mirror of
https://github.com/python/cpython.git
synced 2024-11-24 00:38:00 +01:00
8cc5aa47ee
Instead of surprise crashes and memory corruption, we now hang threads that attempt to re-enter the Python interpreter after Python runtime finalization has started. These are typically daemon threads (our long standing mis-feature) but could also be threads spawned by extension modules that then try to call into Python. This marks the `PyThread_exit_thread` public C API as deprecated as there is no plausible safe way to accomplish that on any supported platform in the face of things like C++ code with finalizers anywhere on a thread's stack. Doing this was the least bad option. Co-authored-by: Gregory P. Smith <greg@krypto.org>
532 lines
12 KiB
C
532 lines
12 KiB
C
#include "pycore_interp.h" // _PyInterpreterState.threads.stacksize
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#include "pycore_time.h" // _PyTime_AsMicroseconds()
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/* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
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/* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */
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/* Eliminated some memory leaks, gsw@agere.com */
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#include <windows.h>
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#include <limits.h>
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#ifdef HAVE_PROCESS_H
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#include <process.h>
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#endif
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/* options */
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#ifndef _PY_USE_CV_LOCKS
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#define _PY_USE_CV_LOCKS 1 /* use locks based on cond vars */
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#endif
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/* Now, define a non-recursive mutex using either condition variables
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* and critical sections (fast) or using operating system mutexes
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* (slow)
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*/
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#if _PY_USE_CV_LOCKS
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#include "condvar.h"
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typedef struct _NRMUTEX
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{
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PyMUTEX_T cs;
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PyCOND_T cv;
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int locked;
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} NRMUTEX;
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typedef NRMUTEX *PNRMUTEX;
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static PNRMUTEX
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AllocNonRecursiveMutex(void)
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{
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PNRMUTEX m = (PNRMUTEX)PyMem_RawMalloc(sizeof(NRMUTEX));
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if (!m)
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return NULL;
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if (PyCOND_INIT(&m->cv))
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goto fail;
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if (PyMUTEX_INIT(&m->cs)) {
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PyCOND_FINI(&m->cv);
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goto fail;
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}
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m->locked = 0;
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return m;
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fail:
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PyMem_RawFree(m);
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return NULL;
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}
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static VOID
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FreeNonRecursiveMutex(PNRMUTEX mutex)
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{
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if (mutex) {
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PyCOND_FINI(&mutex->cv);
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PyMUTEX_FINI(&mutex->cs);
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PyMem_RawFree(mutex);
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}
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}
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static DWORD
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EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
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{
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DWORD result = WAIT_OBJECT_0;
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if (PyMUTEX_LOCK(&mutex->cs))
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return WAIT_FAILED;
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if (milliseconds == INFINITE) {
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while (mutex->locked) {
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if (PyCOND_WAIT(&mutex->cv, &mutex->cs)) {
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result = WAIT_FAILED;
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break;
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}
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}
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} else if (milliseconds != 0) {
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/* wait at least until the deadline */
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PyTime_t timeout = (PyTime_t)milliseconds * (1000 * 1000);
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PyTime_t deadline = _PyDeadline_Init(timeout);
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while (mutex->locked) {
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PyTime_t microseconds = _PyTime_AsMicroseconds(timeout,
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_PyTime_ROUND_TIMEOUT);
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if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, microseconds) < 0) {
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result = WAIT_FAILED;
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break;
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}
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timeout = _PyDeadline_Get(deadline);
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if (timeout <= 0) {
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break;
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}
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}
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}
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if (!mutex->locked) {
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mutex->locked = 1;
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result = WAIT_OBJECT_0;
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} else if (result == WAIT_OBJECT_0)
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result = WAIT_TIMEOUT;
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/* else, it is WAIT_FAILED */
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PyMUTEX_UNLOCK(&mutex->cs); /* must ignore result here */
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return result;
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}
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static BOOL
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LeaveNonRecursiveMutex(PNRMUTEX mutex)
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{
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BOOL result;
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if (PyMUTEX_LOCK(&mutex->cs))
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return FALSE;
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mutex->locked = 0;
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/* condvar APIs return 0 on success. We need to return TRUE on success. */
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result = !PyCOND_SIGNAL(&mutex->cv);
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PyMUTEX_UNLOCK(&mutex->cs);
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return result;
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}
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#else /* if ! _PY_USE_CV_LOCKS */
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/* NR-locks based on a kernel mutex */
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#define PNRMUTEX HANDLE
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static PNRMUTEX
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AllocNonRecursiveMutex(void)
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{
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return CreateSemaphore(NULL, 1, 1, NULL);
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}
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static VOID
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FreeNonRecursiveMutex(PNRMUTEX mutex)
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{
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/* No in-use check */
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CloseHandle(mutex);
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}
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static DWORD
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EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
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{
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return WaitForSingleObjectEx(mutex, milliseconds, FALSE);
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}
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static BOOL
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LeaveNonRecursiveMutex(PNRMUTEX mutex)
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{
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return ReleaseSemaphore(mutex, 1, NULL);
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}
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#endif /* _PY_USE_CV_LOCKS */
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unsigned long PyThread_get_thread_ident(void);
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#ifdef PY_HAVE_THREAD_NATIVE_ID
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unsigned long PyThread_get_thread_native_id(void);
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#endif
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/*
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* Initialization for the current runtime.
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*/
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static void
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PyThread__init_thread(void)
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{
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// Initialization of the C package should not be needed.
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}
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/*
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* Thread support.
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*/
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typedef struct {
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void (*func)(void*);
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void *arg;
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} callobj;
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/* thunker to call adapt between the function type used by the system's
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thread start function and the internally used one. */
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static unsigned __stdcall
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bootstrap(void *call)
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{
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callobj *obj = (callobj*)call;
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void (*func)(void*) = obj->func;
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void *arg = obj->arg;
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HeapFree(GetProcessHeap(), 0, obj);
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func(arg);
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return 0;
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}
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int
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PyThread_start_joinable_thread(void (*func)(void *), void *arg,
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PyThread_ident_t* ident, PyThread_handle_t* handle) {
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HANDLE hThread;
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unsigned threadID;
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callobj *obj;
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if (!initialized)
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PyThread_init_thread();
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obj = (callobj*)HeapAlloc(GetProcessHeap(), 0, sizeof(*obj));
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if (!obj)
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return -1;
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obj->func = func;
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obj->arg = arg;
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PyThreadState *tstate = _PyThreadState_GET();
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size_t stacksize = tstate ? tstate->interp->threads.stacksize : 0;
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hThread = (HANDLE)_beginthreadex(0,
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Py_SAFE_DOWNCAST(stacksize, Py_ssize_t, unsigned int),
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bootstrap, obj,
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0, &threadID);
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if (hThread == 0) {
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/* I've seen errno == EAGAIN here, which means "there are
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* too many threads".
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*/
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HeapFree(GetProcessHeap(), 0, obj);
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return -1;
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}
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*ident = threadID;
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// The cast is safe since HANDLE is pointer-sized
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*handle = (PyThread_handle_t) hThread;
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return 0;
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}
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unsigned long
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PyThread_start_new_thread(void (*func)(void *), void *arg) {
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PyThread_handle_t handle;
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PyThread_ident_t ident;
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if (PyThread_start_joinable_thread(func, arg, &ident, &handle)) {
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return PYTHREAD_INVALID_THREAD_ID;
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}
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CloseHandle((HANDLE) handle);
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// The cast is safe since the ident is really an unsigned int
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return (unsigned long) ident;
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}
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int
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PyThread_join_thread(PyThread_handle_t handle) {
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HANDLE hThread = (HANDLE) handle;
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int errored = (WaitForSingleObject(hThread, INFINITE) != WAIT_OBJECT_0);
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CloseHandle(hThread);
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return errored;
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}
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int
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PyThread_detach_thread(PyThread_handle_t handle) {
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HANDLE hThread = (HANDLE) handle;
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return (CloseHandle(hThread) == 0);
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}
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/*
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* Return the thread Id instead of a handle. The Id is said to uniquely identify the
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* thread in the system
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*/
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PyThread_ident_t
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PyThread_get_thread_ident_ex(void)
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{
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if (!initialized)
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PyThread_init_thread();
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return GetCurrentThreadId();
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}
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unsigned long
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PyThread_get_thread_ident(void)
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{
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return (unsigned long) PyThread_get_thread_ident_ex();
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}
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#ifdef PY_HAVE_THREAD_NATIVE_ID
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/*
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* Return the native Thread ID (TID) of the calling thread.
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* The native ID of a thread is valid and guaranteed to be unique system-wide
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* from the time the thread is created until the thread has been terminated.
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*/
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unsigned long
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PyThread_get_thread_native_id(void)
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{
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if (!initialized) {
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PyThread_init_thread();
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}
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DWORD native_id;
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native_id = GetCurrentThreadId();
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return (unsigned long) native_id;
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}
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#endif
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void _Py_NO_RETURN
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PyThread_exit_thread(void)
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{
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if (!initialized)
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exit(0);
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_endthreadex(0);
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}
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void _Py_NO_RETURN
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PyThread_hang_thread(void)
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{
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while (1) {
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SleepEx(INFINITE, TRUE);
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}
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}
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/*
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* Lock support. It has to be implemented as semaphores.
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* I [Dag] tried to implement it with mutex but I could find a way to
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* tell whether a thread already own the lock or not.
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*/
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PyThread_type_lock
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PyThread_allocate_lock(void)
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{
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PNRMUTEX mutex;
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if (!initialized)
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PyThread_init_thread();
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mutex = AllocNonRecursiveMutex() ;
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PyThread_type_lock aLock = (PyThread_type_lock) mutex;
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assert(aLock);
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return aLock;
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}
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void
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PyThread_free_lock(PyThread_type_lock aLock)
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{
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FreeNonRecursiveMutex(aLock) ;
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}
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// WaitForSingleObject() accepts timeout in milliseconds in the range
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// [0; 0xFFFFFFFE] (DWORD type). INFINITE value (0xFFFFFFFF) means no
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// timeout. 0xFFFFFFFE milliseconds is around 49.7 days.
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const DWORD TIMEOUT_MS_MAX = 0xFFFFFFFE;
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/*
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* Return 1 on success if the lock was acquired
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*
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* and 0 if the lock was not acquired. This means a 0 is returned
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* if the lock has already been acquired by this thread!
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*/
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PyLockStatus
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PyThread_acquire_lock_timed(PyThread_type_lock aLock,
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PY_TIMEOUT_T microseconds, int intr_flag)
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{
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assert(aLock);
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/* Fow now, intr_flag does nothing on Windows, and lock acquires are
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* uninterruptible. */
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PyLockStatus success;
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PY_TIMEOUT_T milliseconds;
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if (microseconds >= 0) {
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milliseconds = microseconds / 1000;
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// Round milliseconds away from zero
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if (microseconds % 1000 > 0) {
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milliseconds++;
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}
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if (milliseconds > (PY_TIMEOUT_T)TIMEOUT_MS_MAX) {
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// bpo-41710: PyThread_acquire_lock_timed() cannot report timeout
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// overflow to the caller, so clamp the timeout to
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// [0, TIMEOUT_MS_MAX] milliseconds.
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//
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// _thread.Lock.acquire() and _thread.RLock.acquire() raise an
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// OverflowError if microseconds is greater than PY_TIMEOUT_MAX.
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milliseconds = TIMEOUT_MS_MAX;
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}
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assert(milliseconds != INFINITE);
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}
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else {
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milliseconds = INFINITE;
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}
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if (EnterNonRecursiveMutex((PNRMUTEX)aLock,
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(DWORD)milliseconds) == WAIT_OBJECT_0) {
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success = PY_LOCK_ACQUIRED;
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}
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else {
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success = PY_LOCK_FAILURE;
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}
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return success;
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}
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int
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PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
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{
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return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0, 0);
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}
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void
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PyThread_release_lock(PyThread_type_lock aLock)
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{
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assert(aLock);
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(void)LeaveNonRecursiveMutex((PNRMUTEX) aLock);
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}
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/* minimum/maximum thread stack sizes supported */
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#define THREAD_MIN_STACKSIZE 0x8000 /* 32 KiB */
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#define THREAD_MAX_STACKSIZE 0x10000000 /* 256 MiB */
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/* set the thread stack size.
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* Return 0 if size is valid, -1 otherwise.
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*/
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static int
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_pythread_nt_set_stacksize(size_t size)
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{
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/* set to default */
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if (size == 0) {
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_PyInterpreterState_GET()->threads.stacksize = 0;
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return 0;
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}
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/* valid range? */
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if (size >= THREAD_MIN_STACKSIZE && size < THREAD_MAX_STACKSIZE) {
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_PyInterpreterState_GET()->threads.stacksize = size;
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return 0;
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}
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return -1;
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}
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#define THREAD_SET_STACKSIZE(x) _pythread_nt_set_stacksize(x)
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/* Thread Local Storage (TLS) API
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This API is DEPRECATED since Python 3.7. See PEP 539 for details.
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*/
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int
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PyThread_create_key(void)
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{
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DWORD result = TlsAlloc();
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if (result == TLS_OUT_OF_INDEXES)
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return -1;
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return (int)result;
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}
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void
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PyThread_delete_key(int key)
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{
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TlsFree(key);
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}
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int
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PyThread_set_key_value(int key, void *value)
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{
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BOOL ok = TlsSetValue(key, value);
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return ok ? 0 : -1;
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}
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void *
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PyThread_get_key_value(int key)
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{
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return TlsGetValue(key);
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}
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void
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PyThread_delete_key_value(int key)
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{
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/* NULL is used as "key missing", and it is also the default
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* given by TlsGetValue() if nothing has been set yet.
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*/
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TlsSetValue(key, NULL);
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}
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/* reinitialization of TLS is not necessary after fork when using
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* the native TLS functions. And forking isn't supported on Windows either.
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*/
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void
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PyThread_ReInitTLS(void)
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{
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}
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/* Thread Specific Storage (TSS) API
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Platform-specific components of TSS API implementation.
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*/
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int
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PyThread_tss_create(Py_tss_t *key)
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{
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assert(key != NULL);
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/* If the key has been created, function is silently skipped. */
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if (key->_is_initialized) {
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return 0;
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}
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DWORD result = TlsAlloc();
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if (result == TLS_OUT_OF_INDEXES) {
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return -1;
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}
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/* In Windows, platform-specific key type is DWORD. */
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key->_key = result;
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key->_is_initialized = 1;
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return 0;
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}
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void
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PyThread_tss_delete(Py_tss_t *key)
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{
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assert(key != NULL);
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/* If the key has not been created, function is silently skipped. */
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if (!key->_is_initialized) {
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return;
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}
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TlsFree(key->_key);
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key->_key = TLS_OUT_OF_INDEXES;
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key->_is_initialized = 0;
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}
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int
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PyThread_tss_set(Py_tss_t *key, void *value)
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{
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assert(key != NULL);
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BOOL ok = TlsSetValue(key->_key, value);
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return ok ? 0 : -1;
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}
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void *
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PyThread_tss_get(Py_tss_t *key)
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{
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assert(key != NULL);
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int err = GetLastError();
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void *r = TlsGetValue(key->_key);
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if (r || !GetLastError()) {
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SetLastError(err);
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}
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return r;
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}
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