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58 lines
1.4 KiB
Go
58 lines
1.4 KiB
Go
package syncx
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import "sync"
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type (
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// LockedCalls makes sure the calls with the same key to be called sequentially.
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// For example, A called F, before it's done, B called F, then B's call would not blocked,
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// after A's call finished, B's call got executed.
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// The calls with the same key are independent, not sharing the returned values.
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// A ------->calls F with key and executes<------->returns
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// B ------------------>calls F with key<--------->executes<---->returns
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LockedCalls interface {
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Do(key string, fn func() (interface{}, error)) (interface{}, error)
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}
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lockedGroup struct {
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mu sync.Mutex
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m map[string]*sync.WaitGroup
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}
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)
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// NewLockedCalls returns a LockedCalls.
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func NewLockedCalls() LockedCalls {
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return &lockedGroup{
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m: make(map[string]*sync.WaitGroup),
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}
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}
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func (lg *lockedGroup) Do(key string, fn func() (interface{}, error)) (interface{}, error) {
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begin:
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lg.mu.Lock()
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if wg, ok := lg.m[key]; ok {
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lg.mu.Unlock()
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wg.Wait()
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goto begin
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}
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return lg.makeCall(key, fn)
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}
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func (lg *lockedGroup) makeCall(key string, fn func() (interface{}, error)) (interface{}, error) {
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var wg sync.WaitGroup
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wg.Add(1)
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lg.m[key] = &wg
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lg.mu.Unlock()
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defer func() {
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// delete key first, done later. can't reverse the order, because if reverse,
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// another Do call might wg.Wait() without get notified with wg.Done()
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lg.mu.Lock()
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delete(lg.m, key)
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lg.mu.Unlock()
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wg.Done()
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}()
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return fn()
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}
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