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com.tangosol.io.journal
Class FlashJournalRM.WriterDaemon

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.Daemon
com.tangosol.io.journal.FlashJournalRM.WriterDaemon

All Implemented Interfaces:

Guardable, java.lang.Runnable

Enclosing class:

FlashJournalRM

protected class FlashJournalRM.WriterDaemon

extends Daemon

The WriterDaemon takes the enqueued Buffer objects from the PreparerDaemon, and appends them to a JournalFile.

Nested Class Summary

protected class	FlashJournalRM.WriterDaemon.FileFullTask A task that gets queued to perform cleanup on a file (on the WriterDaemon thread) when the file is full (no more writes will occur to the file).
protected class	FlashJournalRM.WriterDaemon.PendingWriteTask A task that gets queued to perform an asynchronous appending write on the WriterDaemon thread.

Nested classes/interfaces inherited from class com.tangosol.util.Daemon

Daemon.DaemonWorker

Field Summary

protected long	m_cMillisMultiBlockWrites The number of milliseconds total spent writing blocks in groups.
protected long	m_cMillisSingleBlockWrites The number of milliseconds total spent writing blocks individually.
protected long	m_cMultiBlockWrites The number of blocks written in groups (as part of a multi-buffer write).
protected long	m_cSingleBlockWrites The number of blocks written individually.
protected boolean	m_fPreferSingleBlockWrites Set to true if it becomes apparent that single block writes are preferable.
protected java.util.concurrent.BlockingQueue	m_queue A Queue of items for this daemon to execute.

Constructor Summary

FlashJournalRM.WriterDaemon()
Construct a WriterDaemon.

Method Summary

void	enqueueBuffer(FlashJournalRM.JournalFile jrnlfile, FlashJournalRM.Buffer buf, int cbBuffer) Notify the writer thread that a buffer needs to be written.
int	getAvgBlockWriteMillis() Determine the average number of milliseconds to write each block.
int	getAvgMultiBlockWriteMillis() Determine the average number of milliseconds to write each block using the NIO "scatter/gather" functionality.
int	getAvgSingleBlockWriteMillis() Determine the average number of milliseconds to write each block using the NIO "single buffer write" functionality.
long	getBlockWriteCount() Determine the total number of blocks written by this daemon.
protected java.lang.String	getDescription() Format the Daemon attributes into a String for inclusion in the String returned from the Daemon.toString() method.
long	getMultiBlockWriteCount() Determine the number of blocks written by this daemon using the NIO "scatter/gather" functionality.
long	getSingleBlockWriteCount() Determine the number of blocks written by this daemon using the NIO "single buffer write" functionality.
boolean	isSingleBlockWritePreferred() Determine if the next write should automatically use the "single buffer write" capability of NIO, instead of attempting to use the NIO scatter/gather capability.
void	notifyFileFull(FlashJournalRM.JournalFile jrnlfile) Notify the writer thread that a file is done being written to.
void	run() The daemon's implementation method.
protected void	setGuardPolicy(Guardian guardian, long cTimeoutMillis, float flPctRecover) Set the Guardian and policy to guard this Daemon with.
void	stop() Request the daemon to stop.

Methods inherited from class com.tangosol.util.Daemon

changeState, configureWorker, ensureThreadGroup, finishStarting, finishStopping, getConfiguredName, getConfiguredPriority, getContext, getGuardRegisterAction, getMaxWaitMillis, getState, getThread, getThreadContextClassLoader, getWorker, guardIfNeeded, heartbeat, heartbeat, instantiateWorker, isGuarded, isOnWorkerThread, isRunning, isStopping, recover, setConfiguredName, setConfiguredPriority, setContext, setGuardRegisterAction, setThreadContextClassLoader, shutdown, start, terminate, toStateString, toString

Field Detail

m_queue

protected java.util.concurrent.BlockingQueue m_queue

A Queue of items for this daemon to execute.

m_cSingleBlockWrites

protected long m_cSingleBlockWrites

The number of blocks written individually.

m_cMillisSingleBlockWrites

protected long m_cMillisSingleBlockWrites

The number of milliseconds total spent writing blocks individually.

m_cMultiBlockWrites

protected long m_cMultiBlockWrites

The number of blocks written in groups (as part of a multi-buffer write).

m_cMillisMultiBlockWrites

protected long m_cMillisMultiBlockWrites

The number of milliseconds total spent writing blocks in groups.

m_fPreferSingleBlockWrites

protected boolean m_fPreferSingleBlockWrites

Set to true if it becomes apparent that single block writes are preferable.

Constructor Detail

FlashJournalRM.WriterDaemon

public FlashJournalRM.WriterDaemon()

Construct a WriterDaemon.

Method Detail

stop

public void stop()

Request the daemon to stop. This method will only have an effect if the daemon sub-class respects the value returned from Daemon.isStopping().

Overrides:

stop in class Daemon

run

public void run()

The daemon's implementation method. Override this method to implement a daemon.

An example implementation is:

   while (!isStopping())
       {
       // do some processing
       // ...

       synchronized (this)
           {
           // wait for notification of more work
           wait();
           }
       }
 

Specified by:

run in interface java.lang.Runnable

Specified by:

run in class Daemon

setGuardPolicy

protected void setGuardPolicy(Guardian guardian,
                              long cTimeoutMillis,
                              float flPctRecover)

Set the Guardian and policy to guard this Daemon with. The Daemon is registered with the specified Guardian each time the Daemon is started, and is released each time the Daemon is stopped.

Overrides:

setGuardPolicy in class Daemon

Parameters:

guardian - the Guardian that will be guarding this Daemon

cTimeoutMillis - the timeout in ms for this Daemon, or 0 for the service guardian timeout

flPctRecover - the recovery percentage for this Daemon

getDescription

protected java.lang.String getDescription()

Format the Daemon attributes into a String for inclusion in the String returned from the Daemon.toString() method.

Overrides:

getDescription in class Daemon

Returns:

a String listing the attributes of the Daemon

isSingleBlockWritePreferred

public boolean isSingleBlockWritePreferred()

Determine if the next write should automatically use the "single buffer write" capability of NIO, instead of attempting to use the NIO scatter/gather capability.

Returns:

true iff the next write should not attempt to use NIO scatter/gather functionality

getBlockWriteCount

public long getBlockWriteCount()

Determine the total number of blocks written by this daemon.

Returns:

the total number of blocks written by this daemon

getSingleBlockWriteCount

public long getSingleBlockWriteCount()

Determine the number of blocks written by this daemon using the NIO "single buffer write" functionality.

Returns:

the number of NIO individual buffer writes

getMultiBlockWriteCount

public long getMultiBlockWriteCount()

Determine the number of blocks written by this daemon using the NIO "scatter/gather" functionality. This is not the number of writes, since each write involves multiple blocks being written, one in each buffer.

Returns:

the number of NIO scatter/gather buffer writes

getAvgBlockWriteMillis

public int getAvgBlockWriteMillis()

Determine the average number of milliseconds to write each block.

Returns:

the average number of milliseconds to write each block

getAvgSingleBlockWriteMillis

public int getAvgSingleBlockWriteMillis()

Determine the average number of milliseconds to write each block using the NIO "single buffer write" functionality.

Returns:

the average number of milliseconds for NIO individual buffer writes

getAvgMultiBlockWriteMillis

public int getAvgMultiBlockWriteMillis()

Determine the average number of milliseconds to write each block using the NIO "scatter/gather" functionality.

Returns:

the average number of milliseconds for NIO scatter/gather writes

enqueueBuffer

public void enqueueBuffer(FlashJournalRM.JournalFile jrnlfile,
                          FlashJournalRM.Buffer buf,
                          int cbBuffer)

Notify the writer thread that a buffer needs to be written.

Parameters:

jrnlfile - the file to append to

buf - the buffer to append

cbBuffer - the number of bytes to append from the buffer

notifyFileFull

public void notifyFileFull(FlashJournalRM.JournalFile jrnlfile)

Notify the writer thread that a file is done being written to.

Parameters:

jrnlfile - the file to append to

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