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package org.jruby.ext.thread;

import java.util.concurrent.locks.ReentrantLock;

import org.jruby.CompatVersion;

import org.jruby.Ruby;

import org.jruby.RubyBoolean;

import org.jruby.RubyClass;

import org.jruby.RubyObject;

import org.jruby.anno.JRubyClass;

import org.jruby.anno.JRubyMethod;

import org.jruby.runtime.Block;

import org.jruby.runtime.ObjectAllocator;

import org.jruby.runtime.ThreadContext;

import org.jruby.runtime.builtin.IRubyObject;

/**

* The "Mutex" class from the 'thread' library.

*/

@JRubyClass(name = "Mutex")

public class Mutex extends RubyObject {

ReentrantLock lock = new ReentrantLock();

@JRubyMethod(name = "new", rest = true, meta = true)

public static Mutex newInstance(ThreadContext context, IRubyObject recv, IRubyObject[] args, Block block) {

Mutex result = new Mutex(context.runtime, (RubyClass) recv);

result.callInit(context, args, block);

return result;

}

public Mutex(Ruby runtime, RubyClass type) {

super(runtime, type);

}

public static void setup(Ruby runtime) {

RubyClass cMutex = runtime.defineClass("Mutex", runtime.getObject(), new ObjectAllocator() {

public IRubyObject allocate(Ruby runtime, RubyClass klass) {

return new Mutex(runtime, klass);

}

});

cMutex.setReifiedClass(Mutex.class);

cMutex.defineAnnotatedMethods(Mutex.class);

}

@JRubyMethod(name = "locked?")

public synchronized RubyBoolean locked_p(ThreadContext context) {

return context.runtime.newBoolean(lock.isLocked());

}

@JRubyMethod

public RubyBoolean try_lock(ThreadContext context) {

if (lock.isHeldByCurrentThread()) {

return context.runtime.getFalse();

}

return context.runtime.newBoolean(context.getThread().tryLock(lock));

}

@JRubyMethod

public IRubyObject lock(ThreadContext context) {

try {

context.getThread().enterSleep();

try {

checkRelocking(context);

context.getThread().lockInterruptibly(lock);

} catch (InterruptedException ex) {

context.pollThreadEvents();

throw context.runtime.newConcurrencyError("interrupted waiting for mutex: " + ex.getMessage());

}

} finally {

context.getThread().exitSleep();

}

return this;

}

@JRubyMethod

public synchronized IRubyObject unlock(ThreadContext context) {

Ruby runtime = context.runtime;

if (!lock.isLocked()) {

throw runtime.newThreadError("Mutex is not locked");

}

if (!lock.isHeldByCurrentThread()) {

throw runtime.newThreadError("Mutex is not owned by calling thread");

}

boolean hasQueued = lock.hasQueuedThreads();

context.getThread().unlock(lock);

return hasQueued ? context.nil : this;

}

@JRubyMethod(compat = CompatVersion.RUBY1_9)

public IRubyObject sleep(ThreadContext context) {

long beg = System.currentTimeMillis();

try {

unlock(context);

context.getThread().sleep(-1);

} catch (InterruptedException ex) {

// ignore interrupted

} finally {

lock(context);

}

return context.runtime.newFixnum((System.currentTimeMillis() - beg) / 1000);

}

@JRubyMethod(compat = CompatVersion.RUBY1_9)

public IRubyObject sleep(ThreadContext context, IRubyObject timeout) {

long beg = System.currentTimeMillis();

try {

unlock(context);

context.getThread().sleep((long) (timeout.convertToFloat().getDoubleValue() * 1000));

} catch (InterruptedException ex) {

// ignore interrupted

} finally {

lock(context);

}

return context.runtime.newFixnum((System.currentTimeMillis() - beg) / 1000);

}

@JRubyMethod

public IRubyObject synchronize(ThreadContext context, Block block) {

lock(context);

try {

return block.yield(context, null);

} finally {

unlock(context);

}

}

private void checkRelocking(ThreadContext context) {

if (lock.isHeldByCurrentThread()) {

throw context.runtime.newThreadError("Mutex relocking by same thread");

}

}

}