Modules/threadmodule.c

   1 /***********************************************************
   2 Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
   3 The Netherlands.
   4
   5                         All Rights Reserved
   6
   7 Permission to use, copy, modify, and distribute this software and its
   8 documentation for any purpose and without fee is hereby granted,
   9 provided that the above copyright notice appear in all copies and that
  10 both that copyright notice and this permission notice appear in
  11 supporting documentation, and that the names of Stichting Mathematisch
  12 Centrum or CWI or Corporation for National Research Initiatives or
  13 CNRI not be used in advertising or publicity pertaining to
  14 distribution of the software without specific, written prior
  15 permission.
  16
  17 While CWI is the initial source for this software, a modified version
  18 is made available by the Corporation for National Research Initiatives
  19 (CNRI) at the Internet address ftp://ftp.python.org.
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  21 STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
  22 REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
  23 MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
  24 CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
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  28 PERFORMANCE OF THIS SOFTWARE.
  29
  30 ******************************************************************/
  31
  32 /* Thread module */
  33 /* Interface to Sjoerd's portable C thread library */
  34
  35 #include "Python.h"
  36
  37 #ifndef WITH_THREAD
  38 #error "Error!  The rest of Python is not compiled with thread support."
  39 #error "Rerun configure, adding a --with-thread option."
  40 #error "Then run `make clean' followed by `make'."
  41 #endif
  42
  43 #include "pythread.h"
  44
  45 static PyObject *ThreadError;
  46
  47
  48 /* Lock objects */
  49
  50 typedef struct {
  51         PyObject_HEAD
  52         PyThread_type_lock lock_lock;
  53 } lockobject;
  54
  55 staticforward PyTypeObject Locktype;
  56
  57 static lockobject *
  58 newlockobject()
  59 {
  60         lockobject *self;
  61         self = PyObject_NEW(lockobject, &Locktype);
  62         if (self == NULL)
  63                 return NULL;
  64         self->lock_lock = PyThread_allocate_lock();
  65         if (self->lock_lock == NULL) {
  66                 PyMem_DEL(self);
  67                 self = NULL;
  68                 PyErr_SetString(ThreadError, "can't allocate lock");
  69         }
  70         return self;
  71 }
  72
  73 static void
  74 lock_dealloc(self)
  75         lockobject *self;
  76 {
  77         /* Unlock the lock so it's safe to free it */
  78         PyThread_acquire_lock(self->lock_lock, 0);
  79         PyThread_release_lock(self->lock_lock);
  80
  81         PyThread_free_lock(self->lock_lock);
  82         PyMem_DEL(self);
  83 }
  84
  85 static PyObject *
  86 lock_PyThread_acquire_lock(self, args)
  87         lockobject *self;
  88         PyObject *args;
  89 {
  90         int i;
  91
  92         if (args != NULL) {
  93                 if (!PyArg_Parse(args, "i", &i))
  94                         return NULL;
  95         }
  96         else
  97                 i = 1;
  98
  99         Py_BEGIN_ALLOW_THREADS
 100         i = PyThread_acquire_lock(self->lock_lock, i);
 101         Py_END_ALLOW_THREADS
 102
 103         if (args == NULL) {
 104                 Py_INCREF(Py_None);
 105                 return Py_None;
 106         }
 107         else
 108                 return PyInt_FromLong((long)i);
 109 }
 110
 111 static char acquire_doc[] =
 112 "acquire([wait]) -> None or Boolean\n\
 113 (PyThread_acquire_lock() is an obsolete synonym)\n\
 114 \n\
 115 Lock the lock.  Without argument, this blocks if the lock is already\n\
 116 locked (even by the same thread), waiting for another thread to release\n\
 117 the lock, and return None when the lock is acquired.\n\
 118 With a Boolean argument, this will only block if the argument is true,\n\
 119 and the return value reflects whether the lock is acquired.\n\
 120 The blocking operation is not interruptible.";
 121
 122 static PyObject *
 123 lock_PyThread_release_lock(self, args)
 124         lockobject *self;
 125         PyObject *args;
 126 {
 127         if (!PyArg_NoArgs(args))
 128                 return NULL;
 129
 130         /* Sanity check: the lock must be locked */
 131         if (PyThread_acquire_lock(self->lock_lock, 0)) {
 132                 PyThread_release_lock(self->lock_lock);
 133                 PyErr_SetString(ThreadError, "release unlocked lock");
 134                 return NULL;
 135         }
 136
 137         PyThread_release_lock(self->lock_lock);
 138         Py_INCREF(Py_None);
 139         return Py_None;
 140 }
 141
 142 static char release_doc[] =
 143 "release()\n\
 144 (PyThread_release_lock() is an obsolete synonym)\n\
 145 \n\
 146 Release the lock, allowing another thread that is blocked waiting for\n\
 147 the lock to acquire the lock.  The lock must be in the locked state,\n\
 148 but it needn't be locked by the same thread that unlocks it.";
 149
 150 static PyObject *
 151 lock_locked_lock(self, args)
 152         lockobject *self;
 153         PyObject *args;
 154 {
 155         if (!PyArg_NoArgs(args))
 156                 return NULL;
 157
 158         if (PyThread_acquire_lock(self->lock_lock, 0)) {
 159                 PyThread_release_lock(self->lock_lock);
 160                 return PyInt_FromLong(0L);
 161         }
 162         return PyInt_FromLong(1L);
 163 }
 164
 165 static char locked_doc[] =
 166 "locked() -> Boolean\n\
 167 (locked_lock() is an obsolete synonym)\n\
 168 \n\
 169 Return whether the lock is in the locked state.";
 170
 171 static PyMethodDef lock_methods[] = {
 172         {"acquire_lock", (PyCFunction)lock_PyThread_acquire_lock, 0, acquire_doc},
 173         {"acquire",      (PyCFunction)lock_PyThread_acquire_lock, 0, acquire_doc},
 174         {"release_lock", (PyCFunction)lock_PyThread_release_lock, 0, release_doc},
 175         {"release",      (PyCFunction)lock_PyThread_release_lock, 0, release_doc},
 176         {"locked_lock",  (PyCFunction)lock_locked_lock,  0, locked_doc},
 177         {"locked",       (PyCFunction)lock_locked_lock,  0, locked_doc},
 178         {NULL,           NULL}          /* sentinel */
 179 };
 180
 181 static PyObject *
 182 lock_getattr(self, name)
 183         lockobject *self;
 184         char *name;
 185 {
 186         return Py_FindMethod(lock_methods, (PyObject *)self, name);
 187 }
 188
 189 static PyTypeObject Locktype = {
 190         PyObject_HEAD_INIT(&PyType_Type)
 191         0,                              /*ob_size*/
 192         "lock",                         /*tp_name*/
 193         sizeof(lockobject),             /*tp_size*/
 194         0,                              /*tp_itemsize*/
 195         /* methods */
 196         (destructor)lock_dealloc,       /*tp_dealloc*/
 197         0,                              /*tp_print*/
 198         (getattrfunc)lock_getattr,      /*tp_getattr*/
 199         0,                              /*tp_setattr*/
 200         0,                              /*tp_compare*/
 201         0,                              /*tp_repr*/
 202 };
 203
 204
 205 /* Module functions */
 206
 207 struct bootstate {
 208         PyInterpreterState *interp;
 209         PyObject *func;
 210         PyObject *args;
 211         PyObject *keyw;
 212 };
 213
 214 static void
 215 t_bootstrap(boot_raw)
 216         void *boot_raw;
 217 {
 218         struct bootstate *boot = (struct bootstate *) boot_raw;
 219         PyThreadState *tstate;
 220         PyObject *res;
 221
 222         tstate = PyThreadState_New(boot->interp);
 223         PyEval_AcquireThread(tstate);
 224         res = PyEval_CallObjectWithKeywords(
 225                 boot->func, boot->args, boot->keyw);
 226         Py_DECREF(boot->func);
 227         Py_DECREF(boot->args);
 228         Py_XDECREF(boot->keyw);
 229         PyMem_DEL(boot_raw);
 230         if (res == NULL) {
 231                 if (PyErr_ExceptionMatches(PyExc_SystemExit))
 232                         PyErr_Clear();
 233                 else {
 234                         fprintf(stderr, "Unhandled exception in thread:\n");
 235                         PyErr_PrintEx(0);
 236                 }
 237         }
 238         else
 239                 Py_DECREF(res);
 240         PyThreadState_Clear(tstate);
 241         PyEval_ReleaseThread(tstate);
 242         PyThreadState_Delete(tstate);
 243         PyThread_exit_thread();
 244 }
 245
 246 static PyObject *
 247 thread_PyThread_start_new_thread(self, fargs)
 248         PyObject *self; /* Not used */
 249         PyObject *fargs;
 250 {
 251         PyObject *func, *args = NULL, *keyw = NULL;
 252         struct bootstate *boot;
 253
 254         if (!PyArg_ParseTuple(fargs, "OO|O", &func, &args, &keyw))
 255                 return NULL;
 256         if (!PyCallable_Check(func)) {
 257                 PyErr_SetString(PyExc_TypeError,
 258                                 "first arg must be callable");
 259                 return NULL;
 260         }
 261         if (!PyTuple_Check(args)) {
 262                 PyErr_SetString(PyExc_TypeError,
 263                                 "optional 2nd arg must be a tuple");
 264                 return NULL;
 265         }
 266         if (keyw != NULL && !PyDict_Check(keyw)) {
 267                 PyErr_SetString(PyExc_TypeError,
 268                                 "optional 3rd arg must be a dictionary");
 269                 return NULL;
 270         }
 271         boot = PyMem_NEW(struct bootstate, 1);
 272         if (boot == NULL)
 273                 return PyErr_NoMemory();
 274         boot->interp = PyThreadState_Get()->interp;
 275         boot->func = func;
 276         boot->args = args;
 277         boot->keyw = keyw;
 278         Py_INCREF(func);
 279         Py_INCREF(args);
 280         Py_XINCREF(keyw);
 281         PyEval_InitThreads(); /* Start the interpreter's thread-awareness */
 282         if (!PyThread_start_new_thread(t_bootstrap, (void*) boot)) {
 283                 PyErr_SetString(ThreadError, "can't start new thread\n");
 284                 Py_DECREF(func);
 285                 Py_DECREF(args);
 286                 Py_XDECREF(keyw);
 287                 PyMem_DEL(boot);
 288                 return NULL;
 289         }
 290         Py_INCREF(Py_None);
 291         return Py_None;
 292 }
 293
 294 static char start_new_doc[] =
 295 "start_new_thread(functon, args[, kwargs])\n\
 296 (start_new() is an obsolete synonym)\n\
 297 \n\
 298 Start a new thread.  The thread will call the function with positional\n\
 299 arguments from the tuple args and keyword arguments taken from the optional\n\
 300 dictionary kwargs.  The thread exits when the function returns; the return\n\
 301 value is ignored.  The thread will also exit when the function raises an\n\
 302 unhandled exception; a stack trace will be printed unless the exception is\n\
 303 SystemExit.";
 304
 305 static PyObject *
 306 thread_PyThread_exit_thread(self, args)
 307         PyObject *self; /* Not used */
 308         PyObject *args;
 309 {
 310         if (!PyArg_NoArgs(args))
 311                 return NULL;
 312         PyErr_SetNone(PyExc_SystemExit);
 313         return NULL;
 314 }
 315
 316 static char exit_doc[] =
 317 "exit()\n\
 318 (PyThread_exit_thread() is an obsolete synonym)\n\
 319 \n\
 320 This is synonymous to ``raise SystemExit''.  It will cause the current\n\
 321 thread to exit silently unless the exception is caught.";
 322
 323 #ifndef NO_EXIT_PROG
 324 static PyObject *
 325 thread_PyThread_exit_prog(self, args)
 326         PyObject *self; /* Not used */
 327         PyObject *args;
 328 {
 329         int sts;
 330         if (!PyArg_Parse(args, "i", &sts))
 331                 return NULL;
 332         Py_Exit(sts); /* Calls PyThread_exit_prog(sts) or _PyThread_exit_prog(sts) */
 333         for (;;) { } /* Should not be reached */
 334 }
 335 #endif
 336
 337 static PyObject *
 338 thread_PyThread_allocate_lock(self, args)
 339         PyObject *self; /* Not used */
 340         PyObject *args;
 341 {
 342         if (!PyArg_NoArgs(args))
 343                 return NULL;
 344         return (PyObject *) newlockobject();
 345 }
 346
 347 static char allocate_doc[] =
 348 "allocate_lock() -> lock object\n\
 349 (allocate() is an obsolete synonym)\n\
 350 \n\
 351 Create a new lock object.  See LockType.__doc__ for information about locks.";
 352
 353 static PyObject *
 354 thread_get_ident(self, args)
 355         PyObject *self; /* Not used */
 356         PyObject *args;
 357 {
 358         long ident;
 359         if (!PyArg_NoArgs(args))
 360                 return NULL;
 361         ident = PyThread_get_thread_ident();
 362         if (ident == -1) {
 363                 PyErr_SetString(ThreadError, "no current thread ident");
 364                 return NULL;
 365         }
 366         return PyInt_FromLong(ident);
 367 }
 368
 369 static char get_ident_doc[] =
 370 "get_ident() -> integer\n\
 371 \n\
 372 Return a non-zero integer that uniquely identifies the current thread\n\
 373 amongst other threads that exist simultaneously.\n\
 374 This may be used to identify per-thread resources.\n\
 375 Even though on some platforms threads identities may appear to be\n\
 376 allocated consecutive numbers starting at 1, this behavior should not\n\
 377 be relied upon, and the number should be seen purely as a magic cookie.\n\
 378 A thread's identity may be reused for another thread after it exits.";
 379
 380 static PyMethodDef thread_methods[] = {
 381         {"start_new_thread",    (PyCFunction)thread_PyThread_start_new_thread, 1,
 382                                 start_new_doc},
 383         {"start_new",           (PyCFunction)thread_PyThread_start_new_thread, 1,
 384                                 start_new_doc},
 385         {"allocate_lock",       (PyCFunction)thread_PyThread_allocate_lock, 0,
 386                                 allocate_doc},
 387         {"allocate",            (PyCFunction)thread_PyThread_allocate_lock, 0,
 388                                 allocate_doc},
 389         {"exit_thread",         (PyCFunction)thread_PyThread_exit_thread, 0,
 390                                 exit_doc},
 391         {"exit",                (PyCFunction)thread_PyThread_exit_thread, 0,
 392                                 exit_doc},
 393         {"get_ident",           (PyCFunction)thread_get_ident, 0,
 394                                 get_ident_doc},
 395 #ifndef NO_EXIT_PROG
 396         {"exit_prog",           (PyCFunction)thread_PyThread_exit_prog},
 397 #endif
 398         {NULL,                  NULL}           /* sentinel */
 399 };
 400
 401
 402 /* Initialization function */
 403
 404 static char thread_doc[] =
 405 "This module provides primitive operations to write multi-threaded programs.\n\
 406 The 'threading' module provides a more convenient interface.";
 407
 408 static char lock_doc[] =
 409 "A lock object is a synchronization primitive.  To create a lock,\n\
 410 call the PyThread_allocate_lock() function.  Methods are:\n\
 411 \n\
 412 acquire() -- lock the lock, possibly blocking until it can be obtained\n\
 413 release() -- unlock of the lock\n\
 414 locked() -- test whether the lock is currently locked\n\
 415 \n\
 416 A lock is not owned by the thread that locked it; another thread may\n\
 417 unlock it.  A thread attempting to lock a lock that it has already locked\n\
 418 will block until another thread unlocks it.  Deadlocks may ensue.";
 419
 420 DL_EXPORT(void)
 421 initthread()
 422 {
 423         PyObject *m, *d;
 424
 425         /* Create the module and add the functions */
 426         m = Py_InitModule3("thread", thread_methods, thread_doc);
 427
 428         /* Add a symbolic constant */
 429         d = PyModule_GetDict(m);
 430         ThreadError = PyErr_NewException("thread.error", NULL, NULL);
 431         PyDict_SetItemString(d, "error", ThreadError);
 432         Locktype.tp_doc = lock_doc;
 433         Py_INCREF(&Locktype);
 434         PyDict_SetItemString(d, "LockType", (PyObject *)&Locktype);
 435
 436         /* Initialize the C thread library */
 437         PyThread_init_thread();
 438 }