Python/thread_pth.h

   1
   2 /* GNU pth threads interface
   3    http://www.gnu.org/software/pth
   4    2000-05-03 Andy Dustman <andy@dustman.net>
   5
   6    Adapted from Posix threads interface
   7    12 May 1997 -- david arnold <davida@pobox.com>
   8  */
   9
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <pth.h>
  13
  14 /* A pth mutex isn't sufficient to model the Python lock type
  15  * because pth mutexes can be acquired multiple times by the
  16  * same thread.
  17  *
  18  * The pth_lock struct implements a Python lock as a "locked?" bit
  19  * and a <condition, mutex> pair.  In general, if the bit can be acquired
  20  * instantly, it is, else the pair is used to block the thread until the
  21  * bit is cleared.
  22  */
  23
  24 typedef struct {
  25         char             locked; /* 0=unlocked, 1=locked */
  26         /* a <cond, mutex> pair to handle an acquire of a locked lock */
  27         pth_cond_t   lock_released;
  28         pth_mutex_t  mut;
  29 } pth_lock;
  30
  31 #define CHECK_STATUS(name)  if (status == -1) { printf("%d ", status); perror(name); error = 1; }
  32
  33 /*
  34  * Initialization.
  35  */
  36
  37 static void PyThread__init_thread(void)
  38 {
  39         pth_init();
  40 }
  41
  42 /*
  43  * Thread support.
  44  */
  45
  46
  47 long PyThread_start_new_thread(void (*func)(void *), void *arg)
  48 {
  49         pth_t th;
  50         dprintf(("PyThread_start_new_thread called\n"));
  51         if (!initialized)
  52                 PyThread_init_thread();
  53
  54         th = pth_spawn(PTH_ATTR_DEFAULT,
  55                                  (void* (*)(void *))func,
  56                                  (void *)arg
  57                                  );
  58
  59         return th;
  60 }
  61
  62 long PyThread_get_thread_ident(void)
  63 {
  64         volatile pth_t threadid;
  65         if (!initialized)
  66                 PyThread_init_thread();
  67         /* Jump through some hoops for Alpha OSF/1 */
  68         threadid = pth_self();
  69         return (long) *(long *) &threadid;
  70 }
  71
  72 static void do_PyThread_exit_thread(int no_cleanup)
  73 {
  74         dprintf(("PyThread_exit_thread called\n"));
  75         if (!initialized) {
  76                 if (no_cleanup)
  77                         _exit(0);
  78                 else
  79                         exit(0);
  80         }
  81 }
  82
  83 void PyThread_exit_thread(void)
  84 {
  85         do_PyThread_exit_thread(0);
  86 }
  87
  88 void PyThread__exit_thread(void)
  89 {
  90         do_PyThread_exit_thread(1);
  91 }
  92
  93 #ifndef NO_EXIT_PROG
  94 static void do_PyThread_exit_prog(int status, int no_cleanup)
  95 {
  96         dprintf(("PyThread_exit_prog(%d) called\n", status));
  97         if (!initialized)
  98                 if (no_cleanup)
  99                         _exit(status);
 100                 else
 101                         exit(status);
 102 }
 103
 104 void PyThread_exit_prog(int status)
 105 {
 106         do_PyThread_exit_prog(status, 0);
 107 }
 108
 109 void PyThread__exit_prog(int status)
 110 {
 111         do_PyThread_exit_prog(status, 1);
 112 }
 113 #endif /* NO_EXIT_PROG */
 114
 115 /*
 116  * Lock support.
 117  */
 118 PyThread_type_lock PyThread_allocate_lock(void)
 119 {
 120         pth_lock *lock;
 121         int status, error = 0;
 122
 123         dprintf(("PyThread_allocate_lock called\n"));
 124         if (!initialized)
 125                 PyThread_init_thread();
 126
 127         lock = (pth_lock *) malloc(sizeof(pth_lock));
 128         memset((void *)lock, '\0', sizeof(pth_lock));
 129         if (lock) {
 130                 lock->locked = 0;
 131                 status = pth_mutex_init(&lock->mut);
 132                 CHECK_STATUS("pth_mutex_init");
 133                 status = pth_cond_init(&lock->lock_released);
 134                 CHECK_STATUS("pth_cond_init");
 135                 if (error) {
 136                         free((void *)lock);
 137                         lock = NULL;
 138                 }
 139         }
 140         dprintf(("PyThread_allocate_lock() -> %p\n", lock));
 141         return (PyThread_type_lock) lock;
 142 }
 143
 144 void PyThread_free_lock(PyThread_type_lock lock)
 145 {
 146         pth_lock *thelock = (pth_lock *)lock;
 147
 148         dprintf(("PyThread_free_lock(%p) called\n", lock));
 149
 150         free((void *)thelock);
 151 }
 152
 153 int PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
 154 {
 155         int success;
 156         pth_lock *thelock = (pth_lock *)lock;
 157         int status, error = 0;
 158
 159         dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag));
 160
 161         status = pth_mutex_acquire(&thelock->mut, !waitflag, NULL);
 162         CHECK_STATUS("pth_mutex_acquire[1]");
 163         success = thelock->locked == 0;
 164         if (success) thelock->locked = 1;
 165         status = pth_mutex_release( &thelock->mut );
 166         CHECK_STATUS("pth_mutex_release[1]");
 167
 168         if ( !success && waitflag ) {
 169                 /* continue trying until we get the lock */
 170
 171                 /* mut must be locked by me -- part of the condition
 172                  * protocol */
 173                 status = pth_mutex_acquire( &thelock->mut, !waitflag, NULL );
 174                 CHECK_STATUS("pth_mutex_acquire[2]");
 175                 while ( thelock->locked ) {
 176                         status = pth_cond_await(&thelock->lock_released,
 177                                                 &thelock->mut, NULL);
 178                         CHECK_STATUS("pth_cond_await");
 179                 }
 180                 thelock->locked = 1;
 181                 status = pth_mutex_release( &thelock->mut );
 182                 CHECK_STATUS("pth_mutex_release[2]");
 183                 success = 1;
 184         }
 185         if (error) success = 0;
 186         dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success));
 187         return success;
 188 }
 189
 190 void PyThread_release_lock(PyThread_type_lock lock)
 191 {
 192         pth_lock *thelock = (pth_lock *)lock;
 193         int status, error = 0;
 194
 195         dprintf(("PyThread_release_lock(%p) called\n", lock));
 196
 197         status = pth_mutex_acquire( &thelock->mut, 0, NULL );
 198         CHECK_STATUS("pth_mutex_acquire[3]");
 199
 200         thelock->locked = 0;
 201
 202         status = pth_mutex_release( &thelock->mut );
 203         CHECK_STATUS("pth_mutex_release[3]");
 204
 205         /* wake up someone (anyone, if any) waiting on the lock */
 206         status = pth_cond_notify( &thelock->lock_released, 0 );
 207         CHECK_STATUS("pth_cond_notify");
 208 }