80 lines
1.6 KiB
Go
80 lines
1.6 KiB
Go
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package stackless
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import (
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"runtime"
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"sync"
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)
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// NewFunc returns stackless wrapper for the function f.
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//
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// Unlike f, the returned stackless wrapper doesn't use stack space
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// on the goroutine that calls it.
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// The wrapper may save a lot of stack space if the following conditions
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// are met:
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//
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// - f doesn't contain blocking calls on network, I/O or channels;
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// - f uses a lot of stack space;
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// - the wrapper is called from high number of concurrent goroutines.
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//
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// The stackless wrapper returns false if the call cannot be processed
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// at the moment due to high load.
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func NewFunc(f func(ctx interface{})) func(ctx interface{}) bool {
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if f == nil {
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panic("BUG: f cannot be nil")
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}
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funcWorkCh := make(chan *funcWork, runtime.GOMAXPROCS(-1)*2048)
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onceInit := func() {
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n := runtime.GOMAXPROCS(-1)
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for i := 0; i < n; i++ {
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go funcWorker(funcWorkCh, f)
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}
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}
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var once sync.Once
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return func(ctx interface{}) bool {
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once.Do(onceInit)
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fw := getFuncWork()
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fw.ctx = ctx
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select {
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case funcWorkCh <- fw:
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default:
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putFuncWork(fw)
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return false
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}
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<-fw.done
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putFuncWork(fw)
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return true
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}
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}
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func funcWorker(funcWorkCh <-chan *funcWork, f func(ctx interface{})) {
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for fw := range funcWorkCh {
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f(fw.ctx)
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fw.done <- struct{}{}
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}
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}
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func getFuncWork() *funcWork {
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v := funcWorkPool.Get()
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if v == nil {
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v = &funcWork{
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done: make(chan struct{}, 1),
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}
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}
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return v.(*funcWork)
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}
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func putFuncWork(fw *funcWork) {
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fw.ctx = nil
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funcWorkPool.Put(fw)
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}
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var funcWorkPool sync.Pool
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type funcWork struct {
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ctx interface{}
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done chan struct{}
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}
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