protocol

const (
	// BinHeaderLen is the fixed 24-byte binary-protocol header size.
	BinHeaderLen = 24

	// MagicRequest marks a request packet (client → server).
	MagicRequest byte = 0x80
	// MagicResponse marks a response packet (server → client).
	MagicResponse byte = 0x81
)

const (
	// OpGet retrieves a value (no extras on request).
	OpGet byte = 0x00
	// OpSet stores a value (4-byte flags + 4-byte exptime extras on request).
	OpSet byte = 0x01
	// OpAdd stores a value only if the key does not exist.
	OpAdd byte = 0x02
	// OpReplace stores a value only if the key already exists.
	OpReplace byte = 0x03
	// OpDelete removes a key.
	OpDelete byte = 0x04
	// OpIncrement atomically adds to a counter.
	OpIncrement byte = 0x05
	// OpDecrement atomically subtracts from a counter.
	OpDecrement byte = 0x06
	// OpQuit closes the connection.
	OpQuit byte = 0x07
	// OpFlush wipes all data (optional 4-byte expiration extras).
	OpFlush byte = 0x08
	// OpGetQ is the quiet variant of GET (no reply on miss).
	OpGetQ byte = 0x09
	// OpNoop is a no-op that forces a reply (used to terminate multi-get
	// pipelines made of OpGetQ packets).
	OpNoop byte = 0x0a
	// OpVersion returns the server version string as the value body.
	OpVersion byte = 0x0b
	// OpGetK is like OpGet but includes the key in the response body.
	OpGetK byte = 0x0c
	// OpGetKQ is the quiet variant of OpGetK.
	OpGetKQ byte = 0x0d
	// OpAppend appends to an existing value.
	OpAppend byte = 0x0e
	// OpPrepend prepends to an existing value.
	OpPrepend byte = 0x0f
	// OpStat requests server statistics (multi-reply terminated by a zero-
	// length key response).
	OpStat byte = 0x10
	// OpTouch updates the expiration of a key without fetching the value.
	OpTouch byte = 0x1c
	// OpGAT gets a value and updates its expiration.
	OpGAT byte = 0x1d
	// OpGATQ is the quiet variant of OpGAT.
	OpGATQ byte = 0x1e
)

const (
	// StatusOK indicates a successful reply.
	StatusOK uint16 = 0x0000
	// StatusKeyNotFound indicates the key does not exist.
	StatusKeyNotFound uint16 = 0x0001
	// StatusKeyExists indicates the key already exists or CAS mismatch.
	StatusKeyExists uint16 = 0x0002
	// StatusValueTooLarge indicates the value exceeded the server's limit.
	StatusValueTooLarge uint16 = 0x0003
	// StatusInvalidArgs indicates malformed request.
	StatusInvalidArgs uint16 = 0x0004
	// StatusItemNotStored indicates add/replace preconditions failed.
	StatusItemNotStored uint16 = 0x0005
	// StatusNonNumeric indicates incr/decr on a non-numeric value.
	StatusNonNumeric uint16 = 0x0006
	// StatusUnknownCommand indicates an unknown opcode.
	StatusUnknownCommand uint16 = 0x0081
	// StatusOutOfMemory indicates server-side OOM.
	StatusOutOfMemory uint16 = 0x0082
)

const MaxValueLen = 128 * 1024 * 1024