Lua listen_events(), await_event() => get_event_{pumps,next}().

Don't set up a Lua callback to receive incoming events, a la listen_events().
Don't listen on an arbitrary event pump, a la await_event().

Instead, the new get_event_pumps() entry point simply delivers the reply pump
and command pump names (as listen_events() did) without storing a Lua
callback.

Make LuaListener capture incoming events on the reply pump in a queue. This
avoids the problem of multiple events arriving too quickly for the Lua script
to retrieve. If the queue gets too big, discard the excess instead of blocking
the caller of post().

Then the new get_event_next() entry point retrieves the next (pump, data) pair
from the queue, blocking the Lua script until a suitable event arrives. This
is closer to the use of stdin for a LEAP plugin. It also addresses the
question: what should the Lua script's C++ coroutine do while waiting for an
incoming reply pump event?

Recast llluamanager_test.cpp for this new, more straightforward API.

Move LLLeap's and LuaListener's reply LLEventPump into LLLeapListener, which
they both use. This simplifies LLLeapListener's API, which was a little
convoluted: the caller supplied a connect callback to allow LLLeapListener to
connect some listener to the caller's reply pump. Now, instead, the caller
simply passes a bool(pumpname, data) callback to receive events incoming on
LLLeapListener's own reply pump.

Fix a latent bug in LLLeapListener: if a plugin called listen() more than once
with the same listener name, the new connection would not have been saved.

While at it, replace some older Boost features in LLLeapListener and LLLeap.

1 files changed, 14 insertions, 21 deletions

diff --git a/indra/newview/tests/llluamanager_test.cpp b/indra/newview/tests/llluamanager_test.cpp
index 1f25fd5f3b..81ec186cf4 100644
--- a/indra/newview/tests/llluamanager_test.cpp
+++ b/indra/newview/tests/llluamanager_test.cpp
@@ -108,7 +108,6 @@ namespace tut
             replypump.listen("llluamanager_test",
                              listener([&fromlua](const LLSD& data){ fromlua = data; })));
         const std::string lua(stringize(
-            "-- test LLSD synthesized by Lua\n",
             "data = ", construct, "\n"
             "post_on('testpump', data)\n"
         ));
@@ -134,7 +133,7 @@ namespace tut
     template<> template<>
     void object::test<3>()
     {
-        set_test_name("test post_on(), listen_events(), await_event()");
+        set_test_name("test post_on(), get_event_pumps(), get_event_next()");
         StringVec posts;
         LLEventStream replypump("testpump");
         LLTempBoundListener conn(
@@ -142,17 +141,14 @@ namespace tut
                              listener([&posts](const LLSD& data)
                              { posts.push_back(data.asString()); })));
         const std::string lua(
-            "-- test post_on,listen_events,await_event\n"
+            "-- test post_on,get_event_pumps,get_event_next\n"
             "post_on('testpump', 'entry')\n"
-            "callback = function(pump, data)\n"
-            "    -- just echo the data we received\n"
-            "    post_on('testpump', data)\n"
-            "end\n"
-            "post_on('testpump', 'listen_events()')\n"
-            "replypump, cmdpump = listen_events(callback)\n"
+            "post_on('testpump', 'get_event_pumps()')\n"
+            "replypump, cmdpump = get_event_pumps()\n"
             "post_on('testpump', replypump)\n"
-            "post_on('testpump', 'await_event()')\n"
-            "await_event(replypump)\n"
+            "post_on('testpump', 'get_event_next()')\n"
+            "pump, data = get_event_next()\n"
+            "post_on('testpump', data)\n"
             "post_on('testpump', 'exit')\n"
         );
         LuaState L;
@@ -162,9 +158,9 @@ namespace tut
         auto future = LLLUAmanager::startScriptLine(L, lua);
         StringVec expected{
             "entry",
-            "listen_events()",
+            "get_event_pumps()",
             "",
-            "await_event()",
+            "get_event_next()",
             "message",
             "exit"
         };
@@ -188,18 +184,15 @@ namespace tut
                              listener([&reply](const LLSD& post){ reply = post; })));
         const std::string lua(
             "-- test LLSD round trip\n"
-            "callback = function(pump, data)\n"
-            "    -- just echo the data we received\n"
-            "    post_on('testpump', data)\n"
-            "end\n"
-            "replypump, cmdpump = listen_events(callback)\n"
+            "replypump, cmdpump = get_event_pumps()\n"
             "post_on('testpump', replypump)\n"
-            "await_event(replypump)\n"
+            "pump, data = get_event_next()\n"
+            "return data\n"
         );
         LuaState L;
         auto future = LLLUAmanager::startScriptLine(L, lua);
         // We woke up again ourselves because the coroutine running Lua has
-        // reached the await_event() call, which suspends the calling C++
+        // reached the get_event_next() call, which suspends the calling C++
         // coroutine (including the Lua code running on it) until we post
         // something to that reply pump.
         auto luapump{ reply.asString() };
@@ -208,7 +201,7 @@ namespace tut
         // The C++ coroutine running the Lua script is now ready to run. Run
         // it so it will echo the LLSD back to us.
         auto [count, result] = future.get();
-        ensure_equals(desc, reply, expect);
+        ensure_equals(desc, result, expect);
     }
 
     // Define an RTItem to be used for round-trip LLSD testing: what it is,