| |
| /* Thread and interpreter state structures and their interfaces */ |
| |
| #include "Python.h" |
| |
| /* -------------------------------------------------------------------------- |
| CAUTION |
| |
| Always use malloc() and free() directly in this file. A number of these |
| functions are advertised as safe to call when the GIL isn't held, and in |
| a debug build Python redirects (e.g.) PyMem_NEW (etc) to Python's debugging |
| obmalloc functions. Those aren't thread-safe (they rely on the GIL to avoid |
| the expense of doing their own locking). |
| -------------------------------------------------------------------------- */ |
| |
| #ifdef HAVE_DLOPEN |
| #ifdef HAVE_DLFCN_H |
| #include <dlfcn.h> |
| #endif |
| #ifndef RTLD_LAZY |
| #define RTLD_LAZY 1 |
| #endif |
| #endif |
| |
| |
| #ifdef WITH_THREAD |
| #include "pythread.h" |
| static PyThread_type_lock head_mutex = NULL; /* Protects interp->tstate_head */ |
| #define HEAD_INIT() (void)(head_mutex || (head_mutex = PyThread_allocate_lock())) |
| #define HEAD_LOCK() PyThread_acquire_lock(head_mutex, WAIT_LOCK) |
| #define HEAD_UNLOCK() PyThread_release_lock(head_mutex) |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /* The single PyInterpreterState used by this process' |
| GILState implementation |
| */ |
| static PyInterpreterState *autoInterpreterState = NULL; |
| static int autoTLSkey = 0; |
| #else |
| #define HEAD_INIT() /* Nothing */ |
| #define HEAD_LOCK() /* Nothing */ |
| #define HEAD_UNLOCK() /* Nothing */ |
| #endif |
| |
| static PyInterpreterState *interp_head = NULL; |
| |
| PyThreadState *_PyThreadState_Current = NULL; |
| PyThreadFrameGetter _PyThreadState_GetFrame = NULL; |
| |
| #ifdef WITH_THREAD |
| static void _PyGILState_NoteThreadState(PyThreadState* tstate); |
| #endif |
| |
| |
| PyInterpreterState * |
| PyInterpreterState_New(void) |
| { |
| PyInterpreterState *interp = (PyInterpreterState *) |
| malloc(sizeof(PyInterpreterState)); |
| |
| if (interp != NULL) { |
| HEAD_INIT(); |
| #ifdef WITH_THREAD |
| if (head_mutex == NULL) |
| Py_FatalError("Can't initialize threads for interpreter"); |
| #endif |
| interp->modules = NULL; |
| interp->modules_reloading = NULL; |
| interp->modules_by_index = NULL; |
| interp->sysdict = NULL; |
| interp->builtins = NULL; |
| interp->tstate_head = NULL; |
| interp->codec_search_path = NULL; |
| interp->codec_search_cache = NULL; |
| interp->codec_error_registry = NULL; |
| interp->codecs_initialized = 0; |
| #ifdef HAVE_DLOPEN |
| #ifdef RTLD_NOW |
| interp->dlopenflags = RTLD_NOW; |
| #else |
| interp->dlopenflags = RTLD_LAZY; |
| #endif |
| #endif |
| #ifdef WITH_TSC |
| interp->tscdump = 0; |
| #endif |
| |
| HEAD_LOCK(); |
| interp->next = interp_head; |
| interp_head = interp; |
| HEAD_UNLOCK(); |
| } |
| |
| return interp; |
| } |
| |
| |
| void |
| PyInterpreterState_Clear(PyInterpreterState *interp) |
| { |
| PyThreadState *p; |
| HEAD_LOCK(); |
| for (p = interp->tstate_head; p != NULL; p = p->next) |
| PyThreadState_Clear(p); |
| HEAD_UNLOCK(); |
| Py_CLEAR(interp->codec_search_path); |
| Py_CLEAR(interp->codec_search_cache); |
| Py_CLEAR(interp->codec_error_registry); |
| Py_CLEAR(interp->modules); |
| Py_CLEAR(interp->modules_by_index); |
| Py_CLEAR(interp->modules_reloading); |
| Py_CLEAR(interp->sysdict); |
| Py_CLEAR(interp->builtins); |
| } |
| |
| |
| static void |
| zapthreads(PyInterpreterState *interp) |
| { |
| PyThreadState *p; |
| /* No need to lock the mutex here because this should only happen |
| when the threads are all really dead (XXX famous last words). */ |
| while ((p = interp->tstate_head) != NULL) { |
| PyThreadState_Delete(p); |
| } |
| } |
| |
| |
| void |
| PyInterpreterState_Delete(PyInterpreterState *interp) |
| { |
| PyInterpreterState **p; |
| zapthreads(interp); |
| HEAD_LOCK(); |
| for (p = &interp_head; ; p = &(*p)->next) { |
| if (*p == NULL) |
| Py_FatalError( |
| "PyInterpreterState_Delete: invalid interp"); |
| if (*p == interp) |
| break; |
| } |
| if (interp->tstate_head != NULL) |
| Py_FatalError("PyInterpreterState_Delete: remaining threads"); |
| *p = interp->next; |
| HEAD_UNLOCK(); |
| free(interp); |
| } |
| |
| |
| /* Default implementation for _PyThreadState_GetFrame */ |
| static struct _frame * |
| threadstate_getframe(PyThreadState *self) |
| { |
| return self->frame; |
| } |
| |
| static PyThreadState * |
| new_threadstate(PyInterpreterState *interp, int init) |
| { |
| PyThreadState *tstate = (PyThreadState *)malloc(sizeof(PyThreadState)); |
| |
| if (_PyThreadState_GetFrame == NULL) |
| _PyThreadState_GetFrame = threadstate_getframe; |
| |
| if (tstate != NULL) { |
| tstate->interp = interp; |
| |
| tstate->frame = NULL; |
| tstate->recursion_depth = 0; |
| tstate->overflowed = 0; |
| tstate->recursion_critical = 0; |
| tstate->tracing = 0; |
| tstate->use_tracing = 0; |
| tstate->tick_counter = 0; |
| tstate->gilstate_counter = 0; |
| tstate->async_exc = NULL; |
| #ifdef WITH_THREAD |
| tstate->thread_id = PyThread_get_thread_ident(); |
| #else |
| tstate->thread_id = 0; |
| #endif |
| |
| tstate->dict = NULL; |
| |
| tstate->curexc_type = NULL; |
| tstate->curexc_value = NULL; |
| tstate->curexc_traceback = NULL; |
| |
| tstate->exc_type = NULL; |
| tstate->exc_value = NULL; |
| tstate->exc_traceback = NULL; |
| |
| tstate->c_profilefunc = NULL; |
| tstate->c_tracefunc = NULL; |
| tstate->c_profileobj = NULL; |
| tstate->c_traceobj = NULL; |
| |
| if (init) |
| _PyThreadState_Init(tstate); |
| |
| HEAD_LOCK(); |
| tstate->next = interp->tstate_head; |
| interp->tstate_head = tstate; |
| HEAD_UNLOCK(); |
| } |
| |
| return tstate; |
| } |
| |
| PyThreadState * |
| PyThreadState_New(PyInterpreterState *interp) |
| { |
| return new_threadstate(interp, 1); |
| } |
| |
| PyThreadState * |
| _PyThreadState_Prealloc(PyInterpreterState *interp) |
| { |
| return new_threadstate(interp, 0); |
| } |
| |
| void |
| _PyThreadState_Init(PyThreadState *tstate) |
| { |
| #ifdef WITH_THREAD |
| _PyGILState_NoteThreadState(tstate); |
| #endif |
| } |
| |
| PyObject* |
| PyState_FindModule(struct PyModuleDef* m) |
| { |
| Py_ssize_t index = m->m_base.m_index; |
| PyInterpreterState *state = PyThreadState_GET()->interp; |
| PyObject *res; |
| if (index == 0) |
| return NULL; |
| if (state->modules_by_index == NULL) |
| return NULL; |
| if (index > PyList_GET_SIZE(state->modules_by_index)) |
| return NULL; |
| res = PyList_GET_ITEM(state->modules_by_index, index); |
| return res==Py_None ? NULL : res; |
| } |
| |
| int |
| _PyState_AddModule(PyObject* module, struct PyModuleDef* def) |
| { |
| PyInterpreterState *state = PyThreadState_GET()->interp; |
| if (!def) |
| return -1; |
| if (!state->modules_by_index) { |
| state->modules_by_index = PyList_New(0); |
| if (!state->modules_by_index) |
| return -1; |
| } |
| while(PyList_GET_SIZE(state->modules_by_index) <= def->m_base.m_index) |
| if (PyList_Append(state->modules_by_index, Py_None) < 0) |
| return -1; |
| Py_INCREF(module); |
| return PyList_SetItem(state->modules_by_index, |
| def->m_base.m_index, module); |
| } |
| |
| void |
| PyThreadState_Clear(PyThreadState *tstate) |
| { |
| if (Py_VerboseFlag && tstate->frame != NULL) |
| fprintf(stderr, |
| "PyThreadState_Clear: warning: thread still has a frame\n"); |
| |
| Py_CLEAR(tstate->frame); |
| |
| Py_CLEAR(tstate->dict); |
| Py_CLEAR(tstate->async_exc); |
| |
| Py_CLEAR(tstate->curexc_type); |
| Py_CLEAR(tstate->curexc_value); |
| Py_CLEAR(tstate->curexc_traceback); |
| |
| Py_CLEAR(tstate->exc_type); |
| Py_CLEAR(tstate->exc_value); |
| Py_CLEAR(tstate->exc_traceback); |
| |
| tstate->c_profilefunc = NULL; |
| tstate->c_tracefunc = NULL; |
| Py_CLEAR(tstate->c_profileobj); |
| Py_CLEAR(tstate->c_traceobj); |
| } |
| |
| |
| /* Common code for PyThreadState_Delete() and PyThreadState_DeleteCurrent() */ |
| static void |
| tstate_delete_common(PyThreadState *tstate) |
| { |
| PyInterpreterState *interp; |
| PyThreadState **p; |
| PyThreadState *prev_p = NULL; |
| if (tstate == NULL) |
| Py_FatalError("PyThreadState_Delete: NULL tstate"); |
| interp = tstate->interp; |
| if (interp == NULL) |
| Py_FatalError("PyThreadState_Delete: NULL interp"); |
| HEAD_LOCK(); |
| for (p = &interp->tstate_head; ; p = &(*p)->next) { |
| if (*p == NULL) |
| Py_FatalError( |
| "PyThreadState_Delete: invalid tstate"); |
| if (*p == tstate) |
| break; |
| /* Sanity check. These states should never happen but if |
| * they do we must abort. Otherwise we'll end up spinning in |
| * in a tight loop with the lock held. A similar check is done |
| * in thread.c find_key(). */ |
| if (*p == prev_p) |
| Py_FatalError( |
| "PyThreadState_Delete: small circular list(!)" |
| " and tstate not found."); |
| prev_p = *p; |
| if ((*p)->next == interp->tstate_head) |
| Py_FatalError( |
| "PyThreadState_Delete: circular list(!) and" |
| " tstate not found."); |
| } |
| *p = tstate->next; |
| HEAD_UNLOCK(); |
| free(tstate); |
| } |
| |
| |
| void |
| PyThreadState_Delete(PyThreadState *tstate) |
| { |
| if (tstate == _PyThreadState_Current) |
| Py_FatalError("PyThreadState_Delete: tstate is still current"); |
| tstate_delete_common(tstate); |
| #ifdef WITH_THREAD |
| if (autoInterpreterState && PyThread_get_key_value(autoTLSkey) == tstate) |
| PyThread_delete_key_value(autoTLSkey); |
| #endif /* WITH_THREAD */ |
| } |
| |
| |
| #ifdef WITH_THREAD |
| void |
| PyThreadState_DeleteCurrent() |
| { |
| PyThreadState *tstate = _PyThreadState_Current; |
| if (tstate == NULL) |
| Py_FatalError( |
| "PyThreadState_DeleteCurrent: no current tstate"); |
| _PyThreadState_Current = NULL; |
| tstate_delete_common(tstate); |
| if (autoInterpreterState && PyThread_get_key_value(autoTLSkey) == tstate) |
| PyThread_delete_key_value(autoTLSkey); |
| PyEval_ReleaseLock(); |
| } |
| #endif /* WITH_THREAD */ |
| |
| |
| PyThreadState * |
| PyThreadState_Get(void) |
| { |
| if (_PyThreadState_Current == NULL) |
| Py_FatalError("PyThreadState_Get: no current thread"); |
| |
| return _PyThreadState_Current; |
| } |
| |
| |
| PyThreadState * |
| PyThreadState_Swap(PyThreadState *newts) |
| { |
| PyThreadState *oldts = _PyThreadState_Current; |
| |
| _PyThreadState_Current = newts; |
| /* It should not be possible for more than one thread state |
| to be used for a thread. Check this the best we can in debug |
| builds. |
| */ |
| #if defined(Py_DEBUG) && defined(WITH_THREAD) |
| if (newts) { |
| /* This can be called from PyEval_RestoreThread(). Similar |
| to it, we need to ensure errno doesn't change. |
| */ |
| int err = errno; |
| PyThreadState *check = PyGILState_GetThisThreadState(); |
| if (check && check->interp == newts->interp && check != newts) |
| Py_FatalError("Invalid thread state for this thread"); |
| errno = err; |
| } |
| #endif |
| return oldts; |
| } |
| |
| /* An extension mechanism to store arbitrary additional per-thread state. |
| PyThreadState_GetDict() returns a dictionary that can be used to hold such |
| state; the caller should pick a unique key and store its state there. If |
| PyThreadState_GetDict() returns NULL, an exception has *not* been raised |
| and the caller should assume no per-thread state is available. */ |
| |
| PyObject * |
| PyThreadState_GetDict(void) |
| { |
| if (_PyThreadState_Current == NULL) |
| return NULL; |
| |
| if (_PyThreadState_Current->dict == NULL) { |
| PyObject *d; |
| _PyThreadState_Current->dict = d = PyDict_New(); |
| if (d == NULL) |
| PyErr_Clear(); |
| } |
| return _PyThreadState_Current->dict; |
| } |
| |
| |
| /* Asynchronously raise an exception in a thread. |
| Requested by Just van Rossum and Alex Martelli. |
| To prevent naive misuse, you must write your own extension |
| to call this, or use ctypes. Must be called with the GIL held. |
| Returns the number of tstates modified (normally 1, but 0 if `id` didn't |
| match any known thread id). Can be called with exc=NULL to clear an |
| existing async exception. This raises no exceptions. */ |
| |
| int |
| PyThreadState_SetAsyncExc(long id, PyObject *exc) { |
| PyThreadState *tstate = PyThreadState_GET(); |
| PyInterpreterState *interp = tstate->interp; |
| PyThreadState *p; |
| |
| /* Although the GIL is held, a few C API functions can be called |
| * without the GIL held, and in particular some that create and |
| * destroy thread and interpreter states. Those can mutate the |
| * list of thread states we're traversing, so to prevent that we lock |
| * head_mutex for the duration. |
| */ |
| HEAD_LOCK(); |
| for (p = interp->tstate_head; p != NULL; p = p->next) { |
| if (p->thread_id == id) { |
| /* Tricky: we need to decref the current value |
| * (if any) in p->async_exc, but that can in turn |
| * allow arbitrary Python code to run, including |
| * perhaps calls to this function. To prevent |
| * deadlock, we need to release head_mutex before |
| * the decref. |
| */ |
| PyObject *old_exc = p->async_exc; |
| Py_XINCREF(exc); |
| p->async_exc = exc; |
| HEAD_UNLOCK(); |
| Py_XDECREF(old_exc); |
| return 1; |
| } |
| } |
| HEAD_UNLOCK(); |
| return 0; |
| } |
| |
| |
| /* Routines for advanced debuggers, requested by David Beazley. |
| Don't use unless you know what you are doing! */ |
| |
| PyInterpreterState * |
| PyInterpreterState_Head(void) |
| { |
| return interp_head; |
| } |
| |
| PyInterpreterState * |
| PyInterpreterState_Next(PyInterpreterState *interp) { |
| return interp->next; |
| } |
| |
| PyThreadState * |
| PyInterpreterState_ThreadHead(PyInterpreterState *interp) { |
| return interp->tstate_head; |
| } |
| |
| PyThreadState * |
| PyThreadState_Next(PyThreadState *tstate) { |
| return tstate->next; |
| } |
| |
| /* The implementation of sys._current_frames(). This is intended to be |
| called with the GIL held, as it will be when called via |
| sys._current_frames(). It's possible it would work fine even without |
| the GIL held, but haven't thought enough about that. |
| */ |
| PyObject * |
| _PyThread_CurrentFrames(void) |
| { |
| PyObject *result; |
| PyInterpreterState *i; |
| |
| result = PyDict_New(); |
| if (result == NULL) |
| return NULL; |
| |
| /* for i in all interpreters: |
| * for t in all of i's thread states: |
| * if t's frame isn't NULL, map t's id to its frame |
| * Because these lists can mutate even when the GIL is held, we |
| * need to grab head_mutex for the duration. |
| */ |
| HEAD_LOCK(); |
| for (i = interp_head; i != NULL; i = i->next) { |
| PyThreadState *t; |
| for (t = i->tstate_head; t != NULL; t = t->next) { |
| PyObject *id; |
| int stat; |
| struct _frame *frame = t->frame; |
| if (frame == NULL) |
| continue; |
| id = PyLong_FromLong(t->thread_id); |
| if (id == NULL) |
| goto Fail; |
| stat = PyDict_SetItem(result, id, (PyObject *)frame); |
| Py_DECREF(id); |
| if (stat < 0) |
| goto Fail; |
| } |
| } |
| HEAD_UNLOCK(); |
| return result; |
| |
| Fail: |
| HEAD_UNLOCK(); |
| Py_DECREF(result); |
| return NULL; |
| } |
| |
| /* Python "auto thread state" API. */ |
| #ifdef WITH_THREAD |
| |
| /* Keep this as a static, as it is not reliable! It can only |
| ever be compared to the state for the *current* thread. |
| * If not equal, then it doesn't matter that the actual |
| value may change immediately after comparison, as it can't |
| possibly change to the current thread's state. |
| * If equal, then the current thread holds the lock, so the value can't |
| change until we yield the lock. |
| */ |
| static int |
| PyThreadState_IsCurrent(PyThreadState *tstate) |
| { |
| /* Must be the tstate for this thread */ |
| assert(PyGILState_GetThisThreadState()==tstate); |
| /* On Windows at least, simple reads and writes to 32 bit values |
| are atomic. |
| */ |
| return tstate == _PyThreadState_Current; |
| } |
| |
| /* Internal initialization/finalization functions called by |
| Py_Initialize/Py_Finalize |
| */ |
| void |
| _PyGILState_Init(PyInterpreterState *i, PyThreadState *t) |
| { |
| assert(i && t); /* must init with valid states */ |
| autoTLSkey = PyThread_create_key(); |
| autoInterpreterState = i; |
| assert(PyThread_get_key_value(autoTLSkey) == NULL); |
| assert(t->gilstate_counter == 0); |
| |
| _PyGILState_NoteThreadState(t); |
| } |
| |
| void |
| _PyGILState_Fini(void) |
| { |
| PyThread_delete_key(autoTLSkey); |
| autoInterpreterState = NULL; |
| } |
| |
| /* When a thread state is created for a thread by some mechanism other than |
| PyGILState_Ensure, it's important that the GILState machinery knows about |
| it so it doesn't try to create another thread state for the thread (this is |
| a better fix for SF bug #1010677 than the first one attempted). |
| */ |
| static void |
| _PyGILState_NoteThreadState(PyThreadState* tstate) |
| { |
| /* If autoTLSkey isn't initialized, this must be the very first |
| threadstate created in Py_Initialize(). Don't do anything for now |
| (we'll be back here when _PyGILState_Init is called). */ |
| if (!autoInterpreterState) |
| return; |
| |
| /* Stick the thread state for this thread in thread local storage. |
| |
| The only situation where you can legitimately have more than one |
| thread state for an OS level thread is when there are multiple |
| interpreters, when: |
| |
| a) You shouldn't really be using the PyGILState_ APIs anyway, |
| and: |
| |
| b) The slightly odd way PyThread_set_key_value works (see |
| comments by its implementation) means that the first thread |
| state created for that given OS level thread will "win", |
| which seems reasonable behaviour. |
| */ |
| if (PyThread_set_key_value(autoTLSkey, (void *)tstate) < 0) |
| Py_FatalError("Couldn't create autoTLSkey mapping"); |
| |
| /* PyGILState_Release must not try to delete this thread state. */ |
| tstate->gilstate_counter = 1; |
| } |
| |
| /* The public functions */ |
| PyThreadState * |
| PyGILState_GetThisThreadState(void) |
| { |
| if (autoInterpreterState == NULL) |
| return NULL; |
| return (PyThreadState *)PyThread_get_key_value(autoTLSkey); |
| } |
| |
| PyGILState_STATE |
| PyGILState_Ensure(void) |
| { |
| int current; |
| PyThreadState *tcur; |
| /* Note that we do not auto-init Python here - apart from |
| potential races with 2 threads auto-initializing, pep-311 |
| spells out other issues. Embedders are expected to have |
| called Py_Initialize() and usually PyEval_InitThreads(). |
| */ |
| assert(autoInterpreterState); /* Py_Initialize() hasn't been called! */ |
| tcur = (PyThreadState *)PyThread_get_key_value(autoTLSkey); |
| if (tcur == NULL) { |
| /* Create a new thread state for this thread */ |
| tcur = PyThreadState_New(autoInterpreterState); |
| if (tcur == NULL) |
| Py_FatalError("Couldn't create thread-state for new thread"); |
| /* This is our thread state! We'll need to delete it in the |
| matching call to PyGILState_Release(). */ |
| tcur->gilstate_counter = 0; |
| current = 0; /* new thread state is never current */ |
| } |
| else |
| current = PyThreadState_IsCurrent(tcur); |
| if (current == 0) |
| PyEval_RestoreThread(tcur); |
| /* Update our counter in the thread-state - no need for locks: |
| - tcur will remain valid as we hold the GIL. |
| - the counter is safe as we are the only thread "allowed" |
| to modify this value |
| */ |
| ++tcur->gilstate_counter; |
| return current ? PyGILState_LOCKED : PyGILState_UNLOCKED; |
| } |
| |
| void |
| PyGILState_Release(PyGILState_STATE oldstate) |
| { |
| PyThreadState *tcur = (PyThreadState *)PyThread_get_key_value( |
| autoTLSkey); |
| if (tcur == NULL) |
| Py_FatalError("auto-releasing thread-state, " |
| "but no thread-state for this thread"); |
| /* We must hold the GIL and have our thread state current */ |
| /* XXX - remove the check - the assert should be fine, |
| but while this is very new (April 2003), the extra check |
| by release-only users can't hurt. |
| */ |
| if (! PyThreadState_IsCurrent(tcur)) |
| Py_FatalError("This thread state must be current when releasing"); |
| assert(PyThreadState_IsCurrent(tcur)); |
| --tcur->gilstate_counter; |
| assert(tcur->gilstate_counter >= 0); /* illegal counter value */ |
| |
| /* If we're going to destroy this thread-state, we must |
| * clear it while the GIL is held, as destructors may run. |
| */ |
| if (tcur->gilstate_counter == 0) { |
| /* can't have been locked when we created it */ |
| assert(oldstate == PyGILState_UNLOCKED); |
| PyThreadState_Clear(tcur); |
| /* Delete the thread-state. Note this releases the GIL too! |
| * It's vital that the GIL be held here, to avoid shutdown |
| * races; see bugs 225673 and 1061968 (that nasty bug has a |
| * habit of coming back). |
| */ |
| PyThreadState_DeleteCurrent(); |
| } |
| /* Release the lock if necessary */ |
| else if (oldstate == PyGILState_UNLOCKED) |
| PyEval_SaveThread(); |
| } |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif /* WITH_THREAD */ |
| |
| |