gcc/objc/thr-win32.c

   1 /* GNU Objective C Runtime Thread Interface - Win32 Implementation
   2    Copyright (C) 1996 Free Software Foundation, Inc.
   3    Contributed by Galen C. Hunt (gchunt@cs.rochester.edu)
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify it under the
   8 terms of the GNU General Public License as published by the Free Software
   9 Foundation; either version 2, or (at your option) any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13 FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  14 details.
  15
  16 You should have received a copy of the GNU General Public License along with
  17 GNU CC; see the file COPYING.  If not, write to the Free Software
  18 Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 /* As a special exception, if you link this library with files compiled with
  22    GCC to produce an executable, this does not cause the resulting executable
  23    to be covered by the GNU General Public License. This exception does not
  24    however invalidate any other reasons why the executable file might be
  25    covered by the GNU General Public License.  */
  26
  27 #include <windows.h>
  28
  29 /********
  30  *  This structure represents a single mutual exclusion lock.  Lock semantics
  31  *  are detailed with the subsequent functions.  We use whatever lock is
  32  *  provided by the system.  We augment it with depth and current owner id
  33  *  fields to implement and re-entrant lock.
  34  */
  35 struct _objc_mutex
  36 {
  37   volatile _objc_thread_t       owner;          /* Id of thread that owns.  */
  38   volatile int                  depth;          /* # of acquires.           */
  39   HANDLE                        handle;         /* Win32 mutex HANDLE.      */
  40 };
  41
  42 /*****************************************************************************
  43  *  Static variables.
  44  */
  45 static DWORD    __objc_data_tls = (DWORD)-1;    /* Win32 Thread Local Index.*/
  46
  47 /********
  48  *  Initialize the threads subsystem.  Returns 0 if successful, or -1 if no
  49  *  thread support is available.
  50  */
  51 int
  52 __objc_init_thread_system(void)
  53 {
  54   DEBUG_PRINTF("__objc_init_thread_system\n");
  55
  56   if ((__objc_data_tls = TlsAlloc()) != (DWORD)-1)
  57     return 0;                                   /* Yes, return success.     */
  58
  59   return -1;                                    /* Failed.                  */
  60 }
  61
  62 int
  63 __objc_fini_thread_system(void)
  64 {
  65   if (__objc_data_tls != (DWORD)-1) {
  66     TlsFree(__objc_data_tls);
  67     return 0;
  68   }
  69   return -1;
  70 }
  71
  72 /********
  73  *  Create a new thread of execution and return its id.  Return NULL if fails.
  74  *  The new thread starts in "func" with the given argument.
  75  */
  76 _objc_thread_t
  77 objc_thread_create(void (*func)(void *arg), void *arg)
  78 {
  79   DWORD         thread_id = 0;                  /* Detached thread id.      */
  80   HANDLE        win32_handle;                   /* Win32 thread handle.     */
  81
  82   objc_mutex_lock(__objc_runtime_mutex);
  83
  84   if ((win32_handle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)func,
  85                                    arg, 0, &thread_id))) {
  86       __objc_runtime_threads_alive++;
  87   }
  88   else
  89       thread_id = 0;
  90
  91   objc_mutex_unlock(__objc_runtime_mutex);
  92
  93   return (_objc_thread_t)thread_id;
  94 }
  95
  96 /********
  97  *  Set the current thread's priority.
  98  */
  99 int
 100 objc_thread_set_priority(int priority)
 101 {
 102   int           sys_priority = 0;
 103
 104   switch (priority) {
 105   case OBJC_THREAD_INTERACTIVE_PRIORITY:
 106     sys_priority = THREAD_PRIORITY_NORMAL;
 107     break;
 108   default:
 109   case OBJC_THREAD_BACKGROUND_PRIORITY:
 110     sys_priority = THREAD_PRIORITY_BELOW_NORMAL;
 111     break;
 112   case OBJC_THREAD_LOW_PRIORITY:
 113     sys_priority = THREAD_PRIORITY_LOWEST;
 114     break;
 115   }
 116   if (SetThreadPriority(GetCurrentThread(), sys_priority))
 117     return 0;                                   /* Changed priority. End.   */
 118
 119   return -1;                                    /* Failed.                  */
 120 }
 121
 122 /********
 123  *  Return the current thread's priority.
 124  */
 125 int
 126 objc_thread_get_priority(void)
 127 {
 128   int           sys_priority;
 129
 130   sys_priority = GetThreadPriority(GetCurrentThread());
 131
 132   switch (sys_priority) {
 133   case THREAD_PRIORITY_HIGHEST:
 134   case THREAD_PRIORITY_TIME_CRITICAL:
 135   case THREAD_PRIORITY_ABOVE_NORMAL:
 136   case THREAD_PRIORITY_NORMAL:
 137     return OBJC_THREAD_INTERACTIVE_PRIORITY;
 138
 139   default:
 140   case THREAD_PRIORITY_BELOW_NORMAL:
 141     return OBJC_THREAD_BACKGROUND_PRIORITY;
 142
 143   case THREAD_PRIORITY_IDLE:
 144   case THREAD_PRIORITY_LOWEST:
 145     return OBJC_THREAD_LOW_PRIORITY;
 146   }
 147   return -1;                                    /* Couldn't get priority.   */
 148 }
 149
 150 /********
 151  *  Yield our process time to another thread.  Any BUSY waiting that is done
 152  *  by a thread should use this function to make sure that other threads can
 153  *  make progress even on a lazy uniprocessor system.
 154  */
 155 void
 156 objc_thread_yield(void)
 157 {
 158   Sleep(0);                                     /* Yield to equal thread.   */
 159 }
 160
 161 /********
 162  *  Terminate the current tread.  Doesn't return anything.  Doesn't return.
 163  *  Actually, if it failed returns -1.
 164  */
 165 int
 166 objc_thread_exit(void)
 167 {
 168   objc_mutex_lock(__objc_runtime_mutex);
 169   __objc_runtime_threads_alive--;
 170   objc_mutex_unlock(__objc_runtime_mutex);
 171
 172   ExitThread(__objc_thread_exit_status);        /* Terminate thread.        */
 173   return -1;
 174 }
 175
 176 /********
 177  *  Returns an integer value which uniquely describes a thread.  Must not be
 178  *  -1 which is reserved as a marker for "no thread".
 179  */
 180 _objc_thread_t
 181 objc_thread_id(void)
 182 {
 183   return (_objc_thread_t)GetCurrentThreadId();  /* Return thread id.        */
 184 }
 185
 186 /********
 187  *  Sets the thread's local storage pointer.  Returns 0 if successful or -1
 188  *  if failed.
 189  */
 190 int
 191 objc_thread_set_data(void *value)
 192 {
 193   if (TlsSetValue(__objc_data_tls, value))
 194     return 0;                                   /* Return thread data.      */
 195   return -1;
 196 }
 197
 198 /********
 199  *  Returns the thread's local storage pointer.  Returns NULL on failure.
 200  */
 201 void *
 202 objc_thread_get_data(void)
 203 {
 204   return TlsGetValue(__objc_data_tls);          /* Return thread data.      */
 205 }
 206
 207 /********
 208  *  Allocate a mutex.  Return the mutex pointer if successful or NULL if
 209  *  the allocation fails for any reason.
 210  */
 211 _objc_mutex_t
 212 objc_mutex_allocate(void)
 213 {
 214     _objc_mutex_t mutex;
 215     int         err = 0;
 216
 217     if (!(mutex = (_objc_mutex_t)__objc_xmalloc(sizeof(struct _objc_mutex))))
 218         return NULL;                            /* Abort if malloc failed.  */
 219
 220     if ((mutex->handle = CreateMutex(NULL, 0, NULL)) == NULL) {
 221         free(mutex);                            /* Failed, free memory.     */
 222         return NULL;                            /* Abort.                   */
 223     }
 224     mutex->owner = NULL;                        /* No owner.                */
 225     mutex->depth = 0;                           /* No locks.                */
 226     return mutex;                               /* Return mutex handle.     */
 227 }
 228
 229 /********
 230  *  Deallocate a mutex.  Note that this includes an implicit mutex_lock to
 231  *  insure that no one else is using the lock.  It is legal to deallocate
 232  *  a lock if we have a lock on it, but illegal to deallotcate a lock held
 233  *  by anyone else.
 234  *  Returns the number of locks on the thread.  (1 for deallocate).
 235  */
 236 int
 237 objc_mutex_deallocate(_objc_mutex_t mutex)
 238 {
 239     int         depth;                          /* # of locks on mutex.     */
 240
 241     if (!mutex)                                 /* Is argument bad?         */
 242         return -1;                              /* Yes, abort.              */
 243     depth = objc_mutex_lock(mutex);             /* Must have lock.          */
 244
 245     CloseHandle(mutex->handle);                 /* Close Win32 handle.      */
 246
 247     free(mutex);                                /* Free memory.             */
 248     return depth;                               /* Return last depth.       */
 249 }
 250
 251 /********
 252  *  Grab a lock on a mutex.  If this thread already has a lock on this mutex
 253  *  then we increment the lock count.  If another thread has a lock on the
 254  *  mutex we block and wait for the thread to release the lock.
 255  *  Returns the lock count on the mutex held by this thread.
 256  */
 257 int
 258 objc_mutex_lock(_objc_mutex_t mutex)
 259 {
 260     _objc_thread_t      thread_id;              /* Cache our thread id.     */
 261     int                 status;
 262
 263     if (!mutex)                                 /* Is argument bad?         */
 264         return -1;                              /* Yes, abort.              */
 265     thread_id = objc_thread_id();               /* Get this thread's id.    */
 266     if (mutex->owner == thread_id)              /* Already own lock?        */
 267         return ++mutex->depth;                  /* Yes, increment depth.    */
 268
 269     status = WaitForSingleObject(mutex->handle, INFINITE);
 270     if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 271         return -1;                              /* Failed, abort.           */
 272
 273     mutex->owner = thread_id;                   /* Mark thread as owner.    */
 274
 275     return ++mutex->depth;                      /* Increment depth to end.  */
 276 }
 277
 278 /********
 279  *  Try to grab a lock on a mutex.  If this thread already has a lock on
 280  *  this mutex then we increment the lock count and return it.  If another
 281  *  thread has a lock on the mutex returns -1.
 282  */
 283 int
 284 objc_mutex_trylock(_objc_mutex_t mutex)
 285 {
 286     _objc_thread_t      thread_id;              /* Cache our thread id.     */
 287     DWORD               status;                 /* Return status from Win32.*/
 288
 289     if (!mutex)                                 /* Is argument bad?         */
 290         return -1;                              /* Yes, abort.              */
 291     thread_id = objc_thread_id();               /* Get this thread's id.    */
 292     if (mutex->owner == thread_id)              /* Already own lock?        */
 293         return ++mutex->depth;                  /* Yes, increment depth.    */
 294
 295     status = WaitForSingleObject(mutex->handle, 0);
 296     if (status != WAIT_OBJECT_0 && status != WAIT_ABANDONED)
 297         return -1;                              /* Failed, abort.           */
 298
 299     mutex->owner = thread_id;                   /* Mark thread as owner.    */
 300     return ++mutex->depth;                      /* Increment depth to end.  */
 301 }
 302
 303 /********
 304  *  Decrements the lock count on this mutex by one.  If the lock count reaches
 305  *  zero, release the lock on the mutex.  Returns the lock count on the mutex.
 306  *  It is an error to attempt to unlock a mutex which this thread doesn't hold
 307  *  in which case return -1 and the mutex is unaffected.
 308  *  Will also return -1 if the mutex free fails.
 309  */
 310 int
 311 objc_mutex_unlock(_objc_mutex_t mutex)
 312 {
 313     _objc_thread_t      thread_id;              /* Cache our thread id.     */
 314
 315     if (!mutex)                                 /* Is argument bad?         */
 316         return -1;                              /* Yes, abort.              */
 317     thread_id = objc_thread_id();               /* Get this thread's id.    */
 318     if (mutex->owner != thread_id)              /* Does some else own lock? */
 319         return -1;                              /* Yes, abort.              */
 320     if (mutex->depth > 1)                       /* Released last lock?      */
 321         return --mutex->depth;                  /* No, Decrement depth, end.*/
 322     mutex->depth = 0;                           /* Yes, reset depth to 0.   */
 323     mutex->owner = NULL;                        /* Set owner to "no thread".*/
 324
 325     if (ReleaseMutex(mutex->handle) == 0)
 326         return -1;                              /* Failed, abort.           */
 327
 328     return 0;                                   /* No, return success.      */
 329 }
 330
 331 /* End of File */