code: /**
   * This file is part of Eclipse Steady.
   *
   * 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.
   *
   * SPDX-License-Identifier: Apache-2.0
   * SPDX-FileCopyrightText: Copyright (c) 2018-2020 SAP SE or an SAP affiliate company and Eclipse Steady contributors
   */
  package org.eclipse.steady.shared.util;
  
  import org.apache.logging.log4j.Logger;
  
  /**
   * <p>ThreadUtil class.</p>
   */
  public class ThreadUtil {
  
    private static final Logger log = org.apache.logging.log4j.LogManager.getLogger(ThreadUtil.class);
  
    /** Constant <code>NO_OF_THREADS="vulas.core.noThreads"</code> */
    public static final String NO_OF_THREADS = "vulas.core.noThreads";
  
    /**
     * Returns true if the value of configuration setting {@link NO_OF_THREADS} is equal to AUTO, false otherwise.
     * @return
     */
    private static boolean isAutoThreading(VulasConfiguration _cfg) {
      return "AUTO".equalsIgnoreCase(_cfg.getConfiguration().getString(NO_OF_THREADS, null));
    }
  
    /**
     * Returns the number of threads to be used for parallelized processing steps, thereby taking the configuration setting
     * {@link NO_OF_THREADS} and the number of cores into account.
     *
     * @param _multiply_if_auto a int.
     * @return a int.
     */
    public static final int getNoThreads(final int _multiply_if_auto) {
      return getNoThreads(VulasConfiguration.getGlobal(), _multiply_if_auto);
    }
  
    /**
     * Returns the number of threads to be used for parallelized processing steps, thereby taking the configuration setting
     * {@link NO_OF_THREADS} and the number of cores into account.
     *
     * @param _cfg a {@link org.eclipse.steady.shared.util.VulasConfiguration} object.
     * @param _multiply_if_auto a int.
     * @return a int.
     */
    public static final int getNoThreads(final VulasConfiguration _cfg, final int _multiply_if_auto) {
      int number = 1;
      if (isAutoThreading(_cfg)) {
        number = Runtime.getRuntime().availableProcessors() * _multiply_if_auto;
        log.info(
            "Auto-threading enabled: Number of threads is ["
                + _multiply_if_auto
                + " x "
                + Runtime.getRuntime().availableProcessors()
                + " cores]");
      } else {
        final String value = _cfg.getConfiguration().getString(NO_OF_THREADS, "1");
        try {
          number = Integer.parseInt(value);
          log.info("Auto-threading disabled: Number of threads is [" + number + "]");
        } catch (NumberFormatException nfe) {
          number = 1;
          log.error(
              "Auto-threading disabled: Configuration setting ["
                  + NO_OF_THREADS
                  + "] must be AUTO or integer, but is ["
                  + value
                  + "], defaulting to [1]");
        }
      }
      return number;
    }
  
    /**
     * <p>getNoThreads.</p>
     *
     * @return a int.
     */
    public static int getNoThreads() {
      return getNoThreads(1);
    }
  }
  