com.google.common.util.concurrent.TimeLimiter Maven / Gradle / Ivy
/*
* Copyright (C) 2006 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.util.concurrent;
import com.google.common.annotations.Beta;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
/**
* Produces proxies that impose a time limit on method
* calls to the proxied object. For example, to return the value of
* {@code target.someMethod()}, but substitute {@code 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 {@code SimpleTimeLimiterTest} for more usage examples.
*
* @author Kevin Bourrillion
* @since 1.0
*/
@Beta
public interface TimeLimiter {
/**
* Returns an instance of {@code interfaceType} that delegates all method
* calls to the {@code target} object, enforcing the specified time limit on
* each call. This time-limited delegation is also performed for calls to
* {@link Object#equals}, {@link Object#hashCode}, and
* {@link 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 {@link 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.
*
* @param target the object to proxy
* @param interfaceType the interface you wish the returned proxy to
* implement
* @param timeoutDuration with timeoutUnit, the maximum length of time that
* callers are willing to wait on each method call to the proxy
* @param timeoutUnit with timeoutDuration, the maximum length of time that
* callers are willing to wait on each method call to the proxy
* @return a time-limiting proxy
* @throws IllegalArgumentException if {@code interfaceType} is a regular
* class, enum, or annotation type, rather than an interface
*/
T newProxy(T target, Class interfaceType,
long timeoutDuration, TimeUnit timeoutUnit);
/**
* 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 {@link UncheckedTimeoutException} to the caller.
*
* Warning: The future of this method is in doubt. It may be nuked, or
* changed significantly.
*
* @param callable the Callable to execute
* @param timeoutDuration with timeoutUnit, the maximum length of time to wait
* @param timeoutUnit with timeoutDuration, the maximum length of time to wait
* @param 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.
* @return the result returned by the Callable
* @throws InterruptedException if {@code interruptible} is true and our
* thread is interrupted during execution
* @throws UncheckedTimeoutException if the time limit is reached
* @throws Exception
*/
T callWithTimeout(Callable callable, long timeoutDuration,
TimeUnit timeoutUnit, boolean interruptible) throws Exception;
}