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import EDU.oswego.cs.dl.util.concurrent.*;
import java.util.*;
public class BufferTasks extends FJTask {
static int niters = 1024 * 64;
static int[] pairs = {1, 2, 4, 8, 16, 32, 64};
static int[] sizes = { 1024, 64, 1 };
public static void main(String[] args) {
try {
int procs;
try {
procs = Integer.parseInt(args[0]);
}
catch (Exception e) {
System.out.println("Usage: java BufferTasks <threads>");
return;
}
System.out.print("pairs:");
for (int p = 0; p < pairs.length; ++p)
System.out.print("\t" + pairs[p]);
System.out.print("\n");
FJTaskRunnerGroup g = new FJTaskRunnerGroup(procs);
g.invoke(new BufferTasks());
}
catch (InterruptedException ex) {}
}
public void run() {
for (int s = 0; s < sizes.length; ++s) {
System.out.println("cap: " + sizes[s]);
for (int p = 0; p < pairs.length; ++p) {
buffer = new Buffer(sizes[s]);
int npairs = pairs[p];
int iters = niters / npairs;
long startTime = System.currentTimeMillis();
setCallbackCount(npairs * 2);
for (int k = 0; k < npairs; ++k) {
new Producer(iters).fork();
new Consumer(iters).fork();
}
while (!checkDone()) yield();
long now = System.currentTimeMillis();
long time = now - startTime;
long tpi = (time * 1000) / (npairs * niters);
System.out.print("\t" + tpi);
}
System.out.print("\n");
getFJTaskRunnerGroup().stats();
}
}
/**
* Keep track of callbacks so that test driver knows when
* to terminate
**/
int callbackCount;
synchronized void notifyDone() { --callbackCount; }
synchronized void setCallbackCount(int c) { callbackCount = c; }
synchronized boolean checkDone() { return callbackCount == 0; }
/** The shared buffer **/
Buffer buffer;
class Producer extends FJTask {
final int iters;
Producer(int n) { iters = n; }
public void run() {
for (int n = iters; n > 0; --n) {
// If cannot continue, create a new task to
// take our place, and start it.
if (!buffer.offer(new Integer(n))) { // Doesn't matter what's put in
yield();
new Producer(n).start();
return;
}
}
notifyDone();
}
}
class Consumer extends FJTask {
final int iters;
Consumer(int n) { iters = n; }
public void run() {
for (int n = iters; n > 0; --n) {
// If cannot continue, create a new task to
// take our place, and start it.
if (buffer.poll() == null) {
yield();
new Consumer(n).start();
return;
}
}
notifyDone();
}
}
static class Buffer {
protected Object[] array_; // the elements
protected int putPtr_ = 0; // circular indices
protected int takePtr_ = 0;
final NonBlockingSemaphore putPermits;
final NonBlockingSemaphore takePermits;
public Buffer(int capacity){
putPermits = new NonBlockingSemaphore(capacity);
takePermits = new NonBlockingSemaphore(0);
array_ = new Object[capacity];
}
public boolean offer(Object x){
if (!putPermits.attempt()) return false;
synchronized(this) {
array_[putPtr_] = x;
if (++putPtr_ == array_.length) putPtr_ = 0;
}
takePermits.release();
return true;
}
public Object poll() {
if (!takePermits.attempt()) return null;
Object x;
synchronized(this) {
x = array_[takePtr_];
array_[takePtr_] = null;
if (++takePtr_ == array_.length) takePtr_ = 0;
}
putPermits.release();
return x;
}
}
static class NonBlockingSemaphore {
private long permits_;
public NonBlockingSemaphore(long initialPermits) {
permits_ = initialPermits;
}
public synchronized boolean attempt() {
if (permits_ > 0) {
--permits_;
return true;
}
else
return false;
}
public synchronized void release() {
++permits_;
}
}
}
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