Package org.eclipse.jetty.util.thread

Class ReservedThreadExecutor

java.lang.Object

org.eclipse.jetty.util.component.AbstractLifeCycle

org.eclipse.jetty.util.thread.ReservedThreadExecutor

All Implemented Interfaces:

java.util.concurrent.Executor, LifeCycle, TryExecutor

@ManagedObject("A pool for reserved threads")
public class ReservedThreadExecutor
extends AbstractLifeCycle
implements TryExecutor

An Executor using preallocated/reserved Threads from a wrapped Executor.

Calls to execute(Runnable) on a ReservedThreadExecutor will either succeed with a Thread immediately being assigned the Runnable task, or fail if no Thread is available.

Threads are reserved lazily, with a new reserved thread being allocated from a wrapped Executor when an execution fails. If the setIdleTimeout(long, TimeUnit) is set to non zero (default 1 minute), then the reserved thread pool will shrink by 1 thread whenever it has been idle for that period.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private class	ReservedThreadExecutor.ReservedThread

Nested classes/interfaces inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

AbstractLifeCycle.AbstractLifeCycleListener

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.component.LifeCycle

LifeCycle.Listener

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.thread.TryExecutor

TryExecutor.NoTryExecutor

Field Summary

Fields

Modifier and Type	Field	Description
private int	_capacity
private java.util.concurrent.Executor	_executor
private long	_idleTime
private java.util.concurrent.TimeUnit	_idleTimeUnit
private ThreadPoolBudget.Lease	_lease
private java.util.concurrent.atomic.AtomicInteger	_pending
private java.util.concurrent.atomic.AtomicInteger	_size
private java.util.concurrent.ConcurrentLinkedDeque<ReservedThreadExecutor.ReservedThread>	_stack
private static Logger	LOG
private static java.lang.Runnable	STOP

Fields inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

FAILED, RUNNING, STARTED, STARTING, STOPPED, STOPPING

Fields inherited from interface org.eclipse.jetty.util.thread.TryExecutor

NO_TRY

Constructor Summary

Constructors

Constructor	Description
ReservedThreadExecutor(java.util.concurrent.Executor executor, int capacity)

Method Summary

Modifier and Type	Method	Description
void	doStart()
void	doStop()
void	execute(java.lang.Runnable task)
int	getAvailable()
int	getCapacity()
java.util.concurrent.Executor	getExecutor()
long	getIdleTimeoutMs()
int	getPending()
private static int	reservedThreads(java.util.concurrent.Executor executor, int capacity)
void	setIdleTimeout(long idleTime, java.util.concurrent.TimeUnit idleTimeUnit)	Set the idle timeout for shrinking the reserved thread pool
private void	startReservedThread()
java.lang.String	toString()
boolean	tryExecute(java.lang.Runnable task)	Executes the given task if and only if a reserved thread is available.

Methods inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

addLifeCycleListener, getState, getState, getStopTimeout, isFailed, isRunning, isStarted, isStarting, isStopped, isStopping, removeLifeCycleListener, setStopTimeout, start, stop

Methods inherited from class java.lang.Object

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

Field Detail

LOG

private static final Logger LOG

STOP

private static final java.lang.Runnable STOP

_executor

private final java.util.concurrent.Executor _executor

_capacity

private final int _capacity

_stack

private final java.util.concurrent.ConcurrentLinkedDeque<ReservedThreadExecutor.ReservedThread> _stack

_size

private final java.util.concurrent.atomic.AtomicInteger _size

_pending

private final java.util.concurrent.atomic.AtomicInteger _pending

_lease

private ThreadPoolBudget.Lease _lease

_idleTime

private long _idleTime

_idleTimeUnit

private java.util.concurrent.TimeUnit _idleTimeUnit

Constructor Detail

ReservedThreadExecutor

public ReservedThreadExecutor(java.util.concurrent.Executor executor,
                              int capacity)

Parameters:

executor - The executor to use to obtain threads

capacity - The number of threads to preallocate. If less than 0 then capacity is calculated based on a heuristic from the number of available processors and thread pool size.

Method Detail

reservedThreads

private static int reservedThreads(java.util.concurrent.Executor executor,
                                   int capacity)

Parameters:

executor - The executor to use to obtain threads

capacity - The number of threads to preallocate, If less than 0 then capacity is calculated based on a heuristic from the number of available processors and thread pool size.

Returns:

the number of reserved threads that would be used by a ReservedThreadExecutor constructed with these arguments.

getExecutor

public java.util.concurrent.Executor getExecutor()

getCapacity

@ManagedAttribute(value="max number of reserved threads",
                  readonly=true)
public int getCapacity()

Returns:

the maximum number of reserved threads

getAvailable

@ManagedAttribute(value="available reserved threads",
                  readonly=true)
public int getAvailable()

Returns:

the number of threads available to tryExecute(Runnable)

getPending

@ManagedAttribute(value="pending reserved threads",
                  readonly=true)
public int getPending()

getIdleTimeoutMs

@ManagedAttribute(value="idletimeout in MS",
                  readonly=true)
public long getIdleTimeoutMs()

setIdleTimeout

public void setIdleTimeout(long idleTime,
                           java.util.concurrent.TimeUnit idleTimeUnit)

Set the idle timeout for shrinking the reserved thread pool

Parameters:

idleTime - Time to wait before shrinking, or 0 for no timeout.

idleTimeUnit - Time units for idle timeout

doStart

public void doStart()
             throws java.lang.Exception

Overrides:

doStart in class AbstractLifeCycle

Throws:

java.lang.Exception

doStop

public void doStop()
            throws java.lang.Exception

Overrides:

doStop in class AbstractLifeCycle

Throws:

java.lang.Exception

execute

public void execute(java.lang.Runnable task)
             throws java.util.concurrent.RejectedExecutionException

Specified by:

execute in interface java.util.concurrent.Executor

Specified by:

execute in interface TryExecutor

Throws:

java.util.concurrent.RejectedExecutionException

tryExecute

public boolean tryExecute(java.lang.Runnable task)

Executes the given task if and only if a reserved thread is available.

Specified by:

tryExecute in interface TryExecutor

Parameters:

task - the task to run

Returns:

true if and only if a reserved thread was available and has been assigned the task to run.

startReservedThread

private void startReservedThread()

toString

public java.lang.String toString()

Overrides:

toString in class AbstractLifeCycle