org.silverpeas.core.util.exec.ExternalExecution.java Source code

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Here is the source code for org.silverpeas.core.util.exec.ExternalExecution.java

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/*
 * Copyright (C) 2000 - 2018 Silverpeas
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * As a special exception to the terms and conditions of version 3.0 of
 * the GPL, you may redistribute this Program in connection with Free/Libre
 * Open Source Software ("FLOSS") applications as described in Silverpeas's
 * FLOSS exception.  You should have received a copy of the text describing
 * the FLOSS exception, and it is also available here:
 * "https://www.silverpeas.org/legal/floss_exception.html"
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.silverpeas.core.util.exec;

import org.silverpeas.core.silvertrace.SilverTrace;
import org.apache.commons.exec.CommandLine;
import org.apache.commons.io.IOUtils;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

public class ExternalExecution {

    /**
     * Execute the given external command into the context defined by a default {@link
     * ExternalExecution.Config} (provided by {@link Config#init()}).
     * @param commandLine the external command to execute.
     * @return a {@link List} of console lines written by the external command.
     */
    public static List<String> exec(final CommandLine commandLine) throws ExternalExecutionException {
        return exec(commandLine, Config.init());
    }

    /**
     * Execute the given external command into the context defined by the given {@link
     * ExternalExecution.Config}.
     * @param commandLine the external command to execute.
     * @param config the configuration that permits to perform the execution of the command with
     * some flexibility.
     * @return a {@link List} of console lines written by the external command.
     */
    public static List<String> exec(final CommandLine commandLine, final Config config)
            throws ExternalExecutionException {

        final List<String> result = new LinkedList<>();
        final List<String> errors = new LinkedList<>();
        CollectingLogOutputStream logErrors = new CollectingLogOutputStream(errors);
        final Process process;
        Thread errEater = null, outEater = null;
        try {
            process = Runtime.getRuntime().exec(commandLine.toStrings());
            errEater = new Thread(() -> {
                try {
                    errors.addAll(IOUtils.readLines(process.getErrorStream()));
                } catch (final IOException e) {
                    throw new ExternalExecutionException(e);
                }
            });
            errEater.start();
            outEater = new Thread(() -> {
                try {
                    result.addAll(IOUtils.readLines(process.getInputStream()));
                } catch (final IOException e) {
                    throw new ExternalExecutionException(e);
                }
            });
            outEater.start();
            process.waitFor();
            int exitStatus = process.exitValue();
            if (exitStatus != config.getSuccessfulExitStatusValue()) {
                try {
                    errEater.join();
                } catch (InterruptedException e) {
                }
                throw new RuntimeException("Exit error status : " + exitStatus + " " + logErrors.getMessage());
            }
        } catch (final IOException | InterruptedException | RuntimeException e) {
            performExternalExecutionException(config, e);
        } finally {
            IOUtils.closeQuietly(logErrors);
        }
        try {
            outEater.join();
        } catch (InterruptedException e) {
        }
        return result;
    }

    private static void performExternalExecutionException(Config config, Exception e) {
        if (config.isDisplayErrorTraceEnabled()) {
            SilverTrace.error("util", "ExternalExecution.exec", "Command execution error", e);
        }
        throw new ExternalExecutionException(e);
    }

    /**
     * This class permits to parametrize the external execution of a command.
     */
    public static class Config {
        private int successfulExitStatusValue = 0;
        private boolean displayErrorTrace = true;

        /**
         * Initializes a config with default values:
         * <ul>
         * <li>the code value of a successful exit status is <b>0</b></li>
         * <li>the exception errors are traced by {@link SilverTrace#error(String, String,
         * String)}</li>
         * </ul>
         * @return an instance of {@link ExternalExecution.Config} initialized with default values.
         */
        public static Config init() {
            return new Config();
        }

        private Config() {
        }

        /**
         * Sets the code value of a successful exit status.
         * @param successfulExitStatusValue an {@link Integer} that represents the code value of a
         * successful exit status.
         * @return the {@link ExternalExecution.Config} instance completed with the given information.
         */
        public Config successfulExitStatusValueIs(final int successfulExitStatusValue) {
            this.successfulExitStatusValue = successfulExitStatusValue;
            return this;
        }

        /**
         * Gets the code value of a successful exit status.
         * @return an integer that represents the code value.
         */
        public int getSuccessfulExitStatusValue() {
            return successfulExitStatusValue;
        }

        /**
         * Calling this method avoids to log errors thrown during the execution of a command into log
         * handlers of the server.<br>
         * It is useful for a command for which an execution error can be interpreted as a functional
         * information. For example, a command that verifies the existence of an external tool.
         * @return the {@link ExternalExecution.Config} instance completed with the given information.
         */
        public Config doNotDisplayErrorTrace() {
            this.displayErrorTrace = false;
            return this;
        }

        /**
         * Indicates if the Silverpeas error trace must be displayed when an execution error is
         * detected.
         * @return true if errors must be traced, false otherwise.
         */
        public boolean isDisplayErrorTraceEnabled() {
            return displayErrorTrace;
        }
    }
}