RedisStore

Redis-backed BaseStore implementation.

Key layout

For each item with namespace [a, b, c] and key k, two Redis keys are used:

• Item hash <prefix>item:<ns>\0<k> — a Redis hash with fields value (JSON-encoded Map<String,Object>) and version (a stringified long).

• Namespace index <prefix>idx:<ns> — a sorted set (all scores 0) holding every k written under that exact namespace, enabling lexicographic #search via ZRANGEBYLEX without scanning the keyspace.

<ns> is the namespace components joined with "\0".

Concurrency

#put and #putIfVersion both run as a single Lua EVAL, making the version read + hash write + index update one atomic Redis operation. This makes #putIfVersion safe to use as a distributed compare-and-swap primitive across multiple processes sharing the same Redis instance.

#search is not in the same transaction as #put: index members may temporarily refer to an item whose hash has not yet been written (window between ZADD and HSET, which is closed by the Lua atomicity above) or to an item that was concurrently deleted. The implementation tolerates the latter by skipping missing items.