README

Standard PECL ext-memcached with dynamic mode/auto-discovery support for Memcached AWS ElastiCache.

Why?

Use the stable and performant standard ext-memcached from PECL while still taking advantage of AWS ElastiCache auto-discovery.

How does it work?

References to ext-memcached's Memcached class will be replaced using PHP Code Shift to references to the src/Memcached/MemcachedHook.php class in this package.

Additionally, session connections can also take advantage of auto-discovery.

When adding a server, if dynamic mode is enabled for this package in nytris.config.php, the AWS ElastiCache auto-discovery feature will be used, and all discovered nodes added to the Memcached instance.

Currently, by default the following references to Memcached will be hooked, but this can be customised using new MemcachedPackage(memcachedClassHookFilter: ...):

• Stash's Memcached sub-adapter
• Symfony Cache's Memcached adapter

Usage

Install this package with Composer:

$ composer require nytris/memcached tasque/tasque tasque/event-loop

Configure Nytris platform:

nytris.config.php

<?php

declare(strict_types=1);

use Nytris\Boot\BootConfig;
use Nytris\Boot\PlatformConfig;
use Nytris\Memcached\Library\ClientMode;
use Nytris\Memcached\MemcachedPackage;
use Tasque\EventLoop\TasqueEventLoopPackage;
use Tasque\TasquePackage;

$bootConfig = new BootConfig(new PlatformConfig(__DIR__ . '/var/cache/nytris/'));

$bootConfig->installPackage(new TasquePackage(
    // Disabled for this example, but also works with Tasque in preemptive mode.
    preemptive: false
));
$bootConfig->installPackage(new TasqueEventLoopPackage());
$bootConfig->installPackage(new MemcachedPackage(
    // Use dynamic mode/auto-discovery when connecting to an AWS ElastiCache cluster.
    clientMode: ClientMode::DYNAMIC
));

return $bootConfig;

Optimal host resolution

Where possible, the private IP returned from AWS ElastiCache auto-discovery will be used. Otherwise, if the $dnsResolverFactory constructor argument is provided to MemcachedPackage, the host returned will be resolved by the given ReactPHP DNS resolver, which can then be cached, unlike the PECL ext-memcached DNS resolution which is not.

$ composer require nytris/dns

nytris.config.php

<?php

declare(strict_types=1);

use Nytris\Dns\Dns;
use Nytris\Memcached\MemcachedPackage;

// ...

$bootConfig->installPackage(new MemcachedPackage(
    // Use dynamic mode/auto-discovery when connecting to an AWS ElastiCache cluster.
    clientMode: ClientMode::DYNAMIC,

    // Perform DNS lookups via ReactPHP DNS resolver.
    // Note that $cachePath is provided as a convenient way to refer to the cache directory
    // if using an on-disk cache.
    dnsResolverFactory: static fn (string $cachePath) => (new Dns())->createResolver(
        cache: new ReactCacheAdapter(
            // Cache DNS across requests in APCu.
            psrCachePool: new LightApcuAdapter(
                namespace: 'nytris.react_dns',
            )
        )
    )
));

// ...

Sessions support

Sessions are supported with the native ext-memcached session handling via Nytris\Memcached\Session\NativeMemcachedSessionHandler.

This will perform auto-discovery if enabled when the config endpoint is provided with either the session.save_path INI setting or the $savePath constructor argument.

<?php

use Nytris\Memcached\Session\NativeMemcachedSessionHandler;

session_set_save_handler(new NativeMemcachedSessionHandler());

See also

• PHP Code Shift