Fix iohandler prompt race condition.
This issue caused the lldb prompt to not show up in certain cases, very
noticeable on Linux systems.
See details on this review:
http://reviews.llvm.org/D4863
And on this lldb-commits thread:
http://lists.cs.uiuc.edu/pipermail/lldb-commits/Week-of-Mon-20140811/012306.html
Change by Shawn Best.
(Much useful help and testing by the rest of the community, thanks all!)
llvm-svn: 215446
diff --git a/lldb/source/Commands/CommandObjectProcess.cpp b/lldb/source/Commands/CommandObjectProcess.cpp
index 5dde4dd..5678ae4 100644
--- a/lldb/source/Commands/CommandObjectProcess.cpp
+++ b/lldb/source/Commands/CommandObjectProcess.cpp
@@ -773,10 +773,16 @@
process->GetThreadList().GetThreadAtIndex(idx)->SetResumeState (eStateRunning, override_suspend);
}
}
-
+
Error error(process->Resume());
+
if (error.Success())
{
+ // There is a race condition where this thread will return up the call stack to the main command
+ // handler and show an (lldb) prompt before HandlePrivateEvent (from PrivateStateThread) has
+ // a chance to call PushProcessIOHandler().
+ process->SyncIOHandler(2000);
+
result.AppendMessageWithFormat ("Process %" PRIu64 " resuming\n", process->GetID());
if (synchronous_execution)
{
diff --git a/lldb/source/Commands/CommandObjectThread.cpp b/lldb/source/Commands/CommandObjectThread.cpp
index c58e9e8..e7a8652 100644
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -624,7 +624,11 @@
process->GetThreadList().SetSelectedThreadByID (thread->GetID());
process->Resume ();
-
+
+ // There is a race condition where this thread will return up the call stack to the main command handler
+ // and show an (lldb) prompt before HandlePrivateEvent (from PrivateStateThread) has
+ // a chance to call PushProcessIOHandler().
+ process->SyncIOHandler(2000);
if (synchronous_execution)
{
diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp
index 89f89e2..1609182 100644
--- a/lldb/source/Target/Process.cpp
+++ b/lldb/source/Target/Process.cpp
@@ -687,6 +687,7 @@
m_stderr_data (),
m_profile_data_comm_mutex (Mutex::eMutexTypeRecursive),
m_profile_data (),
+ m_iohandler_sync (false),
m_memory_cache (*this),
m_allocated_memory_cache (*this),
m_should_detach (false),
@@ -885,6 +886,34 @@
return state;
}
+bool
+Process::SyncIOHandler (uint64_t timeout_msec)
+{
+ bool timed_out = false;
+
+ // don't sync (potentially context switch) in case where there is no process IO
+ if (m_process_input_reader)
+ {
+ TimeValue timeout = TimeValue::Now();
+ timeout.OffsetWithMicroSeconds(timeout_msec*1000);
+
+ m_iohandler_sync.WaitForValueEqualTo(true, &timeout, &timed_out);
+
+ Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS));
+ if(log)
+ {
+ if(timed_out)
+ log->Printf ("Process::%s pid %" PRIu64 " (timeout=%" PRIu64 "ms): FAIL", __FUNCTION__, GetID (), timeout_msec);
+ else
+ log->Printf ("Process::%s pid %" PRIu64 ": SUCCESS", __FUNCTION__, GetID ());
+ }
+
+ // reset sync one-shot so it will be ready for next time
+ m_iohandler_sync.SetValue(false, eBroadcastNever);
+ }
+
+ return !timed_out;
+}
StateType
Process::WaitForProcessToStop (const TimeValue *timeout, lldb::EventSP *event_sp_ptr, bool wait_always, Listener *hijack_listener)
@@ -3884,9 +3913,11 @@
// as this means the curses GUI is in use...
if (!GetTarget().GetDebugger().IsForwardingEvents())
PushProcessIOHandler ();
+ m_iohandler_sync.SetValue(true, eBroadcastAlways);
}
else if (StateIsStoppedState(new_state, false))
{
+ m_iohandler_sync.SetValue(false, eBroadcastNever);
if (!Process::ProcessEventData::GetRestartedFromEvent(event_sp.get()))
{
// If the lldb_private::Debugger is handling the events, we don't
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index f959010..e3fd790 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -2420,9 +2420,14 @@
m_process_sp->RestoreProcessEvents ();
error = m_process_sp->PrivateResume();
-
+
if (error.Success())
{
+ // there is a race condition where this thread will return up the call stack to the main command
+ // handler and show an (lldb) prompt before HandlePrivateEvent (from PrivateStateThread) has
+ // a chance to call PushProcessIOHandler()
+ m_process_sp->SyncIOHandler(2000);
+
if (synchronous_execution)
{
state = m_process_sp->WaitForProcessToStop (NULL, NULL, true, hijack_listener_sp.get());