com.bigdata.btree

Interface IReadWriteLockManager

All Known Subinterfaces:

ICheckpointProtocol, ISolutionSet

All Known Implementing Classes:

AbstractBTree, AbstractHTree, BTree, CommitRecordIndex, CommitTimeIndex, CounterSetBTree, EventReceiver.EventBTree, HTree, IndexSegment, IndexSegmentIndex, JournalIndex, MetadataIndex, Name2Addr, ReadWriteLockManager, SolutionSetStream, Stream, TestMROWTransactions.MyBTree, TestRestartSafe.MyBTree, TxId2CommitTimeIndex, UnisolatedReadWriteIndex

public interface IReadWriteLockManager

Interface for managing read/write locks on persistence capable data structures.

See Also:

AssertionError: Child does not have persistent identity

Method Summary

Methods

Modifier and Type	Method and Description
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.

Method Detail

readLock

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. 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.

Returns:

The lock.

writeLock

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. This is exposed for processes which need to obtain the write lock to coordinate external operations.

Returns:

The lock.

Throws:

UnsupportedOperationException - unless the view supports mutation.

getReadLockCount

int getReadLockCount()

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

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).

isReadOnly

boolean isReadOnly()

Return true iff the data structure is read-only.