Re: Bad news, many errors on linux

It is important to keep in mind that the CS event system is driven by
the hosting program[1], and thus events are dispatched from the queue
only as frequently as the hosting program chooses. The hosting program
can even suspend processing of the queue, therefore there is no
guarantee that messages sent via the event queue between plugins will
be delivered in a timely fashion. The event system does not promise
on-time delivery. This may or may not matter for the type of usage you
have in mind, but should be taken into consideration.

Footnotes[5]:

[1] By "driven by the hosting program", I mean that the program in
which CS is embedded is responsible for invoking
iEventQueue::Process() periodically to "run" the CS engine. This is by
design; it is not an accident. In many cases, the queue is processed
by csDefaultRunLoop(), thus events get dispatched frequently, but this
is not guaranteed to be so. csDefaultRunLoop() is just that: a
_default_ implementation of a run-loop for "running" CS. In that role,
it may or may not be suitable for any given program embedding CS, and
programs are encouraged to shun csDefaultRunLoop() and instead invoke
iEventQueue::Process() manually if the behavior or lack-of-flexibility
of csDefaultRunLoop() is unsuitable[2].

[2] By "unsuitable", I mean that the generic csDefaultRunLoop()
implementation does not, within CS's limited purview[3], know how to
interact with native facilities of the host system or application
framework, nor does it have knowledge about how the hosting program
expects to employ CS[4].

[3] Mac OS X's Cocoa framework is a canonical example. Cocoa supplies
its own application run-loop which implements the many functionalities
common to all OSX applications. "Running" CS is just one of the very
many responsibilities of the Cocoa run-loop. iOS for iPhone, iPod, and
iPad is similarly burdened. For Cocoa, CS does implement a specially
customized csDefaultRunLoop() which works properly in conjunction with
Cocoa's own run-loop, but even this implementation may not be
suitable[4] for all applications due to its inflexibility.

[4] csDefaultRunLoop() is intentionally simple-minded, assuming that
it is being employed by high-framerate, fast-paced action games.
However, not every program is an action game, hence not every program
needs to "run" CS as fast-as-possible. For such programs, it may be
more resource-economical to "run" CS by processing its event queue
only when needed. The canonical example is an editor built with
platform-native toolkits, in which one or a few CS "views" display
some 3D content. These views may need to be updated only in response
to some user action, or in response to the change of an attribute in
some native control which would impact the 3D view. A turned-based
game, in which one or more CS 3D views are hosted in a platform-native
application is another good example for which CS may be "run" only at
infrequent intervals.

[5] This email badly abuses footnotes.

-- ES


On Fri, Jun 29, 2012 at 7:35 AM, Christian Van Brussel
<[email protected]> wrote:
>> Also I have experienced in the
>> past that
>> the event system performance goes down considerably if you have many event
>> handlers
>> registered to it.
>
> The event queue is using several hash data structures, hence with an
> access of the objects with a complexity of a priori O(log n).
>
> One way to deal with that may therefore to have several different event
> queues, eg each one dedicated to a specific domain.
>
>
>
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