Tribblix: manual page: dat_ia

DAT_IA_CLOSE(3DAT) Direct Access Transport Library Functions

NAME

dat_ia_close - close an IA

SYNOPSIS

cc [ flag... ] file... -ldat [ library... ]
#include <dat/udat.h>

DAT_RETURN
dat_ia_close (
IN DAT_IA_HANDLE ia_handle,
IN DAT_CLOSE_FLAGS ia_flags
)

PARAMETERS

ia_handle
Handle for an instance of a DAT IA.

ia_flags
Flags for IA closure. Flag definitions are:

DAT_CLOSE_ABRUPT_FLAG
Abrupt close. Abrupt
cascading close of IA
including all Consumer
created DAT objects.

DAT_CLOSE_GRACEFUL_FLAG
Graceful close. Closure is
successful only if all DAT
objects created by the
Consumer have been freed
before the graceful closure
call.

Default value of DAT_CLOSE_DEFAULT =
DAT_CLOSE_ABRUPT_FLAG represents abrupt closure of IA.

DESCRIPTION

The dat_ia_close() function closes an IA (destroys an instance of the
Interface Adapter).

The ia_flags specify whether the Consumer wants abrupt or graceful
close.

The abrupt close does a phased, cascading destroy. All DAT Objects
associated with an IA instance are destroyed. These include all the
connection oriented Objects: public and reserved Service Points;
Endpoints, Connection Requests, LMRs (including lmr_contexts), RMRs
(including rmr_contexts), Event Dispatchers, CNOs, and Protection
Zones. All the waiters on all CNOs, including the OS Wait Proxy
Agents, are unblocked with the DAT_HANDLE_NULL handle returns for an
unblocking EVD. All direct waiters on all EVDs are also unblocked and
return with DAT_ABORT.

The graceful close does a destroy only if the Consumer has done a
cleanup of all DAT objects created by the Consumer with the exception
of the asynchronous EVD. Otherwise, the operation does not destroy
the IA instance and returns the DAT_INVALID_STATE.

If async EVD was created as part of the of dat_ia_open(3DAT),
dat_ia_close() must destroy it. If async_evd_handle was passed in by
the Consumer at dat_ia_open(), this handle is not destroyed. This is
applicable to both abrupt and graceful ia_flags values.

Because the Consumer did not create async EVD explicitly, the
Consumer does not need to destroy it for graceful close to succeed.

RETURN VALUES

DAT_SUCCESS
The operation was successful.

DAT_INSUFFICIENT_RESOURCES
The operation failed due to resource
limitations. This is a catastrophic
error.

DAT_INVALID_HANDLE
Invalid DAT handle; ia_handle is
invalid.

DAT_INVALID_PARAMETER
Invalid parameter; ia_flags is invalid.

DAT_INVALID_STATE
Parameter in an invalid state. IA
instance has Consumer-created objects
associated with it.

USAGE

The dat_ia_close() function is the root cleanup method for the
Provider, and, thus, all Objects.

Consumers are advised to explicitly destroy all Objects they created
prior to closing the IA instance, but can use this function to clean
up everything associated with an open instance of IA. This allows the
Consumer to clean up in case of errors.

Note that an abrupt close implies destruction of EVDs and CNOs. Just
as with explicit destruction of an EVD or CNO, the Consumer should
take care to avoid a race condition where a Consumer ends up
attempting to wait on an EVD or CNO that has just been deleted.

The techniques described in dat_cno_free(3DAT) and dat_evd_free(3DAT)
can be used for these purposes.

If the Consumer desires to shut down the IA as quickly as possible,
the Consumer can call dat_ia_close(abrupt) without unblocking CNO and
EVD waiters in an orderly fashion. There is a slight chance that an
invalidated DAT handle will cause a memory fault for a waiter. But
this might be an acceptable behavior, especially if the Consumer is
shutting down the process.

No provision is made for blocking on event completion or pulling
events from queues.

This is the general cleanup and last resort method for Consumer
recovery. An implementation must provide for successful completion
under all conditions, avoiding hidden resource leakage (dangling
memory, zombie processes, and so on) eventually leading to a reboot
of the operating system.

The dat_ia_close() function deletes all Objects that were created
using the IA handle.

The dat_ia_close() function can decrement a reference count for the
Provider Library that is incremented by dat_ia_open() to ensure that
the Provider Library cannot be removed when it is in use by a DAT
Consumer.

ATTRIBUTES