There are potential deadlock situations that can occur if code executing
within the context of a job aquires a lock, and then pauses the job. This
adds an ability to temporarily block pauses from occuring whilst performing
work and holding a lock.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Even with _XOPEN_SOURCE defined OS-X still displays warnings that
makecontext and friends are deprecated. This isn't a problem until you
try and build with --strict-warnings, and the build fails. This change
suppresses the warnings. We know they are deprecated but there is no
alternative!
Reviewed-by: Rich Salz <rsalz@openssl.org>
async_fibre_makecontext was initialise the fibre first and then calling
getcontext(). It should be the other way around because the getcontext
call may overwrite some of the things we just initialised. This didn't
cause an issue on Linux and so the problem went unnoticed. On OS-X it
causes a crash.
Reviewed-by: Rich Salz <rsalz@openssl.org>
_longjmp/_setjmp do not manipulate the signal mask whilst
longjmp/setjmp may do. Online sources suggest this could result
in a significant speed up in the context switching.
Reviewed-by: Rich Salz <rsalz@openssl.org>
If config'd without -d (--debug), asynctest was crashing with:
*** longjmp causes uninitialized stack frame ***
This is because gcc will add certain checks for some functions
(including longjmp). The checks assume you can only longjmp down the
stack not up. However, if we are actually jumping to a different
fibre then it can appear as if we are going up the stack when we are
not really. This change disables the check.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Add some clarifications to the async documentation. Also changed
ASYNC_pause_job() so that it returns success if you are not within the
context of a job. This is so that engines can be used either asynchronously
or synchronously and can treat an error from ASYNC_pause_job() as a real
error.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Don't recreate a new ASYNC_CTX every time we call ASYNC_start_job() - the
same one can be used for the life of the thread. Instead we only free it
up when we call ASYNC_free_pool().
Reviewed-by: Rich Salz <rsalz@openssl.org>
The ASYNC null implementation has not kept pace with the rest of the async
development and so was failing to compile.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Initial API implemented for notifying applications that an ASYNC_JOB
has completed. Currently only s_server is using this. The Dummy Async
engine "cheats" in that it notifies that it has completed *before* it
pauses the job. A normal async engine would not do that.
Only the posix version of this has been implemented so far, so it will
probably fail to compile on Windows at the moment.
Reviewed-by: Rich Salz <rsalz@openssl.org>
It is expensive to create the ASYNC_JOB objects due to the "makecontext"
call. This change adds support for pools of ASYNC_JOB objects so that we
don't have to create a new ASYNC_JOB every time we want to use one.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Where we can we should use longjmp and setjmp in preference to swapcontext/
setcontext as they seem to be more performant.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Removed the function ASYNC_job_is_waiting() as it was redundant. The only
time user code has a handle on a job is when one is waiting, so all they
need to do is check whether the job is NULL. Also did some cleanups to
make sure the job really is NULL after it has been freed!
Reviewed-by: Rich Salz <rsalz@openssl.org>
Create a "null" async implementation for platforms that lack support. This
just does nothing when called and therefore performs synchronously.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Provides support for running asynchronous jobs. Currently this is completely
stand alone. Future commits will integrate this into libssl and s_server/
s_client. An asynchronous capable engine will be required to see any benefit
from this capability.
Reviewed-by: Rich Salz <rsalz@openssl.org>
