Trying to solve our disappearing thread issues by making thread list updates safer.

The current ProcessGDBRemote function that updates the threads could end up with an empty list if any other thread had the sequence mutex. We now don't clear the thread list when we can't access it, and we also have changed how lldb_private::Process handles the return code from the:

virtual bool
Process::UpdateThreadList (lldb_private::ThreadList &old_thread_list, 
                       	   lldb_private::ThreadList &new_thread_list) = 0;

A bool is now returned to indicate if the list was actually updated or not and the lldb_private::Process class will only update the stop ID of the validity of the thread list if "true" is returned.

The ProcessGDBRemote also got an extra assertion that will hopefully assert when running debug builds so we can find the source of this issue.

llvm-svn: 154365

1 files changed, 9 insertions, 8 deletions

diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp
index d17449128d0..6ad0ed05c6e 100644
--- a/lldb/source/Target/Process.cpp
+++ b/lldb/source/Target/Process.cpp
@@ -1236,13 +1236,15 @@ Process::UpdateThreadListIfNeeded ()
             // and the os->UpdateThreadList(...) so it doesn't change on us
             ThreadList new_thread_list(this);
             // Always update the thread list with the protocol specific
-            // thread list
-            UpdateThreadList (m_thread_list, new_thread_list);
-            OperatingSystem *os = GetOperatingSystem ();
-            if (os)
-                os->UpdateThreadList (m_thread_list, new_thread_list);
-            m_thread_list.Update (new_thread_list);
-            m_thread_list.SetStopID (stop_id);
+            // thread list, but only update if "true" is returned
+            if (UpdateThreadList (m_thread_list, new_thread_list))
+            {
+                OperatingSystem *os = GetOperatingSystem ();
+                if (os)
+                    os->UpdateThreadList (m_thread_list, new_thread_list);
+                m_thread_list.Update (new_thread_list);
+                m_thread_list.SetStopID (stop_id);
+            }
         }
     }
 }
@@ -4281,7 +4283,6 @@ Process::RunThreadPlan (ExecutionContext &exe_ctx,
     if (IS_VALID_LLDB_HOST_THREAD(backup_private_state_thread))
     {
         StopPrivateStateThread();
-        lldb::thread_result_t thread_result;
         Error error;
         // Host::ThreadJoin(m_private_state_thread, &thread_result, &error);
         m_private_state_thread = backup_private_state_thread;