Summary

Add RedisCluster pipeline support restricted to a single hash slot (hash tags respected).
Enforce slot consistency at queue time; cross-slot pipelines throw RedisClusterException.
Handle pipeline exec/cleanup safely and keep MULTI behavior unchanged.
Update stubs/arginfo and cluster documentation.
Add extensive RedisCluster tests covering pipeline, multi, atomic modes, cross-slot errors, invalid operations, and recovery.

Motivation

Currently RedisCluster rejects PIPELINING entirely. Other clients (e.g. redis-py) allow pipelining for same-slot keys. This change brings PhpRedis to parity while preserving Redis Cluster safety guarantees.

Behavior

• Pipelines are allowed if all keys resolve to the same hash slot.
• Cross-slot pipelines throw RedisClusterException.
• Multi-key commands validate slot consistency.
• Existing MULTI behavior remains unchanged.

Testing

Ran tests in a container:

cd /path/to/phpredis

docker run --rm -it \
  --platform=linux/amd64 \
  -v "$PWD:/usr/src/phpredis" \
  -w /usr/src/phpredis \
  php:8.5.2-cli-trixie \
  bash

Note:

• If you plan to build inside this container, install optional PHP extensions (igbinary, msgpack, etc.), preferably via pecl.

• If you plan to start the test cluster inside the same container, make sure to install redis-server as well.

# 1. Build extension
cd /usr/src/phpredis
phpize && ./configure && make -j"$(nproc)" && make test && make install

# 2. Start cluster
cd tests
./make-cluster.sh -y start

# 3. Run pipeline tests
php TestRedis.php --class RedisCluster --test
# expected output: All tests passed. \o/

# 4. Stop cluster when done
./make-cluster.sh stop

Performance (local cluster)

Measured testClusterPipelineTiming before and after:

Before Pipeline Support

• RedisCluster::multi() warned that PIPELINING was not supported
• MGET Time: 0.000579667 seconds
• Pipeline GET Time: 0.026290541 seconds

After Pipeline Support

• MGET Time: 0.000635542 seconds
• Pipeline GET Time: 0.000456541 seconds

Pipeline performance is now in line with expectations and significantly faster.