Terminate Lua scripts hanging in LL.get_event_next().

Make LuaListener listen for "LLApp" viewer shutdown events. On receiving such,
it closes its queue. Then the C++ coroutine calling getNext() wakes up with an
LLThreadSafeQueue exception, and calls LLCoros::checkStop() to throw one of
the exceptions recognized by LLCoros::toplevel().

Add an llluamanager_test.cpp test to verify this behavior.

3 files changed, 52 insertions, 2 deletions

diff --git a/indra/llcommon/lualistener.cpp b/indra/llcommon/lualistener.cpp
index ed34133924..37ce27a2a4 100644
--- a/indra/llcommon/lualistener.cpp
+++ b/indra/llcommon/lualistener.cpp
@@ -36,7 +36,24 @@ LuaListener::LuaListener(lua_State* L):
     mListener(new LLLeapListener(
         "LuaListener",
         [this](const std::string& pump, const LLSD& data)
-        { return queueEvent(pump, data); }))
+        { return queueEvent(pump, data); })),
+    // Listen for shutdown events on the "LLApp" LLEventPump.
+    mShutdownConnection(
+        LLEventPumps::instance().obtain("LLApp").listen(
+            LLEventPump::inventName("LuaState"),
+            [this](const LLSD& status)
+            {
+                LL_DEBUGS("LuaListener") << "caught " << status << LL_ENDL;
+                const auto& statsd = status["status"];
+                if (statsd.asString() != "running")
+                {
+                    // If a Lua script is still blocked in getNext() during
+                    // viewer shutdown, close the queue to wake up getNext().
+                    LL_DEBUGS("LuaListener") << "closing queue" << LL_ENDL;
+                    mQueue.close();
+                }
+                return false;
+            }))
 {}
 
 LuaListener::~LuaListener()
@@ -87,5 +104,15 @@ bool LuaListener::queueEvent(const std::string& pump, const LLSD& data)
 
 LuaListener::PumpData LuaListener::getNext()
 {
-    return mQueue.pop();
+    try
+    {
+        return mQueue.pop();
+    }
+    catch (const LLThreadSafeQueueInterrupt& exc)
+    {
+        // mQueue has been closed. The only way that happens is when we detect
+        // viewer shutdown. Terminate the calling coroutine.
+        LLCoros::checkStop();
+        return {};
+    }
 }
diff --git a/indra/llcommon/lualistener.h b/indra/llcommon/lualistener.h
index c13b7bbd5f..40ccfba8fe 100644
--- a/indra/llcommon/lualistener.h
+++ b/indra/llcommon/lualistener.h
@@ -12,6 +12,7 @@
 #if ! defined(LL_LUALISTENER_H)
 #define LL_LUALISTENER_H
 
+#include "llevents.h"
 #include "llinstancetracker.h"
 #include "llsd.h"
 #include "llthreadsafequeue.h"
@@ -73,6 +74,7 @@ private:
     LLThreadSafeQueue<PumpData> mQueue;
 
     std::unique_ptr<LLLeapListener> mListener;
+    LLTempBoundListener mShutdownConnection;
 };
 
 #endif /* ! defined(LL_LUALISTENER_H) */
diff --git a/indra/newview/tests/llluamanager_test.cpp b/indra/newview/tests/llluamanager_test.cpp
index e10dedcf53..682289bd93 100644
--- a/indra/newview/tests/llluamanager_test.cpp
+++ b/indra/newview/tests/llluamanager_test.cpp
@@ -418,4 +418,25 @@ namespace tut
         auto [count, result] = future.get();
         ensure_equals("leap.lua: " + result.asString(), count, 0);
     }
+
+    template<> template<>
+    void object::test<7>()
+    {
+        set_test_name("stop hanging Lua script");
+        const std::string lua(
+            "-- hanging Lua script should terminate\n"
+            "\n"
+            "LL.get_event_next()\n"
+        );
+        LuaState L;
+        auto future = LLLUAmanager::startScriptLine(L, lua);
+        // The problem with this test is that the LuaState is destroyed
+        // (disconnecting the listener) before the LLTestApp instance mApp is
+        // destroyed (sending the shutdown event). Explicitly simulate LLApp's
+        // event.
+        LLEventPumps::instance().obtain("LLApp").post(llsd::map("status", "quitting"));
+        // but now we have to give the startScriptLine() coroutine a chance to run
+        auto [count, result] = future.get();
+        ensure_equals(result.asString(), count, 0);
+    }
 } // namespace tut