LDAP_OPEN(3) Library Functions Manual LDAP_OPEN(3)
ldap_dup, ldap_destroy, - Duplicate and destroy LDAP session handles
OpenLDAP LDAP (libldap, -lldap)
LDAP *old );
LDAP *old );
ldap_dup() duplicates an existing LDAP (LDAP *) session handle. The
new session handle may be used concurrently with the original session
handle. In a threaded environment, different threads may execute con-
current requests on the same connection/session without fear of contam-
ination. Each session handle manages its own private error results.
ldap_destroy() destroys an existing session handle.
The ldap_dup() and ldap_destroy() functions are used in conjunction
with a "thread safe" version of libldap (libldap_r) to enable operation
thread safe API calls, so that a single session may be simultaneously
used across multiple threads with consistent error handling.
When a session is created through the use of one of the session cre-
ation functions including ldap_open(3), ldap_init(3), ldap_initial-
ize(3) or ldap_init_fd(3) an LDAP * session handle is returned to the
application. The session handle may be shared amongst threads, however
the error codes are unique to a session handle. Multiple threads per-
forming different operations using the same session handle will result
in inconsistent error codes and return values.
To prevent this confusion, ldap_dup() is used duplicate an existing
session handle so that multiple threads can share the session, and
maintain consistent error information and results.
The message queues for a session are shared between sibling session
handles. Results of operations on a sibling session handles are acces-
sible to all the sibling session handles. Applications desiring
results associated with a specific operation should provide the appro-
priate msgid to ldap_result(). Applications should avoid calling
ldap_result() with LDAP_RES_ANY as that may "steal" and return results
in the calling thread that another operation in a different thread,
using a different session handle, may require to complete.
When ldap_unbind() is called on a session handle with siblings, all the
siblings become invalid.
Siblings must be destroyed using ldap_destroy(). Session handle
resources associated with the original (LDAP *) will be freed when the
last session handle is destroyed or when ldap_unbind() is called, if no
other session handles currently exist.
If an error occurs, ldap_dup() will return NULL and errno should be set
appropriately. ldap_destroy() will directly return the LDAP code asso-
ciated to the error (or LDAP_SUCCESS in case of success); errno should
be set as well whenever appropriate.
ldap_open(3), ldap_init(3), ldap_initialize(3), ldap_init_fd(3),
This work is based on the previously proposed LDAP C API Concurrency
Extensions draft (draft-zeilenga-ldap-c-api-concurrency-00.txt) effort.
OpenLDAP Software is developed and maintained by The OpenLDAP Project
<http://www.openldap.org/>. OpenLDAP Software is derived from the Uni-
versity of Michigan LDAP 3.3 Release.
OpenLDAP 2017/06/01 LDAP_OPEN(3)
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