curator-master/curator-framework/src/test/java/org/apache/curator/framework/state/TestCircuitBreaker.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.curator.framework.state;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.time.Duration;
import java.time.temporal.ChronoUnit;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.curator.RetryPolicy;
import org.apache.curator.retry.RetryForever;
import org.apache.curator.retry.RetryNTimes;
import org.apache.curator.retry.RetryUntilElapsed;
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.Test;

public class TestCircuitBreaker {
    private static Duration[] lastDelay = new Duration[] {Duration.ZERO};
    private static ScheduledThreadPoolExecutor service = new ScheduledThreadPoolExecutor(1) {
        @Override
        public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
            lastDelay[0] = Duration.of(unit.toNanos(delay), ChronoUnit.NANOS);
            command.run();
            return null;
        }
    };

    @AfterAll
    public static void tearDown() {
        service.shutdownNow();
    }

    @Test
    public void testBasic() {
        final int retryQty = 1;
        final Duration delay = Duration.ofSeconds(10);

        CircuitBreaker circuitBreaker =
                CircuitBreaker.build(new RetryNTimes(retryQty, (int) delay.toMillis()), service);
        AtomicInteger counter = new AtomicInteger(0);

        assertTrue(circuitBreaker.tryToOpen(counter::incrementAndGet));
        assertEquals(lastDelay[0], delay);

        assertFalse(circuitBreaker.tryToOpen(counter::incrementAndGet));
        assertEquals(circuitBreaker.getRetryCount(), 1);
        assertEquals(counter.get(), 1);
        assertFalse(circuitBreaker.tryToRetry(counter::incrementAndGet));
        assertEquals(circuitBreaker.getRetryCount(), 1);
        assertEquals(counter.get(), 1);

        assertTrue(circuitBreaker.close());
        assertEquals(circuitBreaker.getRetryCount(), 0);
        assertFalse(circuitBreaker.close());
    }

    @Test
    public void testVariousOpenRetryFails() {
        CircuitBreaker circuitBreaker = CircuitBreaker.build(new RetryForever(1), service);
        assertFalse(circuitBreaker.tryToRetry(() -> {}));
        assertTrue(circuitBreaker.tryToOpen(() -> {}));
        assertFalse(circuitBreaker.tryToOpen(() -> {}));
        assertTrue(circuitBreaker.close());
        assertFalse(circuitBreaker.close());
    }

    @Test
    public void testWithRetryUntilElapsed() {
        RetryPolicy retryPolicy = new RetryUntilElapsed(10000, 10000);
        CircuitBreaker circuitBreaker = CircuitBreaker.build(retryPolicy, service);
        assertTrue(circuitBreaker.tryToOpen(() -> {}));
        assertEquals(lastDelay[0], Duration.ofMillis(10000));
    }
}
