Utility class to simulate dependencies between breakpoints in the Eclipse debugger.

Breaks.java

/*
 * Copyright (c) 2010, Olivier Michallat
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The names of the author or contributors may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ConcurrentSkipListSet;

/**
 * Utility class to simulate dependencies between breakpoints in the Eclipse debugger (e.g "stop at
 * breakpoint X only if we have stopped at breakpoint Y before").
 *
 * Usage :
 * - create conditional breakpoints in your code (see the "Breakpoint properties" menu in Eclipse) ;
 * - inside of the breakpoint's condition, use:
 *   - #set or #setAndBreak to set a marker,
 *   - #test or #testAndClear to depend on a marker set by a previous breakpoint.
 */
public abstract class Breaks {
  
  /** Returns an instance that maintains a private set of markers for each thread. */
  public static final Breaks threadLocal() { return THREAD_LOCAL; }
  
  /** Returns an instance that maintains a shared set of markers for all threads. */
  public static final Breaks allThreads() { return ALL_THREADS; }
  
  protected abstract Set<String> markers();
  
  /** Use this in the condition of a breakpoint where you want to set a marker but not stop. */
  public final boolean set(String marker) {
    innerSet(marker);
    return false;
  }
  
  /** Use this in the condition of a breakpoint where you want to set a marker and stop. */
  public final boolean setAndBreak(String marker) {
    innerSet(marker);
    return true;
  }
  
  private void innerSet(String marker) {
    boolean wasNew = markers().add(marker);
    assert wasNew;
  }
  
  /** Use this in the condition of a breakpoint where you want to stop if a marker is set. */
  public final boolean test(String marker) { return markers().contains(marker); }
  
  /**
   * Use this in the condition of a breakpoint if you want to stop if the marker is set, and then
   * clear the marker.
   */
  public final boolean testAndClear(String marker) { return markers().remove(marker); }
  
  private static Breaks THREAD_LOCAL = new Breaks() {
    private final ThreadLocal<Set<String>> markers = new ThreadLocal<Set<String>>() {
      @Override protected java.util.Set<String> initialValue() { return new HashSet<String>(); };
    };

    @Override protected java.util.Set<String> markers() { return markers.get(); }
  };
  
  private static Breaks ALL_THREADS  = new Breaks() {
    private final Set<String> markers = new ConcurrentSkipListSet<String>();

    @Override protected java.util.Set<String> markers() { return markers; }
  };
}