are started instead of init (pid = 1). This allows an embedded
implementation quite like VxWorks, with (possibly) a single threaded
program running instead of init. The neat thing is that the same threaded
process can run in a multi-user workstation environment too.
initialized mutex. Statically initialized mutexes are actually
initialized at first use (pthread_mutex_lock/pthread_mutex_trylock).
To prevent concurrent initialization by multiple threads, all
static initializations are now serialized by a spinlock.
Reviewed by: jb
signal can arrive before the thread is woken from it's wait4. In this
case, don't return an EINTR, just set the thread state to running and
the wait4 wrapper will loop and get the exit status of the process.
line number every time a file descriptor is locked.
This looks like a big change but it isn't. It should reduce the size
of libc_r and make it run slightly faster.
with -D_LOCK_DEBUG. This adds the file name and line number to each lock
call and these are stored in the spinlock structure. When using debug
mode, the lock function will check if the thread is trying to lock
something it has already locked. This is not supposed to happen because
the lock will be freed too early.
Without lock debug, libc_r should be smaller and slightly faster.
cleanup destructor, so trap this case to prevent me from being being
burnt again by applications that try to do this. With this change, an
application (like one using a mis-configured ACE) will exit the process
after displaying a message quoting the POSIX section that the application
has violated.
is allocated or not, rather than keeping a count and attempting to
know it it is in-use. POSIX says that once a key is deleted, using the
key again results in undefined behaviour.
written without returning to the caller. This only occurs on pipes
where either the number of bytes written is greater than the pipe
buffer or if there is insufficient space in the pipe buffer because the
reader is reading slower than the writer is writing.
for the process, not a separate set for each thread). By default, the
process now only has signal handlers installed for SIGVTALRM, SIGINFO
and SIGCHLD. The thread kernel signal handler is installed for other
signals on demand. This means that SIG_IGN and SIG_DFL processing is now
left to the kernel, not the thread kernel.
Change the signal dispatch to no longer use a signal thread, and
call the signal handler using the stack of the thread that has the
signal pending.
Change the atomic lock method to use test-and-set asm code with
a yield if blocked. This introduces separate locks for each type
of object instead of blocking signals to prevent a context
switch. It was this blocking of signals that caused the performance
degradation the people have noted.
This is a *big* change!
it was. Add a FILE_WAIT state and queue threads waiting for a FILE
lock. Start using the sys/queue.h macros instead of the way that MIT
pthreads did it.
Add a thread name to the private thread structure and a non-POSIX
function to set this. This helps (me at least) when sending a SIGINFO
to a threaded process to get a /tmp/uthread.dump to see what the
<expletive deleted> threads are doing this time. It is nice to be
able to recognise (yes, I spell that with an 's' too) which threads
are which.
threads from invalid ones. The pthread structure is opaque to the user
so this change does not cause any incompatibilities.
Hopefully this change will help code that was written for draft 4
fail gracefully if the programmer ignores the compiler warning about
the change in the level of indirection for the argument passed to
pthread_detach(). I got burnt, so I fixed then (expletive deleted)
thing.
These functions comply with the revised standard. That should shut
Terry up!
specifically:
uthread_accept.c: Fix for inherited socket not getting correct entry in
pthread flags.
uthread_create.c: Fix to allow pthread_t pointer return to be null if
caller doesn't care about return.
uthread_fd.c: Fix for return codes to be placed into correct errno.
uthread_init.c: Changes to make gcc-2.8 thread aware for exception stack
frames (WARNING: This is #ifdef'ed out by default and is
different from the Cygnus egcs fix).
uthread_ioctl.c: Fix for blocking/non-blocking ioctl.
uthread_kern.c: Signal handling fixes (only one case left to fix,
that of an externally sent SIGSEGV and friends -
a fairly unusual case).
uthread_write.c: Fix for lock of fd - ask for write lock, not read/write.
uthread_writev.c: Fix for lock of fd - ask for write lock, not read/write.
Pthreads now works well enough to run the LDAP and ACAPD(with the gcc 2.8 fix)
sample implementations.
functions would return -1 and set errno to indicate the specific error.
POSIX requires that the functions return the error code as the return
value of the function instead.
John Birrell
Alexander Langer
Bruce Evans
Julian Elischer