libsecurity_asn1/lib/prthread.h

   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/
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   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
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  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___ */