import java.io.*;

import java.util.*;

import java.util.concurrent.*;

import java.util.concurrent.locks.*;

public class Count {

final Random rnd = new Random();

void lock(Lock lock) {

try {

switch (rnd.nextInt(4)) {

case 0: lock.lock(); break;

case 1: lock.lockInterruptibly(); break;

case 2: check(lock.tryLock()); break;

case 3: check(lock.tryLock(45, TimeUnit.MINUTES)); break;

}

} catch (Throwable t) { unexpected(t); }

}

void test(String[] args) throws Throwable {

for (boolean fair : new boolean[] { true, false })

for (boolean serialClone : new boolean[] { true, false }) {

testReentrantLocks(fair, serialClone);

testConcurrentReadLocks(fair, serialClone);

}

}

void testConcurrentReadLocks(final boolean fair,

final boolean serialClone) throws Throwable {

final int nThreads = 10;

final CyclicBarrier barrier = new CyclicBarrier(nThreads);

final ExecutorService es = Executors.newFixedThreadPool(nThreads);

final ReentrantReadWriteLock rwl = serialClone ?

serialClone(new ReentrantReadWriteLock(fair)) :

new ReentrantReadWriteLock(fair);

for (int i = 0; i < nThreads; i++) {

es.submit(new Runnable() { public void run() {

try {

int n = 5;

for (int i = 0; i < n; i++) {

barrier.await();

equal(rwl.getReadHoldCount(), i);

equal(rwl.getWriteHoldCount(), 0);

check(! rwl.isWriteLocked());

equal(rwl.getReadLockCount(), nThreads * i);

barrier.await();

lock(rwl.readLock());

}

for (int i = 0; i < n; i++) {

rwl.readLock().unlock();

barrier.await();

equal(rwl.getReadHoldCount(), n-i-1);

equal(rwl.getReadLockCount(), nThreads*(n-i-1));

equal(rwl.getWriteHoldCount(), 0);

check(! rwl.isWriteLocked());

barrier.await();

}

THROWS(IllegalMonitorStateException.class,

new F(){void f(){rwl.readLock().unlock();}},

new F(){void f(){rwl.writeLock().unlock();}});

barrier.await();

} catch (Throwable t) { unexpected(t); }}});}

es.shutdown();

check(es.awaitTermination(10, TimeUnit.SECONDS));

}

void testReentrantLocks(final boolean fair,

final boolean serialClone) throws Throwable {

final ReentrantLock rl = serialClone ?

serialClone(new ReentrantLock(fair)) :

new ReentrantLock(fair);

final ReentrantReadWriteLock rwl = serialClone ?

serialClone(new ReentrantReadWriteLock(fair)) :

new ReentrantReadWriteLock(fair);

final int depth = 10;

equal(rl.isFair(), fair);

equal(rwl.isFair(), fair);

check(! rl.isLocked());

check(! rwl.isWriteLocked());

check(! rl.isHeldByCurrentThread());

check(! rwl.isWriteLockedByCurrentThread());

check(! rwl.writeLock().isHeldByCurrentThread());

for (int i = 0; i < depth; i++) {

equal(rl.getHoldCount(), i);

equal(rwl.getReadLockCount(), i);

equal(rwl.getReadHoldCount(), i);

equal(rwl.getWriteHoldCount(), i);

equal(rwl.writeLock().getHoldCount(), i);

equal(rl.isLocked(), i > 0);

equal(rwl.isWriteLocked(), i > 0);

lock(rl);

lock(rwl.writeLock());

lock(rwl.readLock());

}

for (int i = depth; i > 0; i--) {

check(! rl.hasQueuedThreads());

check(! rwl.hasQueuedThreads());

check(! rl.hasQueuedThread(Thread.currentThread()));

check(! rwl.hasQueuedThread(Thread.currentThread()));

check(rl.isLocked());

check(rwl.isWriteLocked());

check(rl.isHeldByCurrentThread());

check(rwl.isWriteLockedByCurrentThread());

check(rwl.writeLock().isHeldByCurrentThread());

equal(rl.getQueueLength(), 0);

equal(rwl.getQueueLength(), 0);

equal(rwl.getReadLockCount(), i);

equal(rl.getHoldCount(), i);

equal(rwl.getReadHoldCount(), i);

equal(rwl.getWriteHoldCount(), i);

equal(rwl.writeLock().getHoldCount(), i);

rwl.readLock().unlock();

rwl.writeLock().unlock();

rl.unlock();

}

THROWS(IllegalMonitorStateException.class,

new F(){void f(){rl.unlock();}},

new F(){void f(){rwl.readLock().unlock();}},

new F(){void f(){rwl.writeLock().unlock();}});

}

//--------------------- Infrastructure ---------------------------

volatile int passed = 0, failed = 0;

void pass() {passed++;}

void fail() {failed++; Thread.dumpStack();}

void fail(String msg) {System.err.println(msg); fail();}

void unexpected(Throwable t) {failed++; t.printStackTrace();}

void check(boolean cond) {if (cond) pass(); else fail();}

void equal(Object x, Object y) {

if (x == null ? y == null : x.equals(y)) pass();

else fail(x + " not equal to " + y);}

public static void main(String[] args) throws Throwable {

new Count().instanceMain(args);}

void instanceMain(String[] args) throws Throwable {

try {test(args);} catch (Throwable t) {unexpected(t);}

System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);

if (failed > 0) throw new AssertionError("Some tests failed");}

abstract class F {abstract void f() throws Throwable;}

void THROWS(Class<? extends Throwable> k, F... fs) {

for (F f : fs)

try {f.f(); fail("Expected " + k.getName() + " not thrown");}

catch (Throwable t) {

if (k.isAssignableFrom(t.getClass())) pass();

else unexpected(t);}}

static byte[] serializedForm(Object obj) {

try {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

new ObjectOutputStream(baos).writeObject(obj);

return baos.toByteArray();

} catch (IOException e) { throw new RuntimeException(e); }}

static Object readObject(byte[] bytes)

throws IOException, ClassNotFoundException {

InputStream is = new ByteArrayInputStream(bytes);

return new ObjectInputStream(is).readObject();}

@SuppressWarnings("unchecked")

static <T> T serialClone(T obj) {

try { return (T) readObject(serializedForm(obj)); }

catch (Exception e) { throw new RuntimeException(e); }}

}