net.kuujo.vertigo.util.CountingCompletionHandler.java Source code

Introduction

Here is the source code for net.kuujo.vertigo.util.CountingCompletionHandler.java

Source

/*
 * Copyright 2014 the original author or authors.
 *
 * 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 net.kuujo.vertigo.util;

import io.vertx.core.AsyncResult;
import io.vertx.core.Future;
import io.vertx.core.Handler;

/**
 * A copy of the Vert.x core counting completion handler for handling
 * multiple remote calls asynchronously.
 *
 * @author <a href="http://github.com/kuujo">Jordan Halterman</a>
 */
public class CountingCompletionHandler<T> implements Handler<AsyncResult<T>> {
    private int count;
    private int required;
    private Handler<AsyncResult<T>> doneHandler;
    private Throwable cause;
    private boolean failed;

    public CountingCompletionHandler(int required) {
        this.required = required;
    }

    public CountingCompletionHandler(int required, Handler<AsyncResult<T>> handler) {
        this.required = required;
        this.doneHandler = handler;
    }

    @Override
    public void handle(AsyncResult<T> result) {
        if (result.failed()) {
            fail(result.cause());
        } else {
            succeed();
        }
    }

    /**
     * Indicates that a call succeeded.
     */
    public void succeed() {
        count++;
        checkDone();
    }

    /**
     * Indicates that a call failed. This will immediately fail the handler.
     *
     * @param t The cause of the failure.
     */
    public void fail(Throwable t) {
        if (!failed) {
            if (doneHandler != null) {
                doneHandler.handle(Future.failedFuture(t));
            } else {
                cause = t;
            }
            failed = true;
        }
    }

    /**
     * Sets the completion handler.
     *
     * @param doneHandler An asynchronous handler to be called once all calls have completed.
     */
    public CountingCompletionHandler<T> setHandler(Handler<AsyncResult<T>> doneHandler) {
        this.doneHandler = doneHandler;
        checkDone();
        return this;
    }

    /**
     * Checks whether the handler should be called.
     */
    private void checkDone() {
        if (doneHandler != null) {
            if (cause != null) {
                doneHandler.handle(Future.failedFuture(cause));
            } else {
                if (count == required) {
                    doneHandler.handle(Future.succeededFuture());
                }
            }
        }
    }

}