com.mgmtp.perfload.agent.Agent.java Source code

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Here is the source code for com.mgmtp.perfload.agent.Agent.java

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/*
 * Copyright (c) 2013-2014 mgm technology partners GmbH
 *
 * 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.mgmtp.perfload.agent;

import java.io.File;
import java.lang.instrument.Instrumentation;
import java.lang.management.ManagementFactory;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.inject.Inject;

import org.apache.commons.io.FileUtils;

import com.google.inject.Injector;

/**
 * Java agent main class. Called by the JVM.
 * 
 * @author rnaegele
 */
public class Agent {

    private final AgentLogger logger;
    private final Transformer transformer;

    @Inject
    Agent(final AgentLogger logger, final Transformer transformer) {
        this.logger = logger;
        this.transformer = transformer;
    }

    void addTransformer(final Instrumentation instrumentation) {
        logger.writeln("Adding transformer...");
        instrumentation.addTransformer(transformer);
    }

    /**
     * @param agentArgs
     *            arguments for the agent; not used
     * @param instrumentation
     *            the {@link Instrumentation} instance
     */
    public static void premain(final String agentArgs, final Instrumentation instrumentation) {
        AgentLogger logger = null;
        try {
            File agentDir = getAgentDir();
            int pid = retrievePid();
            File agentLog = new File(agentDir, String.format("perfload-agent-%d.log", pid));
            logger = new AgentLogger(agentLog);

            logger.writeln("Initializing perfLoad Agent...");

            Injector injector = InjectorHolder.INSTANCE.createInjector(new AgentModule(agentDir, logger, pid));
            injector.getInstance(Agent.class).addTransformer(instrumentation);
        } catch (Exception ex) {
            ex.printStackTrace();
            if (logger != null) {
                logger.writeln("Error initializing perfLoad Agent.", ex);
                logger.close();
            }
        }
    }

    private static File getAgentDir() {
        URL location = Agent.class.getProtectionDomain().getCodeSource().getLocation();
        File jarFile = FileUtils.toFile(location);
        return jarFile.getParentFile();
    }

    static int retrievePid() {
        try {
            // There is no SecurityManager involved retrieving this bean,
            // but just to be safe, we catch exceptions.
            String jvmName = ManagementFactory.getRuntimeMXBean().getName();
            Matcher matcher = Pattern.compile("\\d*").matcher(jvmName);
            return matcher.find() ? Integer.parseInt(matcher.group()) : -1;
        } catch (Exception ex) {
            System.err.println("Error retrieving process id.");
            ex.printStackTrace();
            return -1;
        }
    }
}