com.google.common.util.concurrent
Class SimpleTimeLimiter

java.lang.Object
  com.google.common.util.concurrent.SimpleTimeLimiter

All Implemented Interfaces:

TimeLimiter

public class SimpleTimeLimiter
extends Object
implements TimeLimiter

A TimeLimiter that runs method calls in the background using an ExecutorService. If the time limit expires for a given method call, the thread running the call will be interrupted.

Since:

2009.09.15 tentative

Author:

Kevin Bourrillion

Constructor Summary

SimpleTimeLimiter()
Constructs a TimeLimiter instance using a Executors.newCachedThreadPool() to execute proxied method calls.

SimpleTimeLimiter(ExecutorService executor)
Constructs a TimeLimiter instance using the given executor service to execute proxied method calls.

Method Summary

<T> T	callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit, boolean amInterruptible) Invokes a specified Callable, timing out after the specified time limit.
<T> T	newProxy(T target, Class<T> interfaceType, long timeoutDuration, TimeUnit timeoutUnit) Returns an instance of interfaceType that delegates all method calls to the target object, enforcing the specified time limit on each call.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleTimeLimiter

public SimpleTimeLimiter(ExecutorService executor)

Constructs a TimeLimiter instance using the given executor service to execute proxied method calls.

Warning: using a bounded executor may be counterproductive! If the thread pool fills up, any time callers spend waiting for a thread may count toward their time limit, and in this case the call may even time out before the target method is ever invoked.

Parameters:

executor - the ExecutorService that will execute the method calls on the target objects; for example, a Executors.newCachedThreadPool().

SimpleTimeLimiter

public SimpleTimeLimiter()

Constructs a TimeLimiter instance using a Executors.newCachedThreadPool() to execute proxied method calls.

Warning: using a bounded executor may be counterproductive! If the thread pool fills up, any time callers spend waiting for a thread may count toward their time limit, and in this case the call may even time out before the target method is ever invoked.

Method Detail

newProxy

public <T> T newProxy(T target,
                      Class<T> interfaceType,
                      long timeoutDuration,
                      TimeUnit timeoutUnit)

Description copied from interface: TimeLimiter

Returns an instance of interfaceType that delegates all method calls to the target object, enforcing the specified time limit on each call. This time-limited delegation is also performed for calls to Object.equals(java.lang.Object), Object.hashCode(), and Object.toString().

If the target method call finishes before the limit is reached, the return value or exception is propagated to the caller exactly as-is. If, on the other hand, the time limit is reached, the proxy will attempt to abort the call to the target, and will throw an UncheckedTimeoutException to the caller.

It is important to note that the primary purpose of the proxy object is to return control to the caller when the timeout elapses; aborting the target method call is of secondary concern. The particular nature and strength of the guarantees made by the proxy is implementation-dependent. However, it is important that each of the methods on the target object behaves appropriately when its thread is interrupted.

Specified by:

newProxy in interface TimeLimiter

Parameters:

target - the object to proxy

interfaceType - the interface you wish the returned proxy to implement

timeoutDuration - with timeoutUnit, the maximum length of time that callers are willing to wait on each method call to the proxy

timeoutUnit - with timeoutDuration, the maximum length of time that callers are willing to wait on each method call to the proxy

Returns:

a time-limiting proxy

callWithTimeout

public <T> T callWithTimeout(Callable<T> callable,
                             long timeoutDuration,
                             TimeUnit timeoutUnit,
                             boolean amInterruptible)
                  throws Exception

Description copied from interface: TimeLimiter

Invokes a specified Callable, timing out after the specified time limit. If the target method call finished before the limit is reached, the return value or exception is propagated to the caller exactly as-is. If, on the other hand, the time limit is reached, we attempt to abort the call to the target, and throw an UncheckedTimeoutException to the caller.

Warning: The future of this method is in doubt. It may be nuked, or changed significantly.

Specified by:

callWithTimeout in interface TimeLimiter

Parameters:

callable - the Callable to execute

timeoutDuration - with timeoutUnit, the maximum length of time to wait

timeoutUnit - with timeoutDuration, the maximum length of time to wait

amInterruptible - whether to respond to thread interruption by aborting the operation and throwing InterruptedException; if false, the operation is allowed to complete or time out, and the current thread's interrupt status is re-asserted.

Returns:

the result returned by the Callable

Throws:

InterruptedException - if interruptible is true and our thread is interrupted during execution

UncheckedTimeoutException - if the time limit is reached

Exception