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 pth_attr_t PyThread_attr;
  34
  35 /*
  36  * Initialization.
  37  */
  38
  39 static void PyThread__init_thread(void)
  40 {
  41         pth_init();
  42         PyThread_attr = pth_attr_new();
  43         pth_attr_set(PyThread_attr, PTH_ATTR_STACK_SIZE, 1<<18);
  44         pth_attr_set(PyThread_attr, PTH_ATTR_JOINABLE, FALSE);
  45 }
  46
  47 /*
  48  * Thread support.
  49  */
  50
  51
  52 long PyThread_start_new_thread(void (*func)(void *), void *arg)
  53 {
  54         pth_t th;
  55         dprintf(("PyThread_start_new_thread called\n"));
  56         if (!initialized)
  57                 PyThread_init_thread();
  58
  59         th = pth_spawn(PyThread_attr,
  60                                  (void* (*)(void *))func,
  61                                  (void *)arg
  62                                  );
  63
  64         return th;
  65 }
  66
  67 long PyThread_get_thread_ident(void)
  68 {
  69         volatile pth_t threadid;
  70         if (!initialized)
  71                 PyThread_init_thread();
  72         /* Jump through some hoops for Alpha OSF/1 */
  73         threadid = pth_self();
  74         return (long) *(long *) &threadid;
  75 }
  76
  77 static void do_PyThread_exit_thread(int no_cleanup)
  78 {
  79         dprintf(("PyThread_exit_thread called\n"));
  80         if (!initialized) {
  81                 if (no_cleanup)
  82                         _exit(0);
  83                 else
  84                         exit(0);
  85         }
  86 }
  87
  88 void PyThread_exit_thread(void)
  89 {
  90         do_PyThread_exit_thread(0);
  91 }
  92
  93 void PyThread__exit_thread(void)
  94 {
  95         do_PyThread_exit_thread(1);
  96 }
  97
  98 #ifndef NO_EXIT_PROG
  99 static void do_PyThread_exit_prog(int status, int no_cleanup)
 100 {
 101         dprintf(("PyThread_exit_prog(%d) called\n", status));
 102         if (!initialized)
 103                 if (no_cleanup)
 104                         _exit(status);
 105                 else
 106                         exit(status);
 107 }
 108
 109 void PyThread_exit_prog(int status)
 110 {
 111         do_PyThread_exit_prog(status, 0);
 112 }
 113
 114 void PyThread__exit_prog(int status)
 115 {
 116         do_PyThread_exit_prog(status, 1);
 117 }
 118 #endif /* NO_EXIT_PROG */
 119
 120 /*
 121  * Lock support.
 122  */
 123 PyThread_type_lock PyThread_allocate_lock(void)
 124 {
 125         pth_lock *lock;
 126         int status, error = 0;
 127
 128         dprintf(("PyThread_allocate_lock called\n"));
 129         if (!initialized)
 130                 PyThread_init_thread();
 131
 132         lock = (pth_lock *) malloc(sizeof(pth_lock));
 133         memset((void *)lock, '\0', sizeof(pth_lock));
 134         if (lock) {
 135                 lock->locked = 0;
 136                 status = pth_mutex_init(&lock->mut);
 137                 CHECK_STATUS("pth_mutex_init");
 138                 status = pth_cond_init(&lock->lock_released);
 139                 CHECK_STATUS("pth_cond_init");
 140                 if (error) {
 141                         free((void *)lock);
 142                         lock = NULL;
 143                 }
 144         }
 145         dprintf(("PyThread_allocate_lock() -> %p\n", lock));
 146         return (PyThread_type_lock) lock;
 147 }
 148
 149 void PyThread_free_lock(PyThread_type_lock lock)
 150 {
 151         pth_lock *thelock = (pth_lock *)lock;
 152
 153         dprintf(("PyThread_free_lock(%p) called\n", lock));
 154
 155         free((void *)thelock);
 156 }
 157
 158 int PyThread_acquire_lock(PyThread_type_lock lock, int waitflag)
 159 {
 160         int success;
 161         pth_lock *thelock = (pth_lock *)lock;
 162         int status, error = 0;
 163
 164         dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag));
 165
 166         status = pth_mutex_acquire(&thelock->mut, !waitflag, NULL);
 167         CHECK_STATUS("pth_mutex_acquire[1]");
 168         success = thelock->locked == 0;
 169         if (success) thelock->locked = 1;
 170         status = pth_mutex_release( &thelock->mut );
 171         CHECK_STATUS("pth_mutex_release[1]");
 172
 173         if ( !success && waitflag ) {
 174                 /* continue trying until we get the lock */
 175
 176                 /* mut must be locked by me -- part of the condition
 177                  * protocol */
 178                 status = pth_mutex_acquire( &thelock->mut, !waitflag, NULL );
 179                 CHECK_STATUS("pth_mutex_acquire[2]");
 180                 while ( thelock->locked ) {
 181                         status = pth_cond_await(&thelock->lock_released,
 182                                                 &thelock->mut, NULL);
 183                         CHECK_STATUS("pth_cond_await");
 184                 }
 185                 thelock->locked = 1;
 186                 status = pth_mutex_release( &thelock->mut );
 187                 CHECK_STATUS("pth_mutex_release[2]");
 188                 success = 1;
 189         }
 190         if (error) success = 0;
 191         dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success));
 192         return success;
 193 }
 194
 195 void PyThread_release_lock(PyThread_type_lock lock)
 196 {
 197         pth_lock *thelock = (pth_lock *)lock;
 198         int status, error = 0;
 199
 200         dprintf(("PyThread_release_lock(%p) called\n", lock));
 201
 202         status = pth_mutex_acquire( &thelock->mut, 0, NULL );
 203         CHECK_STATUS("pth_mutex_acquire[3]");
 204
 205         thelock->locked = 0;
 206
 207         status = pth_mutex_release( &thelock->mut );
 208         CHECK_STATUS("pth_mutex_release[3]");
 209
 210         /* wake up someone (anyone, if any) waiting on the lock */
 211         status = pth_cond_notify( &thelock->lock_released, 0 );
 212         CHECK_STATUS("pth_cond_notify");
 213 }