Group Services Programming Guide and Reference

ha_gs_delayed_error_callback subroutine

Purpose

ha_gs_delayed_error_callback - A callback routine that the Group Services subsystem calls to deliver an asynchronous error notification to a GS client

Library

GSAPI Thread-Safe Library (libha_gs_r.a)

GSAPI Library (not thread-safe) (libha_gs.a)

Syntax

#include <ha_gs.h>
 
void
    ha_gs_delayed_error_callback(
        const   ha_gs_delayed_error_notification_t      *notification)
 
 

Parameters

notification

A pointer to a delayed error notification block.

Description

Delayed errors are asynchronous errors. They occur when a GS client has submitted a proposal, (such as to join a group, broadcast a message, or change the group's state value) and the Group Services subsystem later discovers a problem with the proposal. When such an error occurs, Group Services delivers it to the GS client by invoking a callback routine.

The ha_gs_delayed_error_callback subroutine defines a GS client's delayed error callback routine. The GS client uses it to handle delayed error notifications from the Group Services subsystem. The process provides the address of the delayed error callback routine to the Group Services subsystem on the ha_gs_init subroutine during GSAPI initialization. The Group Services subsystem then calls the delayed error callback routine when it has a delayed error notification to deliver to the GS client.

On input, the delayed error callback routine receives a pointer to the delayed error notification block. The delayed error notification block has the following definition:

typedef struct  {
    ha_gs_notification_type_t   gs_notification_type;
    ha_gs_token_t               gs_request_token 
    ha_gs_request_t             gs_protocol_type;
    ha_gs_rc_t                  gs_delayed_return_code;
    ha_gs_proposal_ info_t      *gs_failing_request;
} ha_gs_delayed_error_notification_t;

The gs_notification_type field contains the type of notification. For a delayed error notification, it contains a value of HA_GS_DELAYED_ERROR_NOTIFICATION.

The gs_protocol_type field contains the type of request for which this delayed error is being delivered.

HA_GS_JOIN

This provider's join request is invalid because its group attributes do not match those that were specified by the group.

HA_GS_LEAVE

A provider is voluntarily leaving the group. If the error is HA_GS_COLLIDE, then the Group Services subsystem has chosen another protocol to run instead of this one.

HA_GS_EXPEL

A provider is attempting to expel one or more providers from the group. If the error is HA_GS_COLLIDE, then the Group Services subsystem has chosen another protocol to run instead of this one.

HA_GS_STATE_VALUE_CHANGE

A provider is trying to change the group's state value. If the error is HA_GS_COLLIDE, then the Group Services subsystem has chosen another protocol to run instead of this one.

HA_GS_PROVIDER_MESSAGE

A provider is broadcasting a message to the group. If the error is HA_GS_COLLIDE, then the Group Services subsystem has chosen another protocol to run instead of this one.

HA_GS_SUBSCRIBE

This subscriber's request is invalid because the group specified on the request does not exist.

HA_GS_GROUP_ATTRIBUTE_CHANGE

This provider's group attribute change request is invalid or not supported.

The gs_delayed_return_code field contains error number of the delayed error. The GSAPI error numbers are defined in the ha_gs.h header file. For more information on GSAPI errors, see GSAPI errors (err_gsapi).

The gs_failing_request field points to the proposal information block for the proposal that is in error.

The proposal information block has the following definition:

#define gs_join_request              _gs_protocol_info._gs_join_request
#define gs_state_change_request      _gs_protocol_info._gs_state_change_request
#define gs_message_request           _gs_protocol_info._gs_message_request
#define gs_leave_request             _gs_protocol_info._gs_leave_request
#define gs_expel_request             _gs_protocol_info._gs_expel_request
#define gs_subscribe_request         _gs_protocol_info._gs_subscribe_request
#define gs_attribute_change_request  _gs_protocol_info._gs_attribute_change_request
typedef  struct
{
    union {
        ha_gs_join_request_t              _gs_join_request;
        ha_gs_state_change_request_t      _gs_state_change_request;
        ha_gs_message_request_t           _gs_message_request;
        ha_gs_leave_request_t             _gs_leave_request;
        ha_gs_expel_request_t             _gs_expel_request;
        ha_gs_subscribe_request_t         _gs_subscribe_request;
        ha_gs_attribute_change_request_t  _gs_attribute_change_request;
    } _gs_protocol_info;
} ha_gs_proposal_info_t;

For details on the block that defines each type of proposal, see the subroutine that is used to initiate the proposal, as follows:

Proposal

Subroutine

Joining a group

ha_gs_join

Changing the group's attributes

ha_gs_change_attributes

Changing the group's state value

ha_gs_change_state_value

Broadcasting a message to all of a group's providers

ha_gs_send_message

Leaving a group

ha_gs_leave

Expelling one or more providers from the group

ha_gs_expel

Subscribing to a group

ha_gs_subscribe

Restrictions

For important information about multiprocessing considerations that apply to all callback routines, see the ha_gs_n_phase_callback man page.

Return Values

None.

Error Values

None.

For information about GSAPI synchronous and asynchronous errors, see GSAPI errors (err_gsapi).

Synchronous Errors

None.

Asynchronous Errors

None.

Files

ha_gs.h

Prerequisite Information

Understanding Group Services.

Related Information

Subroutines: ha_gs_init, ha_gs_join, ha_gs_change_state_value, ha_gs_send_message, ha_gs_leave, ha_gs_expel, ha_gs_subscribe, ha_gs_change_attributes