Fixed a race condition that could cause ProcessGDBRemote::DoResume() to return

an error saying the resume timed out. Previously the thread that was trying
to resume the process would eventually call ProcessGDBRemote::DoResume() which
would broadcast an event over to the async GDB remote thread which would sent the
continue packet to the remote gdb server. Right after this was sent, it would
set a predicate boolean value (protected by a mutex and condition) and then the
thread that issued the ProcessGDBRemote::DoResume() would then wait for that
condition variable to be set. If the async gdb thread was too quick though, the
predicate boolean value could have been set to true and back to false by the
time the thread that issued the ProcessGDBRemote::DoResume() checks the boolean
value. So we can't use the predicate value as a handshake. I have changed the code
over to using a Event by having the GDB remote communication object post an
event: 

	GDBRemoteCommunication::eBroadcastBitRunPacketSent

This allows reliable handshaking between the two threads and avoids the erroneous
ProcessGDBRemote::DoResume() errors.

Added a host backtrace service to allow in process backtraces when trying to track
down tricky issues. I need to see if LLVM has any backtracing abilities abstracted
in it already, and if so, use that, but I needed something ASAP for the current issue
I was working on. The static function is:

void
Host::Backtrace (Stream &strm, uint32_t max_frames);

And it will backtrace at most "max_frames" frames for the current thread and can be
used with any of the Stream subclasses for logging.

llvm-svn: 120793

1 files changed, 7 insertions, 0 deletions

diff --git a/lldb/source/Host/common/Host.cpp b/lldb/source/Host/common/Host.cpp
index a51fa3d6def..c00c87f5ef7 100644
--- a/lldb/source/Host/common/Host.cpp
+++ b/lldb/source/Host/common/Host.cpp
@@ -402,6 +402,13 @@ void
 Host::ThreadCreated (const char *thread_name)
 {
 }
+
+void
+Host::Backtrace (Stream &strm, uint32_t max_frames)
+{
+    // TODO: Is there a way to backtrace the current process on linux?
+}
+
 #endif
 
 struct HostThreadCreateInfo