man pages section 3: Extended Library Functions, Volume 1

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Updated: July 2014
 
 

dat_ia_close(3DAT)

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

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
Unsafe
Standard
uDAPL, 1.1, 1.2

See Also

dat_cno_free(3DAT), dat_evd_free(3DAT), dat_ia_open(3DAT), libdat(3LIB), attributes(5)