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package template;
import java.util.concurrent.locks.ReadWriteLock;
public class ThreadWaiter {
/** Wait for all threads to start running */
public static final <T extends Thread> boolean waitForThreadsToStart(Iterable<T> iter){
//Wait for all threads to start running
boolean success=true;
for(T t : iter){
//Wait until this thread has started
while(t.getState()==Thread.State.NEW){
Thread.yield();
}
}
return success;
}
/** Wait for completion of all threads */
public static final <T extends Thread> boolean waitForThreadsToFinish(Iterable<T> iter){
//Wait for completion of all threads
boolean success=true;
for(T t : iter){
//Wait until this thread has terminated
while(t.getState()!=Thread.State.TERMINATED){
try {
//Attempt a join operation
t.join();
} catch (InterruptedException e) {
//Potentially handle this, if it is expected to occur
e.printStackTrace();
}
}
}
return success;
}
public static final <T extends Thread> void startThreads(Iterable<T> iter){
for(Thread t : iter){t.start();}
}
/**
* @param iter List of Threads.
* @return success
*/
public static final <T extends Thread> boolean startAndWait(Iterable<T> iter){
startThreads(iter);
boolean sr=waitForThreadsToStart(iter);
boolean fr=waitForThreadsToFinish(iter);
return fr && sr;
}
/**
* @param iter List of Threads.
* @return success
*/
public static final <T extends Thread> boolean startAndWait(Iterable<T> iter,
Accumulator<T> acc){
final ReadWriteLock rwlock=acc.rwlock();
if(rwlock!=null) {
// rwlock.writeLock().lock();
rwlock.readLock().lock();
}
startThreads(iter);
boolean sr=waitForThreadsToStart(iter);
if(rwlock!=null) {
// rwlock.writeLock().unlock();
// rwlock.readLock().lock();
}
boolean fr=waitForThreadsToFinish(iter);
if(rwlock!=null) {
rwlock.readLock().unlock();
rwlock.writeLock().lock();
}
boolean ar=accumulate(iter, acc);
if(rwlock!=null) {
rwlock.writeLock().unlock();
}
return fr && sr && ar;
}
/** Wait for completion of all threads, and accumulate results */
public static final <T extends Thread> boolean waitForThreadsToFinish(Iterable<T> iter,
Accumulator<T> acc){
final ReadWriteLock rwlock=acc.rwlock();
if(rwlock!=null) {
// rwlock.writeLock().lock();
rwlock.readLock().lock();
}
// startThreads(iter);
boolean sr=waitForThreadsToStart(iter);
if(rwlock!=null) {
// rwlock.writeLock().unlock();
// rwlock.readLock().lock();
}
boolean fr=waitForThreadsToFinish(iter);
if(rwlock!=null) {
rwlock.readLock().unlock();
rwlock.writeLock().lock();
}
boolean ar=accumulate(iter, acc);
if(rwlock!=null) {
rwlock.writeLock().unlock();
}
return fr && sr && ar;
}
/** Accumulate results from all threads */
private static final <T> boolean accumulate(Iterable<T> iter, Accumulator<T> acc){
//Wait for completion of all threads
for(T t : iter){
// assert(t.getState()==Thread.State.TERMINATED);//Not strictly necessary; requires T to be a thread.
//Accumulate per-thread statistics
acc.accumulate(t);
}
return acc.success();
}
}
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