introduction.md

Swoole Atomic

Integer variable allows any processor to atomically test and modify. Implemented based on CPU atomic instructions.

The Swoole atomic variables have to defined before swoole_server->start.

Compare-and-swap (CAS) is an atomic instruction used in multithreading to achieve synchronization. It compares the contents of a memory location with a given value and, only if they are the same, modifies the contents of that memory location to a new given value.

Example

<?php
$atomic = new swoole_atomic(123);
echo $atomic->add(12)."\n";
echo $atomic->sub(11)."\n";
echo $atomic->cmpset(122, 999)."\n";
echo $atomic->cmpset(124, 999)."\n";
echo $atomic->get()."\n";

Methods

swoole_atomic->__construct();

Construct a swoole atomic object.

swoole_atomic->add($add_value);

Add a number to the value fo the atomic object.

swoole_atomic->sub($sub_value);

Subtract a number to the value of the atomic object.

swoole_atomic->get();

Get the current value of the atomic object.

swoole_atomic->set($value);

Set the value to the atomic object.

swoole_atomic->cmpset($value);

Compare and set the value of the atomic object. See more about Compare and set.

swoole_atomic->wait($timeout);

Wait the value to be changed for a duration.

swoole_atomic->wakeup();

Wakeup processes waiting on the lock.