Manpages - ldap_dup.3

ldap_dup, ldap_destroy, - Duplicate and destroy LDAP session handles

OpenLDAP LDAP (libldap, -lldap)

  #include <ldap.h>
  LDAP *ldap_dup(
  LDAP *old );
  int ldap_destroy(
  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 concurrent requests on the same connection/session without fear of contamination. 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 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 creation functions including ldap_open*(3), *ldap_init*(3), *ldap_initialize*(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 performing 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 accessible to all the sibling session handles. Applications desiring results associated with a specific operation should provide the appropriate 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 associated 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), *errno*(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 University of Michigan LDAP 3.3 Release.