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[3.8] bpo-39794: Add --without-decimal-contextvar (GH-18702) 

(cherry picked from commit 815280eb16)
This commit is contained in:
Stefan Krah 2020-02-29 22:16:32 +01:00 committed by GitHub
parent e4686b7979
commit 4d7012410c
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GPG Key ID: 4AEE18F83AFDEB23
11 changed files with 248 additions and 36 deletions
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15
Doc/library/decimal.rst
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@ -1475,9 +1475,18 @@ are also included in the pure Python version for compatibility.
.. data:: HAVE_THREADS
The default value is ``True``. If Python is compiled without threads, the
C version automatically disables the expensive thread local context
machinery. In this case, the value is ``False``.
The value is ``True``. Deprecated, because Python now always has threads.
.. deprecated:: 3.9
.. data:: HAVE_CONTEXTVAR
The default value is ``True``. If Python is compiled ``--without-decimal-contextvar``,
the C version uses a thread-local rather than a coroutine-local context and the value
is ``False``. This is slightly faster in some nested context scenarios.
.. versionadded:: 3.9, backported to 3.7 and 3.8
Rounding modes
--------------

8
Lib/_pydecimal.py
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@ -140,8 +140,11 @@ __all__ = [
# Limits for the C version for compatibility
'MAX_PREC', 'MAX_EMAX', 'MIN_EMIN', 'MIN_ETINY',
# C version: compile time choice that enables the thread local context
'HAVE_THREADS'
# C version: compile time choice that enables the thread local context (deprecated, now always true)
'HAVE_THREADS',
# C version: compile time choice that enables the coroutine local context
'HAVE_CONTEXTVAR'
]
__xname__ = __name__ # sys.modules lookup (--without-threads)
@ -172,6 +175,7 @@ ROUND_05UP = 'ROUND_05UP'
# Compatibility with the C version
HAVE_THREADS = True
HAVE_CONTEXTVAR = True
if sys.maxsize == 2**63-1:
MAX_PREC = 999999999999999999
MAX_EMAX = 999999999999999999

1
Lib/test/test_asyncio/test_context.py
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@ -7,6 +7,7 @@ def tearDownModule():
asyncio.set_event_loop_policy(None)
@unittest.skipUnless(decimal.HAVE_CONTEXTVAR, "decimal is built with a thread-local context")
class DecimalContextTest(unittest.TestCase):
def test_asyncio_task_decimal_context(self):

2
Misc/NEWS.d/next/Library/2020-02-29-19-17-39.bpo-39794.7VjatS.rst Normal file
View File

@ -0,0 +1,2 @@
Add --without-decimal-contextvar build option. This enables a thread-local
rather than a coroutine local context.

169
Modules/_decimal/_decimal.c
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@ -122,7 +122,14 @@ incr_false(void)
}
#ifndef WITH_DECIMAL_CONTEXTVAR
/* Key for thread state dictionary */
static PyObject *tls_context_key = NULL;
/* Invariant: NULL or the most recently accessed thread local context */
static PyDecContextObject *cached_context = NULL;
#else
static PyObject *current_context_var;
#endif
/* Template for creating new thread contexts, calling Context() without
* arguments and initializing the module_context on first access. */
@ -1217,6 +1224,12 @@ context_new(PyTypeObject *type, PyObject *args UNUSED, PyObject *kwds UNUSED)
static void
context_dealloc(PyDecContextObject *self)
{
#ifndef WITH_DECIMAL_CONTEXTVAR
if (self == cached_context) {
cached_context = NULL;
}
#endif
Py_XDECREF(self->traps);
Py_XDECREF(self->flags);
Py_TYPE(self)->tp_free(self);
@ -1491,6 +1504,134 @@ static PyGetSetDef context_getsets [] =
* operation.
*/
#ifndef WITH_DECIMAL_CONTEXTVAR
/* Get the context from the thread state dictionary. */
static PyObject *
current_context_from_dict(void)
{
PyObject *dict;
PyObject *tl_context;
PyThreadState *tstate;
dict = PyThreadState_GetDict();
if (dict == NULL) {
PyErr_SetString(PyExc_RuntimeError,
"cannot get thread state");
return NULL;
}
tl_context = PyDict_GetItemWithError(dict, tls_context_key);
if (tl_context != NULL) {
/* We already have a thread local context. */
CONTEXT_CHECK(tl_context);
}
else {
if (PyErr_Occurred()) {
return NULL;
}
/* Set up a new thread local context. */
tl_context = context_copy(default_context_template, NULL);
if (tl_context == NULL) {
return NULL;
}
CTX(tl_context)->status = 0;
if (PyDict_SetItem(dict, tls_context_key, tl_context) < 0) {
Py_DECREF(tl_context);
return NULL;
}
Py_DECREF(tl_context);
}
/* Cache the context of the current thread, assuming that it
* will be accessed several times before a thread switch. */
tstate = PyThreadState_GET();
if (tstate) {
cached_context = (PyDecContextObject *)tl_context;
cached_context->tstate = tstate;
}
/* Borrowed reference with refcount==1 */
return tl_context;
}
/* Return borrowed reference to thread local context. */
static PyObject *
current_context(void)
{
PyThreadState *tstate;
tstate = PyThreadState_GET();
if (cached_context && cached_context->tstate == tstate) {
return (PyObject *)cached_context;
}
return current_context_from_dict();
}
/* ctxobj := borrowed reference to the current context */
#define CURRENT_CONTEXT(ctxobj) \
ctxobj = current_context(); \
if (ctxobj == NULL) { \
return NULL; \
}
/* Return a new reference to the current context */
static PyObject *
PyDec_GetCurrentContext(PyObject *self UNUSED, PyObject *args UNUSED)
{
PyObject *context;
context = current_context();
if (context == NULL) {
return NULL;
}
Py_INCREF(context);
return context;
}
/* Set the thread local context to a new context, decrement old reference */
static PyObject *
PyDec_SetCurrentContext(PyObject *self UNUSED, PyObject *v)
{
PyObject *dict;
CONTEXT_CHECK(v);
dict = PyThreadState_GetDict();
if (dict == NULL) {
PyErr_SetString(PyExc_RuntimeError,
"cannot get thread state");
return NULL;
}
/* If the new context is one of the templates, make a copy.
* This is the current behavior of decimal.py. */
if (v == default_context_template ||
v == basic_context_template ||
v == extended_context_template) {
v = context_copy(v, NULL);
if (v == NULL) {
return NULL;
}
CTX(v)->status = 0;
}
else {
Py_INCREF(v);
}
cached_context = NULL;
if (PyDict_SetItem(dict, tls_context_key, v) < 0) {
Py_DECREF(v);
return NULL;
}
Py_DECREF(v);
Py_RETURN_NONE;
}
#else
static PyObject *
init_current_context(void)
{
@ -1570,6 +1711,7 @@ PyDec_SetCurrentContext(PyObject *self UNUSED, PyObject *v)
Py_RETURN_NONE;
}
#endif
/* Context manager object for the 'with' statement. The manager
* owns one reference to the global (outer) context and one
@ -4388,15 +4530,8 @@ _dec_hash(PyDecObject *v)
mpd_ssize_t exp;
uint32_t status = 0;
mpd_context_t maxctx;
PyObject *context;
context = current_context();
if (context == NULL) {
return -1;
}
Py_DECREF(context);
if (mpd_isspecial(MPD(v))) {
if (mpd_issnan(MPD(v))) {
PyErr_SetString(PyExc_TypeError,
@ -5538,11 +5673,6 @@ PyInit__decimal(void)
mpd_free = PyMem_Free;
mpd_setminalloc(_Py_DEC_MINALLOC);
/* Init context variable */
current_context_var = PyContextVar_New("decimal_context", NULL);
if (current_context_var == NULL) {
goto error;
}
/* Init external C-API functions */
_py_long_multiply = PyLong_Type.tp_as_number->nb_multiply;
@ -5714,6 +5844,15 @@ PyInit__decimal(void)
CHECK_INT(PyModule_AddObject(m, "DefaultContext",
default_context_template));
#ifndef WITH_DECIMAL_CONTEXTVAR
ASSIGN_PTR(tls_context_key, PyUnicode_FromString("___DECIMAL_CTX__"));
Py_INCREF(Py_False);
CHECK_INT(PyModule_AddObject(m, "HAVE_CONTEXTVAR", Py_False));
#else
ASSIGN_PTR(current_context_var, PyContextVar_New("decimal_context", NULL));
Py_INCREF(Py_True);
CHECK_INT(PyModule_AddObject(m, "HAVE_CONTEXTVAR", Py_True));
#endif
Py_INCREF(Py_True);
CHECK_INT(PyModule_AddObject(m, "HAVE_THREADS", Py_True));
@ -5773,9 +5912,13 @@ error:
Py_CLEAR(SignalTuple); /* GCOV_NOT_REACHED */
Py_CLEAR(DecimalTuple); /* GCOV_NOT_REACHED */
Py_CLEAR(default_context_template); /* GCOV_NOT_REACHED */
#ifndef WITH_DECIMAL_CONTEXTVAR
Py_CLEAR(tls_context_key); /* GCOV_NOT_REACHED */
#else
Py_CLEAR(current_context_var); /* GCOV_NOT_REACHED */
#endif
Py_CLEAR(basic_context_template); /* GCOV_NOT_REACHED */
Py_CLEAR(extended_context_template); /* GCOV_NOT_REACHED */
Py_CLEAR(current_context_var); /* GCOV_NOT_REACHED */
Py_CLEAR(m); /* GCOV_NOT_REACHED */
return NULL; /* GCOV_NOT_REACHED */

32
Modules/_decimal/tests/runall-memorydebugger.sh
View File

@ -1,8 +1,8 @@
#!/bin/sh
#
# Purpose: test all machine configurations, pydebug, refleaks, release build
# and release build with valgrind.
# Purpose: test with and without contextvar, all machine configurations, pydebug,
# refleaks, release build and release build with valgrind.
#
# Synopsis: ./runall-memorydebugger.sh [--all-configs64 | --all-configs32]
#
@ -57,6 +57,7 @@ print_config ()
cd ..
# test_decimal: refleak, regular and Valgrind tests
for args in "--without-decimal-contextvar" ""; do
for config in $CONFIGS; do
unset PYTHON_DECIMAL_WITH_MACHINE
@ -69,12 +70,12 @@ for config in $CONFIGS; do
fi
############ refleak tests ###########
print_config "refleak tests: config=$config"
print_config "refleak tests: config=$config" $args
printf "\nbuilding python ...\n\n"
cd ../../
$GMAKE distclean > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --with-pydebug > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --with-pydebug $args > /dev/null 2>&1
$GMAKE | grep _decimal
printf "\n\n# ======================== refleak tests ===========================\n\n"
@ -82,11 +83,11 @@ for config in $CONFIGS; do
############ regular tests ###########
print_config "regular tests: config=$config"
print_config "regular tests: config=$config" $args
printf "\nbuilding python ...\n\n"
$GMAKE distclean > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" $args > /dev/null 2>&1
$GMAKE | grep _decimal
printf "\n\n# ======================== regular tests ===========================\n\n"
@ -103,10 +104,10 @@ for config in $CONFIGS; do
esac
esac
print_config "valgrind tests: config=$config"
print_config "valgrind tests: config=$config" $args
printf "\nbuilding python ...\n\n"
$GMAKE distclean > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --without-pymalloc > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --without-pymalloc $args > /dev/null 2>&1
$GMAKE | grep _decimal
printf "\n\n# ======================== valgrind tests ===========================\n\n"
@ -114,9 +115,11 @@ for config in $CONFIGS; do
cd Modules/_decimal
done
done
# deccheck
cd ../../
for args in "--without-decimal-contextvar" ""; do
for config in $CONFIGS; do
unset PYTHON_DECIMAL_WITH_MACHINE
@ -126,22 +129,22 @@ for config in $CONFIGS; do
fi
############ debug ############
print_config "deccheck: config=$config --with-pydebug"
print_config "deccheck: config=$config --with-pydebug" $args
printf "\nbuilding python ...\n\n"
$GMAKE distclean > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --with-pydebug > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --with-pydebug $args > /dev/null 2>&1
$GMAKE | grep _decimal
printf "\n\n# ========================== debug ===========================\n\n"
./python Modules/_decimal/tests/deccheck.py
########### regular ###########
print_config "deccheck: config=$config "
print_config "deccheck: config=$config" $args
printf "\nbuilding python ...\n\n"
$GMAKE distclean > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" $args > /dev/null 2>&1
$GMAKE | grep _decimal
printf "\n\n# ======================== regular ===========================\n\n"
@ -157,16 +160,17 @@ for config in $CONFIGS; do
esac
esac
print_config "valgrind deccheck: config=$config "
print_config "valgrind deccheck: config=$config" $args
printf "\nbuilding python ...\n\n"
$GMAKE distclean > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --without-pymalloc > /dev/null 2>&1
./configure CFLAGS="$ADD_CFLAGS" LDFLAGS="$ADD_LDFLAGS" --without-pymalloc $args > /dev/null 2>&1
$GMAKE | grep _decimal
printf "\n\n# ======================== valgrind ==========================\n\n"
$valgrind ./python Modules/_decimal/tests/deccheck.py
done
done

4
PC/pyconfig.h
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@ -470,6 +470,10 @@ Py_NO_ENABLE_SHARED to find out. Also support MS_NO_COREDLL for b/w compat */
(which you can't on SCO ODT 3.0). */
/* #undef SYS_SELECT_WITH_SYS_TIME */
/* Define if you want build the _decimal module using a coroutine-local rather
than a thread-local context */
#define WITH_DECIMAL_CONTEXTVAR 1
/* Define if you want documentation strings in extension modules */
#define WITH_DOC_STRINGS 1

4
aclocal.m4 vendored
View File

@ -1,6 +1,6 @@
# generated automatically by aclocal 1.16.1 -*- Autoconf -*-
# generated automatically by aclocal 1.15 -*- Autoconf -*-
# Copyright (C) 1996-2018 Free Software Foundation, Inc.
# Copyright (C) 1996-2014 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,

26
configure vendored
View File

@ -826,6 +826,7 @@ with_libs
with_system_expat
with_system_ffi
with_system_libmpdec
with_decimal_contextvar
enable_loadable_sqlite_extensions
with_tcltk_includes
with_tcltk_libs
@ -1529,6 +1530,9 @@ Optional Packages:
--with-system-ffi build _ctypes module using an installed ffi library
--with-system-libmpdec build _decimal module using an installed libmpdec
library
--with-decimal-contextvar
build _decimal module using a coroutine-local rather
than a thread-local context (default is yes)
--with-tcltk-includes='-I...'
override search for Tcl and Tk include files
--with-tcltk-libs='-L...'
@ -10419,6 +10423,28 @@ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_system_libmpdec" >&5
$as_echo "$with_system_libmpdec" >&6; }
# Check whether _decimal should use a coroutine-local or thread-local context
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-decimal-contextvar" >&5
$as_echo_n "checking for --with-decimal-contextvar... " >&6; }
# Check whether --with-decimal_contextvar was given.
if test "${with_decimal_contextvar+set}" = set; then :
withval=$with_decimal_contextvar;
else
with_decimal_contextvar="yes"
fi
if test "$with_decimal_contextvar" != "no"
then
$as_echo "#define WITH_DECIMAL_CONTEXTVAR 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_decimal_contextvar" >&5
$as_echo "$with_decimal_contextvar" >&6; }
# Check for support for loadable sqlite extensions
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for --enable-loadable-sqlite-extensions" >&5
$as_echo_n "checking for --enable-loadable-sqlite-extensions... " >&6; }

15
configure.ac
View File

@ -3004,6 +3004,21 @@ AC_ARG_WITH(system_libmpdec,
AC_MSG_RESULT($with_system_libmpdec)
# Check whether _decimal should use a coroutine-local or thread-local context
AC_MSG_CHECKING(for --with-decimal-contextvar)
AC_ARG_WITH(decimal_contextvar,
AS_HELP_STRING([--with-decimal-contextvar], [build _decimal module using a coroutine-local rather than a thread-local context (default is yes)]),
[],
[with_decimal_contextvar="yes"])
if test "$with_decimal_contextvar" != "no"
then
AC_DEFINE(WITH_DECIMAL_CONTEXTVAR, 1,
[Define if you want build the _decimal module using a coroutine-local rather than a thread-local context])
fi
AC_MSG_RESULT($with_decimal_contextvar)
# Check for support for loadable sqlite extensions
AC_MSG_CHECKING(for --enable-loadable-sqlite-extensions)
AC_ARG_ENABLE(loadable-sqlite-extensions,

4
pyconfig.h.in
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@ -1518,6 +1518,10 @@
/* Define if WINDOW in curses.h offers a field _flags. */
#undef WINDOW_HAS_FLAGS
/* Define if you want build the _decimal module using a coroutine-local rather
than a thread-local context */
#undef WITH_DECIMAL_CONTEXTVAR
/* Define if you want documentation strings in extension modules */
#undef WITH_DOC_STRINGS