kdb

Key-value in memory object cache, support PUB/SUB event base on object, support most of memcached text protocol(not include append and prepend command).

Space

The format of key of kdb like: a.b.c, a is the top level space, b is the second level space, c is the object.

Subcribe/Publish

The new command of kdb support sub/pub mode, the command list below:

1. sub
2. subkey
3. leave
4. leavekey

For example, there is a space a.b.c and several objects in space a.b.c: a.b.c.c1, a.b.c.c2. I subscribe the key: subkey a.b.c.c2, the PUB event occurs when someone run store command. I also can subscribe the whole space: sub a.b.c or sub a, the PUB event coming when any object in space has been changed. leavekey a.b.c.c2 cancel the PUB/SUB mode for the object, leave a.b cancel the PUB/SUB mode for the space.

Plugin

User can write the plugin to hook the event in kdb process, the plugin is a common .dll or .so and expose some predefined API:

/*! called after server stated */
typedef int (*kdb_server_on_after_start_t)(kdb_server_t*);
/*! called after server thread stopped, but the momery still can access */
typedef int (*kdb_server_on_after_stop_t)(kdb_server_t*);
/*! called when new space or object added  */
typedef int (*kdb_server_on_key_after_add_t)(kdb_server_t*, kdb_space_value_t*);
/*! called when object updated */
typedef int (*kdb_server_on_key_after_update_t)(kdb_server_t*, kdb_space_value_t*);
/*! called before delete object */
typedef int (*kdb_server_on_key_before_delete_t)(kdb_server_t*, kdb_space_value_t*);
/*! malloc */
typedef void* (*kdb_server_malloc_t)(int);
/*! realloc */
typedef void* (*kdb_server_realloc_t)(void*, int);
/*! free */
typedef void (*kdb_server_free_t)(void*);

The expose API symbol name:

 on_start
 on_stop
 on_add
 on_update
 on_delete
 on_malloc
 on_realloc
 on_free

exptime

The exptime of memcached for now is not implemented, please set exptime to zero.

PUB/SUB protocol

addspace <key> <exptime>\r\n    New space
deletespace <key>\r\n           Delete space(include all objects and child spaces)
sub <key>\r\n                   Subscribe space
subkey <key>\r\n                Subscribe object
leave <key>\r\n                 Cancel space observing
leavekey <key>\r\n              Cancel object observing

Possible acknowledge:

STORED\r\n       success
NOT_FOUND\r\n    <key> not found
DELETED\r\n      space deleted

PUB event - object update notification:

PUB UPDATED <key> <bytes>\r\n
data\r\n
END\r\n

PUB event - space deleting notification:

PUB DELETED SPACE <key>\r\n

PUB event - object deleting notification:

PUB DELETED OBJECT <key> <bytes>\r\n
data\r\n
END\r\n

PUB event - new space notification:

PUB ADDED SPACE <key>\r\n

PUB event - new object notification:

PUB ADDED OBJECT <key> <bytes>\r\n
data\r\n
END\r\n

Build

Dependency

knet http://github.com/dennis-kk/knet

Linux

run build.sh

Windows

see /win-proj. Please set environment variable first:
	$(KNET_INCLUDE) knet include path,
	$(KNET_LIB)     knet library path.

Future

1. Client
2. User defined hash function
3. Performance