/*
* ManagerExecution.java
*
* Copyright (c) 2011, Ralf Biedert All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are
* permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer. 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.
*
* Neither the name of the author 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 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 OWNER 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 net.jcores.jre.managers;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import net.jcores.jre.interfaces.functions.F0;
import net.jcores.jre.utils.internal.structures.ProfileInformation;
/**
* Manages the execution of threads.
*
* @since 1.0
* @author Ralf Biedert
*/
public class ManagerExecution extends Manager {
/** The executor with which we execute tasks. */
ExecutorService executor;
/** Our profile information so we know how long new tasks took */
ProfileInformation profile;
/** Creates our execution manager. */
public ManagerExecution() {
// Create an executor that does not prevent us from quitting.
this.executor = Executors.newCachedThreadPool(new ThreadFactory() {
public Thread newThread(Runnable r) {
final Thread t = new Thread(r);
t.setDaemon(true);
return t;
}
});
this.profile = profile();
}
/**
* Returns our executor.
*
* @return Our executor.
*/
public ExecutorService getExecutor() {
return this.executor;
}
/**
* Benchmark the VM. Dirty, but should give us some rough estimates
*
* @return
*/
private ProfileInformation profile() {
final ProfileInformation p = new ProfileInformation();
final int RUNS = 10;
final int N = 5;
// Measure how long it takes to fork a thread and to wait for it again. We
// test 10 times and take the average of the last 5 runs.
long times[] = new long[RUNS];
for (int i = 0; i < RUNS; i++) {
times[i] = measure(new F0() {
@Override
public void f() {
final CyclicBarrier barrier = new CyclicBarrier(2);
// Execute the given task in the executor.
ManagerExecution.this.executor.submit(new Runnable() {
@Override
public void run() {
try {
barrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}
});
try {
barrier.await();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}
});
}
// Now take the average
for (int i = RUNS - N; i < times.length; i++) {
p.forkTime += times[i];
}
p.forkTime /= N;
p.numCPUs = Runtime.getRuntime().availableProcessors();
return p;
}
/**
* Measures how long the execution of the given function took. The result
* will be returned in nanoseconds.
*
* @param f The function to execute.
* @return The elapsed time in nanoseconds.
*/
private long measure(F0 f) {
final long start = System.nanoTime();
f.f();
final long end = System.nanoTime();
return end - start;
}
/**
* Returns the profile information we generated.
*
* @return The profile information.
*/
public ProfileInformation getProfile() {
return this.profile;
}
}