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>

llvm-svn: 162401

1 files changed, 1 insertions, 1 deletions

diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index df86869cc33..7ff006c6bce 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -708,7 +708,7 @@ Thread::PopPlan ()
 {
     LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
 
-    if (m_plan_stack.empty())
+    if (m_plan_stack.size() <= 1)
         return;
     else
     {