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66 lines
1.4 KiB
66 lines
1.4 KiB
package util
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// initial version comes from https://hackernoon.com/asyncawait-in-golang-an-introductory-guide-ol1e34sg
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import (
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"container/list"
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"context"
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"sync"
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)
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type Future interface {
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Await() interface{}
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}
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type future struct {
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await func(ctx context.Context) interface{}
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}
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func (f future) Await() interface{} {
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return f.await(context.Background())
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}
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type LimitedAsyncExecutor struct {
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executor *LimitedConcurrentExecutor
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futureList *list.List
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futureListCond *sync.Cond
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}
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func NewLimitedAsyncExecutor(limit int) *LimitedAsyncExecutor {
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return &LimitedAsyncExecutor{
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executor: NewLimitedConcurrentExecutor(limit),
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futureList: list.New(),
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futureListCond: sync.NewCond(&sync.Mutex{}),
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}
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}
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func (ae *LimitedAsyncExecutor) Execute(job func() interface{}) {
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var result interface{}
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c := make(chan struct{})
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ae.executor.Execute(func() {
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defer close(c)
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result = job()
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})
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f := future{await: func(ctx context.Context) interface{} {
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select {
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case <-ctx.Done():
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return ctx.Err()
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case <-c:
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return result
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}
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}}
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ae.futureListCond.L.Lock()
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ae.futureList.PushBack(f)
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ae.futureListCond.Signal()
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ae.futureListCond.L.Unlock()
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}
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func (ae *LimitedAsyncExecutor) NextFuture() Future {
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ae.futureListCond.L.Lock()
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for ae.futureList.Len() == 0 {
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ae.futureListCond.Wait()
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}
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f := ae.futureList.Remove(ae.futureList.Front())
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ae.futureListCond.L.Unlock()
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return f.(Future)
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}
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