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document once

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R=rsc
DELTA=14  (7 added, 5 deleted, 2 changed)
OCL=25818
CL=25834
This commit is contained in:
Rob Pike 2009-03-06 03:36:50 -08:00
parent 85647c94e6
commit 5b4fa1ad22
1 changed files with 9 additions and 7 deletions
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16
src/lib/once.go
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@ -2,13 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// For one-time initialization that is not done during init.
// Wrap the initialization in a niladic function f() and call
// once.Do(f)
// If multiple processes call once.Do(f) simultaneously
// with the same f argument, only one will call f, and the
// others will block until f finishes running.
// This package provides a single function, Do, to run a function
// exactly once, usually used as part of initialization.
package once
import "sync"
@ -21,6 +16,13 @@ type job struct {
var jobs = make(map[func()]*job)
var joblock sync.Mutex;
// Do is the the only exported piece of the package.
// For one-time initialization that is not done during init,
// wrap the initialization in a niladic function f() and call
// Do(f)
// If multiple processes call Do(f) simultaneously
// with the same f argument, only one will call f, and the
// others will block until f finishes running.
func Do(f func()) {
joblock.Lock();
j, present := jobs[f];