Import Upstream version 0.6.5~20141030

1 files changed, 134 insertions, 0 deletions

diff --git a/src/de/lmu/ifi/dbs/elki/parallel/ParallelCore.java b/src/de/lmu/ifi/dbs/elki/parallel/ParallelCore.java
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+++ b/src/de/lmu/ifi/dbs/elki/parallel/ParallelCore.java
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+package de.lmu.ifi.dbs.elki.parallel;
+
+/*
+ This file is part of ELKI:
+ Environment for Developing KDD-Applications Supported by Index-Structures
+
+ Copyright (C) 2014
+ Ludwig-Maximilians-Universität München
+ Lehr- und Forschungseinheit für Datenbanksysteme
+ ELKI Development Team
+
+ 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.
+
+ 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/>.
+ */
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Core for parallel processing in ELKI, based on {@link ThreadPoolExecutor}.
+ * 
+ * TODO: make configurable how many threads are used.
+ * 
+ * @author Erich Schubert
+ */
+public class ParallelCore {
+  /**
+   * The number of CPUs to use.
+   */
+  public static final int ALL_PROCESSORS = Runtime.getRuntime().availableProcessors();
+
+  /**
+   * Static core
+   */
+  private static final ParallelCore STATIC = new ParallelCore(ALL_PROCESSORS);
+
+  /**
+   * Executor service.
+   */
+  ThreadPoolExecutor executor;
+
+  /**
+   * Number of connected submitters.
+   */
+  private AtomicInteger connected = new AtomicInteger(0);
+
+  /**
+   * Maximum number of processors to use.
+   */
+  private int processors;
+
+  /**
+   * Constructor.
+   */
+  protected ParallelCore(int processors) {
+    super();
+    this.processors = processors;
+  }
+
+  /**
+   * Get the static core object.
+   * 
+   * @return Core
+   */
+  public static ParallelCore getCore() {
+    return STATIC;
+  }
+
+  /**
+   * Get desired level of parallelism
+   * 
+   * @return Number of threads to run in parallel
+   */
+  public int getParallelism() {
+    return executor.getMaximumPoolSize();
+  }
+
+  /**
+   * Submit a task to the executor core.
+   * 
+   * @param task Submitted task
+   * 
+   * @return Future to observe completion
+   */
+  public <T> Future<T> submit(Callable<T> task) {
+    return executor.submit(task);
+  }
+
+  /**
+   * Connect to the executor.
+   */
+  public void connect() {
+    if(executor == null) {
+      synchronized(this) {
+        if(executor == null) {
+          executor = new ThreadPoolExecutor(0, processors, 10L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>());
+          executor.allowCoreThreadTimeOut(true);
+        }
+      }
+    }
+    int c = this.connected.incrementAndGet();
+    if(c == 1) {
+      executor.allowCoreThreadTimeOut(false);
+      executor.setCorePoolSize(executor.getMaximumPoolSize());
+    }
+  }
+
+  /**
+   * Disconnect to the executor.
+   */
+  public void disconnect() {
+    int c = this.connected.decrementAndGet();
+    if(c == 0) {
+      synchronized(this) {
+        executor.allowCoreThreadTimeOut(true);
+        executor.setCorePoolSize(0);
+      }
+    }
+  }
+}