com.msp.jsvc.JRubyDaemon.java Source code

Introduction

Here is the source code for com.msp.jsvc.JRubyDaemon.java

Source

/*
 *  Copyright 2010 Media Service Provider Ltd
 *
 *  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 com.msp.jsvc;

import java.io.IOException;
import java.net.URL;

import org.apache.commons.daemon.Daemon;
import org.apache.commons.daemon.DaemonContext;
import org.apache.commons.daemon.DaemonController;
import org.apache.commons.daemon.DaemonInitException;
import org.jruby.Ruby;
import org.jruby.RubyException;
import org.jruby.RubyInstanceConfig;
import org.jruby.RubyModule;
import org.jruby.exceptions.MainExitException;
import org.jruby.exceptions.RaiseException;
import org.jruby.javasupport.JavaEmbedUtils;

/**
 * Implements commons Daemon to bootstrap a jruby instance, initialize your
 * application, and then tell the application to start doing whatever it does.
 * @author Nick Griffiths <nicobrevin@gmail.com>
 */
public class JRubyDaemon implements Daemon {

    private static final String PROP_MODULE_NAME = "jruby.daemon.module.name";
    private static final String DAEMON = "Daemon";
    private Ruby runtime;
    private Thread thread;
    private RubyModule appModule;
    private boolean debug;
    private RubyModule daemon;
    private String appModuleName;
    private RubyInstanceConfig rubyConfig;
    private DaemonController controller;

    public JRubyDaemon() {
    }

    /**
     */
    public void init(DaemonContext arguments) throws Exception {
        this.controller = arguments.getController();

        init(arguments.getArguments());
    }

    public void init(String[] arguments) throws Exception {
        initParams();
        initJRuby(arguments);
        loadScript();
        checkDaemon();
    }

    private void loadScript() throws DaemonInitException {
        if (debug)
            log("Executing script from: " + rubyConfig.getScriptFileName());

        // boot her up. The script should yield control back to us so we
        // can give control back to jsvc once
        try {
            runtime.runFromMain(rubyConfig.getScriptSource(), rubyConfig.getScriptFileName());
        } catch (RaiseException e) {
            RubyException re = e.getException();
            if (re.getType().getName().equals("JSVC::DaemonInitError")) {
                throw new DaemonInitException(re.message.toString());
            } else {
                log("Script raised an error: " + e);
                throw e;
            }
        } catch (RuntimeException e) {
            log("Error executing script: " + e);
            throw e;
        }

        appModule = runtime.getModule(appModuleName);
        if (appModule == null) {
            throw new RuntimeException("Couldn't get module '" + appModuleName + "' from JRuby runtime");
        }
        daemon = (RubyModule) appModule.getConstantAt(DAEMON);
        if (daemon == null) {
            throw new RuntimeException("Couldn't get " + DAEMON + " module from " + appModuleName);
        }
    }

    private void initJRuby(String[] arguments) {
        // mimicking startup from org.jruby.Main
        this.rubyConfig = new RubyInstanceConfig();
        rubyConfig.processArguments(arguments);
        runtime = Ruby.newInstance(rubyConfig);
        Thread.currentThread().setContextClassLoader(runtime.getJRubyClassLoader());
        loadSupportScripts();
    }

    private void loadSupportScripts() {
        String errorsPath = "/ruby/lib/jsvc/errors.rb";
        URL scriptResource = getClass().getResource(errorsPath);
        try {
            runtime.loadFile(scriptResource.toString(), scriptResource.openStream(), false);
        } catch (IOException e) {
            throw new RuntimeException("Couldn't load script from " + errorsPath);
        }
    }

    private void initParams() throws Exception {
        this.debug = "true".equals(System.getProperty("JRubyDaemon.debug"));
        this.appModuleName = System.getProperty(PROP_MODULE_NAME);
        if (appModuleName == null) {
            throw new Exception("Property " + PROP_MODULE_NAME + " must be set");
        }
    }

    private String daemonName() {
        return this.appModuleName + "::" + DAEMON;
    }

    public void start() throws Exception {
        // do it in a separate thread, because jsvc expects this method to return.
        thread = new Thread("jsvc-daemon-main") {
            @Override
            public void run() {
                if (debug)
                    log("thread " + thread + " starting daemon...");
                daemon.callMethod("start");
            }
        };
        thread.setDaemon(false);
        thread.setContextClassLoader(runtime.getJRubyClassLoader());
        thread.start();
    }

    public void stop() throws Exception {
        if (debug)
            log("Stopping...");
        try {
            daemon.callMethod("stop");
        } catch (MainExitException e) {
        }
        if (debug)
            log("Stopped");
    }

    public void destroy() {
        runtime.tearDown();
    }

    private void checkDaemon() {
        // check it has come up OK
        Boolean wasSetup = (Boolean) JavaEmbedUtils.rubyToJava(runtime, daemon.callMethod("setup?"), Boolean.class);

        if (!wasSetup.booleanValue()) {
            throw new RuntimeException(
                    "Daemon script did not call " + daemonName() + ".setup - can't tell if init succeeded.");
        }

    }

    private void log(String msg) {
        System.err.println("JRubyDaemon: " + msg);
    }

}