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evthread(3)                Library Functions Manual                evthread(3)



NAME
       evthread - Functions for multi-threaded applications using Libevent.


SYNOPSIS
       #include <event2/thread.h>
       #include <event2/visibility.h>
       #include <event2/event-config.h>


   Data Structures
       struct evthread_condition_callbacks
           This structure describes the interface a threading library uses for
           condition variables.
       struct evthread_lock_callbacks
           This structure describes the interface a threading library uses for
           locking.

   Macros
       #define EVTHREAD_CONDITION_API_VERSION   1
       #define EVTHREAD_LOCK_API_VERSION   1
       #define EVTHREAD_USE_PTHREADS_IMPLEMENTED   1
           Defined if Libevent was built with support for
           evthread_use_pthreads()
       #define EVTHREAD_USE_WINDOWS_THREADS_IMPLEMENTED   1
           Defined if Libevent was built with support for
           evthread_use_windows_threads()

       Flags passed to lock functions

           #define EVTHREAD_WRITE   0x04
               A flag passed to a locking callback when the lock was allocated
               as a read-write lock, and we want to acquire or release the
               lock for writing.
           #define EVTHREAD_READ   0x08
               A flag passed to a locking callback when the lock was allocated
               as a read-write lock, and we want to acquire or release the
               lock for reading.
           #define EVTHREAD_TRY   0x10
               A flag passed to a locking callback when we don't want to block
               waiting for the lock; if we can't get the lock immediately, we
               will instead return nonzero from the locking callback.

       Types of locks

           #define EVTHREAD_LOCKTYPE_RECURSIVE   1
               A recursive lock is one that can be acquired multiple times at
               once by the same thread.
           #define EVTHREAD_LOCKTYPE_READWRITE   2

   Functions
       EVENT2_EXPORT_SYMBOL void evthread_enable_lock_debugging (void)
           Enable debugging wrappers around the current lock callbacks.
       EVENT2_EXPORT_SYMBOL void evthread_enable_lock_debuging (void)
       EVENT2_EXPORT_SYMBOL int evthread_make_base_notifiable (struct
           event_base *base)
           Make sure it's safe to tell an event base to wake up from another
           thread or a signal handler.
       EVENT2_EXPORT_SYMBOL int evthread_set_condition_callbacks (const struct
           evthread_condition_callbacks *)
           Sets a group of functions that Libevent should use for condition
           variables.
       EVENT2_EXPORT_SYMBOL void evthread_set_id_callback (unsigned
           long(*id_fn)(void))
           Sets the function for determining the thread id.
       EVENT2_EXPORT_SYMBOL int evthread_set_lock_callbacks (const struct
           evthread_lock_callbacks *)
           Sets a group of functions that Libevent should use for locking.
       EVENT2_EXPORT_SYMBOL int evthread_use_pthreads (void)
           Sets up Libevent for use with Pthreads locking and thread ID
           functions.
       EVENT2_EXPORT_SYMBOL int evthread_use_windows_threads (void)
           Sets up Libevent for use with Windows builtin locking and thread ID
           functions.

Detailed Description
       Functions for multi-threaded applications using Libevent.

       When using a multi-threaded application in which multiple threads add
       and delete events from a single event base, Libevent needs to lock its
       data structures.

       Like the memory-management function hooks, all of the threading
       functions must be set up before an event_base is created if you want
       the base to use them.

       Most programs will either be using Windows threads or Posix threads.
       You can configure Libevent to use one of these
       event_use_windows_threads() or event_use_pthreads() respectively. If
       you're using another threading library, you'll need to configure
       threading functions manually using evthread_set_lock_callbacks() and
       evthread_set_condition_callbacks().

Macro Definition Documentation
   #define EVTHREAD_LOCKTYPE_RECURSIVE   1
       A recursive lock is one that can be acquired multiple times at once by
       the same thread. No other process can allocate the lock until the
       thread that has been holding it has unlocked it as many times as it
       locked it.

   #define EVTHREAD_READ   0x08
       A flag passed to a locking callback when the lock was allocated as a
       read-write lock, and we want to acquire or release the lock for
       reading.

   #define EVTHREAD_TRY   0x10
       A flag passed to a locking callback when we don't want to block waiting
       for the lock; if we can't get the lock immediately, we will instead
       return nonzero from the locking callback.

   #define EVTHREAD_WRITE   0x04
       A flag passed to a locking callback when the lock was allocated as a
       read-write lock, and we want to acquire or release the lock for
       writing.

Function Documentation
   EVENT2_EXPORT_SYMBOL void evthread_enable_lock_debugging (void)
       Enable debugging wrappers around the current lock callbacks. If
       Libevent makes one of several common locking errors, exit with an
       assertion failure.

       If you're going to call this function, you must do so before any locks
       are allocated.

   EVENT2_EXPORT_SYMBOL int evthread_make_base_notifiable (struct event_base *
       base)
       Make sure it's safe to tell an event base to wake up from another
       thread or a signal handler. You shouldn't need to call this by hand;
       configuring the base with thread support should be necessary and
       sufficient.

       Returns:
           0 on success, -1 on failure.

   EVENT2_EXPORT_SYMBOL int evthread_set_condition_callbacks (const struct
       evthread_condition_callbacks *)
       Sets a group of functions that Libevent should use for condition
       variables. For full information on the required callback API, see the
       documentation for the individual members of
       evthread_condition_callbacks.

       Note that if you're using Windows or the Pthreads threading library,
       you probably shouldn't call this function; instead, use
       evthread_use_windows_threads() or evthread_use_pthreads() if you can.

   EVENT2_EXPORT_SYMBOL void evthread_set_id_callback (unsigned long(*)(void)
       id_fn)
       Sets the function for determining the thread id.

       Parameters:
           base the event base for which to set the id function
           id_fn the identify function Libevent should invoke to determine the
           identity of a thread.

   EVENT2_EXPORT_SYMBOL int evthread_set_lock_callbacks (const struct
       evthread_lock_callbacks *)
       Sets a group of functions that Libevent should use for locking. For
       full information on the required callback API, see the documentation
       for the individual members of evthread_lock_callbacks.

       Note that if you're using Windows or the Pthreads threading library,
       you probably shouldn't call this function; instead, use
       evthread_use_windows_threads() or evthread_use_posix_threads() if you
       can.

   EVENT2_EXPORT_SYMBOL int evthread_use_pthreads (void)
       Sets up Libevent for use with Pthreads locking and thread ID functions.
       Unavailable if Libevent is not build for use with pthreads. Requires
       libraries to link against Libevent_pthreads as well as Libevent.

       Returns:
           0 on success, -1 on failure.

   EVENT2_EXPORT_SYMBOL int evthread_use_windows_threads (void)
       Sets up Libevent for use with Windows builtin locking and thread ID
       functions. Unavailable if Libevent is not built for Windows.

       Returns:
           0 on success, -1 on failure.

Author
       Generated automatically by Doxygen for libevent from the source code.



libevent                        Tue Jan 31 2017                    evthread(3)