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cpython/Python/thread.c

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/* Thread package.
This is intended to be usable independently from Python.
The implementation for system foobar is in a file thread_foobar.h
which is included by this file dependent on config settings.
Stuff shared by all thread_*.h files is collected here. */
#include "Python.h"
#include "pycore_ceval.h" // _PyEval_MakePendingCalls()
#include "pycore_pystate.h" // _PyInterpreterState_GET()
#include "pycore_structseq.h" // _PyStructSequence_FiniBuiltin()
#include "pycore_pythread.h" // _POSIX_THREADS
#ifndef DONT_HAVE_STDIO_H
# include <stdio.h>
#endif
#include <stdlib.h>
// Define PY_TIMEOUT_MAX constant.
#ifdef _POSIX_THREADS
// PyThread_acquire_lock_timed() uses _PyTime_FromNanoseconds(us * 1000),
// convert microseconds to nanoseconds.
# define PY_TIMEOUT_MAX_VALUE (LLONG_MAX / 1000)
#elif defined (NT_THREADS)
// 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.
# if 0xFFFFFFFELL < LLONG_MAX / 1000
# define PY_TIMEOUT_MAX_VALUE (0xFFFFFFFELL * 1000)
# else
# define PY_TIMEOUT_MAX_VALUE LLONG_MAX
# endif
#else
# define PY_TIMEOUT_MAX_VALUE LLONG_MAX
#endif
const long long PY_TIMEOUT_MAX = PY_TIMEOUT_MAX_VALUE;
static void PyThread__init_thread(void); /* Forward */
#define initialized _PyRuntime.threads.initialized
void
PyThread_init_thread(void)
{
if (initialized) {
return;
}
initialized = 1;
PyThread__init_thread();
}
#if defined(HAVE_PTHREAD_STUBS)
# define PYTHREAD_NAME "pthread-stubs"
# include "thread_pthread_stubs.h"
#elif defined(_USE_PTHREADS) /* AKA _PTHREADS */
# if defined(__EMSCRIPTEN__) && !defined(__EMSCRIPTEN_PTHREADS__)
# define PYTHREAD_NAME "pthread-stubs"
# else
# define PYTHREAD_NAME "pthread"
# endif
# include "thread_pthread.h"
#elif defined(NT_THREADS)
# define PYTHREAD_NAME "nt"
# include "thread_nt.h"
#else
# error "Require native threads. See https://bugs.python.org/issue31370"
#endif
/* return the current thread stack size */
size_t
PyThread_get_stacksize(void)
{
return _PyInterpreterState_GET()->threads.stacksize;
}
/* Only platforms defining a THREAD_SET_STACKSIZE() macro
in thread_<platform>.h support changing the stack size.
Return 0 if stack size is valid,
-1 if stack size value is invalid,
-2 if setting stack size is not supported. */
int
PyThread_set_stacksize(size_t size)
{
#if defined(THREAD_SET_STACKSIZE)
return THREAD_SET_STACKSIZE(size);
#else
return -2;
#endif
}
int
PyThread_ParseTimeoutArg(PyObject *arg, int blocking, PY_TIMEOUT_T *timeout_p)
{
assert(_PyTime_FromSeconds(-1) == PyThread_UNSET_TIMEOUT);
if (arg == NULL || arg == Py_None) {
*timeout_p = blocking ? PyThread_UNSET_TIMEOUT : 0;
return 0;
}
if (!blocking) {
PyErr_SetString(PyExc_ValueError,
"can't specify a timeout for a non-blocking call");
return -1;
}
PyTime_t timeout;
if (_PyTime_FromSecondsObject(&timeout, arg, _PyTime_ROUND_TIMEOUT) < 0) {
return -1;
}
if (timeout < 0) {
PyErr_SetString(PyExc_ValueError,
"timeout value must be a non-negative number");
return -1;
}
if (_PyTime_AsMicroseconds(timeout,
_PyTime_ROUND_TIMEOUT) > PY_TIMEOUT_MAX) {
PyErr_SetString(PyExc_OverflowError,
"timeout value is too large");
return -1;
}
*timeout_p = timeout;
return 0;
}
PyLockStatus
PyThread_acquire_lock_timed_with_retries(PyThread_type_lock lock,
PY_TIMEOUT_T timeout)
{
PyThreadState *tstate = _PyThreadState_GET();
PyTime_t endtime = 0;
if (timeout > 0) {
endtime = _PyDeadline_Init(timeout);
}
PyLockStatus r;
do {
PyTime_t microseconds;
microseconds = _PyTime_AsMicroseconds(timeout, _PyTime_ROUND_CEILING);
/* first a simple non-blocking try without releasing the GIL */
r = PyThread_acquire_lock_timed(lock, 0, 0);
if (r == PY_LOCK_FAILURE && microseconds != 0) {
Py_BEGIN_ALLOW_THREADS
r = PyThread_acquire_lock_timed(lock, microseconds, 1);
Py_END_ALLOW_THREADS
}
if (r == PY_LOCK_INTR) {
/* Run signal handlers if we were interrupted. Propagate
* exceptions from signal handlers, such as KeyboardInterrupt, by
* passing up PY_LOCK_INTR. */
if (_PyEval_MakePendingCalls(tstate) < 0) {
return PY_LOCK_INTR;
}
/* If we're using a timeout, recompute the timeout after processing
* signals, since those can take time. */
if (timeout > 0) {
timeout = _PyDeadline_Get(endtime);
/* Check for negative values, since those mean block forever.
*/
if (timeout < 0) {
r = PY_LOCK_FAILURE;
}
}
}
} while (r == PY_LOCK_INTR); /* Retry if we were interrupted. */
return r;
}
/* Thread Specific Storage (TSS) API
Cross-platform components of TSS API implementation.
*/
Py_tss_t *
PyThread_tss_alloc(void)
{
Py_tss_t *new_key = (Py_tss_t *)PyMem_RawMalloc(sizeof(Py_tss_t));
if (new_key == NULL) {
return NULL;
}
new_key->_is_initialized = 0;
return new_key;
}
void
PyThread_tss_free(Py_tss_t *key)
{
if (key != NULL) {
PyThread_tss_delete(key);
PyMem_RawFree((void *)key);
}
}
int
PyThread_tss_is_created(Py_tss_t *key)
{
assert(key != NULL);
return key->_is_initialized;
}
PyDoc_STRVAR(threadinfo__doc__,
"sys.thread_info\n\
\n\
A named tuple holding information about the thread implementation.");
static PyStructSequence_Field threadinfo_fields[] = {
{"name", "name of the thread implementation"},
{"lock", "name of the lock implementation"},
{"version", "name and version of the thread library"},
{0}
};
static PyStructSequence_Desc threadinfo_desc = {
"sys.thread_info", /* name */
threadinfo__doc__, /* doc */
threadinfo_fields, /* fields */
3
};
static PyTypeObject ThreadInfoType;
PyObject*
PyThread_GetInfo(void)
{
PyObject *threadinfo, *value;
int pos = 0;
#if (defined(_POSIX_THREADS) && defined(HAVE_CONFSTR) \
&& defined(_CS_GNU_LIBPTHREAD_VERSION))
char buffer[255];
int len;
#endif
PyInterpreterState *interp = _PyInterpreterState_GET();
if (_PyStructSequence_InitBuiltin(interp, &ThreadInfoType, &threadinfo_desc) < 0) {
return NULL;
}
threadinfo = PyStructSequence_New(&ThreadInfoType);
if (threadinfo == NULL)
return NULL;
value = PyUnicode_FromString(PYTHREAD_NAME);
if (value == NULL) {
Py_DECREF(threadinfo);
return NULL;
}
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
#ifdef HAVE_PTHREAD_STUBS
value = Py_NewRef(Py_None);
#elif defined(_POSIX_THREADS)
#ifdef USE_SEMAPHORES
value = PyUnicode_FromString("semaphore");
#else
value = PyUnicode_FromString("mutex+cond");
#endif
if (value == NULL) {
Py_DECREF(threadinfo);
return NULL;
}
#else
value = Py_NewRef(Py_None);
#endif
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
#if (defined(_POSIX_THREADS) && defined(HAVE_CONFSTR) \
&& defined(_CS_GNU_LIBPTHREAD_VERSION))
value = NULL;
len = confstr(_CS_GNU_LIBPTHREAD_VERSION, buffer, sizeof(buffer));
if (1 < len && (size_t)len < sizeof(buffer)) {
value = PyUnicode_DecodeFSDefaultAndSize(buffer, len-1);
if (value == NULL)
PyErr_Clear();
}
if (value == NULL)
#endif
{
value = Py_NewRef(Py_None);
}
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
return threadinfo;
}
void
_PyThread_FiniType(PyInterpreterState *interp)
{
_PyStructSequence_FiniBuiltin(interp, &ThreadInfoType);
}
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