Re: GIOChannel reference counting

[Axel Simon <A Simon kent ac uk>]

On Mon, 2005-12-12 at 10:56 +0000, Richard Warren wrote:
> Dear all,
>
> I would be grateful if anyone could tell me whether I need to unreference a 
> GIOChannel in order to destroy it properly.
>
> Here's what I'm currently doing:
>
> 1. I create a channel with g_io_channel_unix_new() from a socket.  The docs 
> state that the initial reference count will be 1.
> 2. I then add a watch on it with g_io_add_watch().
> 3. At a later date, I remove the watch with g_source_remove().
> 4. I want to destroy the channel and free all resources, so call 
> g_io_channel_shutdown().
>
> However, the docs for the shutdown function state that the channel will not 
> be freed until the last reference is dropped using g_io_channel_unref(). 
> Does this include the initial reference added on creation, or is that 
> unreferenced by the shutdown function.

The comment in the shutdown function wants to say that
"g_io_channel_shutdown" doesn't touch the reference counter. Hence you
need to unref the channel manually.

What you can (probably) do is the following:
1. Create the channel.
2. Add the watch. The watch should add a reference to the channel.
3. Call unref on the channel. Now the watch holds the only reference to
the channel.
4. Remove the watch with g_source_remove, this will drop the ref count
to 0 and destroy the channel. The channel will be flushed.

In general, every low-level object that is not a GtkObject or derived
therefrom has a reference count of 1 and hence needs to be unref'd by
whomever called the constructor.

Hope this helps,
Axel.