úÎ SÒ     HA type representing the state of a lock: available, in use by a certain + number of readers, or in use by a writer.  OAcquire a lock in read mode, try to execute some action, and release the lock. PAcquire a lock in write mode, try to execute some action, and release the lock.          rwlock-0.0.0.1Control.Concurrent.RWLock RWLockStateWritingReadersOpenRWLock newRWLock newRWLockIO readRWLock readRWLockIOtryTakeReadLocktryPutReadLocktryTakeReadLockIOtryPutReadLockIO takeReadLock putReadLocktakeReadLockIO putReadLockIO withReadLocktryTakeWriteLocktryPutWriteLocktryTakeWriteLockIOtryPutWriteLockIO takeWriteLock putWriteLocktakeWriteLockIOputWriteLockIO withWriteLockLockunLock