The EvIo class
(PECL ev >= 0.2.0)
EvIo watchers check whether a file descriptor(or socket, or a stream castable to numeric file descriptor) is readable or writable in each iteration of the event loop, or, more precisely, when reading would not block the process and writing would at least be able to write some data. This behaviour is called level-triggering because events are kept receiving as long as the condition persists. To stop receiving events just stop the watcher.
The number of read and/or write event watchers per
is unlimited. Setting all file descriptors to non-blocking mode is also
usually a good idea(but not required).
Another thing to watch out for is that it is quite easy to receive false
readiness notifications, i.e. the callback might be called with
but a subsequent
will actually block because there is no data. It is very easy to get into
this situation. Thus it is best to always use non-blocking I/O: An extra
(or similar) is far preferable to a program hanging until some data
If for some reason it is impossible to run the
in non-blocking mode, then separately re-test whether a file descriptor is
really ready. Some people additionally use
and an interval timer, just to be sure thry won't block infinitely.
Always consider using non-blocking mode.
Sinopse da classe
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