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J2V8 is a set of Java bindings for V8
/*******************************************************************************
* Copyright (c) 2015 EclipseSource and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* EclipseSource - initial API and implementation
******************************************************************************/
package com.eclipsesource.v8.utils;
import java.util.LinkedList;
import com.eclipsesource.v8.JavaVoidCallback;
import com.eclipsesource.v8.Releasable;
import com.eclipsesource.v8.V8;
import com.eclipsesource.v8.V8Array;
import com.eclipsesource.v8.V8Object;
/**
* Executes a JS Script on a new V8 runtime in its own thread, and once finished,
* will optionally wait on a message queue. If the executor is *not* long running,
* when the JS Script finishes, the executor will shutdown. If the executor
* *is* long running, the the script will execute, and when finished, the executor
* will wait for messages to arrive. When messages arrive, the messageHandler
* will be invoked with the contents of the message.
*
* Executors can be shutdown in two different ways. forceTermination() will
* stop any executing scripts and immediately terminate the executor. shutdown()
* will indicate that the executor should shutdown, but this will only happen
* once any scripts finish executing and the message queue becomes empty.
*/
public class V8Executor extends Thread {
private final String script;
private V8 runtime;
private String result;
private volatile boolean terminated = false;
private volatile boolean shuttingDown = false;
private volatile boolean forceTerminating = false;
private Exception exception = null;
private LinkedList messageQueue = new LinkedList();
private boolean longRunning;
private String messageHandler;
/**
* Create a new executor and execute the given script on it. Once
* the script has finished executing, the executor can optionally
* wait on a message queue.
*
* @param script The script to execute on this executor.
* @param longRunning True to indicate that this executor should be longRunning.
* @param messageHandler The name of the message handler that should be notified
* when messages are delivered.
*/
public V8Executor(final String script, final boolean longRunning, final String messageHandler) {
this.script = script;
this.longRunning = longRunning;
this.messageHandler = messageHandler;
}
/**
* Create a new executor and execute the given script on it.
*
* @param script The script to execute on this executor.
*/
public V8Executor(final String script) {
this(script, false, null);
}
/**
* Override to provide a custom setup for this V8 runtime.
* This method can be overridden to configure the V8 runtime,
* for example, to add callbacks or to add some additional
* functionality to the global scope.
*
* @param runtime The runtime to configure.
*/
protected void setup(final V8 runtime) {
}
/**
* Gets the result of the JavaScript that was executed
* on this executor.
*
* @return The result of the JS Script that was executed on
* this executor.
*/
public String getResult() {
return result;
}
/**
* Posts a message to the receiver to be processed by the executor
* and sent to the V8 runtime via the messageHandler.
*
* @param message The message to send to the messageHandler
*/
public void postMessage(final String... message) {
synchronized (this) {
messageQueue.add(message);
notify();
}
}
/*
* (non-Javadoc)
* @see java.lang.Thread#run()
*/
@Override
public void run() {
synchronized (this) {
runtime = V8.createV8Runtime();
runtime.registerJavaMethod(new ExecutorTermination(), "__j2v8__checkThreadTerminate");
setup(runtime);
}
try {
if (!forceTerminating) {
Object scriptResult = runtime.executeScript("__j2v8__checkThreadTerminate();\n" + script, getName(), -1);
if (scriptResult != null) {
result = scriptResult.toString();
}
if (scriptResult instanceof Releasable) {
((Releasable) scriptResult).release();
}
if (scriptResult instanceof Releasable) {
((Releasable) scriptResult).release();
}
}
while (!forceTerminating && longRunning) {
synchronized (this) {
if (messageQueue.isEmpty() && !shuttingDown) {
wait();
}
if ((messageQueue.isEmpty() && shuttingDown) || forceTerminating) {
return;
}
}
if (!messageQueue.isEmpty()) {
String[] message = messageQueue.remove(0);
V8Array parameters = new V8Array(runtime);
V8Array strings = new V8Array(runtime);
try {
for (String string : message) {
strings.push(string);
}
parameters.push(strings);
runtime.executeVoidFunction(messageHandler, parameters);
} finally {
strings.release();
parameters.release();
}
}
}
} catch (Exception e) {
exception = e;
} finally {
synchronized (this) {
if (runtime.getLocker().hasLock()) {
runtime.release();
runtime = null;
}
terminated = true;
}
}
}
/**
* Determines if an exception was thrown during the JavaScript execution.
*
* @return True if an exception was thrown during the JavaScript execution,
* false otherwise.
*/
public boolean hasException() {
return exception != null;
}
/**
* Gets the exception that was thrown during the JavaScript execution.
*
* @return The exception that was thrown during the JavaScript execution,
* or null if no such exception was thrown.
*/
public Exception getException() {
return exception;
}
/**
* Determines if the executor has terminated.
*
* @return True if the executor has terminated, false otherwise.
*/
public boolean hasTerminated() {
return terminated;
}
/**
* Forces the executor to shutdown immediately. Any currently executing
* JavaScript will be interrupted and all outstanding messages will be
* ignored.
*/
public void forceTermination() {
synchronized (this) {
forceTerminating = true;
shuttingDown = true;
if (runtime != null) {
runtime.terminateExecution();
}
notify();
}
}
/**
* Indicates to the executor that it should shutdown. Any currently
* executing JavaScript will be allowed to finish, and any outstanding
* messages will be processed. Only once the message queue is empty,
* will the executor actually shtutdown.
*/
public void shutdown() {
synchronized (this) {
shuttingDown = true;
notify();
}
}
/**
* Returns true if shutdown() or forceTermination() was called to
* shutdown this executor.
*
* @return True if shutdown() or forceTermination() was called, false otherwise.
*/
public boolean isShuttingDown() {
return shuttingDown;
}
/**
* Returns true if forceTermination was called to shutdown
* this executor.
*
* @return True if forceTermination() was called, false otherwise.
*/
public boolean isTerminating() {
return forceTerminating;
}
class ExecutorTermination implements JavaVoidCallback {
@Override
public void invoke(final V8Object receiver, final V8Array parameters) {
if (forceTerminating) {
throw new RuntimeException("V8Thread Termination.");
}
}
}
}