/**
* Attempts to acquire the lock and sleeps for a time if the lock could not be acquired.
*
* @return \Generator
*/
public function acquire() : \Generator
{
$tsl = function () {
return $this->lock ? $this->lock = false : true;
};
while (!$this->lock || $this->synchronized($tsl)) {
yield from Coroutine\sleep(self::LATENCY_TIMEOUT);
}
return new Lock(function () {
$this->release();
});
}
/**
* {@inheritdoc}
*/
public function acquire() : \Generator
{
// Try to create the lock file. If the file already exists, someone else
// has the lock, so set an asynchronous timer and try again.
while (($handle = @fopen($this->fileName, 'x')) === false) {
yield from Coroutine\sleep(self::LATENCY_TIMEOUT);
}
// Return a lock object that can be used to release the lock on the mutex.
$lock = new Lock(function (Lock $lock) {
$this->release();
});
fclose($handle);
return $lock;
}
/**
* Uses a double locking mechanism to acquire a lock without blocking. A
* synchronous mutex is used to make sure that the semaphore is queried one
* at a time to preserve the integrity of the semaphore itself. Then a lock
* count is used to check if a lock is available without blocking.
*
* If a lock is not available, we add the request to a queue and set a timer
* to check again in the future.
*/
public function acquire() : \Generator
{
$tsl = function () {
// If there are no locks available or the wait queue is not empty,
// we need to wait our turn to acquire a lock.
if ($this->locks > 0) {
--$this->locks;
return false;
}
return true;
};
while ($this->locks < 1 || $this->synchronized($tsl)) {
yield from Coroutine\sleep(self::LATENCY_TIMEOUT);
}
return new Lock(function () {
$this->release();
});
}
/**
* {@inheritdoc}
*/
public function acquire()
{
do {
// Attempt to acquire a lock from the semaphore.
if (@msg_receive($this->queue, 0, $type, 1, $chr, false, MSG_IPC_NOWAIT, $errno)) {
// A free lock was found, so resolve with a lock object that can
// be used to release the lock.
yield new Lock(function (Lock $lock) {
$this->release();
});
return;
}
// Check for unusual errors.
if ($errno !== MSG_ENOMSG) {
throw new SemaphoreException('Failed to acquire a lock.');
}
} while (yield Coroutine\sleep(self::LATENCY_TIMEOUT));
}
});
Coroutine\create(function () {
// Create a new child thread that does some blocking stuff.
$context = Thread::spawn(function () {
printf("\$this: %s\n", get_class($this));
printf("Received the following from parent: %s\n", (yield $this->receive()));
print "Sleeping for 3 seconds...\n";
sleep(3); // Blocking call in thread.
yield $this->send('Data sent from child.');
print "Sleeping for 2 seconds...\n";
sleep(2); // Blocking call in thread.
yield 42;
});
print "Waiting 2 seconds to send start data...\n";
yield Coroutine\sleep(2);
yield $context->send('Start data');
printf("Received the following from child: %s\n", (yield $context->receive()));
printf("Thread ended with value %d!\n", (yield $context->join()));
})->cleanup([$timer, 'stop'])->done();
Loop\run();
