchmarkCond1-8 1509849 782.1 ns/op
BenchmarkCond2-8 447687 2589 ns/op
BenchmarkCond4-8 251739 5226 ns/op
BenchmarkCond8-8 118968 11194 ns/op
BenchmarkCond16-8 44931 24098 ns/op
BenchmarkCond32-8 28124 40405 ns/op
Documentation
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Overview ¶
Package contextcond provides a sync.Cond that has a WaitContext method.
Internally it's implemented using channels and mutexes.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Cond ¶
type Cond struct {
// L is held while observing or changing the condition
L sync.Locker
// contains filtered or unexported fields
}
Cond is like sync.Cond with a WaitContext method. Unlike sync.Cond, Cond must be initialized with NewCond.
func (*Cond) Broadcast ¶
func (c *Cond) Broadcast()
Broadcast wakes all goroutines waiting on c.
It is allowed but not required for the caller to hold c.L during the call.
func (*Cond) Signal ¶
func (c *Cond) Signal()
Signal wakes one goroutine waiting on c, if there is any.
It is allowed but not required for the caller to hold c.L during the call.
Signal() does not affect goroutine scheduling priority; if other goroutines are attempting to lock c.L, they may be awoken before a "waiting" goroutine.
func (*Cond) Wait ¶
func (c *Cond) Wait()
Wait atomically unlocks c.L and suspends execution of the calling goroutine. After later resuming execution, Wait locks c.L before returning. Unlike in other systems, Wait cannot return unless awoken by Broadcast or Signal. Because c.L is not locked while Wait is waiting, the caller typically cannot assume that the condition is true when Wait returns. Instead, the caller should Wait in a loop.
Source Files