com.google.common.util.concurrent
Interface TimeLimiter

All Known Implementing Classes:

FakeTimeLimiter, SimpleTimeLimiter

public interface TimeLimiter

Produces proxies that impose a time limit on method calls to the proxied object. For example, to return the value of target.someMethod(), but substitute DEFAULT_VALUE if this method call takes over 50 ms, you can use this code:

   TimeLimiter limiter = . . .;
   TargetType proxy = limiter.newProxy(
       target, TargetType.class, 50, TimeUnit.MILLISECONDS);
   try {
     return proxy.someMethod();
   } catch (UncheckedTimeoutException e) {
     return DEFAULT_VALUE;
   }
 

Please see SimpleTimeLimiterTest for more usage examples.

Since:

2009.09.15 tentative

Author:

Kevin Bourrillion

Method Summary

<T> T	callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit, boolean interruptible) 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.

Method Detail

newProxy

<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. 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.

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

Throws:

IllegalArgumentException - if interfaceType is a regular class, enum, or annotation type, rather than an interface

callWithTimeout

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

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.

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

interruptible - 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