corosync/man/quorum_model_initialize.3.in

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.TH QUORUM_MODEL_INITIALIZE 3 @BUILDDATE@ "corosync Man Page" "Corosync Cluster Engine Programmer's Manual"
.SH NAME
quorum_model_initialize \- Create a new connection to the Quorum service
.SH SYNOPSIS
.B #include <corosync/quorum.h>
.sp
.BI "cs_error_t quorum_model_initialize(quorum_handle_t *" handle ", quorum_model_t " model ", quorum_model_data_t *" model_data ", uint32_t *" quorum_type ",void *" context ");"
.SH DESCRIPTION
The
.B quorum_model_initialize
function is an enhanced way to initialize a connection to the quorum API.
.PP
Each application may have several connections to the quorum API.  Each application
uses the
.I handle
argument to uniquely identify the connection.  The
.I handle
argument is then used in other function calls to identify the connection to be used
for communication with the quorum service.
.PP
The
.I model
is used to explicitly choose set of callbacks and internal parameters. Currently two models
.I QUORUM_MODEL_V0
and
.I QUORUM_MODEL_V1
are defined.
.I QUORUM_MODEL_V0
exists only for compatibility reasons with
.B quorum_initialize(3)
function and it is not recommended to be used as an argument for
.B quorum_model_initialize(3).

The Following description is focused only on
.I QUORUM_MODEL_V1
model.

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

.nf
typedef void (*quorum_v1_quorum_notification_fn_t) (
        quorum_handle_t handle,
        uint32_t quorate,
        struct quorum_ring_id ring_id,
        uint32_t member_list_entries,
        const uint32_t *member_list
);
.fi
.PP
Also every time when membership configuration changes (eg a node joins or leave the cluster) the node list change
callback is called before the quorum callback.
The node list change callback function is described by the following type definitions:

.nf
typedef void (*quorum_v1_nodelist_notification_fn_t) (
        quorum_handle_t handle,
        struct quorum_ring_id ring_id,
        uint32_t member_list_entries,
        const uint32_t *member_list,
        uint32_t joined_list_entries,
        const uint32_t *joined_list,
        uint32_t left_list_entries,
        const uint32_t *left_list
);
.fi
.PP
The
.I model_data
argument for
.I QUORUM_MODEL_V1
is of the type:

.nf
typedef struct {
        quorum_model_t model;
        quorum_v1_quorum_notification_fn_t quorum_notify_fn;
        quorum_v1_nodelist_notification_fn_t nodelist_notify_fn;
} quorum_model_v1_data_t;
.fi

It's not required (nor recommended) to set
.I model
field in the structure. It is also fine if only some of notification callbacks are
used (only these events will be delivered then).

.PP
The
.I quorum_type
argument is set to:

.nf
#define QUORUM_FREE     0
#define QUORUM_SET      1
.fi
.PP
.I QUORUM_FREE
value means that no quorum algorithm is loaded and that no callbacks will take place.
.PP
.I QUORUM_SET
value means that one quorum algorithm is configured and that callbacks will take place.
.PP
The
.I context
argument sets context same way as
.B quorum_context_set(3).
.PP
When a configuration change occurs, the callback
is called from the
.B quorum_dispatch(3)
function.
.PP
.SH RETURN VALUE
This call returns the CS_OK value if successful, otherwise an error is returned.
.PP
.SH ERRORS
@COMMONIPCERRORS@
.SH "SEE ALSO"
.BR quorum_overview (3),
.BR quorum_initialize (3),
.BR quorum_finalize (3),
.BR quorum_getquorate (3),
.BR quorum_trackstart (3),
.BR quorum_trackstop (3),
.BR quorum_fd_get (3),
.BR quorum_dispatch (3),
.BR quorum_context_set (3),
.BR quorum_context_get (3)
.PP