PHP Class malkusch\lock\mutex\CASMutex

This mutex doesn't lock at all. It implements the compare-and-swap approach. I.e. it will repeat executing the code block until it wasn't modified in between. Use this only when you know that concurrency is a rare event.

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Author: Markus Malkusch ([email protected])

Inheritance: extends Mutex

Show file Open project: malkusch/lock Class Usage Examples

Public Methods

Method	Description
__construct ( integer $timeout = 3 )	Sets the timeout.
notify ( )	Notifies the Mutex about a successfull CAS operation.
synchronized ( callable $code ) : mixed	Repeats executing a code until a compare-and-swap operation was succesful.

Method Details

__construct() public method

The default is 3 seconds.

public __construct ( integer $timeout = 3 )
$timeout	integer	The timeout in seconds.

notify() public method

Notifies the Mutex about a successfull CAS operation.

public notify ( )

synchronized() public method

The code has to be designed in a way that it can be repeated without any side effects. When the CAS operation was successful it should notify this mutex by calling {@link CASMutex::notify()}. I.e. the only side effects of the code may happen after a successful CAS operation. The CAS operation itself is a valid side effect as well. If the code throws an exception it will stop repeating the execution. Example:


$mutex = new CASMutex();
$mutex->synchronized(function () use ($memcached, $mutex, $amount) {
    $balance = $memcached->get("balance", null, $casToken);
    $balance -= $amount;
    if (!$memcached->cas($casToken, "balance", $balance)) {
        return;

    }
    $mutex->notify();
});

public synchronized ( callable $code ) : mixed
$code	callable	The synchronized execution block.
return	mixed	The return value of the execution block.