OK...here goes...
My goal is to have a function within a module reference a thread-specific
data item. I want the state of the data item to be settable and gettable
over time, but different for each thread. I don't want to pass an
apr_thread_t object in and out of the function, in fact it has to work the
same for single-threaded code where there are no thread objects created at
all.
I've been staring at the thread/proc stuff for awhile. I think I'm seeing
four different families of functions that relate to "thread-specific" data:
apr_thread_attr_
apr_thread_data_
apr_threadkey_private_
apr_threadkey_data_
The _private_ calls directly relate to thread-specific indices created by
the operating system. These seem to automatically sense what thread you're
in (important to the code I want to write). They don't have cleanup calls
like the second and fourth families.
The first, second, and fourth families seem to use userdata calls associated
with pools. [It's interesting that the pools have optional hashes
associated with them, I'm sure there's a reason for this...]
I'm confused about what the different function families are for...but I
don't actually have to know just now. What I need is to set up a data item
on each thread at need.
I'm thinking that _if_ I had a function like apr_current_thread() I could
use the first or second function families (but what is the difference
between the two?). I could also use the third one to generate a memory
space and then switch to the fourth one with the apr_threadkey_t thus
created and use the cleanup function. Or something like that. But then I
need a place to put the apr_threadkey_t item...associated with the current
thread, of course. So I'm kind of back to square one.
I think that I can dummy up apr_current_thread using apr_os_thread_current
and apr_os_thread_put, but I'm not convinced that I would get the "same"
apr_thread_t object each time. Which is (I think) what I want.
I think I just don't have the right perspective on the problem. Y'all
probably planned for this somehow and I'm just not in the loop, so I've
missed the obvious answer.
I looked briefly in the 2.0 codebase and didn't find any examples.
Marc M. Adkins
