Key handling: rename() overwrites an existing destination, and generic readers reject keys that merely contain the base key #126

RedisAdapter version or revision

main at ff2d5b8; unchanged through the #108 → #109 → #111 stack (0c3b0e6).

Redis version and deployment mode

Redis 7.4.11 standalone (TCP).

Observed behavior

1. rename() overwrites an existing destination.

rename() is documented as "rename a home stream key (dest key must not exist)" (RedisAdapter.hpp), the same wording as copy(). But RedisConnection::rename issues RENAME, which silently replaces the destination, and the call reports success. A caller relying on the documented contract loses the destination stream's data without any error.

A missing source (ERR no such key) also triggers a full adapter reconnect (#123).

2. split_key() matches the base key as a substring.

The guard in addGenericReader()/removeGenericReader() is meant to reject keys of this adapter's own schema ({base}:sub). It uses key.find(_base_key) anywhere in the key, so any generic key that merely contains the base-key text is refused. addGenericReader returns false with no log and registers nothing. Short or common base keys make this likely.

The same substring match also decides the base/sub reported for dispatched entries on non-schema keys.

Expected:

• rename() fails, without reconnecting, when the destination exists (or the docs say it overwrites);
• only keys that start with {<base>} are treated as schema keys.

Reproduction

• addSingleValue(src, "SRC-DATA"); addSingleValue(dst, "DST-DATA"); rename(src, dst) returns 1, and dst now holds SRC-DATA. The previous value is gone.
• With base key "BPM": addGenericReader("raw_frames") = 1, addGenericReader("BPM_raw_frames") = 0, addGenericReader("LINAC:BPMs:raw") = 0.

Build and runtime environment

• Ubuntu 24.04, gcc 13.3
• pinned redis-plus-plus 1.3.15 and hiredis 1.3.0
• a private Redis 7.4.11 in a container

Suggested fix

• Use RENAMENX (redis-plus-plus renamenx) and return false when the destination exists. Treat no such key as a plain false, without reconnect(). If overwriting is intended, correct the header comment and docs instead.
• Test for the exact schema prefix, const auto prefix = "{" + _base_key + "}"; key.compare(0, prefix.size(), prefix) == 0, and derive base/sub in split_key from the delimiter rather than from a substring hit.