/*
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* Copyright (C) 2012 Markus Junginger, greenrobot (http://greenrobot.de)
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package de.greenrobot.event.util;
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import java.lang.reflect.Constructor;
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import java.util.concurrent.Executor;
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import java.util.concurrent.Executors;
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import android.app.Activity;
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import android.util.Log;
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import de.greenrobot.event.EventBus;
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/**
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* Executes an {@link RunnableEx} using a thread pool. Thrown exceptions are propagated by posting failure events of any
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* given type (default is {@link ThrowableFailureEvent}).
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*
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* @author Markus
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*/
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public class AsyncExecutor {
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public static class Builder {
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private Executor threadPool;
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private Class<?> failureEventType;
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private EventBus eventBus;
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private Builder() {
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}
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public Builder threadPool(Executor threadPool) {
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this.threadPool = threadPool;
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return this;
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}
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public Builder failureEventType(Class<?> failureEventType) {
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this.failureEventType = failureEventType;
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return this;
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}
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public Builder eventBus(EventBus eventBus) {
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this.eventBus = eventBus;
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return this;
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}
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public AsyncExecutor build() {
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return buildForScope(null);
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}
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public AsyncExecutor buildForActivityScope(Activity activity) {
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return buildForScope(activity.getClass());
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}
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public AsyncExecutor buildForScope(Object executionContext) {
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if (eventBus == null) {
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eventBus = EventBus.getDefault();
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}
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if (threadPool == null) {
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threadPool = Executors.newCachedThreadPool();
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}
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if (failureEventType == null) {
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failureEventType = ThrowableFailureEvent.class;
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}
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return new AsyncExecutor(threadPool, eventBus, failureEventType, executionContext);
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}
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}
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/** Like {@link Runnable}, but the run method may throw an exception. */
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public interface RunnableEx {
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void run() throws Exception;
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}
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public static Builder builder() {
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return new Builder();
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}
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public static AsyncExecutor create() {
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return new Builder().build();
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}
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private final Executor threadPool;
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private final Constructor<?> failureEventConstructor;
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private final EventBus eventBus;
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private final Object scope;
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private AsyncExecutor(Executor threadPool, EventBus eventBus, Class<?> failureEventType, Object scope) {
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this.threadPool = threadPool;
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this.eventBus = eventBus;
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this.scope = scope;
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try {
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failureEventConstructor = failureEventType.getConstructor(Throwable.class);
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} catch (NoSuchMethodException e) {
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throw new RuntimeException(
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"Failure event class must have a constructor with one parameter of type Throwable", e);
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}
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}
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/** Posts an failure event if the given {@link RunnableEx} throws an Exception. */
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public void execute(final RunnableEx runnable) {
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threadPool.execute(new Runnable() {
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@Override
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public void run() {
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try {
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runnable.run();
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} catch (Exception e) {
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Object event;
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try {
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event = failureEventConstructor.newInstance(e);
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} catch (Exception e1) {
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Log.e(EventBus.TAG, "Original exception:", e);
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throw new RuntimeException("Could not create failure event", e1);
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}
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if (event instanceof HasExecutionScope) {
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((HasExecutionScope) event).setExecutionScope(scope);
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}
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eventBus.post(event);
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}
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}
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});
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}
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}
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