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Diffstat (limited to 'libgo/go/net/singleflight.go')
-rw-r--r-- | libgo/go/net/singleflight.go | 109 |
1 files changed, 0 insertions, 109 deletions
diff --git a/libgo/go/net/singleflight.go b/libgo/go/net/singleflight.go deleted file mode 100644 index bf599f0cc94..00000000000 --- a/libgo/go/net/singleflight.go +++ /dev/null @@ -1,109 +0,0 @@ -// Copyright 2013 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 net - -import "sync" - -// call is an in-flight or completed singleflight.Do call -type call struct { - wg sync.WaitGroup - - // These fields are written once before the WaitGroup is done - // and are only read after the WaitGroup is done. - val interface{} - err error - - // These fields are read and written with the singleflight - // mutex held before the WaitGroup is done, and are read but - // not written after the WaitGroup is done. - dups int - chans []chan<- singleflightResult -} - -// singleflight represents a class of work and forms a namespace in -// which units of work can be executed with duplicate suppression. -type singleflight struct { - mu sync.Mutex // protects m - m map[string]*call // lazily initialized -} - -// singleflightResult holds the results of Do, so they can be passed -// on a channel. -type singleflightResult struct { - v interface{} - err error - shared bool -} - -// Do executes and returns the results of the given function, making -// sure that only one execution is in-flight for a given key at a -// time. If a duplicate comes in, the duplicate caller waits for the -// original to complete and receives the same results. -// The return value shared indicates whether v was given to multiple callers. -func (g *singleflight) Do(key string, fn func() (interface{}, error)) (v interface{}, err error, shared bool) { - g.mu.Lock() - if g.m == nil { - g.m = make(map[string]*call) - } - if c, ok := g.m[key]; ok { - c.dups++ - g.mu.Unlock() - c.wg.Wait() - return c.val, c.err, true - } - c := new(call) - c.wg.Add(1) - g.m[key] = c - g.mu.Unlock() - - g.doCall(c, key, fn) - return c.val, c.err, c.dups > 0 -} - -// DoChan is like Do but returns a channel that will receive the -// results when they are ready. -func (g *singleflight) DoChan(key string, fn func() (interface{}, error)) <-chan singleflightResult { - ch := make(chan singleflightResult, 1) - g.mu.Lock() - if g.m == nil { - g.m = make(map[string]*call) - } - if c, ok := g.m[key]; ok { - c.dups++ - c.chans = append(c.chans, ch) - g.mu.Unlock() - return ch - } - c := &call{chans: []chan<- singleflightResult{ch}} - c.wg.Add(1) - g.m[key] = c - g.mu.Unlock() - - go g.doCall(c, key, fn) - - return ch -} - -// doCall handles the single call for a key. -func (g *singleflight) doCall(c *call, key string, fn func() (interface{}, error)) { - c.val, c.err = fn() - c.wg.Done() - - g.mu.Lock() - delete(g.m, key) - for _, ch := range c.chans { - ch <- singleflightResult{c.val, c.err, c.dups > 0} - } - g.mu.Unlock() -} - -// Forget tells the singleflight to forget about a key. Future calls -// to Do for this key will call the function rather than waiting for -// an earlier call to complete. -func (g *singleflight) Forget(key string) { - g.mu.Lock() - delete(g.m, key) - g.mu.Unlock() -} |