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Diffstat (limited to 'src/pkg/sync/once.go')
-rw-r--r-- | src/pkg/sync/once.go | 43 |
1 files changed, 0 insertions, 43 deletions
diff --git a/src/pkg/sync/once.go b/src/pkg/sync/once.go deleted file mode 100644 index 161ae3b3e..000000000 --- a/src/pkg/sync/once.go +++ /dev/null @@ -1,43 +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 sync - -import ( - "sync/atomic" -) - -// Once is an object that will perform exactly one action. -type Once struct { - m Mutex - done uint32 -} - -// Do calls the function f if and only if Do is being called for the -// first time for this instance of Once. In other words, given -// var once Once -// if once.Do(f) is called multiple times, only the first call will invoke f, -// even if f has a different value in each invocation. A new instance of -// Once is required for each function to execute. -// -// Do is intended for initialization that must be run exactly once. Since f -// is niladic, it may be necessary to use a function literal to capture the -// arguments to a function to be invoked by Do: -// config.once.Do(func() { config.init(filename) }) -// -// Because no call to Do returns until the one call to f returns, if f causes -// Do to be called, it will deadlock. -// -func (o *Once) Do(f func()) { - if atomic.LoadUint32(&o.done) == 1 { - return - } - // Slow-path. - o.m.Lock() - defer o.m.Unlock() - if o.done == 0 { - f() - atomic.StoreUint32(&o.done, 1) - } -} |