bpo-38314: Add is_reading() method to asyncio _UnixReadPipeTransport

Doc/c-api/exceptions.rst

@@ -374,6 +374,8 @@ Querying the error indicator
    own a reference to the return value, so you do not need to :c:func:`Py_DECREF`
    it.
 
+   The caller must hold the GIL.
+
    .. note::
 
       Do not compare the return value to a specific exception; use
@@ -715,15 +717,21 @@ recursion depth automatically).
    case, a :exc:`RecursionError` is set and a nonzero value is returned.
    Otherwise, zero is returned.
 
-   *where* should be a string such as ``" in instance check"`` to be
-   concatenated to the :exc:`RecursionError` message caused by the recursion
+   *where* should be a UTF-8 encoded string such as ``" in instance check"`` to
+   be concatenated to the :exc:`RecursionError` message caused by the recursion
    depth limit.
 
-.. c:function:: void Py_LeaveRecursiveCall()
+   .. versionchanged:: 3.9
+      This function is now also available in the limited API.
+
+.. c:function:: void Py_LeaveRecursiveCall(void)
 
    Ends a :c:func:`Py_EnterRecursiveCall`.  Must be called once for each
    *successful* invocation of :c:func:`Py_EnterRecursiveCall`.
 
+   .. versionchanged:: 3.9
+      This function is now also available in the limited API.
+
 Properly implementing :c:member:`~PyTypeObject.tp_repr` for container types requires
 special recursion handling.  In addition to protecting the stack,
 :c:member:`~PyTypeObject.tp_repr` also needs to track objects to prevent cycles.  The

Doc/c-api/object.rst

@@ -196,6 +196,7 @@ Object Protocol
       This function now includes a debug assertion to help ensure that it
       does not silently discard an active exception.
 
+
 .. c:function:: PyObject* PyObject_Bytes(PyObject *o)
 
    .. index:: builtin: bytes

Doc/library/argparse.rst

@@ -449,7 +449,7 @@ default values to each of the argument help messages::
    >>> parser.add_argument('--foo', type=int, default=42, help='FOO!')
    >>> parser.add_argument('bar', nargs='*', default=[1, 2, 3], help='BAR!')
    >>> parser.print_help()
-   usage: PROG [-h] [--foo FOO] [bar [bar ...]]
+   usage: PROG [-h] [--foo FOO] [bar ...]
 
    positional arguments:
     bar         BAR! (default: [1, 2, 3])

Doc/library/collections.rst

@@ -162,7 +162,7 @@ environment variables which in turn take precedence over default values::
         parser.add_argument('-u', '--user')
         parser.add_argument('-c', '--color')
         namespace = parser.parse_args()
-        command_line_args = {k:v for k, v in vars(namespace).items() if v}
+        command_line_args = {k: v for k, v in vars(namespace).items() if v is not None}
 
         combined = ChainMap(command_line_args, os.environ, defaults)
         print(combined['color'])

Doc/library/functools.rst

@@ -108,6 +108,11 @@ The :mod:`functools` module defines the following functions:
    cached separately.  For example, ``f(3)`` and ``f(3.0)`` will be treated
    as distinct calls with distinct results.
 
+   The wrapped function is instrumented with a :func:`cache_parameters`
+   function that returns a new :class:`dict` showing the values for *maxsize*
+   and *typed*.  This is for information purposes only.  Mutating the values
+   has no effect.
+
    To help measure the effectiveness of the cache and tune the *maxsize*
    parameter, the wrapped function is instrumented with a :func:`cache_info`
    function that returns a :term:`named tuple` showing *hits*, *misses*,
@@ -178,6 +183,9 @@ The :mod:`functools` module defines the following functions:
    .. versionchanged:: 3.8
       Added the *user_function* option.
 
+   .. versionadded:: 3.9
+      Added the function :func:`cache_parameters`
+
 .. decorator:: total_ordering
 
    Given a class defining one or more rich comparison ordering methods, this

Doc/library/http.rst

@@ -38,7 +38,7 @@ associated messages through the :class:`http.HTTPStatus` enum:
       <HTTPStatus.OK: 200>
       >>> HTTPStatus.OK == 200
       True
-      >>> http.HTTPStatus.OK.value
+      >>> HTTPStatus.OK.value
       200
       >>> HTTPStatus.OK.phrase
       'OK'

Doc/library/os.rst

@@ -3539,6 +3539,19 @@ written in Python, such as a mail server's external command delivery program.
    .. availability:: Unix.
 
 
+.. function:: pidfd_open(pid, flags=0)
+
+   Return a file descriptor referring to the process *pid*.  This descriptor can
+   be used to perform process management without races and signals.  The *flags*
+   argument is provided for future extensions; no flag values are currently
+   defined.
+
+   See the :manpage:`pidfd_open(2)` man page for more details.
+
+   .. availability:: Linux 5.3+
+   .. versionadded:: 3.9
+
+
 .. function:: plock(op)
 
    Lock program segments into memory.  The value of *op* (defined in
@@ -3908,7 +3921,8 @@ written in Python, such as a mail server's external command delivery program.
 .. function:: waitid(idtype, id, options)
 
    Wait for the completion of one or more child processes.
-   *idtype* can be :data:`P_PID`, :data:`P_PGID` or :data:`P_ALL`.
+   *idtype* can be :data:`P_PID`, :data:`P_PGID`, :data:`P_ALL`, or
+   :data:`P_PIDFD` on Linux.
    *id* specifies the pid to wait on.
    *options* is constructed from the ORing of one or more of :data:`WEXITED`,
    :data:`WSTOPPED` or :data:`WCONTINUED` and additionally may be ORed with
@@ -3933,6 +3947,15 @@ written in Python, such as a mail server's external command delivery program.
 
    .. versionadded:: 3.3
 
+.. data:: P_PIDFD
+
+   This is a Linux-specific *idtype* that indicates that *id* is a file
+   descriptor that refers to a process.
+
+   .. availability:: Linux 5.4+
+
+   .. versionadded:: 3.9
+
 .. data:: WEXITED
           WSTOPPED
           WNOWAIT

Doc/library/pdb.rst

@@ -296,20 +296,20 @@ by the local file.
    Temporary breakpoint, which is removed automatically when it is first hit.
    The arguments are the same as for :pdbcmd:`break`.
 
-.. pdbcommand:: cl(ear) [filename:lineno | bpnumber [bpnumber ...]]
+.. pdbcommand:: cl(ear) [filename:lineno | bpnumber ...]
 
    With a *filename:lineno* argument, clear all the breakpoints at this line.
    With a space separated list of breakpoint numbers, clear those breakpoints.
    Without argument, clear all breaks (but first ask confirmation).
 
-.. pdbcommand:: disable [bpnumber [bpnumber ...]]
+.. pdbcommand:: disable [bpnumber ...]
 
    Disable the breakpoints given as a space separated list of breakpoint
    numbers.  Disabling a breakpoint means it cannot cause the program to stop
    execution, but unlike clearing a breakpoint, it remains in the list of
    breakpoints and can be (re-)enabled.
 
-.. pdbcommand:: enable [bpnumber [bpnumber ...]]
+.. pdbcommand:: enable [bpnumber ...]
 
    Enable the breakpoints specified.
 

Doc/library/statistics.rst

@@ -77,7 +77,7 @@ However, for reading convenience, most of the examples show sorted sequences.
 
 .. function:: mean(data)
 
-   Return the sample arithmetic mean of *data* which can be a sequence or iterator.
+   Return the sample arithmetic mean of *data* which can be a sequence or iterable.
 
    The arithmetic mean is the sum of the data divided by the number of data
    points.  It is commonly called "the average", although it is only one of many
@@ -122,7 +122,7 @@ However, for reading convenience, most of the examples show sorted sequences.
    Convert *data* to floats and compute the arithmetic mean.
 
    This runs faster than the :func:`mean` function and it always returns a
-   :class:`float`.  The *data* may be a sequence or iterator.  If the input
+   :class:`float`.  The *data* may be a sequence or iterable.  If the input
    dataset is empty, raises a :exc:`StatisticsError`.
 
    .. doctest::
@@ -143,7 +143,7 @@ However, for reading convenience, most of the examples show sorted sequences.
 
    Raises a :exc:`StatisticsError` if the input dataset is empty,
    if it contains a zero, or if it contains a negative value.
-   The *data* may be a sequence or iterator.
+   The *data* may be a sequence or iterable.
 
    No special efforts are made to achieve exact results.
    (However, this may change in the future.)
@@ -158,13 +158,14 @@ However, for reading convenience, most of the examples show sorted sequences.
 
 .. function:: harmonic_mean(data)
 
-   Return the harmonic mean of *data*, a sequence or iterator of
+   Return the harmonic mean of *data*, a sequence or iterable of
    real-valued numbers.
 
    The harmonic mean, sometimes called the subcontrary mean, is the
    reciprocal of the arithmetic :func:`mean` of the reciprocals of the
    data. For example, the harmonic mean of three values *a*, *b* and *c*
-   will be equivalent to ``3/(1/a + 1/b + 1/c)``.
+   will be equivalent to ``3/(1/a + 1/b + 1/c)``.  If one of the values
+   is zero, the result will be zero.
 
    The harmonic mean is a type of average, a measure of the central
    location of the data.  It is often appropriate when averaging
@@ -190,14 +191,18 @@ However, for reading convenience, most of the examples show sorted sequences.
    :exc:`StatisticsError` is raised if *data* is empty, or any element
    is less than zero.
 
+   The current algorithm has an early-out when it encounters a zero
+   in the input.  This means that the subsequent inputs are not tested
+   for validity.  (This behavior may change in the future.)
+
    .. versionadded:: 3.6
 
 
 .. function:: median(data)
 
    Return the median (middle value) of numeric data, using the common "mean of
    middle two" method.  If *data* is empty, :exc:`StatisticsError` is raised.
-   *data* can be a sequence or iterator.
+   *data* can be a sequence or iterable.
 
    The median is a robust measure of central location and is less affected by
    the presence of outliers.  When the number of data points is odd, the
@@ -226,7 +231,7 @@ However, for reading convenience, most of the examples show sorted sequences.
 .. function:: median_low(data)
 
    Return the low median of numeric data.  If *data* is empty,
-   :exc:`StatisticsError` is raised.  *data* can be a sequence or iterator.
+   :exc:`StatisticsError` is raised.  *data* can be a sequence or iterable.
 
    The low median is always a member of the data set.  When the number of data
    points is odd, the middle value is returned.  When it is even, the smaller of
@@ -246,7 +251,7 @@ However, for reading convenience, most of the examples show sorted sequences.
 .. function:: median_high(data)
 
    Return the high median of data.  If *data* is empty, :exc:`StatisticsError`
-   is raised.  *data* can be a sequence or iterator.
+   is raised.  *data* can be a sequence or iterable.
 
    The high median is always a member of the data set.  When the number of data
    points is odd, the middle value is returned.  When it is even, the larger of
@@ -267,7 +272,7 @@ However, for reading convenience, most of the examples show sorted sequences.
 
    Return the median of grouped continuous data, calculated as the 50th
    percentile, using interpolation.  If *data* is empty, :exc:`StatisticsError`
-   is raised.  *data* can be a sequence or iterator.
+   is raised.  *data* can be a sequence or iterable.
 
    .. doctest::
 
@@ -376,7 +381,7 @@ However, for reading convenience, most of the examples show sorted sequences.
 
 .. function:: pvariance(data, mu=None)
 
-   Return the population variance of *data*, a non-empty sequence or iterator
+   Return the population variance of *data*, a non-empty sequence or iterable
    of real-valued numbers.  Variance, or second moment about the mean, is a
    measure of the variability (spread or dispersion) of data.  A large
    variance indicates that the data is spread out; a small variance indicates

Doc/reference/import.rst

@@ -83,7 +83,7 @@ module.  Specifically, any module that contains a ``__path__`` attribute is
 considered a package.
 
 All modules have a name.  Subpackage names are separated from their parent
-package name by dots, akin to Python's standard attribute access syntax.  Thus
+package name by a dot, akin to Python's standard attribute access syntax.  Thus
 you might have a module called :mod:`sys` and a package called :mod:`email`,
 which in turn has a subpackage called :mod:`email.mime` and a module within
 that subpackage called :mod:`email.mime.text`.

Doc/tutorial/interpreter.rst

@@ -23,7 +23,7 @@ is an installation option, other places are possible; check with your local
 Python guru or system administrator.  (E.g., :file:`/usr/local/python` is a
 popular alternative location.)
 
-On Windows machines where you have installed from the :ref:`Microsoft Store
+On Windows machines where you have installed Python from the :ref:`Microsoft Store
 <windows-store>`, the :file:`python3.9` command will be available. If you have
 the :ref:`py.exe launcher <launcher>` installed, you can use the :file:`py`
 command. See :ref:`setting-envvars` for other ways to launch Python.

Doc/whatsnew/3.9.rst

@@ -150,6 +150,10 @@ os
 Added :data:`~os.CLD_KILLED` and :data:`~os.CLD_STOPPED` for :attr:`si_code`.
 (Contributed by Dong-hee Na in :issue:`38493`.)
 
+Exposed the Linux-specific :func:`os.pidfd_open` (:issue:`38692`) and
+:data:`os.P_PIDFD` (:issue:`38713`) for process management with file
+descriptors.
+
 threading
 ---------
 
@@ -197,6 +201,12 @@ Optimizations
 Build and C API Changes
 =======================
 
+* Provide :c:func:`Py_EnterRecursiveCall` and :c:func:`Py_LeaveRecursiveCall`
+  as regular functions for the limited API. Previously, there were defined as
+  macros, but these macros didn't work with the limited API which cannot access
+  ``PyThreadState.recursion_depth`` field. Remove ``_Py_CheckRecursionLimit``
+  from the stable ABI.
+  (Contributed by Victor Stinner in :issue:`38644`.)
 * Add a new public :c:func:`PyObject_CallNoArgs` function to the C API, which
   calls a callable Python object without any arguments. It is the most efficient
   way to call a callable Python object without any argument.

Include/ceval.h

@@ -85,41 +85,8 @@ PyAPI_FUNC(int) Py_MakePendingCalls(void);
 PyAPI_FUNC(void) Py_SetRecursionLimit(int);
 PyAPI_FUNC(int) Py_GetRecursionLimit(void);
 
-#define Py_EnterRecursiveCall(where)  \
-            (_Py_MakeRecCheck(PyThreadState_GET()->recursion_depth) &&  \
-             _Py_CheckRecursiveCall(where))
-#define Py_LeaveRecursiveCall()                         \
-    do{ if(_Py_MakeEndRecCheck(PyThreadState_GET()->recursion_depth))  \
-      PyThreadState_GET()->overflowed = 0;  \
-    } while(0)
-PyAPI_FUNC(int) _Py_CheckRecursiveCall(const char *where);
-
-/* Due to the macros in which it's used, _Py_CheckRecursionLimit is in
-   the stable ABI.  It should be removed therefrom when possible.
-*/
-PyAPI_DATA(int) _Py_CheckRecursionLimit;
-
-#ifdef USE_STACKCHECK
-/* With USE_STACKCHECK, trigger stack checks in _Py_CheckRecursiveCall()
-   on every 64th call to Py_EnterRecursiveCall.
-*/
-#  define _Py_MakeRecCheck(x)  \
-    (++(x) > _Py_CheckRecursionLimit || \
-     ++(PyThreadState_GET()->stackcheck_counter) > 64)
-#else
-#  define _Py_MakeRecCheck(x)  (++(x) > _Py_CheckRecursionLimit)
-#endif
-
-/* Compute the "lower-water mark" for a recursion limit. When
- * Py_LeaveRecursiveCall() is called with a recursion depth below this mark,
- * the overflowed flag is reset to 0. */
-#define _Py_RecursionLimitLowerWaterMark(limit) \
-    (((limit) > 200) \
-        ? ((limit) - 50) \
-        : (3 * ((limit) >> 2)))
-
-#define _Py_MakeEndRecCheck(x) \
-    (--(x) < _Py_RecursionLimitLowerWaterMark(_Py_CheckRecursionLimit))
+PyAPI_FUNC(int) Py_EnterRecursiveCall(const char *where);
+PyAPI_FUNC(void) Py_LeaveRecursiveCall(void);
 
 #define Py_ALLOW_RECURSION \
   do { unsigned char _old = PyThreadState_GET()->recursion_critical;\
@@ -224,6 +191,12 @@ PyAPI_FUNC(int) _PyEval_SliceIndexNotNone(PyObject *, Py_ssize_t *);
 #define FVS_MASK      0x4
 #define FVS_HAVE_SPEC 0x4
 
+#ifndef Py_LIMITED_API
+#  define Py_CPYTHON_CEVAL_H
+#  include  "cpython/ceval.h"
+#  undef Py_CPYTHON_CEVAL_H
+#endif
+
 #ifdef __cplusplus
 }
 #endif