450 lines
11 KiB
C
450 lines
11 KiB
C
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/* Thread and interpreter state structures and their interfaces */
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#include "Python.h"
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#ifdef HAVE_DLOPEN
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#ifdef HAVE_DLFCN_H
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#include <dlfcn.h>
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#endif
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#ifndef RTLD_LAZY
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#define RTLD_LAZY 1
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#endif
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#endif
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#define ZAP(x) { \
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PyObject *tmp = (PyObject *)(x); \
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(x) = NULL; \
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Py_XDECREF(tmp); \
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}
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#ifdef WITH_THREAD
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#include "pythread.h"
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static PyThread_type_lock head_mutex = NULL; /* Protects interp->tstate_head */
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#define HEAD_INIT() (void)(head_mutex || (head_mutex = PyThread_allocate_lock()))
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#define HEAD_LOCK() PyThread_acquire_lock(head_mutex, WAIT_LOCK)
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#define HEAD_UNLOCK() PyThread_release_lock(head_mutex)
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#else
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#define HEAD_INIT() /* Nothing */
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#define HEAD_LOCK() /* Nothing */
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#define HEAD_UNLOCK() /* Nothing */
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#endif
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static PyInterpreterState *interp_head = NULL;
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PyThreadState *_PyThreadState_Current = NULL;
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PyThreadFrameGetter _PyThreadState_GetFrame = NULL;
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PyInterpreterState *
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PyInterpreterState_New(void)
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{
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PyInterpreterState *interp = PyMem_NEW(PyInterpreterState, 1);
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if (interp != NULL) {
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HEAD_INIT();
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interp->modules = NULL;
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interp->sysdict = NULL;
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interp->builtins = NULL;
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interp->tstate_head = NULL;
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interp->codec_search_path = NULL;
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interp->codec_search_cache = NULL;
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interp->codec_error_registry = NULL;
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#ifdef HAVE_DLOPEN
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#ifdef RTLD_NOW
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interp->dlopenflags = RTLD_NOW;
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#else
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interp->dlopenflags = RTLD_LAZY;
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#endif
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#endif
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HEAD_LOCK();
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interp->next = interp_head;
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interp_head = interp;
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HEAD_UNLOCK();
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}
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return interp;
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}
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void
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PyInterpreterState_Clear(PyInterpreterState *interp)
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{
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PyThreadState *p;
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HEAD_LOCK();
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for (p = interp->tstate_head; p != NULL; p = p->next)
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PyThreadState_Clear(p);
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HEAD_UNLOCK();
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ZAP(interp->codec_search_path);
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ZAP(interp->codec_search_cache);
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ZAP(interp->codec_error_registry);
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ZAP(interp->modules);
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ZAP(interp->sysdict);
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ZAP(interp->builtins);
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}
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static void
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zapthreads(PyInterpreterState *interp)
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{
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PyThreadState *p;
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/* No need to lock the mutex here because this should only happen
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when the threads are all really dead (XXX famous last words). */
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while ((p = interp->tstate_head) != NULL) {
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PyThreadState_Delete(p);
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}
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}
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void
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PyInterpreterState_Delete(PyInterpreterState *interp)
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{
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PyInterpreterState **p;
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zapthreads(interp);
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HEAD_LOCK();
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for (p = &interp_head; ; p = &(*p)->next) {
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if (*p == NULL)
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Py_FatalError(
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"PyInterpreterState_Delete: invalid interp");
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if (*p == interp)
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break;
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}
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if (interp->tstate_head != NULL)
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Py_FatalError("PyInterpreterState_Delete: remaining threads");
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*p = interp->next;
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HEAD_UNLOCK();
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PyMem_DEL(interp);
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}
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/* Default implementation for _PyThreadState_GetFrame */
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static struct _frame *
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threadstate_getframe(PyThreadState *self)
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{
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return self->frame;
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}
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PyThreadState *
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PyThreadState_New(PyInterpreterState *interp)
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{
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PyThreadState *tstate = PyMem_NEW(PyThreadState, 1);
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if (_PyThreadState_GetFrame == NULL)
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_PyThreadState_GetFrame = threadstate_getframe;
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if (tstate != NULL) {
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tstate->interp = interp;
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tstate->frame = NULL;
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tstate->recursion_depth = 0;
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tstate->tracing = 0;
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tstate->use_tracing = 0;
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tstate->tick_counter = 0;
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tstate->gilstate_counter = 0;
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tstate->dict = NULL;
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tstate->curexc_type = NULL;
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tstate->curexc_value = NULL;
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tstate->curexc_traceback = NULL;
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tstate->exc_type = NULL;
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tstate->exc_value = NULL;
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tstate->exc_traceback = NULL;
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tstate->c_profilefunc = NULL;
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tstate->c_tracefunc = NULL;
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tstate->c_profileobj = NULL;
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tstate->c_traceobj = NULL;
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HEAD_LOCK();
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tstate->next = interp->tstate_head;
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interp->tstate_head = tstate;
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HEAD_UNLOCK();
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}
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return tstate;
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}
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void
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PyThreadState_Clear(PyThreadState *tstate)
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{
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if (Py_VerboseFlag && tstate->frame != NULL)
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fprintf(stderr,
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"PyThreadState_Clear: warning: thread still has a frame\n");
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ZAP(tstate->frame);
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ZAP(tstate->dict);
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ZAP(tstate->curexc_type);
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ZAP(tstate->curexc_value);
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ZAP(tstate->curexc_traceback);
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ZAP(tstate->exc_type);
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ZAP(tstate->exc_value);
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ZAP(tstate->exc_traceback);
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tstate->c_profilefunc = NULL;
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tstate->c_tracefunc = NULL;
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ZAP(tstate->c_profileobj);
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ZAP(tstate->c_traceobj);
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}
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/* Common code for PyThreadState_Delete() and PyThreadState_DeleteCurrent() */
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static void
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tstate_delete_common(PyThreadState *tstate)
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{
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PyInterpreterState *interp;
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PyThreadState **p;
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if (tstate == NULL)
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Py_FatalError("PyThreadState_Delete: NULL tstate");
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interp = tstate->interp;
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if (interp == NULL)
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Py_FatalError("PyThreadState_Delete: NULL interp");
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HEAD_LOCK();
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for (p = &interp->tstate_head; ; p = &(*p)->next) {
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if (*p == NULL)
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Py_FatalError(
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"PyThreadState_Delete: invalid tstate");
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if (*p == tstate)
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break;
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}
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*p = tstate->next;
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HEAD_UNLOCK();
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PyMem_DEL(tstate);
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}
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void
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PyThreadState_Delete(PyThreadState *tstate)
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{
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if (tstate == _PyThreadState_Current)
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Py_FatalError("PyThreadState_Delete: tstate is still current");
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tstate_delete_common(tstate);
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}
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#ifdef WITH_THREAD
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void
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PyThreadState_DeleteCurrent()
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{
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PyThreadState *tstate = _PyThreadState_Current;
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if (tstate == NULL)
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Py_FatalError(
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"PyThreadState_DeleteCurrent: no current tstate");
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_PyThreadState_Current = NULL;
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tstate_delete_common(tstate);
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PyEval_ReleaseLock();
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}
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#endif /* WITH_THREAD */
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PyThreadState *
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PyThreadState_Get(void)
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{
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if (_PyThreadState_Current == NULL)
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Py_FatalError("PyThreadState_Get: no current thread");
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return _PyThreadState_Current;
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}
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PyThreadState *
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PyThreadState_Swap(PyThreadState *new)
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{
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PyThreadState *old = _PyThreadState_Current;
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_PyThreadState_Current = new;
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/* It should not be possible for more than one thread state
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to be used for a thread. Check this the best we can in debug
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builds.
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*/
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#if defined(Py_DEBUG) && defined(WITH_THREAD)
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if (new) {
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PyThreadState *check = PyGILState_GetThisThreadState();
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if (check && check != new)
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Py_FatalError("Invalid thread state for this thread");
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}
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#endif
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return old;
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}
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/* An extension mechanism to store arbitrary additional per-thread state.
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PyThreadState_GetDict() returns a dictionary that can be used to hold such
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state; the caller should pick a unique key and store its state there. If
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PyThreadState_GetDict() returns NULL, an exception has *not* been raised
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and the caller should assume no per-thread state is available. */
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PyObject *
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PyThreadState_GetDict(void)
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{
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if (_PyThreadState_Current == NULL)
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return NULL;
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if (_PyThreadState_Current->dict == NULL) {
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PyObject *d;
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_PyThreadState_Current->dict = d = PyDict_New();
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if (d == NULL)
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PyErr_Clear();
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}
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return _PyThreadState_Current->dict;
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}
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/* Routines for advanced debuggers, requested by David Beazley.
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Don't use unless you know what you are doing! */
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PyInterpreterState *
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PyInterpreterState_Head(void)
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{
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return interp_head;
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}
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PyInterpreterState *
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PyInterpreterState_Next(PyInterpreterState *interp) {
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return interp->next;
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}
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PyThreadState *
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PyInterpreterState_ThreadHead(PyInterpreterState *interp) {
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return interp->tstate_head;
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}
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PyThreadState *
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PyThreadState_Next(PyThreadState *tstate) {
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return tstate->next;
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}
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/* Python "auto thread state" API. */
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#ifdef WITH_THREAD
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/* Keep this as a static, as it is not reliable! It can only
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ever be compared to the state for the *current* thread.
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* If not equal, then it doesn't matter that the actual
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value may change immediately after comparison, as it can't
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possibly change to the current thread's state.
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* If equal, then the current thread holds the lock, so the value can't
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change until we yield the lock.
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*/
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static int
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PyThreadState_IsCurrent(PyThreadState *tstate)
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{
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/* Must be the tstate for this thread */
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assert(PyGILState_GetThisThreadState()==tstate);
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/* On Windows at least, simple reads and writes to 32 bit values
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are atomic.
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*/
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return tstate == _PyThreadState_Current;
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}
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/* The single PyInterpreterState used by this process'
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GILState implementation
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*/
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static PyInterpreterState *autoInterpreterState = NULL;
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static int autoTLSkey = 0;
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/* Internal initialization/finalization functions called by
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Py_Initialize/Py_Finalize
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*/
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void _PyGILState_Init(PyInterpreterState *i, PyThreadState *t)
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{
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assert(i && t); /* must init with a valid states */
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autoTLSkey = PyThread_create_key();
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autoInterpreterState = i;
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/* Now stash the thread state for this thread in TLS */
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PyThread_set_key_value(autoTLSkey, (void *)t);
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assert(t->gilstate_counter==0); /* must be a new thread state */
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t->gilstate_counter = 1;
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}
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void _PyGILState_Fini(void)
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{
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PyThread_delete_key(autoTLSkey);
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autoTLSkey = 0;
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autoInterpreterState = NULL;;
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}
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/* The public functions */
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PyThreadState *PyGILState_GetThisThreadState(void)
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{
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if (autoInterpreterState==NULL || autoTLSkey==0)
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return NULL;
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return (PyThreadState *) PyThread_get_key_value(autoTLSkey);
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}
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PyGILState_STATE PyGILState_Ensure(void)
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{
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int current;
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PyThreadState *tcur;
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/* Note that we do not auto-init Python here - apart from
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potential races with 2 threads auto-initializing, pep-311
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spells out other issues. Embedders are expected to have
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called Py_Initialize() and usually PyEval_InitThreads().
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*/
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assert(autoInterpreterState); /* Py_Initialize() hasn't been called! */
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tcur = PyThread_get_key_value(autoTLSkey);
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if (tcur==NULL) {
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/* Create a new thread state for this thread */
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tcur = PyThreadState_New(autoInterpreterState);
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if (tcur==NULL)
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Py_FatalError("Couldn't create thread-state for new thread");
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PyThread_set_key_value(autoTLSkey, (void *)tcur);
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current = 0; /* new thread state is never current */
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} else
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current = PyThreadState_IsCurrent(tcur);
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if (!current)
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PyEval_RestoreThread(tcur);
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/* Update our counter in the thread-state - no need for locks:
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- tcur will remain valid as we hold the GIL.
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- the counter is safe as we are the only thread "allowed"
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to modify this value
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*/
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tcur->gilstate_counter++;
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return current ? PyGILState_LOCKED : PyGILState_UNLOCKED;
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}
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void PyGILState_Release(PyGILState_STATE oldstate)
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{
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PyThreadState *tcur = PyThread_get_key_value(autoTLSkey);
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if (tcur==NULL)
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Py_FatalError("auto-releasing thread-state, "
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"but no thread-state for this thread");
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/* We must hold the GIL and have our thread state current */
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/* XXX - remove the check - the assert should be fine,
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but while this is very new (April 2003), the extra check
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by release-only users can't hurt.
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*/
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if (!PyThreadState_IsCurrent(tcur))
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Py_FatalError("This thread state must be current when releasing");
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assert (PyThreadState_IsCurrent(tcur));
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tcur->gilstate_counter -= 1;
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assert (tcur->gilstate_counter >= 0); /* illegal counter value */
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/* If we are about to destroy this thread-state, we must
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clear it while the lock is held, as destructors may run
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*/
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if (tcur->gilstate_counter==0) {
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/* can't have been locked when we created it */
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assert(oldstate==PyGILState_UNLOCKED);
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PyThreadState_Clear(tcur);
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}
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/* Release the lock if necessary */
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if (oldstate==PyGILState_UNLOCKED)
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PyEval_ReleaseThread(tcur);
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/* Now complete destruction of the thread if necessary */
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if (tcur->gilstate_counter==0) {
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/* Delete this thread from our TLS */
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PyThread_delete_key_value(autoTLSkey);
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/* Delete the thread-state */
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PyThreadState_Delete(tcur);
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}
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}
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#endif /* WITH_THREAD */
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