1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* 3 * The contents of this file are subject to the Mozilla Public 4 * License Version 1.1 (the "License"); you may not use this file 5 * except in compliance with the License. You may obtain a copy of 6 * the License at http://www.mozilla.org/MPL/ 7 * 8 * Software distributed under the License is distributed on an "AS 9 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or 10 * implied. See the License for the specific language governing 11 * rights and limitations under the License. 12 * 13 * The Original Code is the Netscape Portable Runtime (NSPR). 14 * 15 * The Initial Developer of the Original Code is Netscape 16 * Communications Corporation. Portions created by Netscape are 17 * Copyright (C) 1998-2000 Netscape Communications Corporation. All 18 * Rights Reserved. 19 * 20 * Contributor(s): 21 * 22 * Alternatively, the contents of this file may be used under the 23 * terms of the GNU General Public License Version 2 or later (the 24 * "GPL"), in which case the provisions of the GPL are applicable 25 * instead of those above. If you wish to allow use of your 26 * version of this file only under the terms of the GPL and not to 27 * allow others to use your version of this file under the MPL, 28 * indicate your decision by deleting the provisions above and 29 * replace them with the notice and other provisions required by 30 * the GPL. If you do not delete the provisions above, a recipient 31 * may use your version of this file under either the MPL or the 32 * GPL. 33 */ 34 35 #ifndef prthread_h___ 36 #define prthread_h___ 37 38 /* 39 ** API for NSPR threads. On some architectures (MAC and WIN16 40 ** notably) pre-emptibility is not guaranteed. Hard priority scheduling 41 ** is not guaranteed, so programming using priority based synchronization 42 ** is a no-no. 43 ** 44 ** NSPR threads are scheduled based loosly on their client set priority. 45 ** In general, a thread of a higher priority has a statistically better 46 ** chance of running relative to threads of lower priority. However, 47 ** NSPR uses multiple strategies to provide execution vehicles for thread 48 ** abstraction of various host platforms. As it turns out, there is little 49 ** NSPR can do to affect the scheduling attributes of "GLOBAL" threads. 50 ** However, a semblance of GLOBAL threads is used to implement "LOCAL" 51 ** threads. An arbitrary number of such LOCAL threads can be assigned to 52 ** a single GLOBAL thread. 53 ** 54 ** For scheduling, NSPR will attempt to run the highest priority LOCAL 55 ** thread associated with a given GLOBAL thread. It is further assumed 56 ** that the host OS will apply some form of "fair" scheduling on the 57 ** GLOBAL threads. 58 ** 59 ** Threads have a "system flag" which when set indicates the thread 60 ** doesn't count for determining when the process should exit (the 61 ** process exits when the last user thread exits). 62 ** 63 ** Threads also have a "scope flag" which controls whether the threads 64 ** are scheduled in the local scope or scheduled by the OS globally. This 65 ** indicates whether a thread is permanently bound to a native OS thread. 66 ** An unbound thread competes for scheduling resources in the same process. 67 ** 68 ** Another flag is "state flag" which control whether the thread is joinable. 69 ** It allows other threads to wait for the created thread to reach completion. 70 ** 71 ** Threads can have "per-thread-data" attached to them. Each thread has a 72 ** per-thread error number and error string which are updated when NSPR 73 ** operations fail. 74 */ 75 #include "prtypes.h" 76 #include "prinrval.h" 77 78 PR_BEGIN_EXTERN_C 79 80 typedef struct PRThread PRThread; 81 typedef struct PRThreadStack PRThreadStack; 82 83 typedef enum PRThreadType { 84 PR_USER_THREAD, 85 PR_SYSTEM_THREAD 86 } PRThreadType; 87 88 typedef enum PRThreadScope { 89 PR_LOCAL_THREAD, 90 PR_GLOBAL_THREAD, 91 PR_GLOBAL_BOUND_THREAD 92 } PRThreadScope; 93 94 typedef enum PRThreadState { 95 PR_JOINABLE_THREAD, 96 PR_UNJOINABLE_THREAD 97 } PRThreadState; 98 99 typedef enum PRThreadPriority 100 { 101 PR_PRIORITY_FIRST = 0, /* just a placeholder */ 102 PR_PRIORITY_LOW = 0, /* the lowest possible priority */ 103 PR_PRIORITY_NORMAL = 1, /* most common expected priority */ 104 PR_PRIORITY_HIGH = 2, /* slightly more aggressive scheduling */ 105 PR_PRIORITY_URGENT = 3, /* it does little good to have more than one */ 106 PR_PRIORITY_LAST = 3 /* this is just a placeholder */ 107 } PRThreadPriority; 108 109 /* 110 ** Create a new thread: 111 ** "type" is the type of thread to create 112 ** "start(arg)" will be invoked as the threads "main" 113 ** "priority" will be created thread's priority 114 ** "scope" will specify whether the thread is local or global 115 ** "state" will specify whether the thread is joinable or not 116 ** "stackSize" the size of the stack, in bytes. The value can be zero 117 ** and then a machine specific stack size will be chosen. 118 ** 119 ** This can return NULL if some kind of error occurs, such as if memory is 120 ** tight. 121 ** 122 ** If you want the thread to start up waiting for the creator to do 123 ** something, enter a lock before creating the thread and then have the 124 ** threads start routine enter and exit the same lock. When you are ready 125 ** for the thread to run, exit the lock. 126 ** 127 ** If you want to detect the completion of the created thread, the thread 128 ** should be created joinable. Then, use PR_JoinThread to synchrnoize the 129 ** termination of another thread. 130 ** 131 ** When the start function returns the thread exits. If it is the last 132 ** PR_USER_THREAD to exit then the process exits. 133 */ 134 NSPR_API(PRThread*) PR_CreateThread(PRThreadType type, 135 void (PR_CALLBACK *start)(void *arg), 136 void *arg, 137 PRThreadPriority priority, 138 PRThreadScope scope, 139 PRThreadState state, 140 PRUint32 stackSize); 141 142 /* 143 ** Wait for thread termination: 144 ** "thread" is the target thread 145 ** 146 ** This can return PR_FAILURE if no joinable thread could be found 147 ** corresponding to the specified target thread. 148 ** 149 ** The calling thread is blocked until the target thread completes. 150 ** Several threads cannot wait for the same thread to complete; one thread 151 ** will operate successfully and others will terminate with an error PR_FAILURE. 152 ** The calling thread will not be blocked if the target thread has already 153 ** terminated. 154 */ 155 NSPR_API(PRStatus) PR_JoinThread(PRThread *thread); 156 157 /* 158 ** Return the current thread object for the currently running code. 159 ** Never returns NULL. 160 */ 161 NSPR_API(PRThread*) PR_GetCurrentThread(void); 162 #ifndef NO_NSPR_10_SUPPORT 163 #define PR_CurrentThread() PR_GetCurrentThread() /* for nspr1.0 compat. */ 164 #endif /* NO_NSPR_10_SUPPORT */ 165 166 /* 167 ** Get the priority of "thread". 168 */ 169 NSPR_API(PRThreadPriority) PR_GetThreadPriority(const PRThread *thread); 170 171 /* 172 ** Change the priority of the "thread" to "priority". 173 */ 174 NSPR_API(void) PR_SetThreadPriority(PRThread *thread, PRThreadPriority priority); 175 176 /* 177 ** This routine returns a new index for per-thread-private data table. 178 ** The index is visible to all threads within a process. This index can 179 ** be used with the PR_SetThreadPrivate() and PR_GetThreadPrivate() routines 180 ** to save and retrieve data associated with the index for a thread. 181 ** 182 ** Each index is associationed with a destructor function ('dtor'). The function 183 ** may be specified as NULL when the index is created. If it is not NULL, the 184 ** function will be called when: 185 ** - the thread exits and the private data for the associated index 186 ** is not NULL, 187 ** - new thread private data is set and the current private data is 188 ** not NULL. 189 ** 190 ** The index independently maintains specific values for each binding thread. 191 ** A thread can only get access to its own thread-specific-data. 192 ** 193 ** Upon a new index return the value associated with the index for all threads 194 ** is NULL, and upon thread creation the value associated with all indices for 195 ** that thread is NULL. 196 ** 197 ** Returns PR_FAILURE if the total number of indices will exceed the maximun 198 ** allowed. 199 */ 200 typedef void (PR_CALLBACK *PRThreadPrivateDTOR)(void *priv); 201 202 NSPR_API(PRStatus) PR_NewThreadPrivateIndex( 203 PRUintn *newIndex, PRThreadPrivateDTOR destructor); 204 205 /* 206 ** Define some per-thread-private data. 207 ** "tpdIndex" is an index into the per-thread private data table 208 ** "priv" is the per-thread-private data 209 ** 210 ** If the per-thread private data table has a previously registered 211 ** destructor function and a non-NULL per-thread-private data value, 212 ** the destructor function is invoked. 213 ** 214 ** This can return PR_FAILURE if the index is invalid. 215 */ 216 NSPR_API(PRStatus) PR_SetThreadPrivate(PRUintn tpdIndex, void *priv); 217 218 /* 219 ** Recover the per-thread-private data for the current thread. "tpdIndex" is 220 ** the index into the per-thread private data table. 221 ** 222 ** The returned value may be NULL which is indistinguishable from an error 223 ** condition. 224 ** 225 ** A thread can only get access to its own thread-specific-data. 226 */ 227 NSPR_API(void*) PR_GetThreadPrivate(PRUintn tpdIndex); 228 229 /* 230 ** This routine sets the interrupt request for a target thread. The interrupt 231 ** request remains in the thread's state until it is delivered exactly once 232 ** or explicitly canceled. 233 ** 234 ** A thread that has been interrupted will fail all NSPR blocking operations 235 ** that return a PRStatus (I/O, waiting on a condition, etc). 236 ** 237 ** PR_Interrupt may itself fail if the target thread is invalid. 238 */ 239 NSPR_API(PRStatus) PR_Interrupt(PRThread *thread); 240 241 /* 242 ** Clear the interrupt request for the calling thread. If no such request 243 ** is pending, this operation is a noop. 244 */ 245 NSPR_API(void) PR_ClearInterrupt(void); 246 247 /* 248 ** Block the interrupt for the calling thread. 249 */ 250 NSPR_API(void) PR_BlockInterrupt(void); 251 252 /* 253 ** Unblock the interrupt for the calling thread. 254 */ 255 NSPR_API(void) PR_UnblockInterrupt(void); 256 257 /* 258 ** Make the current thread sleep until "ticks" time amount of time 259 ** has expired. If "ticks" is PR_INTERVAL_NO_WAIT then the call is 260 ** equivalent to calling PR_Yield. Calling PR_Sleep with an argument 261 ** equivalent to PR_INTERVAL_NO_TIMEOUT is an error and will result 262 ** in a PR_FAILURE error return. 263 */ 264 NSPR_API(PRStatus) PR_Sleep(PRIntervalTime ticks); 265 266 /* 267 ** Get the scoping of this thread. 268 */ 269 NSPR_API(PRThreadScope) PR_GetThreadScope(const PRThread *thread); 270 271 /* 272 ** Get the type of this thread. 273 */ 274 NSPR_API(PRThreadType) PR_GetThreadType(const PRThread *thread); 275 276 /* 277 ** Get the join state of this thread. 278 */ 279 NSPR_API(PRThreadState) PR_GetThreadState(const PRThread *thread); 280 281 PR_END_EXTERN_C 282 283 #endif /* prthread_h___ */ 284