mirror of https://github.com/python/cpython
651 lines
28 KiB
ReStructuredText
651 lines
28 KiB
ReStructuredText
:mod:`!select` --- Waiting for I/O completion
|
|
=============================================
|
|
|
|
.. module:: select
|
|
:synopsis: Wait for I/O completion on multiple streams.
|
|
|
|
--------------
|
|
|
|
This module provides access to the :c:func:`!select` and :c:func:`!poll` functions
|
|
available in most operating systems, :c:func:`!devpoll` available on
|
|
Solaris and derivatives, :c:func:`!epoll` available on Linux 2.5+ and
|
|
:c:func:`!kqueue` available on most BSD.
|
|
Note that on Windows, it only works for sockets; on other operating systems,
|
|
it also works for other file types (in particular, on Unix, it works on pipes).
|
|
It cannot be used on regular files to determine whether a file has grown since
|
|
it was last read.
|
|
|
|
.. note::
|
|
|
|
The :mod:`selectors` module allows high-level and efficient I/O
|
|
multiplexing, built upon the :mod:`select` module primitives. Users are
|
|
encouraged to use the :mod:`selectors` module instead, unless they want
|
|
precise control over the OS-level primitives used.
|
|
|
|
.. include:: ../includes/wasm-notavail.rst
|
|
|
|
The module defines the following:
|
|
|
|
|
|
.. exception:: error
|
|
|
|
A deprecated alias of :exc:`OSError`.
|
|
|
|
.. versionchanged:: 3.3
|
|
Following :pep:`3151`, this class was made an alias of :exc:`OSError`.
|
|
|
|
|
|
.. function:: devpoll()
|
|
|
|
(Only supported on Solaris and derivatives.) Returns a ``/dev/poll``
|
|
polling object; see section :ref:`devpoll-objects` below for the
|
|
methods supported by devpoll objects.
|
|
|
|
:c:func:`!devpoll` objects are linked to the number of file
|
|
descriptors allowed at the time of instantiation. If your program
|
|
reduces this value, :c:func:`!devpoll` will fail. If your program
|
|
increases this value, :c:func:`!devpoll` may return an
|
|
incomplete list of active file descriptors.
|
|
|
|
The new file descriptor is :ref:`non-inheritable <fd_inheritance>`.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
.. versionchanged:: 3.4
|
|
The new file descriptor is now non-inheritable.
|
|
|
|
.. function:: epoll(sizehint=-1, flags=0)
|
|
|
|
(Only supported on Linux 2.5.44 and newer.) Return an edge polling object,
|
|
which can be used as Edge or Level Triggered interface for I/O
|
|
events.
|
|
|
|
*sizehint* informs epoll about the expected number of events to be
|
|
registered. It must be positive, or ``-1`` to use the default. It is only
|
|
used on older systems where :c:func:`!epoll_create1` is not available;
|
|
otherwise it has no effect (though its value is still checked).
|
|
|
|
*flags* is deprecated and completely ignored. However, when supplied, its
|
|
value must be ``0`` or ``select.EPOLL_CLOEXEC``, otherwise ``OSError`` is
|
|
raised.
|
|
|
|
See the :ref:`epoll-objects` section below for the methods supported by
|
|
epolling objects.
|
|
|
|
``epoll`` objects support the context management protocol: when used in a
|
|
:keyword:`with` statement, the new file descriptor is automatically closed
|
|
at the end of the block.
|
|
|
|
The new file descriptor is :ref:`non-inheritable <fd_inheritance>`.
|
|
|
|
.. versionchanged:: 3.3
|
|
Added the *flags* parameter.
|
|
|
|
.. versionchanged:: 3.4
|
|
Support for the :keyword:`with` statement was added.
|
|
The new file descriptor is now non-inheritable.
|
|
|
|
.. deprecated:: 3.4
|
|
The *flags* parameter. ``select.EPOLL_CLOEXEC`` is used by default now.
|
|
Use :func:`os.set_inheritable` to make the file descriptor inheritable.
|
|
|
|
|
|
.. function:: poll()
|
|
|
|
(Not supported by all operating systems.) Returns a polling object, which
|
|
supports registering and unregistering file descriptors, and then polling them
|
|
for I/O events; see section :ref:`poll-objects` below for the methods supported
|
|
by polling objects.
|
|
|
|
|
|
.. function:: kqueue()
|
|
|
|
(Only supported on BSD.) Returns a kernel queue object; see section
|
|
:ref:`kqueue-objects` below for the methods supported by kqueue objects.
|
|
|
|
The new file descriptor is :ref:`non-inheritable <fd_inheritance>`.
|
|
|
|
.. versionchanged:: 3.4
|
|
The new file descriptor is now non-inheritable.
|
|
|
|
|
|
.. function:: kevent(ident, filter=KQ_FILTER_READ, flags=KQ_EV_ADD, fflags=0, data=0, udata=0)
|
|
|
|
(Only supported on BSD.) Returns a kernel event object; see section
|
|
:ref:`kevent-objects` below for the methods supported by kevent objects.
|
|
|
|
|
|
.. function:: select(rlist, wlist, xlist[, timeout])
|
|
|
|
This is a straightforward interface to the Unix :c:func:`!select` system call.
|
|
The first three arguments are iterables of 'waitable objects': either
|
|
integers representing file descriptors or objects with a parameterless method
|
|
named :meth:`~io.IOBase.fileno` returning such an integer:
|
|
|
|
* *rlist*: wait until ready for reading
|
|
* *wlist*: wait until ready for writing
|
|
* *xlist*: wait for an "exceptional condition" (see the manual page for what
|
|
your system considers such a condition)
|
|
|
|
Empty iterables are allowed, but acceptance of three empty iterables is
|
|
platform-dependent. (It is known to work on Unix but not on Windows.) The
|
|
optional *timeout* argument specifies a time-out as a floating point number
|
|
in seconds. When the *timeout* argument is omitted the function blocks until
|
|
at least one file descriptor is ready. A time-out value of zero specifies a
|
|
poll and never blocks.
|
|
|
|
The return value is a triple of lists of objects that are ready: subsets of the
|
|
first three arguments. When the time-out is reached without a file descriptor
|
|
becoming ready, three empty lists are returned.
|
|
|
|
.. index::
|
|
single: socket() (in module socket)
|
|
single: popen() (in module os)
|
|
|
|
Among the acceptable object types in the iterables are Python :term:`file
|
|
objects <file object>` (e.g. ``sys.stdin``, or objects returned by
|
|
:func:`open` or :func:`os.popen`), socket objects returned by
|
|
:func:`socket.socket`. You may also define a :dfn:`wrapper` class yourself,
|
|
as long as it has an appropriate :meth:`~io.IOBase.fileno` method (that
|
|
really returns a file descriptor, not just a random integer).
|
|
|
|
.. note::
|
|
|
|
.. index:: single: WinSock
|
|
|
|
File objects on Windows are not acceptable, but sockets are. On Windows,
|
|
the underlying :c:func:`!select` function is provided by the WinSock
|
|
library, and does not handle file descriptors that don't originate from
|
|
WinSock.
|
|
|
|
.. versionchanged:: 3.5
|
|
The function is now retried with a recomputed timeout when interrupted by
|
|
a signal, except if the signal handler raises an exception (see
|
|
:pep:`475` for the rationale), instead of raising
|
|
:exc:`InterruptedError`.
|
|
|
|
|
|
.. attribute:: PIPE_BUF
|
|
|
|
The minimum number of bytes which can be written without blocking to a pipe
|
|
when the pipe has been reported as ready for writing by :func:`~select.select`,
|
|
:func:`!poll` or another interface in this module. This doesn't apply
|
|
to other kind of file-like objects such as sockets.
|
|
|
|
This value is guaranteed by POSIX to be at least 512.
|
|
|
|
.. availability:: Unix
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
|
|
.. _devpoll-objects:
|
|
|
|
``/dev/poll`` Polling Objects
|
|
-----------------------------
|
|
|
|
Solaris and derivatives have ``/dev/poll``. While :c:func:`!select` is
|
|
*O*\ (*highest file descriptor*) and :c:func:`!poll` is *O*\ (*number of file
|
|
descriptors*), ``/dev/poll`` is *O*\ (*active file descriptors*).
|
|
|
|
``/dev/poll`` behaviour is very close to the standard :c:func:`!poll`
|
|
object.
|
|
|
|
|
|
.. method:: devpoll.close()
|
|
|
|
Close the file descriptor of the polling object.
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
|
|
.. attribute:: devpoll.closed
|
|
|
|
``True`` if the polling object is closed.
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
|
|
.. method:: devpoll.fileno()
|
|
|
|
Return the file descriptor number of the polling object.
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
|
|
.. method:: devpoll.register(fd[, eventmask])
|
|
|
|
Register a file descriptor with the polling object. Future calls to the
|
|
:meth:`poll` method will then check whether the file descriptor has any
|
|
pending I/O events. *fd* can be either an integer, or an object with a
|
|
:meth:`~io.IOBase.fileno` method that returns an integer. File objects
|
|
implement :meth:`!fileno`, so they can also be used as the argument.
|
|
|
|
*eventmask* is an optional bitmask describing the type of events you want to
|
|
check for. The constants are the same that with :c:func:`!poll`
|
|
object. The default value is a combination of the constants :const:`POLLIN`,
|
|
:const:`POLLPRI`, and :const:`POLLOUT`.
|
|
|
|
.. warning::
|
|
|
|
Registering a file descriptor that's already registered is not an
|
|
error, but the result is undefined. The appropriate action is to
|
|
unregister or modify it first. This is an important difference
|
|
compared with :c:func:`!poll`.
|
|
|
|
|
|
.. method:: devpoll.modify(fd[, eventmask])
|
|
|
|
This method does an :meth:`unregister` followed by a
|
|
:meth:`register`. It is (a bit) more efficient that doing the same
|
|
explicitly.
|
|
|
|
|
|
.. method:: devpoll.unregister(fd)
|
|
|
|
Remove a file descriptor being tracked by a polling object. Just like the
|
|
:meth:`register` method, *fd* can be an integer or an object with a
|
|
:meth:`~io.IOBase.fileno` method that returns an integer.
|
|
|
|
Attempting to remove a file descriptor that was never registered is
|
|
safely ignored.
|
|
|
|
|
|
.. method:: devpoll.poll([timeout])
|
|
|
|
Polls the set of registered file descriptors, and returns a possibly empty list
|
|
containing ``(fd, event)`` 2-tuples for the descriptors that have events or
|
|
errors to report. *fd* is the file descriptor, and *event* is a bitmask with
|
|
bits set for the reported events for that descriptor --- :const:`POLLIN` for
|
|
waiting input, :const:`POLLOUT` to indicate that the descriptor can be written
|
|
to, and so forth. An empty list indicates that the call timed out and no file
|
|
descriptors had any events to report. If *timeout* is given, it specifies the
|
|
length of time in milliseconds which the system will wait for events before
|
|
returning. If *timeout* is omitted, -1, or :const:`None`, the call will
|
|
block until there is an event for this poll object.
|
|
|
|
.. versionchanged:: 3.5
|
|
The function is now retried with a recomputed timeout when interrupted by
|
|
a signal, except if the signal handler raises an exception (see
|
|
:pep:`475` for the rationale), instead of raising
|
|
:exc:`InterruptedError`.
|
|
|
|
|
|
.. _epoll-objects:
|
|
|
|
Edge and Level Trigger Polling (epoll) Objects
|
|
----------------------------------------------
|
|
|
|
https://linux.die.net/man/4/epoll
|
|
|
|
*eventmask*
|
|
|
|
+-------------------------+-----------------------------------------------+
|
|
| Constant | Meaning |
|
|
+=========================+===============================================+
|
|
| :const:`EPOLLIN` | Available for read |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLOUT` | Available for write |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLPRI` | Urgent data for read |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLERR` | Error condition happened on the assoc. fd |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLHUP` | Hang up happened on the assoc. fd |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLET` | Set Edge Trigger behavior, the default is |
|
|
| | Level Trigger behavior |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLONESHOT` | Set one-shot behavior. After one event is |
|
|
| | pulled out, the fd is internally disabled |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLEXCLUSIVE` | Wake only one epoll object when the |
|
|
| | associated fd has an event. The default (if |
|
|
| | this flag is not set) is to wake all epoll |
|
|
| | objects polling on a fd. |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLRDHUP` | Stream socket peer closed connection or shut |
|
|
| | down writing half of connection. |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLRDNORM` | Equivalent to :const:`EPOLLIN` |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLRDBAND` | Priority data band can be read. |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLWRNORM` | Equivalent to :const:`EPOLLOUT` |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLWRBAND` | Priority data may be written. |
|
|
+-------------------------+-----------------------------------------------+
|
|
| :const:`EPOLLMSG` | Ignored. |
|
|
+-------------------------+-----------------------------------------------+
|
|
|
|
.. versionadded:: 3.6
|
|
:const:`EPOLLEXCLUSIVE` was added. It's only supported by Linux Kernel 4.5
|
|
or later.
|
|
|
|
.. method:: epoll.close()
|
|
|
|
Close the control file descriptor of the epoll object.
|
|
|
|
|
|
.. attribute:: epoll.closed
|
|
|
|
``True`` if the epoll object is closed.
|
|
|
|
|
|
.. method:: epoll.fileno()
|
|
|
|
Return the file descriptor number of the control fd.
|
|
|
|
|
|
.. method:: epoll.fromfd(fd)
|
|
|
|
Create an epoll object from a given file descriptor.
|
|
|
|
|
|
.. method:: epoll.register(fd[, eventmask])
|
|
|
|
Register a fd descriptor with the epoll object.
|
|
|
|
|
|
.. method:: epoll.modify(fd, eventmask)
|
|
|
|
Modify a registered file descriptor.
|
|
|
|
|
|
.. method:: epoll.unregister(fd)
|
|
|
|
Remove a registered file descriptor from the epoll object.
|
|
|
|
.. versionchanged:: 3.9
|
|
The method no longer ignores the :data:`~errno.EBADF` error.
|
|
|
|
|
|
.. method:: epoll.poll(timeout=None, maxevents=-1)
|
|
|
|
Wait for events. timeout in seconds (float)
|
|
|
|
.. versionchanged:: 3.5
|
|
The function is now retried with a recomputed timeout when interrupted by
|
|
a signal, except if the signal handler raises an exception (see
|
|
:pep:`475` for the rationale), instead of raising
|
|
:exc:`InterruptedError`.
|
|
|
|
|
|
.. _poll-objects:
|
|
|
|
Polling Objects
|
|
---------------
|
|
|
|
The :c:func:`!poll` system call, supported on most Unix systems, provides better
|
|
scalability for network servers that service many, many clients at the same
|
|
time. :c:func:`!poll` scales better because the system call only requires listing
|
|
the file descriptors of interest, while :c:func:`!select` builds a bitmap, turns
|
|
on bits for the fds of interest, and then afterward the whole bitmap has to be
|
|
linearly scanned again. :c:func:`!select` is *O*\ (*highest file descriptor*), while
|
|
:c:func:`!poll` is *O*\ (*number of file descriptors*).
|
|
|
|
|
|
.. method:: poll.register(fd[, eventmask])
|
|
|
|
Register a file descriptor with the polling object. Future calls to the
|
|
:meth:`poll` method will then check whether the file descriptor has any
|
|
pending I/O events. *fd* can be either an integer, or an object with a
|
|
:meth:`~io.IOBase.fileno` method that returns an integer. File objects
|
|
implement :meth:`!fileno`, so they can also be used as the argument.
|
|
|
|
*eventmask* is an optional bitmask describing the type of events you want to
|
|
check for, and can be a combination of the constants :const:`POLLIN`,
|
|
:const:`POLLPRI`, and :const:`POLLOUT`, described in the table below. If not
|
|
specified, the default value used will check for all 3 types of events.
|
|
|
|
+-------------------+------------------------------------------+
|
|
| Constant | Meaning |
|
|
+===================+==========================================+
|
|
| :const:`POLLIN` | There is data to read |
|
|
+-------------------+------------------------------------------+
|
|
| :const:`POLLPRI` | There is urgent data to read |
|
|
+-------------------+------------------------------------------+
|
|
| :const:`POLLOUT` | Ready for output: writing will not block |
|
|
+-------------------+------------------------------------------+
|
|
| :const:`POLLERR` | Error condition of some sort |
|
|
+-------------------+------------------------------------------+
|
|
| :const:`POLLHUP` | Hung up |
|
|
+-------------------+------------------------------------------+
|
|
| :const:`POLLRDHUP`| Stream socket peer closed connection, or |
|
|
| | shut down writing half of connection |
|
|
+-------------------+------------------------------------------+
|
|
| :const:`POLLNVAL` | Invalid request: descriptor not open |
|
|
+-------------------+------------------------------------------+
|
|
|
|
Registering a file descriptor that's already registered is not an error, and has
|
|
the same effect as registering the descriptor exactly once.
|
|
|
|
|
|
.. method:: poll.modify(fd, eventmask)
|
|
|
|
Modifies an already registered fd. This has the same effect as
|
|
``register(fd, eventmask)``. Attempting to modify a file descriptor
|
|
that was never registered causes an :exc:`OSError` exception with errno
|
|
:const:`ENOENT` to be raised.
|
|
|
|
|
|
.. method:: poll.unregister(fd)
|
|
|
|
Remove a file descriptor being tracked by a polling object. Just like the
|
|
:meth:`register` method, *fd* can be an integer or an object with a
|
|
:meth:`~io.IOBase.fileno` method that returns an integer.
|
|
|
|
Attempting to remove a file descriptor that was never registered causes a
|
|
:exc:`KeyError` exception to be raised.
|
|
|
|
|
|
.. method:: poll.poll([timeout])
|
|
|
|
Polls the set of registered file descriptors, and returns a possibly empty list
|
|
containing ``(fd, event)`` 2-tuples for the descriptors that have events or
|
|
errors to report. *fd* is the file descriptor, and *event* is a bitmask with
|
|
bits set for the reported events for that descriptor --- :const:`POLLIN` for
|
|
waiting input, :const:`POLLOUT` to indicate that the descriptor can be written
|
|
to, and so forth. An empty list indicates that the call timed out and no file
|
|
descriptors had any events to report. If *timeout* is given, it specifies the
|
|
length of time in milliseconds which the system will wait for events before
|
|
returning. If *timeout* is omitted, negative, or :const:`None`, the call will
|
|
block until there is an event for this poll object.
|
|
|
|
.. versionchanged:: 3.5
|
|
The function is now retried with a recomputed timeout when interrupted by
|
|
a signal, except if the signal handler raises an exception (see
|
|
:pep:`475` for the rationale), instead of raising
|
|
:exc:`InterruptedError`.
|
|
|
|
|
|
.. _kqueue-objects:
|
|
|
|
Kqueue Objects
|
|
--------------
|
|
|
|
.. method:: kqueue.close()
|
|
|
|
Close the control file descriptor of the kqueue object.
|
|
|
|
|
|
.. attribute:: kqueue.closed
|
|
|
|
``True`` if the kqueue object is closed.
|
|
|
|
|
|
.. method:: kqueue.fileno()
|
|
|
|
Return the file descriptor number of the control fd.
|
|
|
|
|
|
.. method:: kqueue.fromfd(fd)
|
|
|
|
Create a kqueue object from a given file descriptor.
|
|
|
|
|
|
.. method:: kqueue.control(changelist, max_events[, timeout]) -> eventlist
|
|
|
|
Low level interface to kevent
|
|
|
|
- changelist must be an iterable of kevent objects or ``None``
|
|
- max_events must be 0 or a positive integer
|
|
- timeout in seconds (floats possible); the default is ``None``,
|
|
to wait forever
|
|
|
|
.. versionchanged:: 3.5
|
|
The function is now retried with a recomputed timeout when interrupted by
|
|
a signal, except if the signal handler raises an exception (see
|
|
:pep:`475` for the rationale), instead of raising
|
|
:exc:`InterruptedError`.
|
|
|
|
|
|
.. _kevent-objects:
|
|
|
|
Kevent Objects
|
|
--------------
|
|
|
|
https://man.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
|
|
|
|
.. attribute:: kevent.ident
|
|
|
|
Value used to identify the event. The interpretation depends on the filter
|
|
but it's usually the file descriptor. In the constructor ident can either
|
|
be an int or an object with a :meth:`~io.IOBase.fileno` method. kevent
|
|
stores the integer internally.
|
|
|
|
.. attribute:: kevent.filter
|
|
|
|
Name of the kernel filter.
|
|
|
|
+---------------------------+---------------------------------------------+
|
|
| Constant | Meaning |
|
|
+===========================+=============================================+
|
|
| :const:`KQ_FILTER_READ` | Takes a descriptor and returns whenever |
|
|
| | there is data available to read |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_WRITE` | Takes a descriptor and returns whenever |
|
|
| | there is data available to write |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_AIO` | AIO requests |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_VNODE` | Returns when one or more of the requested |
|
|
| | events watched in *fflag* occurs |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_PROC` | Watch for events on a process id |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_NETDEV` | Watch for events on a network device |
|
|
| | [not available on macOS] |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_SIGNAL` | Returns whenever the watched signal is |
|
|
| | delivered to the process |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_FILTER_TIMER` | Establishes an arbitrary timer |
|
|
+---------------------------+---------------------------------------------+
|
|
|
|
.. attribute:: kevent.flags
|
|
|
|
Filter action.
|
|
|
|
+---------------------------+---------------------------------------------+
|
|
| Constant | Meaning |
|
|
+===========================+=============================================+
|
|
| :const:`KQ_EV_ADD` | Adds or modifies an event |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_DELETE` | Removes an event from the queue |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_ENABLE` | Permitscontrol() to returns the event |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_DISABLE` | Disablesevent |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_ONESHOT` | Removes event after first occurrence |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_CLEAR` | Reset the state after an event is retrieved |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_SYSFLAGS` | internal event |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_FLAG1` | internal event |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_EOF` | Filter specific EOF condition |
|
|
+---------------------------+---------------------------------------------+
|
|
| :const:`KQ_EV_ERROR` | See return values |
|
|
+---------------------------+---------------------------------------------+
|
|
|
|
|
|
.. attribute:: kevent.fflags
|
|
|
|
Filter specific flags.
|
|
|
|
:const:`KQ_FILTER_READ` and :const:`KQ_FILTER_WRITE` filter flags:
|
|
|
|
+----------------------------+--------------------------------------------+
|
|
| Constant | Meaning |
|
|
+============================+============================================+
|
|
| :const:`KQ_NOTE_LOWAT` | low water mark of a socket buffer |
|
|
+----------------------------+--------------------------------------------+
|
|
|
|
:const:`KQ_FILTER_VNODE` filter flags:
|
|
|
|
+----------------------------+--------------------------------------------+
|
|
| Constant | Meaning |
|
|
+============================+============================================+
|
|
| :const:`KQ_NOTE_DELETE` | *unlink()* was called |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_WRITE` | a write occurred |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_EXTEND` | the file was extended |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_ATTRIB` | an attribute was changed |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_LINK` | the link count has changed |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_RENAME` | the file was renamed |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_REVOKE` | access to the file was revoked |
|
|
+----------------------------+--------------------------------------------+
|
|
|
|
:const:`KQ_FILTER_PROC` filter flags:
|
|
|
|
+----------------------------+--------------------------------------------+
|
|
| Constant | Meaning |
|
|
+============================+============================================+
|
|
| :const:`KQ_NOTE_EXIT` | the process has exited |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_FORK` | the process has called *fork()* |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_EXEC` | the process has executed a new process |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_PCTRLMASK` | internal filter flag |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_PDATAMASK` | internal filter flag |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_TRACK` | follow a process across *fork()* |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_CHILD` | returned on the child process for |
|
|
| | *NOTE_TRACK* |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_TRACKERR` | unable to attach to a child |
|
|
+----------------------------+--------------------------------------------+
|
|
|
|
:const:`KQ_FILTER_NETDEV` filter flags (not available on macOS):
|
|
|
|
+----------------------------+--------------------------------------------+
|
|
| Constant | Meaning |
|
|
+============================+============================================+
|
|
| :const:`KQ_NOTE_LINKUP` | link is up |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_LINKDOWN` | link is down |
|
|
+----------------------------+--------------------------------------------+
|
|
| :const:`KQ_NOTE_LINKINV` | link state is invalid |
|
|
+----------------------------+--------------------------------------------+
|
|
|
|
|
|
.. attribute:: kevent.data
|
|
|
|
Filter specific data.
|
|
|
|
|
|
.. attribute:: kevent.udata
|
|
|
|
User defined value.
|