1 /* $NetBSD: thread.h,v 1.1.1.2 2015/01/29 06:38:27 spz Exp $ */ 2 /* $NetBSD: thread.h,v 1.1.1.2 2015/01/29 06:38:27 spz Exp $ */ 3 /* 4 * Copyright (c) 2008-2012 Niels Provos and Nick Mathewson 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 #ifndef _EVENT2_THREAD_H_ 29 #define _EVENT2_THREAD_H_ 30 31 /** @file event2/thread.h 32 33 Functions for multi-threaded applications using Libevent. 34 35 When using a multi-threaded application in which multiple threads 36 add and delete events from a single event base, Libevent needs to 37 lock its data structures. 38 39 Like the memory-management function hooks, all of the threading functions 40 _must_ be set up before an event_base is created if you want the base to 41 use them. 42 43 Most programs will either be using Windows threads or Posix threads. You 44 can configure Libevent to use one of these event_use_windows_threads() or 45 event_use_pthreads() respectively. If you're using another threading 46 library, you'll need to configure threading functions manually using 47 evthread_set_lock_callbacks() and evthread_set_condition_callbacks(). 48 49 */ 50 51 #ifdef __cplusplus 52 extern "C" { 53 #endif 54 55 #include <event2/event-config.h> 56 57 /** 58 @name Flags passed to lock functions 59 60 @{ 61 */ 62 /** A flag passed to a locking callback when the lock was allocated as a 63 * read-write lock, and we want to acquire or release the lock for writing. */ 64 #define EVTHREAD_WRITE 0x04 65 /** A flag passed to a locking callback when the lock was allocated as a 66 * read-write lock, and we want to acquire or release the lock for reading. */ 67 #define EVTHREAD_READ 0x08 68 /** A flag passed to a locking callback when we don't want to block waiting 69 * for the lock; if we can't get the lock immediately, we will instead 70 * return nonzero from the locking callback. */ 71 #define EVTHREAD_TRY 0x10 72 /**@}*/ 73 74 #if !defined(_EVENT_DISABLE_THREAD_SUPPORT) || defined(_EVENT_IN_DOXYGEN) 75 76 #define EVTHREAD_LOCK_API_VERSION 1 77 78 /** 79 @name Types of locks 80 81 @{*/ 82 /** A recursive lock is one that can be acquired multiple times at once by the 83 * same thread. No other process can allocate the lock until the thread that 84 * has been holding it has unlocked it as many times as it locked it. */ 85 #define EVTHREAD_LOCKTYPE_RECURSIVE 1 86 /* A read-write lock is one that allows multiple simultaneous readers, but 87 * where any one writer excludes all other writers and readers. */ 88 #define EVTHREAD_LOCKTYPE_READWRITE 2 89 /**@}*/ 90 91 /** This structure describes the interface a threading library uses for 92 * locking. It's used to tell evthread_set_lock_callbacks() how to use 93 * locking on this platform. 94 */ 95 struct evthread_lock_callbacks { 96 /** The current version of the locking API. Set this to 97 * EVTHREAD_LOCK_API_VERSION */ 98 int lock_api_version; 99 /** Which kinds of locks does this version of the locking API 100 * support? A bitfield of EVTHREAD_LOCKTYPE_RECURSIVE and 101 * EVTHREAD_LOCKTYPE_READWRITE. 102 * 103 * (Note that RECURSIVE locks are currently mandatory, and 104 * READWRITE locks are not currently used.) 105 **/ 106 unsigned supported_locktypes; 107 /** Function to allocate and initialize new lock of type 'locktype'. 108 * Returns NULL on failure. */ 109 void *(*alloc)(unsigned locktype); 110 /** Funtion to release all storage held in 'lock', which was created 111 * with type 'locktype'. */ 112 void (*free)(void *lock, unsigned locktype); 113 /** Acquire an already-allocated lock at 'lock' with mode 'mode'. 114 * Returns 0 on success, and nonzero on failure. */ 115 int (*lock)(unsigned mode, void *lock); 116 /** Release a lock at 'lock' using mode 'mode'. Returns 0 on success, 117 * and nonzero on failure. */ 118 int (*unlock)(unsigned mode, void *lock); 119 }; 120 121 /** Sets a group of functions that Libevent should use for locking. 122 * For full information on the required callback API, see the 123 * documentation for the individual members of evthread_lock_callbacks. 124 * 125 * Note that if you're using Windows or the Pthreads threading library, you 126 * probably shouldn't call this function; instead, use 127 * evthread_use_windows_threads() or evthread_use_posix_threads() if you can. 128 */ 129 int evthread_set_lock_callbacks(const struct evthread_lock_callbacks *); 130 131 #define EVTHREAD_CONDITION_API_VERSION 1 132 133 struct timeval; 134 135 /** This structure describes the interface a threading library uses for 136 * condition variables. It's used to tell evthread_set_condition_callbacks 137 * how to use locking on this platform. 138 */ 139 struct evthread_condition_callbacks { 140 /** The current version of the conditions API. Set this to 141 * EVTHREAD_CONDITION_API_VERSION */ 142 int condition_api_version; 143 /** Function to allocate and initialize a new condition variable. 144 * Returns the condition variable on success, and NULL on failure. 145 * The 'condtype' argument will be 0 with this API version. 146 */ 147 void *(*alloc_condition)(unsigned condtype); 148 /** Function to free a condition variable. */ 149 void (*free_condition)(void *cond); 150 /** Function to signal a condition variable. If 'broadcast' is 1, all 151 * threads waiting on 'cond' should be woken; otherwise, only on one 152 * thread is worken. Should return 0 on success, -1 on failure. 153 * This function will only be called while holding the associated 154 * lock for the condition. 155 */ 156 int (*signal_condition)(void *cond, int broadcast); 157 /** Function to wait for a condition variable. The lock 'lock' 158 * will be held when this function is called; should be released 159 * while waiting for the condition to be come signalled, and 160 * should be held again when this function returns. 161 * If timeout is provided, it is interval of seconds to wait for 162 * the event to become signalled; if it is NULL, the function 163 * should wait indefinitely. 164 * 165 * The function should return -1 on error; 0 if the condition 166 * was signalled, or 1 on a timeout. */ 167 int (*wait_condition)(void *cond, void *lock, 168 const struct timeval *timeout); 169 }; 170 171 /** Sets a group of functions that Libevent should use for condition variables. 172 * For full information on the required callback API, see the 173 * documentation for the individual members of evthread_condition_callbacks. 174 * 175 * Note that if you're using Windows or the Pthreads threading library, you 176 * probably shouldn't call this function; instead, use 177 * evthread_use_windows_threads() or evthread_use_pthreads() if you can. 178 */ 179 int evthread_set_condition_callbacks( 180 const struct evthread_condition_callbacks *); 181 182 /** 183 Sets the function for determining the thread id. 184 185 @param base the event base for which to set the id function 186 @param id_fn the identify function Libevent should invoke to 187 determine the identity of a thread. 188 */ 189 void evthread_set_id_callback( 190 unsigned long (*id_fn)(void)); 191 192 #if (defined(WIN32) && !defined(_EVENT_DISABLE_THREAD_SUPPORT)) || defined(_EVENT_IN_DOXYGEN) 193 /** Sets up Libevent for use with Windows builtin locking and thread ID 194 functions. Unavailable if Libevent is not built for Windows. 195 196 @return 0 on success, -1 on failure. */ 197 int evthread_use_windows_threads(void); 198 /** 199 Defined if Libevent was built with support for evthread_use_windows_threads() 200 */ 201 #define EVTHREAD_USE_WINDOWS_THREADS_IMPLEMENTED 1 202 #endif 203 204 #if defined(_EVENT_HAVE_PTHREADS) || defined(_EVENT_IN_DOXYGEN) 205 /** Sets up Libevent for use with Pthreads locking and thread ID functions. 206 Unavailable if Libevent is not build for use with pthreads. Requires 207 libraries to link against Libevent_pthreads as well as Libevent. 208 209 @return 0 on success, -1 on failure. */ 210 int evthread_use_pthreads(void); 211 /** Defined if Libevent was built with support for evthread_use_pthreads() */ 212 #define EVTHREAD_USE_PTHREADS_IMPLEMENTED 1 213 214 #endif 215 216 /** Enable debugging wrappers around the current lock callbacks. If Libevent 217 * makes one of several common locking errors, exit with an assertion failure. 218 * 219 * If you're going to call this function, you must do so before any locks are 220 * allocated. 221 **/ 222 void evthread_enable_lock_debuging(void); 223 224 #endif /* _EVENT_DISABLE_THREAD_SUPPORT */ 225 226 struct event_base; 227 /** Make sure it's safe to tell an event base to wake up from another thread 228 or a signal handler. 229 230 @return 0 on success, -1 on failure. 231 */ 232 int evthread_make_base_notifiable(struct event_base *base); 233 234 #ifdef __cplusplus 235 } 236 #endif 237 238 #endif /* _EVENT2_THREAD_H_ */ 239