Transport Redis

Transport: Redis

InitPHP\Queue\Transport\Redis\RedisTransport runs a durable, reliable queue on Redis. Publishing reuses the SDK's BabelQueue\Transport\RedisTransport (RPUSH), so the wire convention every BabelQueue SDK shares is never duplicated; consuming adds the reliable-queue mechanics.

Requires Redis 6.2+ (for BLMOVE) and the pure-PHP predis/predis client.

Construction

use InitPHP\Queue\Transport\Redis\RedisTransport;

$transport = new RedisTransport(
    client:           new Predis\Client('tcp://127.0.0.1:6379'),
    defaultQueue:     'default',
    processingSuffix: ':processing',
    failedSuffix:     ':failed',
    delayedSuffix:    ':delayed',
);

Keys

For a queue named orders:

Key	Type	Role
orders	list	The ready queue. publish() does RPUSH orders <envelope>.
orders:processing	list	In-flight messages reserved by a worker.
orders:delayed	sorted set	Messages waiting out a back-off delay, scored by their due Unix time.
orders:failed	list	Dead-lettered messages.

How it works

Reserve (reliable queue)

reserve() runs BLMOVE orders orders:processing LEFT RIGHT <timeout>: it atomically pops the head of the ready list and pushes it onto the processing list, blocking up to timeout seconds. Because the message sits on orders:processing until acknowledged, a worker crash leaves it recoverable rather than lost.

The blocking timeout has a 1-second floor, so the loop returns periodically to observe a stop signal instead of blocking forever on an empty queue.

Ack

ack() removes the in-flight copy with LREM orders:processing 1 <envelope>.

Retry with delay

release() removes the in-flight copy, then:

• delay 0 → RPUSH orders <envelope> (back onto the ready queue immediately);
• delay > 0 → ZADD orders:delayed <due-time> <envelope>.

On every reserve(), due members of orders:delayed (score <= now) are migrated back onto the ready list — each re-enqueued only by the worker that wins its ZREM, so a delayed retry is never duplicated across workers.

Dead-letter

deadLetter() removes the in-flight copy and RPUSH-es the annotated envelope onto orders:failed.

Delivery semantics

At-least-once. A crashed worker leaves its in-flight message on orders:processing. The graceful SIGTERM shutdown (finish the in-flight message, then exit) avoids stranding messages in normal operation; if you run workers that can be killed mid-job, add a small reaper that moves long-idle orders:processing entries back onto orders.

Using phpredis instead

The consume side is written against Predis\ClientInterface. If you use the ext-redis (phpredis) extension, either:

• install predis/predis (pure PHP, no extension needed — the supported path), or
• wrap phpredis in a thin adapter exposing the same blmove / rpush / lrem / zadd / zrangebyscore / zrem methods.

For publish-only producers, the SDK's one-method Transport is just an RPUSH and is trivial to implement over phpredis directly.

See The Worker for back-off configuration and Retries & Dead-Letters for the failed list.