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mirror of https://github.com/golang/go synced 2024-11-21 18:14:42 -07:00

delete pkg/once

R=rsc
CC=golang-dev
https://golang.org/cl/1995041
This commit is contained in:
Rob Pike 2010-08-13 12:53:27 +10:00
parent 7886318ca0
commit a621a7ef74
5 changed files with 0 additions and 102 deletions

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@ -100,7 +100,6 @@ DIRS=\
net/textproto\
netchan\
nntp\
once\
os\
os/signal\
patch\

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@ -1,11 +0,0 @@
# Copyright 2009 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
include ../../Make.$(GOARCH)
TARG=once
GOFILES=\
once.go\
include ../../Make.pkg

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@ -1,59 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This package provides a single function, Do, to run a function
// exactly once, usually used as part of initialization.
package once
import "sync"
type job struct {
done bool
sync.Mutex // should probably be sync.Notification or some such
}
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.
//
// Since a func() expression typically evaluates to a differerent
// function value each time it is evaluated, it is incorrect to
// pass such values to Do. For example,
// func f(x int) {
// Do(func() { fmt.Println(x) })
// }
// behaves the same as
// func f(x int) {
// fmt.Println(x)
// }
// because the func() expression in the first creates a new
// func each time f runs, and each of those funcs is run once.
func Do(f func()) {
joblock.Lock()
j := jobs[f]
if j == nil {
// run it
j = new(job)
j.Lock()
jobs[f] = j
joblock.Unlock()
f()
j.done = true
j.Unlock()
} else {
// wait for it
joblock.Unlock()
if j.done != true {
j.Lock()
j.Unlock()
}
}
}

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@ -1,30 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package once_test
import (
"once"
"testing"
)
var ncall int
func call() { ncall++ }
func TestDo(t *testing.T) {
ncall = 0
once.Do(call)
if ncall != 1 {
t.Fatalf("once.Do(call) didn't call(): ncall=%d", ncall)
}
once.Do(call)
if ncall != 1 {
t.Fatalf("second once.Do(call) did call(): ncall=%d", ncall)
}
once.Do(call)
if ncall != 1 {
t.Fatalf("third once.Do(call) did call(): ncall=%d", ncall)
}
}

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@ -185,7 +185,6 @@ var packages = []string{
"mime",
"net",
"nntp",
"once",
"os",
"os/signal",
"patch",