Make Random thread safe

This commit is contained in:
Moritz 'Morty' Strübe 2014-10-14 11:09:21 +02:00
parent a50bc08adc
commit 380c6b7622
2 changed files with 89 additions and 1 deletions

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@ -0,0 +1,87 @@
/*
* Copyright (c) 2014, Friedrich-Alexander University Erlangen-Nuremberg.
* 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. Neither the name of the university nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
*
*/
package org.contikios.cooja;
import java.util.Random;
/**
* This ensures that the functions of the random number generator are
* only called by the the thread initializing a simulation or the
* simulation thread itself.
* Rationale: By allowing another thread to use the random number
* generator concurrency is intruduced, thus it can not be guaranteed
* that simulations are reproduceable.
*
*/
public class SafeRandom extends Random {
Simulation sim = null;
Thread initThread = null;
private void assertSimThread() {
// It we are in the simulation thread everything is fine (the default)
// sim can be null, because setSeed is called by the super-constructor.
if(sim != null && !sim.isSimulationThread()) {
// The thread initializing the simulation might differ from the simulation thread.
// If they are the same that is ok, too.
if(initThread == null) initThread = Thread.currentThread();
if(Thread.currentThread() == initThread ) return;
throw new RuntimeException("A random-function was not called from the simulation thread. This can break things!");
}
}
public SafeRandom(Simulation sim) {
// assertSimThread is called by the super-constructor.
super();
this.sim = sim;
}
public SafeRandom(Simulation sim, long seed) {
// assertSimThread is called by the super-constructor.
super(seed);
this.sim = sim;
}
synchronized public void setSeed(long seed) {
assertSimThread();
super.setSeed(seed);
}
/*
* This function is called by all functions returning random numbers
* @see java.util.Random#next(int)
*/
protected int next(int bits) {
assertSimThread();
return super.next(bits);
}
}

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@ -93,7 +93,7 @@ public class Simulation extends Observable implements Runnable {
private long maxMoteStartupDelay = 1000*MILLISECOND;
private Random randomGenerator = new Random();
private SafeRandom randomGenerator;
private boolean hasMillisecondObservers = false;
private MillisecondObservable millisecondObservable = new MillisecondObservable();
@ -322,6 +322,7 @@ public class Simulation extends Observable implements Runnable {
*/
public Simulation(Cooja cooja) {
this.cooja = cooja;
randomGenerator = new SafeRandom(this);
}
/**