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",  ...
       applies (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  bellow.
       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
       unset 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
       directly by Corosync due to speed optimalizations.  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
       dynamically alocated 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.

SEE ALSO
       cmap_track_delete(3),	cmap_initialize(3),   cmap_get(3),   cmap_dis‐
       patch(3), cmap_overview(8)

       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 inturrupted by a signal

       CS_ERR_NOT_SUPPORTED The requested protocol/functuality not supported

       CS_ERR_MESSAGE_ERROR Incorrect auth message received

       CS_ERR_NO_MEMORY Not enough memory to completed the requested task

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

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