This module provides functions to efficiently wait for events on multiple streams.
This module is not available on the BOOST Move hub.
Data is available for reading.
More data can be written.
Error condition happened on the associated stream.
Hang up happened on the associated stream.
register(obj: IO) → None¶
register(obj: IO, eventmask: int) → None
eventmaskis logical OR of:
Note that flags like
POLLERRare not valid as input eventmask (these are unsolicited events which will be returned from
poll()regardless of whether they are asked for). This semantics is per POSIX.
POLLIN | POLLOUT.
It is OK to call this function multiple times for the same
obj. Successive calls will update
obj’s eventmask to the value of
eventmask(i.e. will behave as
unregister(obj: IO) → None¶
modify(obj: IO, eventmask: int) → None¶
objis not registered,
OSErroris raised with error of
poll() → List[Tuple[IO, int]]¶
poll(timeout: int) → List[Tuple[IO, int]]
Wait for at least one of the registered objects to become ready or have an exceptional condition, with optional timeout in milliseconds (if
timeoutarg is not specified or -1, there is no timeout).
Returns list of (
event, …) tuples. There may be other elements in tuple, depending on a platform and version, so don’t assume that its size is 2. The
eventelement specifies which events happened with a stream and is a combination of
POLL*constants described above. Note that flags
POLLERRcan be returned at any time (even if were not asked for), and must be acted on accordingly (the corresponding stream unregistered from poll and likely closed), because otherwise all further invocations of
poll()may return immediately with these flags set for this stream again.
In case of timeout, an empty list is returned.
ipoll() → Iterator[Tuple[IO, int]]¶
ipoll(timeout: int) → Iterator[Tuple[IO, int]]
ipoll(timeout: int, flags: int) → Iterator[Tuple[IO, int]]
poll(), but instead returns an iterator which yields a callee-owned tuple. This function provides an efficient, allocation-free way to poll on streams.
flagsis 1, one-shot behavior for events is employed: streams for which events happened will have their event masks automatically reset (equivalent to
poll.modify(obj, 0)), so new events for such a stream won’t be processed until new mask is set with
modify(). This behavior is useful for asynchronous I/O schedulers.