storage-adapters.md

Storage Adapters

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All adapters implement CircuitBreakerStorageInterface. The circuit breaker owns all state transition logic — adapters are dumb storage.

InMemory (Testing / Development)

use GabrielAnhaia\PhpCircuitBreaker\Storage\InMemoryStorage;

$storage = new InMemoryStorage();

State lives in a PHP array. Useful for tests and single-request scripts.

Redis

use GabrielAnhaia\PhpCircuitBreaker\Storage\RedisStorage;

$redis = new \Redis();
$redis->connect('127.0.0.1', 6379);

$storage = new RedisStorage($redis, prefix: 'cb:');

Uses atomic INCR + EXPIRE in MULTI/EXEC transactions. No KEYS command. Production-recommended.

Key scheme:

{prefix}{service}:failures
{prefix}{service}:successes
{prefix}{service}:state:open
{prefix}{service}:state:half_open
{prefix}{service}:override

APCu

use GabrielAnhaia\PhpCircuitBreaker\Storage\ApcuStorage;

$storage = new ApcuStorage(prefix: 'cb:');

Note: APCu is per-process. CLI and web processes have separate caches. Set apc.enable_cli=1 for CLI usage.

Memcached

use GabrielAnhaia\PhpCircuitBreaker\Storage\MemcachedStorage;

$memcached = new \Memcached();
$memcached->addServer('127.0.0.1', 11211);

$storage = new MemcachedStorage($memcached, prefix: 'cb:');

PSR-6 Cache

use GabrielAnhaia\PhpCircuitBreaker\Storage\Psr6CacheStorage;

$storage = new Psr6CacheStorage($psr6CachePool, prefix: 'cb_');

Note: PSR-6 get-increment-save is not atomic. For high-concurrency production, prefer Redis, Memcached, or APCu.

PSR-16 SimpleCache

use GabrielAnhaia\PhpCircuitBreaker\Storage\Psr16CacheStorage;

$storage = new Psr16CacheStorage($psr16Cache, prefix: 'cb_');

Note: Same atomicity caveat as PSR-6.

Adapter Comparison

Adapter	Shared State	Atomic Ops	TTL Support	Best For
InMemory	-	-	Via clock	Testing, single-process
Redis	Multi-process	MULTI/EXEC	Native	Production
APCu	Per-process	-	Native	Single-server web
Memcached	Multi-process	increment	Native	Production
PSR-6	Depends	-	Via expiresAfter	Framework integration
PSR-16	Depends	-	Via TTL param	Framework integration