/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=4 sts=4 sw=4 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Python 3 │
│ https://docs.python.org/3/license.html │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "third_party/python/Include/pyerrors.h"
#include "third_party/python/Include/pymacro.h"
#include "third_party/python/Include/pymem.h"
#include "third_party/python/Include/pythread.h"
#include "third_party/python/Include/structseq.h"
/* clang-format off */
/* Thread package.
This is intended to be usable independently from Python.
The implementation for system foobar is in a file thread_foobar.inc
which is included by this file dependent on config settings.
Stuff shared by all thread_*.h files is collected here. */
#ifndef _POSIX_THREADS
/* Check if we're running on HP-UX and _SC_THREADS is defined. If so, then
enough of the Posix threads package is implemented to support python
threads.
This is valid for HP-UX 11.23 running on an ia64 system. If needed, add
a check of __ia64 to verify that we're running on an ia64 system instead
of a pa-risc system.
*/
#ifdef __hpux
#ifdef _SC_THREADS
#define _POSIX_THREADS
#endif
#endif
#endif /* _POSIX_THREADS */
#ifdef Py_DEBUG
static int thread_debug = 0;
#define dprintf(args) (void)((thread_debug & 1) && printf args)
#define d2printf(args) ((thread_debug & 8) && printf args)
#else
#define dprintf(args)
#define d2printf(args)
#endif
static int initialized;
static void PyThread__init_thread(void); /* Forward */
void
PyThread_init_thread(void)
{
#ifdef Py_DEBUG
char *p = Py_GETENV("PYTHONTHREADDEBUG");
if (p) {
if (*p)
thread_debug = atoi(p);
else
thread_debug = 1;
}
#endif /* Py_DEBUG */
if (initialized)
return;
initialized = 1;
dprintf(("PyThread_init_thread called\n"));
PyThread__init_thread();
}
/* Support for runtime thread stack size tuning.
A value of 0 means using the platform's default stack size
or the size specified by the THREAD_STACK_SIZE macro. */
static size_t _pythread_stacksize = 0;
#ifdef _POSIX_THREADS
#define PYTHREAD_NAME "pthread"
#include "thread_pthread.inc"
#endif
#ifdef NT_THREADS
#define PYTHREAD_NAME "nt"
#include "thread_nt.inc"
#endif
/*
#ifdef FOOBAR_THREADS
#include "thread_foobar.inc"
#endif
*/
/* return the current thread stack size */
size_t
PyThread_get_stacksize(void)
{
return _pythread_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
}
#ifndef Py_HAVE_NATIVE_TLS
/* If the platform has not supplied a platform specific
TLS implementation, provide our own.
This code stolen from "thread_sgi.h", where it was the only
implementation of an existing Python TLS API.
*/
/* ------------------------------------------------------------------------
Per-thread data ("key") support.
Use PyThread_create_key() to create a new key. This is typically shared
across threads.
Use PyThread_set_key_value(thekey, value) to associate void* value with
thekey in the current thread. Each thread has a distinct mapping of thekey
to a void* value. Caution: if the current thread already has a mapping
for thekey, value is ignored.
Use PyThread_get_key_value(thekey) to retrieve the void* value associated
with thekey in the current thread. This returns NULL if no value is
associated with thekey in the current thread.
Use PyThread_delete_key_value(thekey) to forget the current thread's associated
value for thekey. PyThread_delete_key(thekey) forgets the values associated
with thekey across *all* threads.
While some of these functions have error-return values, none set any
Python exception.
None of the functions does memory management on behalf of the void* values.
You need to allocate and deallocate them yourself. If the void* values
happen to be PyObject*, these functions don't do refcount operations on
them either.
The GIL does not need to be held when calling these functions; they supply
their own locking. This isn't true of PyThread_create_key(), though (see
next paragraph).
There's a hidden assumption that PyThread_create_key() will be called before
any of the other functions are called. There's also a hidden assumption
that calls to PyThread_create_key() are serialized externally.
------------------------------------------------------------------------ */
/* A singly-linked list of struct key objects remembers all the key->value
* associations. File static keyhead heads the list. keymutex is used
* to enforce exclusion internally.
*/
struct key {
/* Next record in the list, or NULL if this is the last record. */
struct key *next;
/* The thread id, according to PyThread_get_thread_ident(). */
long id;
/* The key and its associated value. */
int key;
void *value;
};
static struct key *keyhead = NULL;
static PyThread_type_lock keymutex = NULL;
static int nkeys = 0; /* PyThread_create_key() hands out nkeys+1 next */
/* Internal helper.
* If the current thread has a mapping for key, the appropriate struct key*
* is returned. NB: value is ignored in this case!
* If there is no mapping for key in the current thread, then:
* If value is NULL, NULL is returned.
* Else a mapping of key to value is created for the current thread,
* and a pointer to a new struct key* is returned; except that if
* malloc() can't find room for a new struct key*, NULL is returned.
* So when value==NULL, this acts like a pure lookup routine, and when
* value!=NULL, this acts like dict.setdefault(), returning an existing
* mapping if one exists, else creating a new mapping.
*
* Caution: this used to be too clever, trying to hold keymutex only
* around the "p->next = keyhead; keyhead = p" pair. That allowed
* another thread to mutate the list, via key deletion, concurrent with
* find_key() crawling over the list. Hilarity ensued. For example, when
* the for-loop here does "p = p->next", p could end up pointing at a
* record that PyThread_delete_key_value() was concurrently free()'ing.
* That could lead to anything, from failing to find a key that exists, to
* segfaults. Now we lock the whole routine.
*/
static struct key *
find_key(int set_value, int key, void *value)
{
struct key *p, *prev_p;
long id = PyThread_get_thread_ident();
if (!keymutex)
return NULL;
PyThread_acquire_lock(keymutex, 1);
prev_p = NULL;
for (p = keyhead; p != NULL; p = p->next) {
if (p->id == id && p->key == key) {
if (set_value)
p->value = value;
goto Done;
}
/* Sanity check. These states should never happen but if
* they do we must abort. Otherwise we'll end up spinning
* in a tight loop with the lock held. A similar check is done
* in pystate.c tstate_delete_common(). */
if (p == prev_p)
Py_FatalError("tls find_key: small circular list(!)");
prev_p = p;
if (p->next == keyhead)
Py_FatalError("tls find_key: circular list(!)");
}
if (!set_value && value == NULL) {
assert(p == NULL);
goto Done;
}
p = (struct key *)PyMem_RawMalloc(sizeof(struct key));
if (p != NULL) {
p->id = id;
p->key = key;
p->value = value;
p->next = keyhead;
keyhead = p;
}
Done:
PyThread_release_lock(keymutex);
return p;
}
/* Return a new key. This must be called before any other functions in
* this family, and callers must arrange to serialize calls to this
* function. No violations are detected.
*/
int
PyThread_create_key(void)
{
/* All parts of this function are wrong if it's called by multiple
* threads simultaneously.
*/
if (keymutex == NULL)
keymutex = PyThread_allocate_lock();
return ++nkeys;
}
/* Forget the associations for key across *all* threads. */
void
PyThread_delete_key(int key)
{
struct key *p, **q;
PyThread_acquire_lock(keymutex, 1);
q = &keyhead;
while ((p = *q) != NULL) {
if (p->key == key) {
*q = p->next;
PyMem_RawFree((void *)p);
/* NB This does *not* free p->value! */
}
else
q = &p->next;
}
PyThread_release_lock(keymutex);
}
int
PyThread_set_key_value(int key, void *value)
{
struct key *p;
p = find_key(1, key, value);
if (p == NULL)
return -1;
else
return 0;
}
/* Retrieve the value associated with key in the current thread, or NULL
* if the current thread doesn't have an association for key.
*/
void *
PyThread_get_key_value(int key)
{
struct key *p = find_key(0, key, NULL);
if (p == NULL)
return NULL;
else
return p->value;
}
/* Forget the current thread's association for key, if any. */
void
PyThread_delete_key_value(int key)
{
long id = PyThread_get_thread_ident();
struct key *p, **q;
PyThread_acquire_lock(keymutex, 1);
q = &keyhead;
while ((p = *q) != NULL) {
if (p->key == key && p->id == id) {
*q = p->next;
PyMem_RawFree((void *)p);
/* NB This does *not* free p->value! */
break;
}
else
q = &p->next;
}
PyThread_release_lock(keymutex);
}
/* Forget everything not associated with the current thread id.
* This function is called from PyOS_AfterFork(). It is necessary
* because other thread ids which were in use at the time of the fork
* may be reused for new threads created in the forked process.
*/
void
PyThread_ReInitTLS(void)
{
long id = PyThread_get_thread_ident();
struct key *p, **q;
if (!keymutex)
return;
/* As with interpreter_lock in PyEval_ReInitThreads()
we just create a new lock without freeing the old one */
keymutex = PyThread_allocate_lock();
/* Delete all keys which do not match the current thread id */
q = &keyhead;
while ((p = *q) != NULL) {
if (p->id != id) {
*q = p->next;
PyMem_RawFree((void *)p);
/* NB This does *not* free p->value! */
}
else
q = &p->next;
}
}
#endif /* Py_HAVE_NATIVE_TLS */
PyDoc_STRVAR(threadinfo__doc__,
"sys.thread_info\n\
\n\
A struct sequence 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
if (ThreadInfoType.tp_name == 0) {
if (PyStructSequence_InitType2(&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 _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
Py_INCREF(Py_None);
value = 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
{
Py_INCREF(Py_None);
value = Py_None;
}
PyStructSequence_SET_ITEM(threadinfo, pos++, value);
return threadinfo;
}