55 lines
901 B
Go
55 lines
901 B
Go
package singledo
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import (
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"sync"
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"time"
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)
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type call struct {
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wg sync.WaitGroup
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val interface{}
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err error
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}
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type Single struct {
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mux sync.Mutex
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last time.Time
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wait time.Duration
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call *call
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result *Result
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}
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type Result struct {
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Val interface{}
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Err error
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}
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func (s *Single) Do(fn func() (interface{}, error)) (v interface{}, err error, shared bool) {
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s.mux.Lock()
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now := time.Now()
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if now.Before(s.last.Add(s.wait)) {
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s.mux.Unlock()
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return s.result.Val, s.result.Err, true
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}
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if call := s.call; call != nil {
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s.mux.Unlock()
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call.wg.Wait()
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return call.val, call.err, true
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}
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call := &call{}
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call.wg.Add(1)
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s.call = call
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s.mux.Unlock()
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call.val, call.err = fn()
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call.wg.Done()
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s.call = nil
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s.result = &Result{call.val, call.err}
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s.last = now
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return call.val, call.err, false
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}
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func NewSingle(wait time.Duration) *Single {
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return &Single{wait: wait}
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}
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