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CMAP_TRACK_ADD(3) Corosync Cluster Engine Programmer's ManualCMAP_TRACK_ADD(3)

NAME
       cmap_track_add -	Set tracking function for values in CMAP

SYNOPSIS
       #include	<corosync/cmap.h>

       cs_error_t  cmap_track_add (cmap_handle_t handle, const char *key_name,
       int32_t	track_type,  cmap_notify_fn_t  notify_fn,   void   *user_data,
       cmap_track_handle_t *cmap_track_handle);

DESCRIPTION
       The  cmap_track_add  function  is  used	to  set	 function which	tracks
       changes in CMAP.	One CMAP connection can	track multiple keys  and  also
       it's  possible  to track	one key	multiple times.	The handle argument is
       connection to CMAP  database  obtained  by  calling  cmap_initialize(3)
       function.   key_name  argument is ether exact key name or prefix	of key
       name to track changes on.  track_type is	bitfield which may consist  of
       following values:

       CMAP_TRACK_ADD -	track addition of new key (or key added	in callback)

       CMAP_TRACK_DELETE - track deletion of key (or key deleted in callback)

       CMAP_TRACK_MODIFY - track modification of key (or key modified in call-
       back)

       CMAP_TRACK_PREFIX - whole prefix	is tracked, instead of	key  only,  so
       "totem."	 tracking  means that "totem.nodeid", "totem.version", ... ap-
       plies (this value is never returned in callback)

       notify_fn is pointer to function	which is called	when value is changed.
       It's   definition   and	meaning	 of  parameters	 is  discussed	below.
       user_data argument is passed directly to	notify_fn without any changes.
       cmap_track_handle  is  used  for	 removing  of  tracking	when no	longer
       needed by calling cmap_track_delete(3) function.

       Callback	function is defined as:

	      typedef void (*cmap_notify_fn_t) (
		  cmap_handle_t	cmap_handle,
		  cmap_track_handle_t cmap_track_handle,
		  int32_t event,
		  const	char *key_name,
		  struct cmap_notify_value new_value,
		  struct cmap_notify_value old_value,
		  void *user_data);

       where cmap_handle is handle used	in  registration  of  track  function.
       cmap_track_handle is handle returned by cmap_track_add function.	 event
       is  one	of  CMAP_TRACK_ADD,  CMAP_TRACK_DELETE	or  CMAP_TRACK_MODIFY.
       key_name	is name	of changed key.	 new_value is new value	of key,	or un-
       set if event is CMAP_TRACK_DELETE.  old_value is	previous value of  key
       or  unset  if  event is CMAP_TRACK_ADD or for some special keys set di-
       rectly by Corosync due to  speed	 optimizations.	  Both	new_value  and
       old_value are structures	defined	as:

	      struct cmap_notify_value {
		  cmap_value_types_t type;
		  size_t len;
		  const	void *data;
	      };

       If  value  is  unset, all fields	are set	to 0. Otherwise	type is	one of
       cmap types (as described	in cmap_get(3) function),  len	is  length  of
       value in	cmap and data is pointer to value of item. Data	storage	is dy-
       namically allocated by caller and notify	function must not try to  free
       it.

RETURN VALUE
       This  call  returns  the	 CS_OK	value  if  successful.	It  can	return
       CS_ERR_INVALID_PARAM if notify_fn is  NULL  or  track_type  is  invalid
       value.

NOTES
       Modification tracking of	individual keys	is supported in	the stats map,
       but not prefixes.  Add/Delete  operations  are  supported  on  prefixes
       though so you can track for new ipc connections or knet interfaces.  In
       the icmap map, prefix tracking is fully supported.

SEE ALSO
       cmap_track_delete(3),   cmap_initialize(3),   cmap_get(3),    cmap_dis-
       patch(3), cmap_overview(3)

       CS_ERR_TRY_AGAIN	Resource temporarily unavailable

       CS_ERR_INVALID_PARAM Invalid argument

       CS_ERR_ACCESS Permission	denied

       CS_ERR_LIBRARY The connection failed

       CS_ERR_INTERRUPT	System call interrupted	by a signal

       CS_ERR_NOT_SUPPORTED The	requested protocol/functionality not supported

       CS_ERR_MESSAGE_ERROR Incorrect auth message received

       CS_ERR_NO_MEMORY	Not enough memory to complete the requested task

corosync Man Page		  06/02/2012		     CMAP_TRACK_ADD(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO

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