org.apache.commons.lang3.concurrent.CircuitBreaker Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of commons-lang3 Show documentation

Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang. The code is tested using the latest revision of the JDK for supported LTS releases: 8, 11, 17 and 21 currently. See https://github.com/apache/commons-lang/blob/master/.github/workflows/maven.yml Please ensure your build environment is up-to-date and kindly report any build issues.

There is a newer version: 3.17.0

Show newest version

/*
 * 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.commons.lang3.concurrent;

/**
 * An interface describing a Circuit Breaker component.
 *
 * 
 * A circuit breaker can be used to protect an application against unreliable
 * services or unexpected load. It typically monitors a specific resource. As long as this
 * resource works as expected, it stays in state closed, meaning that the
 * resource can be used. If problems are encountered when using the resource, the circuit
 * breaker can switch into state open; then access to this resource is
 * prohibited. Depending on a concrete implementation, it is possible that the circuit
 * breaker switches back to state closed when the resource becomes available
 * again.
 * 
 * 
 * This interface defines a generic protocol of a circuit breaker component. It should be
 * sufficiently generic to be applied to multiple different use cases.
 * 
 *
 * @param  the type of the value monitored by this circuit breaker
 * @since 3.5
 */
public interface CircuitBreaker {

    /**
     * Checks the state of this circuit breaker and changes it if necessary. The return
     * value indicates whether the circuit breaker is now in state closed; a value
     * of true typically means that the current operation can continue.
     *
     * @return true if the circuit breaker is now closed;
     * false otherwise.
     */
    boolean checkState();

    /**
     * Closes this circuit breaker. Its state is changed to closed. If this circuit
     * breaker is already closed, this method has no effect.
     */
    void close();

    /**
     * Increments the monitored value and performs a check of the current state of this
     * circuit breaker. This method works like {@link #checkState()}, but the monitored
     * value is incremented before the state check is performed.
     *
     * @param increment value to increment in the monitored value of the circuit breaker
     * @return true if the circuit breaker is now closed;
     * false otherwise
     */
    boolean incrementAndCheckState(T increment);

    /**
     * Tests the current closed state of this circuit breaker. A return value of
     * true means that the circuit breaker is currently closed. This
     * means that everything is okay with the monitored subsystem.
     *
     * @return the current closed state of this circuit breaker.
     */
    boolean isClosed();

    /**
     * Tests the current open state of this circuit breaker. A return value of
     * true means that the circuit breaker is currently open indicating a
     * problem in the monitored subsystem.
     *
     * @return the current open state of this circuit breaker.
     */
    boolean isOpen();

    /**
     * Opens this circuit breaker. Its state is changed to open. Depending on a concrete
     * implementation, it may close itself again if the monitored subsystem becomes
     * available. If this circuit breaker is already open, this method has no effect.
     */
    void open();
}