org.apache.cassandra.db.commitlog
Class CommitLogAllocator

java.lang.Object
  org.apache.cassandra.db.commitlog.CommitLogAllocator

public class CommitLogAllocator
extends java.lang.Object

Performs the pre-allocation of commit log segments in a background thread. All the public methods are thread safe.

Field Summary

static int

TICK_CYCLE_TIME The (theoretical) max milliseconds between loop runs to perform janitorial tasks

Constructor Summary

CommitLogAllocator()

Method Summary

void	awaitTermination() Returns when the allocator thread terminates.
long	bytesUsed()
void	enableReserveSegmentCreation() Throws a flag that enables the behavior of keeping at least one spare segment available at all times.
CommitLogSegment	fetchSegment() Fetches an empty segment file.
java.util.Collection<CommitLogSegment>	getActiveSegments()
boolean	manages(java.lang.String name)
void	recycleSegment(CommitLogSegment segment) Indicates that a segment is no longer in use and that it should be recycled.
void	recycleSegment(java.io.File file) Differs from the above because it can work on any file instead of just existing commit log segments managed by this allocator.
void	resetUnsafe() Resets all the segments, for testing purposes.
void	shutdown() Initiates the shutdown process for the allocator thread.

Methods inherited from class java.lang.Object

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

Field Detail

TICK_CYCLE_TIME

public static final int TICK_CYCLE_TIME

The (theoretical) max milliseconds between loop runs to perform janitorial tasks

See Also:

Constant Field Values

Constructor Detail

CommitLogAllocator

public CommitLogAllocator()

Method Detail

fetchSegment

public CommitLogSegment fetchSegment()

Fetches an empty segment file.

Returns:

the next writable segment

recycleSegment

public void recycleSegment(CommitLogSegment segment)

Indicates that a segment is no longer in use and that it should be recycled.

Parameters:

segment - segment that is no longer in use

recycleSegment

public void recycleSegment(java.io.File file)

Differs from the above because it can work on any file instead of just existing commit log segments managed by this allocator.

Parameters:

file - segment file that is no longer in use.

bytesUsed

public long bytesUsed()

Returns:

the space (in bytes) used by all segment files.

manages

public boolean manages(java.lang.String name)

Parameters:

name - the filename to check

Returns:

true if file is managed by this allocator.

enableReserveSegmentCreation

public void enableReserveSegmentCreation()

Throws a flag that enables the behavior of keeping at least one spare segment available at all times.

resetUnsafe

public void resetUnsafe()

Resets all the segments, for testing purposes. DO NOT USE THIS OUTSIDE OF TESTS.

shutdown

public void shutdown()

Initiates the shutdown process for the allocator thread.

awaitTermination

public void awaitTermination()
                      throws java.lang.InterruptedException

Returns when the allocator thread terminates.

Throws:

java.lang.InterruptedException

getActiveSegments

public java.util.Collection<CommitLogSegment> getActiveSegments()

Returns:

a read-only collection of the active commit log segments