Rework how the API mutex is acquired when filling out an ExecutionContext from an ExecutionContextRef,
particularly in the SBThread & SBFrame interfaces. Instead of filling the whole context & then getting
the API mutex, we now get only the target, acquire the API mutex from it, then fill out the rest of the
context. This removes a race condition where you get a ThreadSP, then wait on the API mutex while another
command Destroy's the Thread you've just gotten.
Also fixed the ExecutionContextRef::Get*SP calls so they don't return invalid objects.
Also fixed the ExecutionContext::Has*Scope calls so they don't claim to have a scope if the object representing
that scope has been destroyed.
Also fixed a think-o in Thread::IsValid which was causing it to return the opposite of the desired value.
<rdar://problem/11995490>
git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@162401 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed