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Diffstat (limited to 'Doc/library/select.rst')
| -rw-r--r-- | Doc/library/select.rst | 304 |
1 files changed, 300 insertions, 4 deletions
diff --git a/Doc/library/select.rst b/Doc/library/select.rst index 4a97179..1368c78 100644 --- a/Doc/library/select.rst +++ b/Doc/library/select.rst @@ -7,10 +7,12 @@ This module provides access to the :cfunc:`select` and :cfunc:`poll` functions -available in most operating systems. 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. +available in most operating systems, :cfunc:`epoll` available on Linux 2.5+ and +:cfunc:`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. The module defines the following: @@ -22,6 +24,16 @@ The module defines the following: string, as would be printed by the C function :cfunc:`perror`. +.. type:: epoll([sizehint=-1]) + + (Only supported on Linux 2.5.44 and newer.) Returns an edge polling + object, which can be used as Edge or Level Triggered interface for I/O + events; see section :ref:`epoll-objects` below for the methods supported + by epolling objects. + + .. versionadded:: 2.6 + + .. function:: poll() (Not supported by all operating systems.) Returns a polling object, which @@ -30,6 +42,24 @@ The module defines the following: by polling objects. +.. type:: kqueue() + + (Only supported on BSD.) Returns a kernel queue object + object; see section :ref:`kqueue-objects` below for the methods supported + by kqueue objects. + + .. versionadded:: 2.6 + + +.. type:: kqueue(ident, filter=KQ_FILTER_READ, flags=KQ_ADD, fflags=0, data=0, udata=0) + + (Only supported on BSD.) Returns a kernel event object + object; see section :ref:`kevent-objects` below for the methods supported + by kqueue objects. + + .. versionadded:: 2.6 + + .. function:: select(iwtd, owtd, ewtd[, timeout]) This is a straightforward interface to the Unix :cfunc:`select` system call. @@ -67,6 +97,81 @@ The module defines the following: not handle file descriptors that don't originate from WinSock. +.. _epoll-objects: + +Edge and Level Trigger Polling (epoll) Objects +---------------------------------------------- + + http://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 happend on the assoc. fd | + +-----------------------+-----------------------------------------------+ + | :const:`EPOLLHUP` | Hang up happend 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:`EPOLLRDNORM` | ??? | + +-----------------------+-----------------------------------------------+ + | :const:`EPOLLRDBAND` | ??? | + +-----------------------+-----------------------------------------------+ + | :const:`EPOLLWRNORM` | ??? | + +-----------------------+-----------------------------------------------+ + | :const:`EPOLLWRBAND` | ??? | + +-----------------------+-----------------------------------------------+ + | :const:`EPOLLMSG` | ??? | + +-----------------------+-----------------------------------------------+ + + +.. method:: epoll.close() + + Close the control file descriptor of the epoll object. + + +.. 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 register file descriptor. + + +.. method:: epoll.unregister(fd) + + Remove a registered file descriptor from the epoll object. + + +.. method:: epoll.poll([timeout=-1[, maxevents=-1]]) + + Wait for events. timeout in seconds (float) + + .. _poll-objects: Polling Objects @@ -114,6 +219,16 @@ linearly scanned again. :cfunc:`select` is O(highest file descriptor), while 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 + :meth:`register(fd, eventmask)`. Attempting to modify a file descriptor + that was never registered causes an :exc:`IOError` exception with errno + :const:`ENOENT` to be raised. + + .. versionadded:: 2.6 + + .. method:: poll.unregister(fd) Remove a file descriptor being tracked by a polling object. Just like the @@ -137,3 +252,184 @@ linearly scanned again. :cfunc:`select` is O(highest file descriptor), while returning. If *timeout* is omitted, negative, or :const:`None`, the call will block until there is an event for this poll object. + +.. _kqueue-objects: + +Kqueue Objects +-------------- + +.. method:: kqueue.close() + + Close the control file descriptor of the kqueue object. + + +.. method:: kqueue.fileno() + + Return the file descriptor number of the control fd. + + +.. method:: epoll.fromfd(fd) + + Create a kqueue object from a given file descriptor. + + +.. method:: control(changelist, max_events=0[, timeout=None]) -> eventlist + + Low level interface to kevent + + - changelist must be an iterable of kevent object or None + - max_events must be 0 or a positive integer + - timeout in seconds (floats possible) + + +.. _kevent-objects: + +Kevent Objects +-------------- + + http://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2 + + .. attribute:: 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 fileno() function. kevent stores the integer + internally. + + .. attribute:: 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 read | + +---------------------------+---------------------------------------------+ + | :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 Mac OS X] | + +---------------------------+---------------------------------------------+ + | :const:`KQ_FILTER_SIGNAL` | Returns whenever the watched signal is | + | | delivered to the process | + +---------------------------+---------------------------------------------+ + | :const:`KQ_FILTER_TIMER` | Establishes an arbitrary timer | + +---------------------------+---------------------------------------------+ + + .. attribute:: 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 occurence | + +---------------------------+---------------------------------------------+ + | :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:: 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 occured | + +----------------------------+--------------------------------------------+ + | :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 Mac OS X] + + +----------------------------+--------------------------------------------+ + | 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:: data + + Filter specific data + + + .. attribute:: udata + + User defined value |