001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.mmtk.utility.options;
014    
015    import org.vmmagic.pragma.*;
016    
017    /**
018     * The granularity of the trace being produced.
019     */
020    public final class TraceRate extends org.vmutil.options.IntOption
021      implements org.mmtk.utility.Constants {
022      /**
023       * Create the option.
024       */
025      public TraceRate() {
026        super(Options.set, "Trace Rate",
027            "The granularity of the trace being produced.  By default, the trace has the maximum possible granularity.",
028            Integer.MAX_VALUE);
029      }
030    
031      /**
032       * Return the appropriate value.
033       *
034       * @return the trace rate.
035       */
036      @Override
037      @Uninterruptible
038      public int getValue() {
039        return (this.value < BYTES_IN_ADDRESS) ? 1 : (this.value >> LOG_BYTES_IN_ADDRESS);
040      }
041    
042      /**
043       * Trace rate must be positive.
044       */
045      @Override
046      protected void validate() {
047        failIf(value <= 0, "Can not have a negative trace rate");
048      }
049    }