Revert "[lldb] Fix race condition in Process::WaitForProcessToStop() … (llvm#148915)

…(llvm#144919)"

This was causing a couple of failures on the Ubuntu bots. Reverting
while we wait on a fix for those issues.
This reverts commit 8612926.

Author: jimingham

lldb/include/lldb/Utility/Listener.h

@@ -53,13 +53,6 @@ class Listener : public std::enable_shared_from_this<Listener> {
 
   void AddEvent(lldb::EventSP &event);
 
-  /// Transfers all events matching the specified broadcaster and type to the
-  /// destination listener. This can be useful when setting up a hijack listener,
-  /// to ensure that no relevant events are missed.
-  void MoveEvents(lldb::ListenerSP destination,
-                  Broadcaster *broadcaster, // nullptr for any broadcaster
-                  uint32_t event_type_mask);
-
   void Clear();
 
   const char *GetName() { return m_name.c_str(); }

lldb/source/Utility/Broadcaster.cpp

@@ -335,18 +335,6 @@ bool Broadcaster::BroadcasterImpl::HijackBroadcaster(
       "{0} Broadcaster(\"{1}\")::HijackBroadcaster (listener(\"{2}\")={3})",
       static_cast<void *>(this), GetBroadcasterName(),
       listener_sp->m_name.c_str(), static_cast<void *>(listener_sp.get()));
-
-  // Move pending events from the previous listener to the hijack listener.
-  // This ensures that no relevant event queued before the transition is missed
-  // by the hijack listener.
-  ListenerSP prev_listener;
-  if (!m_hijacking_listeners.empty())
-    prev_listener = m_hijacking_listeners.back();
-  else if (m_primary_listener_sp)
-    prev_listener = m_primary_listener_sp;
-  if (prev_listener && listener_sp)
-    prev_listener->MoveEvents(listener_sp, &m_broadcaster, event_mask);
-
   m_hijacking_listeners.push_back(listener_sp);
   m_hijacking_masks.push_back(event_mask);
   return true;
@@ -379,19 +367,6 @@ void Broadcaster::BroadcasterImpl::RestoreBroadcaster() {
              static_cast<void *>(this), GetBroadcasterName(),
              listener_sp->m_name.c_str(),
              static_cast<void *>(listener_sp.get()));
-
-    // Move any remaining events from the hijack listener back to
-    // the previous listener. This ensures that no events are dropped when
-    // restoring the original listener.
-    ListenerSP prev_listener;
-    if (m_hijacking_listeners.size() > 1)
-      prev_listener = m_hijacking_listeners[m_hijacking_listeners.size() - 2];
-    else if (m_primary_listener_sp)
-      prev_listener = m_primary_listener_sp;
-    if (listener_sp && prev_listener && !m_hijacking_masks.empty())
-      listener_sp->MoveEvents(prev_listener, &m_broadcaster,
-                              m_hijacking_masks.back());
-
     m_hijacking_listeners.pop_back();
   }
   if (!m_hijacking_masks.empty())

lldb/source/Utility/Listener.cpp

@@ -176,33 +176,6 @@ void Listener::AddEvent(EventSP &event_sp) {
   m_events_condition.notify_all();
 }
 
-void Listener::MoveEvents(
-    ListenerSP destination,
-    Broadcaster *broadcaster, // nullptr for any broadcaster
-    uint32_t event_type_mask) {
-  Log *log = GetLog(LLDBLog::Events);
-
-  std::lock_guard<std::mutex> guard(m_events_mutex);
-  auto pos = m_events.begin();
-  while (pos != m_events.end()) {
-    EventSP &event_sp = *pos;
-    if (event_sp &&
-        ((broadcaster == nullptr) || event_sp->BroadcasterIs(broadcaster)) &&
-        (event_type_mask == 0 || event_type_mask & event_sp->GetType())) {
-      LLDB_LOGF(
-          log, "%p Listener('%s')::MoveEvents moving event %p to %p('%s')",
-          static_cast<void *>(this), m_name.c_str(),
-          static_cast<void *>(event_sp.get()),
-          static_cast<void *>(destination.get()), destination->GetName());
-
-      destination->AddEvent(event_sp);
-      pos = m_events.erase(pos);
-    } else {
-      ++pos;
-    }
-  }
-}
-
 bool Listener::FindNextEventInternal(
     std::unique_lock<std::mutex> &lock,
     Broadcaster *broadcaster, // nullptr for any broadcaster

lldb/unittests/Utility/ListenerTest.cpp

@@ -150,84 +150,3 @@ TEST(ListenerTest, StartStopListeningForEventSpec) {
   ASSERT_EQ(event_sp->GetBroadcaster(), &broadcaster1);
   ASSERT_FALSE(listener_sp->GetEvent(event_sp, std::chrono::seconds(0)));
 }
-
-TEST(ListenerTest, MoveEventsOnHijackAndRestore) {
-  Broadcaster broadcaster(nullptr, "test-broadcaster");
-  const uint32_t event_mask = 1;
-  EventSP event_sp;
-
-  // Create the original listener and start listening.
-  ListenerSP original_listener = Listener::MakeListener("original-listener");
-  ASSERT_EQ(event_mask, original_listener->StartListeningForEvents(&broadcaster,
-                                                                   event_mask));
-  broadcaster.SetPrimaryListener(original_listener);
-
-  // Queue two events to original listener, but do not consume them yet.
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-
-  // Hijack.
-  ListenerSP hijack_listener = Listener::MakeListener("hijack-listener");
-  broadcaster.HijackBroadcaster(hijack_listener, event_mask);
-
-  // The events should have been moved to the hijack listener.
-  EXPECT_FALSE(original_listener->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(hijack_listener->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(hijack_listener->GetEvent(event_sp, std::chrono::seconds(0)));
-
-  // Queue two events while hijacked, but do not consume them yet.
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-
-  // Restore the original listener.
-  broadcaster.RestoreBroadcaster();
-
-  // The events queued while hijacked should have been moved back to the
-  // original listener.
-  EXPECT_FALSE(hijack_listener->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(original_listener->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(original_listener->GetEvent(event_sp, std::chrono::seconds(0)));
-}
-
-TEST(ListenerTest, MoveEventsBetweenHijackers) {
-  Broadcaster broadcaster(nullptr, "test-broadcaster");
-  const uint32_t event_mask = 1;
-  EventSP event_sp;
-
-  // Create the original listener and start listening.
-  ListenerSP original_listener = Listener::MakeListener("original-listener");
-  ASSERT_EQ(event_mask, original_listener->StartListeningForEvents(&broadcaster,
-                                                                   event_mask));
-  broadcaster.SetPrimaryListener(original_listener);
-
-  // First hijack.
-  ListenerSP hijack_listener1 = Listener::MakeListener("hijack-listener1");
-  broadcaster.HijackBroadcaster(hijack_listener1, event_mask);
-
-  // Queue two events while hijacked, but do not consume
-  // them yet.
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-
-  // Second hijack.
-  ListenerSP hijack_listener2 = Listener::MakeListener("hijack-listener2");
-  broadcaster.HijackBroadcaster(hijack_listener2, event_mask);
-
-  // The second hijacker should have the events now.
-  EXPECT_FALSE(hijack_listener1->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(hijack_listener2->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(hijack_listener2->GetEvent(event_sp, std::chrono::seconds(0)));
-
-  // Queue two events while hijacked with second hijacker, but do not consume
-  // them yet.
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-  broadcaster.BroadcastEvent(event_mask, nullptr);
-
-  // Restore the previous hijacker.
-  broadcaster.RestoreBroadcaster();
-
-  // The first hijacker should now have the events.
-  EXPECT_FALSE(hijack_listener2->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(hijack_listener1->GetEvent(event_sp, std::chrono::seconds(0)));
-  EXPECT_TRUE(hijack_listener1->GetEvent(event_sp, std::chrono::seconds(0)));
-}