NAME

       votequorum_initialize - Create a new connection to the VoteQuorum service

SYNOPSIS

       #include <corosync/votequorum.h>

       int votequorum_initialize(votequorum_handle_t *handle, votequorum_callbacks_t *callbacks);

DESCRIPTION

       The  votequorum_initialize  function  is used to initialize a connection to the vote-based
       quorum database API.

       Each application may have several connections to the  votequorum  API.   Each  application
       uses the handle argument to uniquely identify the connection.  The handle argument is then
       used in other function calls to identify the connection to be used for communication  with
       the votequorum service.

       Every  time  the  voting  configuration  is  about to change (eg a node joins or leave the
       cluster), the callback is called.  The callback function is  described  by  the  following
       type definitions:

       typedef void (*votequorum_nodelist_notification_fn_t) (
            votequorum_handle_t handle,
            uint64_t context,
            uint32_t node_list_entries,
            uint32_t node_list[]
            );

       Current   ring_id  (one  get  in  votequorum_quorum_notification_fn)  must  be  passed  to
       votequorum_qdevice_poll to make qdevice voting valid.

       Every time the quorum state changes (eg a node joins or leave the cluster),  the  callback
       is called.  The callback function is described by the following type definitions:

       typedef void (*votequorum_quorum_notification_fn_t) (
            votequorum_handle_t handle,
            uint64_t context,
            uint32_t quorate,
            uint32_t node_list_entries,
            votequorum_node_t node_list[]
            );

       The         difference        between        votequorum_nodelist_notification_t        and
       votequorum_quorum_notification_t is subtle but important.  The 'nodelist' callback is sent
       at  the start of a cluster state transition and contains the new ring_id and only the list
       of nodes that are included in the sync state - ie only active nodes. No quorum information
       is included this callback because it is not available at that time.  The 'quorum' callback
       is sent after  the  cluster  state  transition  has  completed  and  does  contain  quorum
       information.   In  addition, the nodelist contains a list of all nodes known to votequorum
       (whether up or down) and their state as  well  as  information  about  the  quorum  device
       attached (if any). Quorum callbacks will not be sent for qdevice up and down events unless
       they affect quorum.

       Every time the expected votes are changed, the callback is  called.   The  expected  votes
       callback function is described by the following type definitions:

       typedef void (*votequorum_expectedvotes_notification_fn_t) (
               votequorum_handle_t handle,
               uint64_t context,
               uint32_t expected_votes);

       The callbacks argument is of the type:

       typedef struct {
            votequorum_quorum_notification_fn_t votequorum_quorum_notify_fn;
            votequorum_expectedvotes_notification_fn_t votequorum_expectedvotes_notify_fn;
            votequorum_nodelist_notification_fn_t votequorum_nodelist_notify_fn;
       } votequorum_callbacks_t;

       When  a configuration change occurs, the callback is called from the votequorum_dispatch()
       function.

RETURN VALUE

       This call returns the CS_OK value if successful, otherwise an error is returned.

ERRORS

       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

SEE ALSO

       votequorum_overview(3),           votequorum_finalize(3),           votequorum_getinfo(3),
       votequorum_trackstart(3),          votequorum_trackstop(3),          votequorum_fd_get(3),
       votequorum_dispatch(3),       votequorum_context_set(3),        votequorum_context_get(3),
       votequorum_setexpected(3), votequorum_setvotes(3)