idle loop callbacks

Hello all:

I just want to check a conclusion to which I've come against the knowledge out there concerning idle events.

In my application, I construct my window and call show_all_children in order to have the window displayed before I connect to the database that is used in the application. If I can successfully connect to that database, I then call Gtk::Main::run; if not, I just call the window's hide() method and exit the application.

I have found that in order to see the window displayed before putting up a child window containing a progress bar while waiting for the database connection and subsequent retrieval of the data to be processed, I must use the following code before actually connecting to the database:


This seems to work very well. In addition to all this, I also have a class that is used to log certain diagnostic data to disk files if error conditions occur. In order to prevent this logging from affecting the timing of certain time sensitive processess during disk I/O, I designed this class such that it puts these diagnostic messages into a memory array object that is then subsequently accessed by a callback function that is connected to the idle loop thusly:

Glib::signal_idle().connect( sigc::bind<gpointer>(&putMessagesToFile,(gpointer)this) );

from within the aforementioned class. The callback function iterates the memory array writing each diagnostic message to disk and subsequently deleting each message from the array, and then it exits with a return value of TRUE. In my class, I connect this callback to the idle loop until the class goes out of scope or is deleted in the case of a dynamically created version, whereupon it returns a FALSE and is discarded by the idle loop. I have described all this to lead up to my conclusion: It appears that connecting this callback to the idle loop creates a defacto ever-present "event" that effects the return value of the Gtk::Main::instance()->events_pending() function. I say this, because so long as my reporting class callback is connected to signal_idle, the events_pending loop never ends.

In order to workaround this phenomenon, I changed my reporting class such that the callback function is connected each time a diagnostic message is added to the array and the callback function always returns false when finishing it's job. This has stopped the "hang" phenomenon.

So, is there something about the way I've implemented this scheme that is causing my problem or is it just an unhappy coincidence?


Bob Caryl

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