utsuro

utsuro

utsuro is an in-memory volatile KVS server that supports a subset of the memcached text protocol.

Name

utsuro comes from the Japanese word utsuro (うつろ), meaning “empty”, “hollow”, or “transient”. It reflects that this server is an in-memory volatile KVS: data may disappear at any time.

Warning

• Data is volatile and may be lost at any time.
• Do not store data that must not disappear.

MVP command subset

• get
• gets
• set
• delete
• incr
• decr

Options

• -listen (default: 127.0.0.1:11211)
• -max-bytes (default: 268435456)
• -target-bytes (default: max-bytes * 95 / 100)
• -evict-max (default: 64)
• -incr-sliding-ttl-seconds (default: 0, disabled)
• -verbose
• -version (print version and exit)

Differences from memcached

• This server implements only a subset of memcached text protocol commands.
• gets is supported and returns the CAS token in VALUE response header.
• cas command is not implemented.
• incr on a missing key creates the key and returns delta (memcached returns NOT_FOUND).
• decr on a missing key creates the key with 0 and returns 0.
• decr is clamped at 0.
• Numeric values are treated as uint64.
• Non-numeric values return CLIENT_ERROR cannot increment or decrement non-numeric value.
• incr overflow (uint64 max exceeded) returns CLIENT_ERROR increment or decrement overflow.
• When -incr-sliding-ttl-seconds > 0, successful incr/decr always set/update TTL to now + ttl.
• If a key is expired at incr/decr time, it is deleted first and treated as missing (then created by rules above).