libdispatch vs glib

[cee1 <fykcee1 gmail com>]

Hi all,

Following is a comparison between libdispatch and glib, just for interest.

First, libdispatch is the user space part of apple's GDC(Grand Central Dispatch), resides at http://libdispatch.macosforge.org. There is also an introduction at http://developer.apple.com/mac/articles/cocoa/introblocksgcd.html.

At first glimpse, libdispatch provides three different types of dispatch queues:

1. Main queue: equivalent of glib's main event loop
2. Global queue: backed up by a thread pool. All the jobs sent to this queue, will be executed in arbitrary threads asynchronously.
3. Private queue: jobs in this queue will be executed serially.

Both private queue and main queue are just threads in global queue. It should be more user-friendly than combining GMainLoop and GThreadPool, e.g. process GSource in another thread (i.e using thread pool in the callback of that GSource).

The private queue can be considered as a pipeline (imaging GstPipeline in gstreamer).

libdispatch also has a type of dispatch_source_t, equivalent of GSource, but the callback is running in global queue, (hence, a different thread)

libdispatch is built on an extension to C (blocks), which is like GClosure.