software.amazon.awssdk.testutils.Waiter Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of test-utils Show documentation
Show all versions of test-utils Show documentation
The AWS SDK for Java - Test Utils module holds the all the utilities that are used by the tests.
/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.testutils;
import java.time.Duration;
import java.time.Instant;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.CompletionException;
import java.util.function.Predicate;
import java.util.function.Supplier;
import software.amazon.awssdk.utils.Logger;
import software.amazon.awssdk.utils.Validate;
/**
* This retries a particular function multiple times until it returns an expected result (or fails with an exception). Certain
* expected exception types can be ignored.
*/
public final class Waiter {
private static final Logger log = Logger.loggerFor(Waiter.class);
private final Supplier thingToTry;
private Predicate whenToStop = t -> true;
private Predicate whenToFail = t -> false;
private Set> whatExceptionsToStopOn = Collections.emptySet();
private Set> whatExceptionsToIgnore = Collections.emptySet();
/**
* @see #run(Supplier)
*/
private Waiter(Supplier thingToTry) {
Validate.paramNotNull(thingToTry, "thingToTry");
this.thingToTry = thingToTry;
}
/**
* Create a waiter that attempts executing the provided function until the condition set with {@link #until(Predicate)} is
* met or until it throws an exception. Expected exception types can be ignored with {@link #ignoringException(Class[])}.
*/
public static Waiter run(Supplier thingToTry) {
return new Waiter<>(thingToTry);
}
/**
* Define the condition on the response under which the thing we are trying is complete.
*
* If this isn't set, it will always be true. ie. if the function call succeeds, we stop waiting.
*/
public Waiter until(Predicate whenToStop) {
this.whenToStop = whenToStop;
return this;
}
/**
* Define the condition on the response under which the thing we are trying has already failed and further
* attempts are pointless.
*
* If this isn't set, it will always be false.
*/
public Waiter failOn(Predicate whenToFail) {
this.whenToFail = whenToFail;
return this;
}
/**
* Define the condition on an exception thrown under which the thing we are trying is complete.
*
* If this isn't set, it will always be false. ie. never stop on any particular exception.
*/
@SafeVarargs
public final Waiter untilException(Class... whenToStopOnException) {
this.whatExceptionsToStopOn = new HashSet<>(Arrays.asList(whenToStopOnException));
return this;
}
/**
* Define the exception types that should be ignored if the thing we are trying throws them.
*/
@SafeVarargs
public final Waiter ignoringException(Class... whatToIgnore) {
this.whatExceptionsToIgnore = new HashSet<>(Arrays.asList(whatToIgnore));
return this;
}
/**
* Execute the function, returning true if the thing we're trying does not succeed after 30 seconds.
*/
public boolean orReturnFalse() {
try {
orFail();
return true;
} catch (AssertionError e) {
return false;
}
}
/**
* Execute the function, throwing an assertion error if the thing we're trying does not succeed after 30 seconds.
*/
public T orFail() {
return orFailAfter(Duration.ofMinutes(1));
}
/**
* Execute the function, throwing an assertion error if the thing we're trying does not succeed after the provided duration.
*/
public T orFailAfter(Duration howLongToTry) {
Validate.paramNotNull(howLongToTry, "howLongToTry");
Instant start = Instant.now();
int attempt = 0;
while (Duration.between(start, Instant.now()).compareTo(howLongToTry) < 0) {
++attempt;
try {
if (attempt > 1) {
wait(attempt);
}
T result = thingToTry.get();
if (whenToStop.test(result)) {
log.debug(() -> "Got expected response: " + result);
return result;
} else if (whenToFail.test(result)) {
throw new AssertionError("Received a response that matched the failOn predicate: " + result);
}
int unsuccessfulAttempt = attempt;
log.info(() -> "Attempt " + unsuccessfulAttempt + " failed predicate.");
} catch (RuntimeException e) {
Throwable t = e instanceof CompletionException ? e.getCause() : e;
if (whatExceptionsToStopOn.contains(t.getClass())) {
log.info(() -> "Got expected exception: " + t.getClass().getSimpleName());
return null;
}
if (whatExceptionsToIgnore.contains(t.getClass())) {
int unsuccessfulAttempt = attempt;
log.info(() -> "Attempt " + unsuccessfulAttempt +
" failed with an expected exception (" + t.getClass() + ")");
} else {
throw e;
}
}
}
throw new AssertionError("Condition was not met after " + attempt + " attempts (" +
Duration.between(start, Instant.now()).getSeconds() + " seconds)");
}
private void wait(int attempt) {
int howLongToWaitMs = 250 << Math.min(attempt - 1, 4); // Max = 250 * 2^4 = 4_000.
try {
Thread.sleep(howLongToWaitMs);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new AssertionError(e);
}
}
}