io.silverware.microservices.Boot.java Source code

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Here is the source code for io.silverware.microservices.Boot.java

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/*
 * -----------------------------------------------------------------------\
 * SilverWare
 * 
 * Copyright (C) 2010 - 2013 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 io.silverware.microservices;

import io.silverware.microservices.util.Utils;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.HelpFormatter;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.LoggerContext;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Map;
import java.util.Properties;

/**
 * Main class to boot the Microservices platforms.
 *
 * @author <a href="mailto:marvenec@gmail.com">Martin Ve?ea</a>
 */
@edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "DM_EXIT", justification = "This class is allowed to terminate the JVM.")
public final class Boot {

    private static final Logger log = LogManager.getLogger(Boot.class);

    private static final String PROPERTY_LETTER = "D";
    private static final String PROPERTY_FILE_LETTER = "p";

    /**
     * Starts the Microservices platform.
     *
     * Uses Executor Microservice Provider as a boot hook.
     *
     * @param args Any additional properties can be specified at the command line via -Dprop=value.
     */
    public static void main(final String... args) {
        preMainConfig();

        log.info("=== Welcome to SilverWare ===");

        try {
            Executor.bootHook(getInitialContext(args));
        } catch (InterruptedException ie) {
            Utils.shutdownLog(log, ie);
        }

        log.info("Goodbye.");
        logFlush(); // this is needed for Ctrl+C termination
    }

    /**
     * Performs some quick system settings for a smooth run.
     */
    private static void preMainConfig() {
        Thread.currentThread().setName(Executor.THREAD_PREFIX + Executor.MAIN_THREAD);
    }

    /**
     * Flushes all appenders and terminate logging.
     */
    private static void logFlush() {
        ((LoggerContext) LogManager.getContext()).stop();
    }

    /**
     * Load custom properties from file on a classpath.
     *
     * @return Properties from silverware.properties when present on a classpath.
     */
    private static Properties loadProperties() {
        Properties props = new Properties();
        try {
            props.load(Boot.class.getResourceAsStream("silverware.properties"));
        } catch (NullPointerException | IOException ioe) {
            log.info("No configuration property file available. Using default values.");
        }

        return props;
    }

    private static Properties loadProperties(final File propertiesFile) {
        Properties props = new Properties();
        try (FileInputStream fis = new FileInputStream(propertiesFile)) {
            props.load(fis);
        } catch (IOException ioe) {
            log.warn("Cannot read configuration property file %s.", propertiesFile.getAbsolutePath());
        }

        return props;
    }

    /**
     * Creates initial context pre-filled with system properties, command line arguments, custom property file and default property file.
     *
     * @param args Command line arguments.
     * @return Initial context pre-filled with system properties, command line arguments, custom property file and default property file.
     */
    @SuppressWarnings("static-access")
    private static Context getInitialContext(final String... args) {
        final Context context = new Context();
        final Map<String, Object> contextProperties = context.getProperties();
        final Options options = new Options();
        final CommandLineParser commandLineParser = new DefaultParser();

        System.getProperties().forEach((key, value) -> contextProperties.put((String) key, value));

        options.addOption(Option.builder(PROPERTY_LETTER).argName("property=value").numberOfArgs(2).valueSeparator()
                .desc("system properties").build());
        options.addOption(Option.builder(PROPERTY_FILE_LETTER).longOpt("properties").desc("Custom property file")
                .hasArg().argName("PROPERTY_FILE").build());

        try {
            final CommandLine commandLine = commandLineParser.parse(options, args);
            commandLine.getOptionProperties(PROPERTY_LETTER)
                    .forEach((key, value) -> contextProperties.put((String) key, value));

            // process custom properties file
            if (commandLine.hasOption(PROPERTY_FILE_LETTER)) {
                final File propertiesFile = new File(commandLine.getOptionValue(PROPERTY_FILE_LETTER));
                if (propertiesFile.exists()) {
                    final Properties props = loadProperties();
                    props.forEach((key, val) -> contextProperties.putIfAbsent(key.toString(), val));
                } else {
                    log.error("Specified property file %s does not exists.", propertiesFile.getAbsolutePath());
                }
            }
        } catch (ParseException pe) {
            log.error("Cannot parse arguments: ", pe);
            new HelpFormatter().printHelp("SilverWare usage:", options);
            System.exit(1);
        }

        // now add in default properties from silverware.properties on a classpath
        loadProperties().forEach((key, val) -> contextProperties.putIfAbsent(key.toString(), val));

        context.getProperties().put(Executor.SHUTDOWN_HOOK, "true");

        return context;
    }
}