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Netscape Directory SDK 3.0 for C Programmer’s Guide
Chapter 17 Data Types and Structures

ldap_thread_fns

The ldap_thread_fns structure contains a set of pointers to functions that you want to use when write a multithreaded client.

The ldap_thread_fns structure is defined as follows:

struct ldap_thread_fns {

   LDAP_TF_MUTEX_ALLOC_CALLBACK *ltf_mutex_alloc;

   LDAP_TF_MUTEX_FREE_CALLBACK *ltf_mutex_free;

   LDAP_TF_MUTEX_LOCK_CALLBACK *ltf_mutex_lock;

   LDAP_TF_MUTEX_UNLOCK_CALLBACK *ltf_mutex_unlock;

   LDAP_TF_GET_ERRNO_CALLBACK *ltf_get_errno;

   LDAP_TF_SET_ERRNO_CALLBACK *ltf_set_errno;

   LDAP_TF_GET_LDERRNO_CALLBACK *ltf_get_lderrno;

   LDAP_TF_SET_LDERRNO_CALLBACK *ltf_set_lderrno;

   void *ltf_lderrno_arg;

};

The fields in this structure are described below:

For an example of setting up the ldap_thread_fns structure, see Chapter 16, "Writing Multithreaded Clients."

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Last Updated: 10/01/98 17:05:28

ltf_mutex_alloc	Function pointer for allocating a mutex. This function is called by the client when needed if the function pointer is not NULL. The function must have the prototype specified by `LDAP_TF_MUTEX_ALLOC_CALLBACK`.
ltf_mutex_free	Function pointer for freeing a mutex. This function is called by the client when needed if the function pointer is not NULL. The function must have the prototype specified by `LDAP_TF_MUTEX_FREE_CALLBACK`.
ltf_mutex_lock	Function pointer for locking critical sections of code. This function is called by the client when needed if the function pointer is not NULL. The function must have the prototype specified by `LDAP_TF_MUTEX_LOCK_CALLBACK`.
ltf_mutex_unlock	Function pointer for unlocking critical sections of code. This function is called by the client when needed if the function pointer is not NULL. The function must have the prototype specified by `LDAP_TF_MUTEX_UNLOCK_CALLBACK`.
ltf_get_errno	Function pointer for getting the value of the `errno` variable. This function is called by the client when needed if the function pointer is not NULL. In a threaded environment, `errno` is typically redefined so that it has a value for each thread, rather than a global value for the entire process. This redefinition is done at compile time. Because the `libldap` library does not know what method your code and threading environment will use to get the value of `errno` for each thread, it calls this function to obtain the value of `errno`. The function must have the prototype specified by `LDAP_TF_GET_ERRNO_CALLBACK`.
ltf_set_errno	Function pointer for setting the value of the `errno` variable. This function is called by the client when needed if the function pointer is not NULL. In a threaded environment, `errno` is typically redefined so that it has a value for each thread, rather than a global value for the entire process. This redefinition is done at compile time. Because the `libldap` library does not know what method your code and threading environment will use to get the value of `errno` for each thread, it calls this function to set the value of `errno`. The function must have the prototype specified by `LDAP_TF_SET_ERRNO_CALLBACK`.
ltf_get_lderrno	Function pointer for getting error values from calls to functions in the `libldap` library. This function is called by the client as needed if the function pointer isn't NULL. If this function pointer is not set, the `libldap` library records these errors in fields in the LDAP structure. The function must have the prototype specified by `LDAP_TF_GET_LDERRNO_CALLBACK`.
ltf_set_lderrno	Function pointer for setting error values from calls to functions in the `libldap` library. This function is called by the client as needed if the function pointer isn't NULL. If this function pointer is not set, the `libldap` library records these errors in fields in the LDAP structure. The function must have the prototype specified by `LDAP_TF_SET_LDERRNO_CALLBACK`.
ltf_lderrno_arg	Additional parameter passed to the functions for getting and setting error values from calls to functions in the `libldap` library. `(ltf_get_lderrno)` and `(ltf_set_lderrno)` identify these functions.