h.b.furuseth@usit.uio.no wrote:
I wonder if we've been waiting for each other... Anyway, I've committed some pending fixes now that HEAD passes all tests for me. I've some more cleanup, but if we are close to a freeze I don't know if that means I should rush it in or wait until afterwards.
Cleanup as in tidying the code, or as in fixing functionality?
We did have code which compared thread IDs with '==' for quite some time. Do you remember if anyone complained, or if the switch to using ldap_pvt_thread_equal() was a "just in case" fix?
Yes, I needed to use pthread_equal() on OS/390 since their thread type was a structure.
I'm not sure, but I gather that's derived from the DCE threads reference implementation where pthread_t has three members 'field1', 'field2' and 'field3'. tls.c can't stuff all of them in a long, so the old one may not get a unique ID. OTOH DCE has a pthread_getunique_np() call which uses just the 2nd field as a unique integer thread ID, I expect we could use that. Except I don't have a host to test such a change on. Dunno why pthread_equal checks all three fields. I've asked on comp.programming.threads.
I don't remember which version of the spec OS/390 implemented, it was certainly old but it wasn't DCE. Might have been Draft 6 IIRC.
Also I note that the DCE struct will get four padding bytes on a 64-bit host which aligns the struct at 8*n addresses, and the compiler is not obliged to preserve these during struct copy.
On the other hand DCE threads are based on an extremely outdated Posix draft, so I don't know how relevant it is now.
Yes, Draft 4, and I don't know of any systems that still use that exclusively.
Another time when tls.c code loses information is if pointers are wider than long, which does happen. (Don't know how it is nowadays, but I remember plenty of postings about it some years ago.)
Probably the OpenSSL API should have used a void * here. Too bad.
[Using address of the thread's stack]
That's what the LDAP_PVT_THREAD_STACK_SIZE macro tells you.
As modified by PTHREAD_STACK_MIN and pthread_attr_getguardsize(). And slight other variations, apparently. I tried on a few hosts and Solaris would a few times use some extra space near the stack of a thread or two.
OTOH we could allocate stack memory ourselves and then use pthread_attr_setstack() to put the stack just where we want it.
However this doesn't help tls.c with threads that have been created by _other_ packages. And the SSL id_callback function apparently has no way to return failure:-(
All in all I still like a thread-specific key better - they are the standard way of doing things like this. We only need it for pthreads since the other thread types as far as I can tell have integer IDs.
OK, suppose we use a pthread thread-specific key here. What are you proposing for the unique value?
It's really not hard. If we were to disallow increasing the number of threads at runtime, we could simply allocate a block of thread stacks all at once, which would then allow our thread IDs to be simple integers from 0-N.
IIRC disallowing that would fix some other tpool problem too, but I don't remember what.
I'm not really keen on that since I like having the ability to both increase and decrease the setting dynamically.
Which led me to notice that the setstacksize call now _decreases_ the stack size on some hosts. I don't suppose that was intentional, so I guess it should be size_t cursize; if( pthread_attr_getstacksize( &attr, &cursize ) || cursize < LDAP_PVT_THREAD_STACK_SIZE ) pthread_attr_setstacksize( &attr, LDAP_PVT_THREAD_STACK_SIZE ); in thr_posix and I don't know what in other thr_* files. A RE24 change I guess, since reduces the max number of threads before slapd gets into trouble.
I don't consider this a bug. If someone wants a larger thread stack they can recompile to get it. Or perhaps we should make it a tunable variable and add a config keyword for it.
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