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cpython/Python/thread_nt.h

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#include "pycore_interp.h" // _PyInterpreterState.threads.stacksize
/* This code implemented by Dag.Gruneau@elsa.preseco.comm.se */
/* Fast NonRecursiveMutex support by Yakov Markovitch, markovitch@iso.ru */
/* Eliminated some memory leaks, gsw@agere.com */
#include <windows.h>
#include <limits.h>
#ifdef HAVE_PROCESS_H
#include <process.h>
#endif
/* options */
#ifndef _PY_USE_CV_LOCKS
#define _PY_USE_CV_LOCKS 1 /* use locks based on cond vars */
#endif
/* Now, define a non-recursive mutex using either condition variables
* and critical sections (fast) or using operating system mutexes
* (slow)
*/
#if _PY_USE_CV_LOCKS
#include "condvar.h"
typedef struct _NRMUTEX
{
PyMUTEX_T cs;
PyCOND_T cv;
int locked;
} NRMUTEX;
typedef NRMUTEX *PNRMUTEX;
static PNRMUTEX
AllocNonRecursiveMutex(void)
{
PNRMUTEX m = (PNRMUTEX)PyMem_RawMalloc(sizeof(NRMUTEX));
if (!m)
return NULL;
if (PyCOND_INIT(&m->cv))
goto fail;
if (PyMUTEX_INIT(&m->cs)) {
PyCOND_FINI(&m->cv);
goto fail;
}
m->locked = 0;
return m;
fail:
PyMem_RawFree(m);
return NULL;
}
static VOID
FreeNonRecursiveMutex(PNRMUTEX mutex)
{
if (mutex) {
PyCOND_FINI(&mutex->cv);
PyMUTEX_FINI(&mutex->cs);
PyMem_RawFree(mutex);
}
}
static DWORD
EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
{
DWORD result = WAIT_OBJECT_0;
if (PyMUTEX_LOCK(&mutex->cs))
return WAIT_FAILED;
if (milliseconds == INFINITE) {
while (mutex->locked) {
if (PyCOND_WAIT(&mutex->cv, &mutex->cs)) {
result = WAIT_FAILED;
break;
}
}
} else if (milliseconds != 0) {
/* wait at least until the deadline */
_PyTime_t nanoseconds = _PyTime_FromNanoseconds((_PyTime_t)milliseconds * 1000000);
_PyTime_t deadline = _PyTime_Add(_PyTime_GetPerfCounter(), nanoseconds);
while (mutex->locked) {
_PyTime_t microseconds = _PyTime_AsMicroseconds(nanoseconds,
_PyTime_ROUND_TIMEOUT);
if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, microseconds) < 0) {
result = WAIT_FAILED;
break;
}
nanoseconds = deadline - _PyTime_GetPerfCounter();
if (nanoseconds <= 0) {
break;
}
}
}
if (!mutex->locked) {
mutex->locked = 1;
result = WAIT_OBJECT_0;
} else if (result == WAIT_OBJECT_0)
result = WAIT_TIMEOUT;
/* else, it is WAIT_FAILED */
PyMUTEX_UNLOCK(&mutex->cs); /* must ignore result here */
return result;
}
static BOOL
LeaveNonRecursiveMutex(PNRMUTEX mutex)
{
BOOL result;
if (PyMUTEX_LOCK(&mutex->cs))
return FALSE;
mutex->locked = 0;
/* condvar APIs return 0 on success. We need to return TRUE on success. */
result = !PyCOND_SIGNAL(&mutex->cv);
PyMUTEX_UNLOCK(&mutex->cs);
return result;
}
#else /* if ! _PY_USE_CV_LOCKS */
/* NR-locks based on a kernel mutex */
#define PNRMUTEX HANDLE
static PNRMUTEX
AllocNonRecursiveMutex(void)
{
return CreateSemaphore(NULL, 1, 1, NULL);
}
static VOID
FreeNonRecursiveMutex(PNRMUTEX mutex)
{
/* No in-use check */
CloseHandle(mutex);
}
static DWORD
EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
{
return WaitForSingleObjectEx(mutex, milliseconds, FALSE);
}
static BOOL
LeaveNonRecursiveMutex(PNRMUTEX mutex)
{
return ReleaseSemaphore(mutex, 1, NULL);
}
#endif /* _PY_USE_CV_LOCKS */
unsigned long PyThread_get_thread_ident(void);
#ifdef PY_HAVE_THREAD_NATIVE_ID
unsigned long PyThread_get_thread_native_id(void);
#endif
/*
* Initialization for the current runtime.
*/
static void
PyThread__init_thread(void)
{
// Initialization of the C package should not be needed.
}
/*
* Thread support.
*/
typedef struct {
void (*func)(void*);
void *arg;
} callobj;
/* thunker to call adapt between the function type used by the system's
thread start function and the internally used one. */
static unsigned __stdcall
bootstrap(void *call)
{
callobj *obj = (callobj*)call;
void (*func)(void*) = obj->func;
void *arg = obj->arg;
HeapFree(GetProcessHeap(), 0, obj);
func(arg);
return 0;
}
int
PyThread_start_joinable_thread(void (*func)(void *), void *arg,
PyThread_ident_t* ident, PyThread_handle_t* handle) {
HANDLE hThread;
unsigned threadID;
callobj *obj;
if (!initialized)
PyThread_init_thread();
obj = (callobj*)HeapAlloc(GetProcessHeap(), 0, sizeof(*obj));
if (!obj)
return -1;
obj->func = func;
obj->arg = arg;
PyThreadState *tstate = _PyThreadState_GET();
size_t stacksize = tstate ? tstate->interp->threads.stacksize : 0;
hThread = (HANDLE)_beginthreadex(0,
Py_SAFE_DOWNCAST(stacksize, Py_ssize_t, unsigned int),
bootstrap, obj,
0, &threadID);
if (hThread == 0) {
/* I've seen errno == EAGAIN here, which means "there are
* too many threads".
*/
HeapFree(GetProcessHeap(), 0, obj);
return -1;
}
*ident = threadID;
// The cast is safe since HANDLE is pointer-sized
*handle = (PyThread_handle_t) hThread;
return 0;
}
unsigned long
PyThread_start_new_thread(void (*func)(void *), void *arg) {
PyThread_handle_t handle;
PyThread_ident_t ident;
if (PyThread_start_joinable_thread(func, arg, &ident, &handle)) {
return PYTHREAD_INVALID_THREAD_ID;
}
CloseHandle((HANDLE) handle);
// The cast is safe since the ident is really an unsigned int
return (unsigned long) ident;
}
int
PyThread_join_thread(PyThread_handle_t handle) {
HANDLE hThread = (HANDLE) handle;
int errored = (WaitForSingleObject(hThread, INFINITE) != WAIT_OBJECT_0);
CloseHandle(hThread);
return errored;
}
int
PyThread_detach_thread(PyThread_handle_t handle) {
HANDLE hThread = (HANDLE) handle;
return (CloseHandle(hThread) == 0);
}
void
PyThread_update_thread_after_fork(PyThread_ident_t* ident, PyThread_handle_t* handle) {
}
/*
* Return the thread Id instead of a handle. The Id is said to uniquely identify the
* thread in the system
*/
PyThread_ident_t
PyThread_get_thread_ident_ex(void)
{
if (!initialized)
PyThread_init_thread();
return GetCurrentThreadId();
}
unsigned long
PyThread_get_thread_ident(void)
{
return (unsigned long) PyThread_get_thread_ident_ex();
}
#ifdef PY_HAVE_THREAD_NATIVE_ID
/*
* Return the native Thread ID (TID) of the calling thread.
* The native ID of a thread is valid and guaranteed to be unique system-wide
* from the time the thread is created until the thread has been terminated.
*/
unsigned long
PyThread_get_thread_native_id(void)
{
if (!initialized) {
PyThread_init_thread();
}
DWORD native_id;
native_id = GetCurrentThreadId();
return (unsigned long) native_id;
}
#endif
void _Py_NO_RETURN
PyThread_exit_thread(void)
{
if (!initialized)
exit(0);
_endthreadex(0);
}
/*
* Lock support. It has to be implemented as semaphores.
* I [Dag] tried to implement it with mutex but I could find a way to
* tell whether a thread already own the lock or not.
*/
PyThread_type_lock
PyThread_allocate_lock(void)
{
PNRMUTEX mutex;
if (!initialized)
PyThread_init_thread();
mutex = AllocNonRecursiveMutex() ;
PyThread_type_lock aLock = (PyThread_type_lock) mutex;
assert(aLock);
return aLock;
}
void
PyThread_free_lock(PyThread_type_lock aLock)
{
FreeNonRecursiveMutex(aLock) ;
}
// WaitForSingleObject() accepts timeout in milliseconds in the range
// [0; 0xFFFFFFFE] (DWORD type). INFINITE value (0xFFFFFFFF) means no
// timeout. 0xFFFFFFFE milliseconds is around 49.7 days.
const DWORD TIMEOUT_MS_MAX = 0xFFFFFFFE;
/*
* Return 1 on success if the lock was acquired
*
* and 0 if the lock was not acquired. This means a 0 is returned
* if the lock has already been acquired by this thread!
*/
PyLockStatus
PyThread_acquire_lock_timed(PyThread_type_lock aLock,
PY_TIMEOUT_T microseconds, int intr_flag)
{
assert(aLock);
/* Fow now, intr_flag does nothing on Windows, and lock acquires are
* uninterruptible. */
PyLockStatus success;
PY_TIMEOUT_T milliseconds;
if (microseconds >= 0) {
milliseconds = microseconds / 1000;
// Round milliseconds away from zero
if (microseconds % 1000 > 0) {
milliseconds++;
}
if (milliseconds > (PY_TIMEOUT_T)TIMEOUT_MS_MAX) {
// bpo-41710: PyThread_acquire_lock_timed() cannot report timeout
// overflow to the caller, so clamp the timeout to
// [0, TIMEOUT_MS_MAX] milliseconds.
//
// _thread.Lock.acquire() and _thread.RLock.acquire() raise an
// OverflowError if microseconds is greater than PY_TIMEOUT_MAX.
milliseconds = TIMEOUT_MS_MAX;
}
assert(milliseconds != INFINITE);
}
else {
milliseconds = INFINITE;
}
if (EnterNonRecursiveMutex((PNRMUTEX)aLock,
(DWORD)milliseconds) == WAIT_OBJECT_0) {
success = PY_LOCK_ACQUIRED;
}
else {
success = PY_LOCK_FAILURE;
}
return success;
}
int
PyThread_acquire_lock(PyThread_type_lock aLock, int waitflag)
{
return PyThread_acquire_lock_timed(aLock, waitflag ? -1 : 0, 0);
}
void
PyThread_release_lock(PyThread_type_lock aLock)
{
assert(aLock);
(void)LeaveNonRecursiveMutex((PNRMUTEX) aLock);
}
/* minimum/maximum thread stack sizes supported */
#define THREAD_MIN_STACKSIZE 0x8000 /* 32 KiB */
#define THREAD_MAX_STACKSIZE 0x10000000 /* 256 MiB */
/* set the thread stack size.
* Return 0 if size is valid, -1 otherwise.
*/
static int
_pythread_nt_set_stacksize(size_t size)
{
/* set to default */
if (size == 0) {
_PyInterpreterState_GET()->threads.stacksize = 0;
return 0;
}
/* valid range? */
if (size >= THREAD_MIN_STACKSIZE && size < THREAD_MAX_STACKSIZE) {
_PyInterpreterState_GET()->threads.stacksize = size;
return 0;
}
return -1;
}
#define THREAD_SET_STACKSIZE(x) _pythread_nt_set_stacksize(x)
/* Thread Local Storage (TLS) API
This API is DEPRECATED since Python 3.7. See PEP 539 for details.
*/
int
PyThread_create_key(void)
{
DWORD result = TlsAlloc();
if (result == TLS_OUT_OF_INDEXES)
return -1;
return (int)result;
}
void
PyThread_delete_key(int key)
{
TlsFree(key);
}
int
PyThread_set_key_value(int key, void *value)
{
BOOL ok = TlsSetValue(key, value);
return ok ? 0 : -1;
}
void *
PyThread_get_key_value(int key)
{
/* because TLS is used in the Py_END_ALLOW_THREAD macro,
* it is necessary to preserve the windows error state, because
* it is assumed to be preserved across the call to the macro.
* Ideally, the macro should be fixed, but it is simpler to
* do it here.
*/
DWORD error = GetLastError();
void *result = TlsGetValue(key);
SetLastError(error);
return result;
}
void
PyThread_delete_key_value(int key)
{
/* NULL is used as "key missing", and it is also the default
* given by TlsGetValue() if nothing has been set yet.
*/
TlsSetValue(key, NULL);
}
/* reinitialization of TLS is not necessary after fork when using
* the native TLS functions. And forking isn't supported on Windows either.
*/
void
PyThread_ReInitTLS(void)
{
}
/* Thread Specific Storage (TSS) API
Platform-specific components of TSS API implementation.
*/
int
PyThread_tss_create(Py_tss_t *key)
{
assert(key != NULL);
/* If the key has been created, function is silently skipped. */
if (key->_is_initialized) {
return 0;
}
DWORD result = TlsAlloc();
if (result == TLS_OUT_OF_INDEXES) {
return -1;
}
/* In Windows, platform-specific key type is DWORD. */
key->_key = result;
key->_is_initialized = 1;
return 0;
}
void
PyThread_tss_delete(Py_tss_t *key)
{
assert(key != NULL);
/* If the key has not been created, function is silently skipped. */
if (!key->_is_initialized) {
return;
}
TlsFree(key->_key);
key->_key = TLS_OUT_OF_INDEXES;
key->_is_initialized = 0;
}
int
PyThread_tss_set(Py_tss_t *key, void *value)
{
assert(key != NULL);
BOOL ok = TlsSetValue(key->_key, value);
return ok ? 0 : -1;
}
void *
PyThread_tss_get(Py_tss_t *key)
{
assert(key != NULL);
/* because TSS is used in the Py_END_ALLOW_THREAD macro,
* it is necessary to preserve the windows error state, because
* it is assumed to be preserved across the call to the macro.
* Ideally, the macro should be fixed, but it is simpler to
* do it here.
*/
DWORD error = GetLastError();
void *result = TlsGetValue(key->_key);
SetLastError(error);
return result;
}
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