org.ow2.clif.storage.lib.filestorage

Class DelayedWriter

java.lang.Object

java.lang.Thread

org.ow2.clif.storage.lib.filestorage.DelayedWriter

All Implemented Interfaces:

java.lang.Runnable

public class DelayedWriter
extends java.lang.Thread

This class supports delayed and timely ascending ordered writing of blade events to a BufferedWriter object. The goal of this feature is to write event blades in the chronological order of their starting date, regardless of the time they are actually available for writing, provided the delay is sufficient. This is mostly useful for action events: depending on response times variations, one action event E2 may be available for writing before another action event E1, while the corresponding request has been sent after, because the response time was shorter. Thanks to delayed writing, and as long as the maximum variation of response times is shorter than the delay, action reports are written in chronological order with regard to the request start date. But, when the maximum variation of response times from one request to another becomes greater than the delay, there is no guaranty that this order will be respected. The delay value in seconds may be set through system property defined by DELAY_S_PROP. Otherwise, default delay is defined by DELAY_S_DEFAULT.

Author:

Bruno Dillenseger

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	closing set to true when the writer must be closed
protected static long	delay_ms minimum age of events before actually writing them
static java.lang.String	DELAY_S_DEFAULT
static java.lang.String	DELAY_S_PROP
protected java.util.SortedSet<BladeEvent>	eventQ
protected static long	maxPending maximum number of young events waiting to be written (subsumes delay_ms)
static java.lang.String	MAXPENDING_DEFAULT
static java.lang.String	MAXPENDING_PROP
protected long	offset Initial time in ms
protected java.io.BufferedWriter	writer

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
DelayedWriter(java.io.BufferedWriter out, long dateOffset_ms) Creates a delayed writer that will order blade events according to their date, before actually writing them using the provided BufferedWriter object, after the delay has expired.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the underlying buffered writer, after flushing all pending blade events to it.
void	run() The delay writer's activity consists in getting events from the blade events queue when they are sufficiently old (with respect to delay and blade event dates), and writing them to the underlying buffered writer.
void	write(BladeEvent event) Delayed writing of a blade event.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

delay_ms

protected static long delay_ms

minimum age of events before actually writing them

DELAY_S_PROP

public static final java.lang.String DELAY_S_PROP

See Also:

Constant Field Values

DELAY_S_DEFAULT

public static final java.lang.String DELAY_S_DEFAULT

See Also:

Constant Field Values

maxPending

protected static long maxPending

maximum number of young events waiting to be written (subsumes delay_ms)

MAXPENDING_PROP

public static final java.lang.String MAXPENDING_PROP

See Also:

Constant Field Values

MAXPENDING_DEFAULT

public static final java.lang.String MAXPENDING_DEFAULT

See Also:

Constant Field Values

eventQ

protected java.util.SortedSet<BladeEvent> eventQ

offset

protected long offset

Initial time in ms

writer

protected java.io.BufferedWriter writer

closing

protected volatile boolean closing

set to true when the writer must be closed

Constructor Detail

DelayedWriter

public DelayedWriter(java.io.BufferedWriter out,
                     long dateOffset_ms)

Creates a delayed writer that will order blade events according to their date, before actually writing them using the provided BufferedWriter object, after the delay has expired.

Parameters:

out - the buffered writer to be used for finally writing blades event

dateOffset_ms - the initial date in ms (this value will be subtracted from the events dates when they are finally written to the buffered writer).

Method Detail

write

public void write(BladeEvent event)
           throws java.io.IOException

Delayed writing of a blade event. The delay applies from the date of the event (not current date when calling this method).

Parameters:

event - the blade event to write

Throws:

java.io.IOException - the delayed writer has been closed and cannot be used anymore.

close

public void close()

Closes the underlying buffered writer, after flushing all pending blade events to it. Any further attempt to write a blade event to this delayed writer will be rejected.

run

public void run()

The delay writer's activity consists in getting events from the blade events queue when they are sufficiently old (with respect to delay and blade event dates), and writing them to the underlying buffered writer. Sleeps if no event is old enough. The sleep duration depends on the delay value and the oldest pending event's date if any. Sleep is interrupted and all pending events are flushed to the buffered writer when the delayed writer is closed.

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread