mirror of
https://github.com/golang/go
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66 lines
1.8 KiB
Go
66 lines
1.8 KiB
Go
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sync
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// A Pool is a set of temporary objects that may be individually saved
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// and retrieved.
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//
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// Any item stored in the Pool may be removed automatically by the
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// implementation at any time without notification.
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// If the Pool holds the only reference when this happens, the item
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// might be deallocated.
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//
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// A Pool is safe for use by multiple goroutines simultaneously.
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//
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// This is an experimental package and might not be released.
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type Pool struct {
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next *Pool // for use by runtime. must be first.
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list []interface{} // offset known to runtime
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mu Mutex // guards list
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// New optionally specifies a function to generate
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// a value when Get would otherwise return nil.
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// It may not be changed concurrently with calls to Get.
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New func() interface{}
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}
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func runtime_registerPool(*Pool)
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// Put adds x to the pool.
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func (p *Pool) Put(x interface{}) {
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if x == nil {
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return
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}
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p.mu.Lock()
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if p.list == nil {
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runtime_registerPool(p)
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}
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p.list = append(p.list, x)
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p.mu.Unlock()
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}
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// Get selects an arbitrary item from the Pool, removes it from the
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// Pool, and returns it to the caller.
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// Get may choose to ignore the pool and treat it as empty.
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// Callers should not assume any relation between values passed to Put and
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// the values returned by Get.
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//
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// If Get would otherwise return nil and p.New is non-nil, Get returns
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// the result of calling p.New.
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func (p *Pool) Get() interface{} {
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p.mu.Lock()
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var x interface{}
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if n := len(p.list); n > 0 {
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x = p.list[n-1]
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p.list[n-1] = nil // Just to be safe
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p.list = p.list[:n-1]
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}
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p.mu.Unlock()
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if x == nil && p.New != nil {
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x = p.New()
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}
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return x
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}
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