1 /*
2 * Copyright (c) 2008-2012 Niels Provos and Nick Mathewson
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 * derived from this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26 #ifndef _EVENT2_THREAD_H_
27 #define _EVENT2_THREAD_H_
28
29 /** @file event2/thread.h
30
31 Functions for multi-threaded applications using Libevent.
32
33 When using a multi-threaded application in which multiple threads
34 add and delete events from a single event base, Libevent needs to
35 lock its data structures.
36
37 Like the memory-management function hooks, all of the threading functions
38 _must_ be set up before an event_base is created if you want the base to
39 use them.
40
41 Most programs will either be using Windows threads or Posix threads. You
42 can configure Libevent to use one of these event_use_windows_threads() or
43 event_use_pthreads() respectively. If you're using another threading
44 library, you'll need to configure threading functions manually using
45 evthread_set_lock_callbacks() and evthread_set_condition_callbacks().
46
47 */
48
49 #ifdef __cplusplus
50 extern "C" {
51 #endif
52
53 #include <event2/event-config.h>
54
55 /**** OMPI CHANGE ****/
56 #include "opal_rename.h"
57 /**** END OMPI CHANGE ****/
58 /**
59 @name Flags passed to lock functions
60
61 @{
62 */
63 /** A flag passed to a locking callback when the lock was allocated as a
64 * read-write lock, and we want to acquire or release the lock for writing. */
65 #define EVTHREAD_WRITE 0x04
66 /** A flag passed to a locking callback when the lock was allocated as a
67 * read-write lock, and we want to acquire or release the lock for reading. */
68 #define EVTHREAD_READ 0x08
69 /** A flag passed to a locking callback when we don't want to block waiting
70 * for the lock; if we can't get the lock immediately, we will instead
71 * return nonzero from the locking callback. */
72 #define EVTHREAD_TRY 0x10
73 /**@}*/
74
75 #if !defined(_EVENT_DISABLE_THREAD_SUPPORT) || defined(_EVENT_IN_DOXYGEN)
76
77 #define EVTHREAD_LOCK_API_VERSION 1
78
79 /**
80 @name Types of locks
81
82 @{*/
83 /** A recursive lock is one that can be acquired multiple times at once by the
84 * same thread. No other process can allocate the lock until the thread that
85 * has been holding it has unlocked it as many times as it locked it. */
86 #define EVTHREAD_LOCKTYPE_RECURSIVE 1
87 /* A read-write lock is one that allows multiple simultaneous readers, but
88 * where any one writer excludes all other writers and readers. */
89 #define EVTHREAD_LOCKTYPE_READWRITE 2
90 /**@}*/
91
92 /** This structure describes the interface a threading library uses for
93 * locking. It's used to tell evthread_set_lock_callbacks() how to use
94 * locking on this platform.
95 */
96 struct evthread_lock_callbacks {
97 /** The current version of the locking API. Set this to
98 * EVTHREAD_LOCK_API_VERSION */
99 int lock_api_version;
100 /** Which kinds of locks does this version of the locking API
101 * support? A bitfield of EVTHREAD_LOCKTYPE_RECURSIVE and
102 * EVTHREAD_LOCKTYPE_READWRITE.
103 *
104 * (Note that RECURSIVE locks are currently mandatory, and
105 * READWRITE locks are not currently used.)
106 **/
107 unsigned supported_locktypes;
108 /** Function to allocate and initialize new lock of type 'locktype'.
109 * Returns NULL on failure. */
110 void *(*alloc)(unsigned locktype);
111 /** Funtion to release all storage held in 'lock', which was created
112 * with type 'locktype'. */
113 void (*free)(void *lock, unsigned locktype);
114 /** Acquire an already-allocated lock at 'lock' with mode 'mode'.
115 * Returns 0 on success, and nonzero on failure. */
116 int (*lock)(unsigned mode, void *lock);
117 /** Release a lock at 'lock' using mode 'mode'. Returns 0 on success,
118 * and nonzero on failure. */
119 int (*unlock)(unsigned mode, void *lock);
120 };
121
122 /** Sets a group of functions that Libevent should use for locking.
123 * For full information on the required callback API, see the
124 * documentation for the individual members of evthread_lock_callbacks.
125 *
126 * Note that if you're using Windows or the Pthreads threading library, you
127 * probably shouldn't call this function; instead, use
128 * evthread_use_windows_threads() or evthread_use_posix_threads() if you can.
129 */
130 int evthread_set_lock_callbacks(const struct evthread_lock_callbacks *);
131
132 #define EVTHREAD_CONDITION_API_VERSION 1
133
134 struct timeval;
135
136 /** This structure describes the interface a threading library uses for
137 * condition variables. It's used to tell evthread_set_condition_callbacks
138 * how to use locking on this platform.
139 */
140 struct evthread_condition_callbacks {
141 /** The current version of the conditions API. Set this to
142 * EVTHREAD_CONDITION_API_VERSION */
143 int condition_api_version;
144 /** Function to allocate and initialize a new condition variable.
145 * Returns the condition variable on success, and NULL on failure.
146 * The 'condtype' argument will be 0 with this API version.
147 */
148 void *(*alloc_condition)(unsigned condtype);
149 /** Function to free a condition variable. */
150 void (*free_condition)(void *cond);
151 /** Function to signal a condition variable. If 'broadcast' is 1, all
152 * threads waiting on 'cond' should be woken; otherwise, only on one
153 * thread is worken. Should return 0 on success, -1 on failure.
154 * This function will only be called while holding the associated
155 * lock for the condition.
156 */
157 int (*signal_condition)(void *cond, int broadcast);
158 /** Function to wait for a condition variable. The lock 'lock'
159 * will be held when this function is called; should be released
160 * while waiting for the condition to be come signalled, and
161 * should be held again when this function returns.
162 * If timeout is provided, it is interval of seconds to wait for
163 * the event to become signalled; if it is NULL, the function
164 * should wait indefinitely.
165 *
166 * The function should return -1 on error; 0 if the condition
167 * was signalled, or 1 on a timeout. */
168 int (*wait_condition)(void *cond, void *lock,
169 const struct timeval *timeout);
170 };
171
172 /** Sets a group of functions that Libevent should use for condition variables.
173 * For full information on the required callback API, see the
174 * documentation for the individual members of evthread_condition_callbacks.
175 *
176 * Note that if you're using Windows or the Pthreads threading library, you
177 * probably shouldn't call this function; instead, use
178 * evthread_use_windows_threads() or evthread_use_pthreads() if you can.
179 */
180 int evthread_set_condition_callbacks(
181 const struct evthread_condition_callbacks *);
182
183 /**
184 Sets the function for determining the thread id.
185
186 @param base the event base for which to set the id function
187 @param id_fn the identify function Libevent should invoke to
188 determine the identity of a thread.
189 */
190 void evthread_set_id_callback(
191 unsigned long (*id_fn)(void));
192
193 #if (defined(WIN32) && !defined(_EVENT_DISABLE_THREAD_SUPPORT)) || defined(_EVENT_IN_DOXYGEN)
194 /** Sets up Libevent for use with Windows builtin locking and thread ID
195 functions. Unavailable if Libevent is not built for Windows.
196
197 @return 0 on success, -1 on failure. */
198 int evthread_use_windows_threads(void);
199 /**
200 Defined if Libevent was built with support for evthread_use_windows_threads()
201 */
202 #define EVTHREAD_USE_WINDOWS_THREADS_IMPLEMENTED 1
203 #endif
204
205 #if defined(_EVENT_HAVE_PTHREADS) || defined(_EVENT_IN_DOXYGEN)
206 /** Sets up Libevent for use with Pthreads locking and thread ID functions.
207 Unavailable if Libevent is not build for use with pthreads. Requires
208 libraries to link against Libevent_pthreads as well as Libevent.
209
210 @return 0 on success, -1 on failure. */
211 int evthread_use_pthreads(void);
212 /** Defined if Libevent was built with support for evthread_use_pthreads() */
213 #define EVTHREAD_USE_PTHREADS_IMPLEMENTED 1
214
215 #endif
216
217 /** Enable debugging wrappers around the current lock callbacks. If Libevent
218 * makes one of several common locking errors, exit with an assertion failure.
219 *
220 * If you're going to call this function, you must do so before any locks are
221 * allocated.
222 **/
223 void evthread_enable_lock_debuging(void);
224
225 #endif /* _EVENT_DISABLE_THREAD_SUPPORT */
226
227 struct event_base;
228 /** Make sure it's safe to tell an event base to wake up from another thread
229 or a signal handler.
230
231 @return 0 on success, -1 on failure.
232 */
233 int evthread_make_base_notifiable(struct event_base *base);
234
235 #ifdef __cplusplus
236 }
237 #endif
238
239 #endif /* _EVENT2_THREAD_H_ */