142 lines
5.2 KiB
Java
142 lines
5.2 KiB
Java
/*
|
|
* Copyright 2015 Christian Basler
|
|
*
|
|
* Licensed 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 ch.dissem.bitmessage.ports;
|
|
|
|
import ch.dissem.bitmessage.utils.Bytes;
|
|
import org.slf4j.Logger;
|
|
import org.slf4j.LoggerFactory;
|
|
|
|
import java.security.MessageDigest;
|
|
import java.security.NoSuchAlgorithmException;
|
|
import java.util.ArrayList;
|
|
import java.util.List;
|
|
import java.util.concurrent.Semaphore;
|
|
|
|
import static ch.dissem.bitmessage.utils.Bytes.inc;
|
|
|
|
/**
|
|
* A POW engine using all available CPU cores.
|
|
*/
|
|
public class MultiThreadedPOWEngine implements ProofOfWorkEngine {
|
|
private static final Logger LOG = LoggerFactory.getLogger(MultiThreadedPOWEngine.class);
|
|
private static final Semaphore semaphore = new Semaphore(1, true);
|
|
|
|
/**
|
|
* This method will block until all pending nonce calculations are done, but not wait for its own calculation
|
|
* to finish.
|
|
* (This implementation becomes very inefficient if multiple nonce are calculated at the same time.)
|
|
*
|
|
* @param initialHash the SHA-512 hash of the object to send, sans nonce
|
|
* @param target the target, representing an unsigned long
|
|
* @param callback called with the calculated nonce as argument. The ProofOfWorkEngine implementation must make
|
|
*/
|
|
@Override
|
|
public void calculateNonce(byte[] initialHash, byte[] target, Callback callback) {
|
|
try {
|
|
semaphore.acquire();
|
|
} catch (InterruptedException e) {
|
|
throw new RuntimeException(e);
|
|
}
|
|
callback = new CallbackWrapper(callback);
|
|
int cores = Runtime.getRuntime().availableProcessors();
|
|
if (cores > 255) cores = 255;
|
|
LOG.info("Doing POW using " + cores + " cores");
|
|
List<Worker> workers = new ArrayList<>(cores);
|
|
for (int i = 0; i < cores; i++) {
|
|
Worker w = new Worker(workers, (byte) cores, i, initialHash, target, callback);
|
|
workers.add(w);
|
|
}
|
|
for (Worker w : workers) {
|
|
// Doing this in the previous loop might cause a ConcurrentModificationException in the worker
|
|
// if a worker finds a nonce while new ones are still being added.
|
|
w.start();
|
|
}
|
|
}
|
|
|
|
private static class Worker extends Thread {
|
|
private final Callback callback;
|
|
private final byte numberOfCores;
|
|
private final List<Worker> workers;
|
|
private final byte[] initialHash;
|
|
private final byte[] target;
|
|
private final MessageDigest mda;
|
|
private final byte[] nonce = new byte[8];
|
|
|
|
public Worker(List<Worker> workers, byte numberOfCores, int core, byte[] initialHash, byte[] target,
|
|
Callback callback) {
|
|
this.callback = callback;
|
|
this.numberOfCores = numberOfCores;
|
|
this.workers = workers;
|
|
this.initialHash = initialHash;
|
|
this.target = target;
|
|
this.nonce[7] = (byte) core;
|
|
try {
|
|
mda = MessageDigest.getInstance("SHA-512");
|
|
} catch (NoSuchAlgorithmException e) {
|
|
LOG.error(e.getMessage(), e);
|
|
throw new RuntimeException(e);
|
|
}
|
|
}
|
|
|
|
@Override
|
|
public void run() {
|
|
do {
|
|
inc(nonce, numberOfCores);
|
|
mda.update(nonce);
|
|
mda.update(initialHash);
|
|
if (!Bytes.lt(target, mda.digest(mda.digest()), 8)) {
|
|
synchronized (callback) {
|
|
if (!Thread.interrupted()) {
|
|
try {
|
|
callback.onNonceCalculated(initialHash, nonce);
|
|
} finally {
|
|
semaphore.release();
|
|
for (Worker w : workers) {
|
|
w.interrupt();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
} while (!Thread.interrupted());
|
|
}
|
|
}
|
|
|
|
public static class CallbackWrapper implements Callback {
|
|
private final Callback callback;
|
|
private final long startTime;
|
|
private boolean waiting = true;
|
|
|
|
public CallbackWrapper(Callback callback) {
|
|
this.startTime = System.currentTimeMillis();
|
|
this.callback = callback;
|
|
}
|
|
|
|
@Override
|
|
public void onNonceCalculated(byte[] initialHash, byte[] nonce) {
|
|
synchronized (this) {
|
|
if (waiting) {
|
|
LOG.info("Nonce calculated in " + ((System.currentTimeMillis() - startTime) / 1000) + " seconds");
|
|
waiting = false;
|
|
callback.onNonceCalculated(initialHash, nonce);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|