Mercurial > lcfOS
diff cos/python/Python/pystate.c @ 27:7f74363f4c82
Added some files for the python port
author | windel |
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date | Tue, 27 Dec 2011 18:59:02 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/cos/python/Python/pystate.c Tue Dec 27 18:59:02 2011 +0100 @@ -0,0 +1,729 @@ + +/* 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) + + +/* 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; + +/* Assuming the current thread holds the GIL, this is the + PyThreadState for the current thread. */ +_Py_atomic_address _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; + interp->fscodec_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); +#ifdef WITH_THREAD + if (interp_head == NULL && head_mutex != NULL) { + PyThread_free_lock(head_mutex); + head_mutex = NULL; + } +#endif +} + + +/* 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 == _Py_atomic_load_relaxed(&_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*)_Py_atomic_load_relaxed( + &_PyThreadState_Current); + if (tstate == NULL) + Py_FatalError( + "PyThreadState_DeleteCurrent: no current tstate"); + _Py_atomic_store_relaxed(&_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) +{ + PyThreadState *tstate = (PyThreadState*)_Py_atomic_load_relaxed( + &_PyThreadState_Current); + if (tstate == NULL) + Py_FatalError("PyThreadState_Get: no current thread"); + + return tstate; +} + + +PyThreadState * +PyThreadState_Swap(PyThreadState *newts) +{ + PyThreadState *oldts = (PyThreadState*)_Py_atomic_load_relaxed( + &_PyThreadState_Current); + + _Py_atomic_store_relaxed(&_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) +{ + PyThreadState *tstate = (PyThreadState*)_Py_atomic_load_relaxed( + &_PyThreadState_Current); + if (tstate == NULL) + return NULL; + + if (tstate->dict == NULL) { + PyObject *d; + tstate->dict = d = PyDict_New(); + if (d == NULL) + PyErr_Clear(); + } + return tstate->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); + _PyEval_SignalAsyncExc(); + 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); + return tstate == _Py_atomic_load_relaxed(&_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(); + if (autoTLSkey == -1) + Py_FatalError("Could not allocate TLS entry"); + 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; +} + +/* Reset the TLS key - called by PyOS_AfterFork(). + * This should not be necessary, but some - buggy - pthread implementations + * don't reset TLS upon fork(), see issue #10517. + */ +void +_PyGILState_Reinit(void) +{ + PyThreadState *tstate = PyGILState_GetThisThreadState(); + PyThread_delete_key(autoTLSkey); + if ((autoTLSkey = PyThread_create_key()) == -1) + Py_FatalError("Could not allocate TLS entry"); + + /* If the thread had an associated auto thread state, reassociate it with + * the new key. */ + if (tstate && PyThread_set_key_value(autoTLSkey, (void *)tstate) < 0) + Py_FatalError("Couldn't create autoTLSkey mapping"); +} + +/* 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(); +} + +#endif /* WITH_THREAD */ + +