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Diffstat (limited to 'src/main/java/org/apache/commons/math3/util/IterationManager.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/util/IterationManager.java | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/util/IterationManager.java b/src/main/java/org/apache/commons/math3/util/IterationManager.java new file mode 100644 index 0000000..83f350b --- /dev/null +++ b/src/main/java/org/apache/commons/math3/util/IterationManager.java @@ -0,0 +1,191 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 org.apache.commons.math3.util; + +import org.apache.commons.math3.exception.MaxCountExceededException; + +import java.util.Collection; +import java.util.concurrent.CopyOnWriteArrayList; + +/** + * This abstract class provides a general framework for managing iterative algorithms. The maximum + * number of iterations can be set, and methods are provided to monitor the current iteration count. + * A lightweight event framework is also provided. + */ +public class IterationManager { + + /** Keeps a count of the number of iterations. */ + private IntegerSequence.Incrementor iterations; + + /** The collection of all listeners attached to this iterative algorithm. */ + private final Collection<IterationListener> listeners; + + /** + * Creates a new instance of this class. + * + * @param maxIterations the maximum number of iterations + */ + public IterationManager(final int maxIterations) { + this.iterations = IntegerSequence.Incrementor.create().withMaximalCount(maxIterations); + this.listeners = new CopyOnWriteArrayList<IterationListener>(); + } + + /** + * Creates a new instance of this class. + * + * @param maxIterations the maximum number of iterations + * @param callBack the function to be called when the maximum number of iterations has been + * reached + * @throws org.apache.commons.math3.exception.NullArgumentException if {@code callBack} is + * {@code null} + * @since 3.1 + * @deprecated as of 3.6, replaced with {@link #IterationManager(int, + * org.apache.commons.math3.util.IntegerSequence.Incrementor.MaxCountExceededCallback)} + */ + @Deprecated + public IterationManager( + final int maxIterations, final Incrementor.MaxCountExceededCallback callBack) { + this( + maxIterations, + new IntegerSequence.Incrementor.MaxCountExceededCallback() { + /** {@inheritDoc} */ + public void trigger(final int maximalCount) throws MaxCountExceededException { + callBack.trigger(maximalCount); + } + }); + } + + /** + * Creates a new instance of this class. + * + * @param maxIterations the maximum number of iterations + * @param callBack the function to be called when the maximum number of iterations has been + * reached + * @throws org.apache.commons.math3.exception.NullArgumentException if {@code callBack} is + * {@code null} + * @since 3.6 + */ + public IterationManager( + final int maxIterations, + final IntegerSequence.Incrementor.MaxCountExceededCallback callBack) { + this.iterations = + IntegerSequence.Incrementor.create() + .withMaximalCount(maxIterations) + .withCallback(callBack); + this.listeners = new CopyOnWriteArrayList<IterationListener>(); + } + + /** + * Attaches a listener to this manager. + * + * @param listener A {@code IterationListener} object. + */ + public void addIterationListener(final IterationListener listener) { + listeners.add(listener); + } + + /** + * Informs all registered listeners that the initial phase (prior to the main iteration loop) + * has been completed. + * + * @param e The {@link IterationEvent} object. + */ + public void fireInitializationEvent(final IterationEvent e) { + for (IterationListener l : listeners) { + l.initializationPerformed(e); + } + } + + /** + * Informs all registered listeners that a new iteration (in the main iteration loop) has been + * performed. + * + * @param e The {@link IterationEvent} object. + */ + public void fireIterationPerformedEvent(final IterationEvent e) { + for (IterationListener l : listeners) { + l.iterationPerformed(e); + } + } + + /** + * Informs all registered listeners that a new iteration (in the main iteration loop) has been + * started. + * + * @param e The {@link IterationEvent} object. + */ + public void fireIterationStartedEvent(final IterationEvent e) { + for (IterationListener l : listeners) { + l.iterationStarted(e); + } + } + + /** + * Informs all registered listeners that the final phase (post-iterations) has been completed. + * + * @param e The {@link IterationEvent} object. + */ + public void fireTerminationEvent(final IterationEvent e) { + for (IterationListener l : listeners) { + l.terminationPerformed(e); + } + } + + /** + * Returns the number of iterations of this solver, 0 if no iterations has been performed yet. + * + * @return the number of iterations. + */ + public int getIterations() { + return iterations.getCount(); + } + + /** + * Returns the maximum number of iterations. + * + * @return the maximum number of iterations. + */ + public int getMaxIterations() { + return iterations.getMaximalCount(); + } + + /** + * Increments the iteration count by one, and throws an exception if the maximum number of + * iterations is reached. This method should be called at the beginning of a new iteration. + * + * @throws MaxCountExceededException if the maximum number of iterations is reached. + */ + public void incrementIterationCount() throws MaxCountExceededException { + iterations.increment(); + } + + /** + * Removes the specified iteration listener from the list of listeners currently attached to + * {@code this} object. Attempting to remove a listener which was <em>not</em> previously + * registered does not cause any error. + * + * @param listener The {@link IterationListener} to be removed. + */ + public void removeIterationListener(final IterationListener listener) { + listeners.remove(listener); + } + + /** Sets the iteration count to 0. This method must be called during the initial phase. */ + public void resetIterationCount() { + iterations = iterations.withStart(0); + } +} |