/*
* Copyright 2014 Ben Manes. 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.
* 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.github.benmanes.caffeine;
import static com.github.benmanes.caffeine.testing.IsEmptyIterable.deeplyEmpty;
import static org.hamcrest.Matchers.hasSize;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.not;
import static org.hamcrest.Matchers.nullValue;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;
import org.hamcrest.Description;
import org.hamcrest.TypeSafeDiagnosingMatcher;
import com.github.benmanes.caffeine.SingleConsumerQueue.Node;
import com.github.benmanes.caffeine.testing.DescriptionBuilder;
import com.google.common.collect.Sets;
/**
* A matcher that evaluates a {@link SingleConsumerQueue} to determine if it is in a valid state.
*
* @author ben.manes@gmail.com (Ben Manes)
*/
public final class IsValidSingleConsumerQueue<E>
extends TypeSafeDiagnosingMatcher<SingleConsumerQueue<E>> {
@Override
public void describeTo(Description description) {
description.appendText("singleConsumerQueue");
}
@Override
protected boolean matchesSafely(SingleConsumerQueue<E> queue, Description description) {
DescriptionBuilder builder = new DescriptionBuilder(description);
if (queue.isEmpty()) {
builder.expectThat("empty queue", queue, is(deeplyEmpty()));
builder.expectThat("empty queue", queue.head, is(queue.tail));
builder.expectThat("empty queue", queue.head.next, is(nullValue()));
}
builder.expectThat("corrupted queue node", queue.tail.next, is(nullValue()));
checkForLoop(queue, builder);
checkArena(queue, builder);
return builder.matches();
}
void checkForLoop(SingleConsumerQueue<E> queue, DescriptionBuilder builder) {
builder.expectThat("Expected sentinel node", queue.head.value, is(nullValue()));
Set<Node<E>> seen = Sets.newIdentityHashSet();
Node<E> node = queue.head.next;
while (node != null) {
Node<E> current = node;
Supplier<String> errorMsg = () -> String.format("Loop detected: %s in %s", current, seen);
builder.expectThat(errorMsg, seen.add(node), is(true));
builder.expectThat("not tail", node, is(not(queue.head)));
builder.expectThat("not completed", node.isDone(), is(true));
builder.expectThat("not null value", node.value, is(not(nullValue())));
node = node.next;
}
builder.expectThat("queue size", queue, hasSize(seen.size()));
}
void checkArena(SingleConsumerQueue<E> queue, DescriptionBuilder builder) {
for (AtomicReference<?> slot : queue.arena) {
builder.expectThat("not null arena slot", slot.get(), is(nullValue()));
}
}
public static <E> IsValidSingleConsumerQueue<E> validate() {
return new IsValidSingleConsumerQueue<E>();
}
}