SourceFuncs#
- class SourceFuncs(*args, **kwargs)#
The GSourceFuncs
struct contains a table of
functions used to handle event sources in a generic manner.
For idle sources, the prepare and check functions always return True
to indicate that the source is always ready to be processed. The prepare
function also returns a timeout value of 0 to ensure that the poll() call
doesn’t block (since that would be time wasted which could have been spent
running the idle function).
For timeout sources, the prepare and check functions both return True
if the timeout interval has expired. The prepare function also returns
a timeout value to ensure that the poll() call doesn’t block too long
and miss the next timeout.
For file descriptor sources, the prepare function typically returns False
,
since it must wait until poll() has been called before it knows whether
any events need to be processed. It sets the returned timeout to -1 to
indicate that it doesn’t mind how long the poll() call blocks. In the
check function, it tests the results of the poll() call to see if the
required condition has been met, and returns True
if so.
Fields#
- class SourceFuncs
- check#
Called after all the file descriptors are polled. The source should return
True
if it is ready to be dispatched. Note that some time may have passed since the previous prepare function was called, so the source should be checked again here. Since 2.36 this may beNone
, in which case the effect is as if the function always returnsFalse
.
- closure_callback#
- closure_marshal#
- dispatch#
Called to dispatch the event source, after it has returned
True
in either itsprepare
or itscheck
function, or if a ready time has been reached. Thedispatch
function receives a callback function and user data. The callback function may beNone
if the source was never connected to a callback usingset_callback
. Thedispatch
function should call the callback function withuser_data
and whatever additional parameters are needed for this type of event source. The return value of thedispatch
function should beSOURCE_REMOVE
if the source should be removed orSOURCE_CONTINUE
to keep it.
- finalize#
Called when the source is finalized. At this point, the source will have been destroyed, had its callback cleared, and have been removed from its
MainContext
, but it will still have its final reference count, so methods can be called on it from within this function.
- prepare#
Called before all the file descriptors are polled. If the source can determine that it is ready here (without waiting for the results of the poll() call) it should return
True
. It can also return a @``timeout_`` value which should be the maximum timeout (in milliseconds) which should be passed to the poll() call. The actual timeout used will be -1 if all sources returned -1, or it will be the minimum of all the @``timeout_`` values returned which were >= 0. Since 2.36 this may beNone
, in which case the effect is as if the function always returnsFalse
with a timeout of -1. Ifprepare
returns a timeout and the source also has a ready time set, then the lower of the two will be used.