com.bigdata.btree

Class ReadWriteLockManager

java.lang.Object

com.bigdata.btree.ReadWriteLockManager

All Implemented Interfaces:

IReadWriteLockManager

public class ReadWriteLockManager
extends Object
implements IReadWriteLockManager

Base class for managing read/write locks for unisolated ICommitters.

Author:

Bryan Thompson

See Also:

AssertionError: Child does not have persistent identity

Method Summary

Methods

Modifier and Type	Method and Description
static ReadWriteLockManager	getLockManager(ICheckpointProtocol index) Canonicalizing factory for the ReadWriteLock for an ICommitter.
int	getReadLockCount() Return the #of read-locks held by the current thread for a mutable index view.
boolean	isReadOnly() Return true iff the data structure is read-only.
Lock	readLock() Return a Lock that may be used to obtain a shared read lock which is used (in the absence of other concurrency control mechanisms) to permit concurrent readers on an unisolated index while serializing access to that index when a writer must run.
Lock	writeLock() Return a Lock that may be used to obtain an exclusive write lock which is used (in the absence of other concurrency control mechanisms) to serialize all processes accessing an unisolated index when a writer must run.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getReadLockCount

public int getReadLockCount()

Description copied from interface: IReadWriteLockManager

Return the #of read-locks held by the current thread for a mutable index view.

Specified by:

getReadLockCount in interface IReadWriteLockManager

Returns:

The #of reentrant read locks held by the current thread -or- ZERO if the index is read-only (read locks are not tracked for a read-only index view).

readLock

public Lock readLock()

Description copied from interface: IReadWriteLockManager

Return a Lock that may be used to obtain a shared read lock which is used (in the absence of other concurrency control mechanisms) to permit concurrent readers on an unisolated index while serializing access to that index when a writer must run. This is exposed for processes which need to obtain the write lock to coordinate external operations.

Note: If the persistence capable data structure is read-only then the returned Lock is a singleton that ignores all lock requests. This is because our read-only persistence capable data structures are already thread-safe for concurrent readers.

Specified by:

readLock in interface IReadWriteLockManager

Returns:

The lock.

writeLock

public Lock writeLock()

Description copied from interface: IReadWriteLockManager

Return a Lock that may be used to obtain an exclusive write lock which is used (in the absence of other concurrency control mechanisms) to serialize all processes accessing an unisolated index when a writer must run. This is exposed for processes which need to obtain the write lock to coordinate external operations.

Specified by:

writeLock in interface IReadWriteLockManager

Returns:

The lock.

isReadOnly

public boolean isReadOnly()

Description copied from interface: IReadWriteLockManager

Return true iff the data structure is read-only.

Specified by:

isReadOnly in interface IReadWriteLockManager

getLockManager

public static ReadWriteLockManager getLockManager(ICheckpointProtocol index)

Canonicalizing factory for the ReadWriteLock for an ICommitter.

Note: This method CAN NOT be exposed since that breaks encapsulation for the WrappedReadLock.

Parameters:

index - The btree.

Returns:

The lock.

Throws:

IllegalArgumentException - if the argument is null.