https://github.com/soulseekah/wp-lock

Locking and mutexes for the WordPress Core
https://github.com/soulseekah/wp-lock

concurrency wordpress

Last synced: about 1 month ago
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Locking and mutexes for the WordPress Core

• Host: GitHub
• URL: https://github.com/soulseekah/wp-lock
• Owner: soulseekah
• Created: 2018-08-24T15:09:30.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2023-05-15T16:02:03.000Z (over 1 year ago)
• Last Synced: 2024-11-24T09:33:43.481Z (about 1 month ago)
• Topics: concurrency, wordpress
• Language: PHP
• Size: 43.9 KB
• Stars: 49
• Watchers: 4
• Forks: 6
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

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README

        
# `WP_Lock`

## because WordPress is not thread-safe

[![PHPUnit Tests](https://github.com/soulseekah/wp-lock/actions/workflows/phpunit.yml/badge.svg)](https://github.com/soulseekah/wp-lock/actions/workflows/phpunit.yml)

WordPress is no longer just a blogging platform. It's a framework. And like all mature frameworks it drastically needs a lock API.

## Example

Consider the following user balance topup function that is susceptible to a race condition:

```php

// topup function that is not thread-safe

public function topup_user_balance( $user_id, $topup ) {

	$balance = get_user_meta( $user_id, 'balance', true );

	$balance = $balance + $topup;

	update_user_meta( $user_id, 'balance', $balance );

	return $balance;

}

```

Try to call the above code 100 times in 16 threads. The balance will be less than it is supposed to be.

```php

// A thread-safe version of the above topup function.

public function topup_user_balance( $user_id, $topup ) {

	$user_balance_lock = new WP_Lock( "$user_id:meta:balance" );

	$user_balance_lock->acquire( WP_Lock::WRITE );

	$balance = get_user_meta( $user_id, 'balance', true );

	$balance = $balance + $topup;

	update_user_meta( $user_id, 'balance', $balance );

	$user_balance_lock->release();

	return $balance;

}

```

The above code is thread safe.

## Lock levels

- `WP_Lock::READ` - other processes can acquire READ but not WRITE until the original lock is released. A shared read lock.

- `WP_Lock::WRITE` (default) - other processes can't acquire READ or WRITE locks until the original lock is released. An exclusive read-write lock

## Usage

Require via Composer `composer require soulseekah/wp-lock` in your plugin.

```php

use soulseekah\WP_Lock;

require 'vendor/autoload.php';

$lock = new WP_Lock\WP_Lock( 'my-first-lock' );

```

## Caveats

In highly concurrent setups you may get Deadlock errors from MySQL. This is normal. The library handles these gracefully and retries the query as needed.