org.force66.circuit.Circuit.java Source code

Introduction

Here is the source code for org.force66.circuit.Circuit.java

Source

/*
 * This software is licensed under the Apache License, Version 2.0
 * (the "License") agreement; 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.force66.circuit;

import java.util.concurrent.Callable;

import org.apache.commons.lang3.Validate;

/**
 * Implementation of the circuit breaker pattern.
 * @author D. Ashmore
 * @see CircuitBreakerAlgorithm
 * @param <T>
 */
public class Circuit<T> {

    private CircuitBreakerAlgorithm circuitBreakerAlgorithm;

    /**
     * @see DefaultCircuitBreakerAlgorithm
     */
    public Circuit() {
        this(new DefaultCircuitBreakerAlgorithm());
    }

    public Circuit(CircuitBreakerAlgorithm algorithm) {
        Validate.notNull(algorithm, "Null algorithm not allowed.");
        circuitBreakerAlgorithm = algorithm;
    }

    public T invoke(Callable<T> operation) {
        Validate.notNull(operation, "Null operation not allowed.");
        if (!circuitBreakerAlgorithm.isExecutionAllowed()) {
            throw new CircuitException("Operation not available.")
                    .addContextValue("callable class", operation.getClass().getName())
                    .addContextValue("callable", operation.toString());
        }

        try {
            T output = operation.call();
            circuitBreakerAlgorithm.reportExecutionSuccess();
            return output;
        } catch (Exception e) {
            circuitBreakerAlgorithm.reportExecutionFailure(e);
            throw new CircuitException(e).addContextValue("callable class", operation.getClass().getName())
                    .addContextValue("callable", operation.toString());
        }

    }

    public CircuitState getCircuitState() {
        return circuitBreakerAlgorithm.getCircuitState();
    }

    protected CircuitBreakerAlgorithm getCircuitBreakerAlgorithm() {
        return circuitBreakerAlgorithm;
    }

}