Redis ExpireMember Module

Introduction

redis_expiremember_module is a custom Redis module that introduces an EXPIREMEMBER command. This command allows setting expiration times on individual hash fields, a feature inspired by KeyDB's EXPIREMEMBER, but with some distinct differences and enhancements.

Features

• Field-Level Expiration: Set expiration times on individual fields within a Redis hash, a Redis set and a Redis zset.
• Custom Expiration Units: Support for specifying expiration times in seconds (s) or milliseconds (ms).
• Expiration Override: Ability to update or override the expiration time for a specific field.
• Expiring runs in a separate thread: The module has been designed to have minimal impact on Redis server's performance and locks Redis's main thread only for actual Redis key delete operations.

Key Differences from KeyDB's EXPIREMEMBER

• Independent Expiration Handling: Unlike KeyDB, expirations set via this module are not affected by other hash operations.
• Explicit Expiration Removal: Requires explicit management when manually removing hash members.

Installation

1. Clone the repository.

2. Build the module using cargo build --release.

3. Load the module into your Redis server.

   redis-server --loadmodule ./target/release/libredis_expiremember_module.so

Usage

Setting Expiration

EXPIREMEMBER key field time [unit]

• key: Redis hash key.
• field: Field within the hash to expire.
• time: Expiration time.
• unit (optional): Time unit (s for seconds, ms for milliseconds). Defaults to seconds.

Overriding Expiration

To update the expiration time for a field, simply execute EXPIREMEMBER again with the new time.

Removing Expiration

To remove expiration from a field:

EXPIREMEMBER key field 0

If you manually delete a field using HDEL, make sure to also remove its expiration.

Example

HSET myhash field1 value1
EXPIREMEMBER myhash field1 10

Sets field1 in myhash to expire in 10 seconds.

OR

SADD myset member1 
EXPIREMEMBER myset member1 10

OR

ZADD myzset member1 
EXPIREMEMBER myzset member1 10

Sets field members in myset to expire in 10 seconds

Development

Dependencies

• Rust
• Cargo (Rust's package manager)
• Redis (for running tests)

Building

Run cargo build to compile the project.

Run ./build-production.sh to compile via Docker to build a production-candidate shared library.

Run ./build-redis.sh to build a Redis server container with this module enabled. Published at: https://hub.docker.com/r/rushpl/redis-expiremember

Testing

Tests are available under the tests module. Run them using cargo test. This will start a server using the redis-server binary.

You can also override the binary, see example below:

REDIS_SERVER_BIN=/sbin/redis-server cargo test