Memcache

The memcache data store speaks the Memcached ASCII (text) protocol. The implementation lives in dynomite::proto::memcache.

Wire format

Memcached commands are newline-terminated ASCII. The engine consumes the stream with one byte-driven state machine for requests (memcache_parse_req) and one for responses (memcache_parse_rsp). Like the RESP parser, the memcache parser is total: arbitrary input either yields a complete message or a parse error.

get user:42\r\n
set user:42 0 0 3\r\nabc\r\n

Command handling

Parsed requests are classified into MsgType values covering the storage, retrieval, arithmetic, and lifecycle commands: get, gets, set, add, replace, append, prepend, cas, delete, incr, decr, touch, and quit.

Classification drives the same machinery as the RESP path:

• Routing by key (or hash tag) through the configured distribution.
• Multi-key fragmentation for the multi-key get / gets forms, with per-peer reply coalescing.

Limitations

• The binary protocol is not implemented; only the ASCII protocol.
• Memcache backends are not authenticated. AUTH is RESP-specific, and memcache binary SASL is not implemented, so redis_requirepass: is ignored for a memcache data_store.
• Read repair is a placeholder for memcache: memcache has no versioned reconciliation the way the RESP path does.