Java in a Nutshell, 5th Edition [Electronic resources]

This class implements the ReadWriteLock interface. The locks returned by the readLock( ) and writeLock( ) methods are instances of the inner classes ReadLock and WriteLock. ReentrantReadWriteLock defines a "fair mode" and includes instrumentation methods like ReentrantLock does.

Any number of threads can acquire the read lock as long as no thread holds or is attempting to acquire the write lock. When a thread attempts to acquire the write lock, no new read locks are granted. When all existing readers have relinquished the lock, the writer acquires the lock, and no reads are allowed until the writer has relinquished it. A thread that holds the write lock may downgrade to a read lock by acquiring the read lock and then relinquishing the write lock.

Because the read lock is not exclusive, it cannot have a Condition associated with it. The ReadLock.newCondition( ) method throws UnsupportedOperationException.

public class 
ReentrantReadWriteLock  implements ReadWriteLock, Serializable {
// Public Constructors
public 
ReentrantReadWriteLock ( );  
public 
ReentrantReadWriteLock (boolean 
fair );  
// Nested Types
public static class 
ReadLock  implements Lock, Serializable; 
public static class 
WriteLock  implements Lock, Serializable; 
// Public Instance Methods
public final int 
getQueueLength ( );                                  default:0
public int 
getReadLockCount ( );                                      default:0
public int 
getWaitQueueLength (Condition 
condition );  
public int 
getWriteHoldCount ( );                                     default:0
public final boolean 
hasQueuedThread (Thread 
thread );  
public final boolean 
hasQueuedThreads ( );  
public boolean 
hasWaiters (Condition 
condition );  
public final boolean 
isFair ( );                                      default:false
public boolean 
isWriteLocked ( );                                     default:false
public boolean 
isWriteLockedByCurrentThread ( );                      default:false
public ReentrantReadWriteLock.ReadLock 
readLock ( );  
public ReentrantReadWriteLock.WriteLock 
writeLock ( );  
// Public Methods Overriding Object
public String 
toString ( );  
// Protected Instance Methods
protected Thread 
getOwner ( );  
protected java.util.Collection<Thread> 
getQueuedReaderThreads ( );  
protected java.util.Collection<Thread> 
getQueuedThreads ( );  
protected java.util.Collection<Thread> 
getQueuedWriterThreads ( );  
protected java.util.Collection<Thread> 
getWaitingThreads (Condition 
condition );  
}

Passed To

ReentrantReadWriteLock.ReadLock.ReadLock( ),

ReentrantReadWriteLock.WriteLock.WriteLock( )