package mutexes import ( "sync" "time" "git.iim.gay/grufwub/go-nowish" ) // TimeoutMutex defines a Mutex with timeouts on locks type TimeoutMutex interface { Mutex // LockFunc is functionally the same as Lock(), but allows setting a custom hook called on timeout LockFunc(func()) func() } // TimeoutRWMutex defines a RWMutex with timeouts on locks type TimeoutRWMutex interface { RWMutex // LockFunc is functionally the same as Lock(), but allows setting a custom hook called on timeout LockFunc(func()) func() // RLockFunc is functionally the same as RLock(), but allows setting a custom hook called on timeout RLockFunc(func()) func() } // WithTimeout wraps the supplied Mutex to add a timeout func WithTimeout(mu Mutex, d time.Duration) TimeoutMutex { return &timeoutMutex{mu: mu, d: d} } // WithTimeoutRW wraps the supplied RWMutex to add read/write timeouts func WithTimeoutRW(mu RWMutex, rd, wd time.Duration) TimeoutRWMutex { return &timeoutRWMutex{mu: mu, rd: rd, wd: wd} } // timeoutMutex wraps a Mutex with timeout type timeoutMutex struct { mu Mutex // mu is the wrapped mutex d time.Duration // d is the timeout duration } func (mu *timeoutMutex) Lock() func() { return mu.LockFunc(func() { panic("timed out") }) } func (mu *timeoutMutex) LockFunc(fn func()) func() { return mutexTimeout(mu.d, mu.mu.Lock(), fn) } // TimeoutRWMutex wraps a RWMutex with timeouts type timeoutRWMutex struct { mu RWMutex // mu is the wrapped rwmutex rd time.Duration // rd is the rlock timeout duration wd time.Duration // wd is the lock timeout duration } func (mu *timeoutRWMutex) Lock() func() { return mu.LockFunc(func() { panic("timed out") }) } func (mu *timeoutRWMutex) LockFunc(fn func()) func() { return mutexTimeout(mu.wd, mu.mu.Lock(), fn) } func (mu *timeoutRWMutex) RLock() func() { return mu.RLockFunc(func() { panic("timed out") }) } func (mu *timeoutRWMutex) RLockFunc(fn func()) func() { return mutexTimeout(mu.rd, mu.mu.RLock(), fn) } // timeoutPool provides nowish.Timeout objects for timeout mutexes var timeoutPool = sync.Pool{ New: func() interface{} { return nowish.NewTimeout() }, } // mutexTimeout performs a timed unlock, calling supplied fn if timeout is reached func mutexTimeout(d time.Duration, unlock func(), fn func()) func() { if d < 1 { // No timeout, just unlock return unlock } // Acquire timeout obj t := timeoutPool.Get().(nowish.Timeout) // Start the timeout with hook t.Start(d, fn) // Return func cancelling timeout, // replacing Timeout in pool and // finally unlocking mutex return func() { t.Cancel() timeoutPool.Put(t) unlock() } }