Merge branch 'release/luau-scripting' into lua-keystroke

9 files changed, 645 insertions, 207 deletions

diff --git a/indra/llcommon/llevents.cpp b/indra/llcommon/llevents.cpp
index 01bba7a620..667e047fd3 100644
--- a/indra/llcommon/llevents.cpp
+++ b/indra/llcommon/llevents.cpp
@@ -726,7 +726,7 @@ void LLReqID::stamp(LLSD& response) const
     response["reqid"] = mReqid;
 }
 
-bool sendReply(const LLSD& reply, const LLSD& request, const std::string& replyKey)
+bool sendReply(LLSD reply, const LLSD& request, const std::string& replyKey)
 {
     // If the original request has no value for replyKey, it's pointless to
     // construct or send a reply event: on which LLEventPump should we send
@@ -739,13 +739,10 @@ bool sendReply(const LLSD& reply, const LLSD& request, const std::string& replyK
 
     // Here the request definitely contains replyKey; reasonable to proceed.
 
-    // Copy 'reply' to modify it.
-    LLSD newreply(reply);
     // Get the ["reqid"] element from request
     LLReqID reqID(request);
-    // and copy it to 'newreply'.
-    reqID.stamp(newreply);
-    // Send reply on LLEventPump named in request[replyKey]. Don't forget to
-    // send the modified 'newreply' instead of the original 'reply'.
-    return LLEventPumps::instance().obtain(request[replyKey]).post(newreply);
+    // and copy it to 'reply'.
+    reqID.stamp(reply);
+    // Send reply on LLEventPump named in request[replyKey].
+    return LLEventPumps::instance().obtain(request[replyKey]).post(reply);
 }
diff --git a/indra/llcommon/llevents.h b/indra/llcommon/llevents.h
index c1dbf4392f..77a405871d 100644
--- a/indra/llcommon/llevents.h
+++ b/indra/llcommon/llevents.h
@@ -151,6 +151,8 @@ typedef boost::signals2::signal<bool(const LLSD&), LLStopWhenHandled, float>  LL
 /// Methods that forward listeners (e.g. constructed with
 /// <tt>boost::bind()</tt>) should accept (const LLEventListener&)
 typedef LLStandardSignal::slot_type LLEventListener;
+/// Accept a void listener too
+typedef std::function<void(const LLSD&)> LLVoidListener;
 /// Result of registering a listener, supports <tt>connected()</tt>,
 /// <tt>disconnect()</tt> and <tt>blocked()</tt>
 typedef boost::signals2::connection LLBoundListener;
@@ -688,6 +690,30 @@ private:
 };
 
 /*****************************************************************************
+*   LLNamedListener
+*****************************************************************************/
+/**
+ * LLNamedListener bundles a concrete LLEventPump subclass with a specific
+ * listener function, with an LLTempBoundListener to ensure that it's
+ * disconnected before destruction.
+ */
+template <class PUMP=LLEventStream>
+class LL_COMMON_API LLNamedListener: PUMP
+{
+    using pump_t = PUMP;
+public:
+    template <typename LISTENER>
+    LLNamedListener(const std::string& name, LISTENER&& listener):
+        pump_t(name, false),        // don't tweak the name
+        mConn(pump_t::listen("func", std::forward<LISTENER>(listener)))
+    {}
+
+private:
+    LLTempBoundListener mConn;
+};
+using LLStreamListener = LLNamedListener<>;
+
+/*****************************************************************************
 *   LLReqID
 *****************************************************************************/
 /**
@@ -779,7 +805,7 @@ private:
  * Before sending the reply event, sendReply() copies the ["reqid"] item from
  * the request to the reply.
  */
-LL_COMMON_API bool sendReply(const LLSD& reply, const LLSD& request,
+LL_COMMON_API bool sendReply(LLSD reply, const LLSD& request,
                              const std::string& replyKey="reply");
 
 #endif /* ! defined(LL_LLEVENTS_H) */
diff --git a/indra/llcommon/lua_function.cpp b/indra/llcommon/lua_function.cpp
index b5de5099ba..441e17dafd 100644
--- a/indra/llcommon/lua_function.cpp
+++ b/indra/llcommon/lua_function.cpp
@@ -17,6 +17,7 @@
 // std headers
 #include <algorithm>
 #include <exception>
+#include <filesystem>
 #include <iomanip>                  // std::quoted
 #include <map>
 #include <memory>                   // std::unique_ptr
@@ -97,8 +98,6 @@ void lua_pushstdstring(lua_State* L, const std::string& str)
 // reached by that block raises a Lua error.
 LLSD lua_tollsd(lua_State* L, int index)
 {
-    LL_DEBUGS("Lua") << "lua_tollsd(" << index << ") of " << lua_gettop(L) << " stack entries: "
-                     << lua_what(L, index) << LL_ENDL;
     switch (lua_type(L, index))
     {
     case LUA_TNONE:
@@ -200,15 +199,12 @@ LLSD lua_tollsd(lua_State* L, int index)
         // we do, below: lua_tollsd(L, -1). If 'index' is -1, then when we
         // push nil, what we find at index -1 is nil, not the table!
         index = lua_absindex(L, index);
-        LL_DEBUGS("Lua") << "checking for empty table" << LL_ENDL;
         lua_pushnil(L);             // first key
-        LL_DEBUGS("Lua") << lua_stack(L) << LL_ENDL;
         if (! lua_next(L, index))
         {
             // it's a table, but the table is empty -- no idea if it should be
             // modeled as empty array or empty map -- return isUndefined(),
             // which can be consumed as either
-            LL_DEBUGS("Lua") << "empty table" << LL_ENDL;
             return {};
         }
         // key is at stack index -2, value at index -1
@@ -217,8 +213,6 @@ LLSD lua_tollsd(lua_State* L, int index)
         LuaPopper popper(L, 2);
         // Remember the type of the first key
         auto firstkeytype{ lua_type(L, -2) };
-        LL_DEBUGS("Lua") << "table not empty, first key type " << lua_typename(L, firstkeytype)
-                         << LL_ENDL;
         switch (firstkeytype)
         {
         case LUA_TNUMBER:
@@ -296,7 +290,6 @@ LLSD lua_tollsd(lua_State* L, int index)
                 // crazy key territory.
                 return lluau::error(L, "Gaps in Lua table too large for conversion to LLSD array");
             }
-            LL_DEBUGS("Lua") << "collected " << keys.size() << " keys, max " << highkey << LL_ENDL;
             // right away expand the result array to the size we'll need
             LLSD result{ LLSD::emptyArray() };
             result[highkey - 1] = LLSD();
@@ -307,7 +300,6 @@ LLSD lua_tollsd(lua_State* L, int index)
                 // key at stack index -2, value at index -1
                 // We've already validated lua_tointegerx() for each key.
                 auto key{ lua_tointeger(L, -2) };
-                LL_DEBUGS("Lua") << "key " << key << ':' << LL_ENDL;
                 // Don't forget to subtract 1 from Lua key for LLSD subscript!
                 result[LLSD::Integer(key) - 1] = lua_tollsd(L, -1);
                 // remove value, keep key for next iteration
@@ -330,7 +322,6 @@ LLSD lua_tollsd(lua_State* L, int index)
                 }
 
                 auto key{ lua_tostdstring(L, -2) };
-                LL_DEBUGS("Lua") << "map key " << std::quoted(key) << ':' << LL_ENDL;
                 result[key] = lua_tollsd(L, -1);
                 // remove value, keep key for next iteration
                 lua_pop(L, 1);
@@ -493,53 +484,100 @@ std::pair<int, LLSD> LuaState::expr(const std::string& desc, const std::string&
     // here we believe there was no error -- did the Lua fragment leave
     // anything on the stack?
     std::pair<int, LLSD> result{ lua_gettop(mState), {} };
-    if (! result.first)
-        return result;
-
-    // aha, at least one entry on the stack!
-    if (result.first == 1)
+    if (result.first)
     {
-        // Don't forget that lua_tollsd() can throw Lua errors.
-        try
+        // aha, at least one entry on the stack!
+        if (result.first == 1)
         {
-            result.second = lua_tollsd(mState, 1);
+            // Don't forget that lua_tollsd() can throw Lua errors.
+            try
+            {
+                result.second = lua_tollsd(mState, 1);
+            }
+            catch (const std::exception& error)
+            {
+                // lua_tollsd() is designed to be called from a lua_function(),
+                // that is, from a C++ function called by Lua. In case of error,
+                // it throws a Lua error to be caught by the Lua runtime. expr()
+                // is a peculiar use case in which our C++ code is calling
+                // lua_tollsd() after return from the Lua runtime. We must catch
+                // the exception thrown for a Lua error, else it will propagate
+                // out to the main coroutine and terminate the viewer -- but since
+                // we instead of the Lua runtime catch it, our lua_State retains
+                // its internal error status. Any subsequent lua_pcall() calls
+                // with this lua_State will report error regardless of whether the
+                // chunk runs successfully. Get a new lua_State().
+                initLuaState();
+                return { -1, stringize(LLError::Log::classname(error), ": ", error.what()) };
+            }
         }
-        catch (const std::exception& error)
+        else
         {
-            // lua_tollsd() is designed to be called from a lua_function(),
-            // that is, from a C++ function called by Lua. In case of error,
-            // it throws a Lua error to be caught by the Lua runtime. expr()
-            // is a peculiar use case in which our C++ code is calling
-            // lua_tollsd() after return from the Lua runtime. We must catch
-            // the exception thrown for a Lua error, else it will propagate
-            // out to the main coroutine and terminate the viewer -- but since
-            // we instead of the Lua runtime catch it, our lua_State retains
-            // its internal error status. Any subsequent lua_pcall() calls
-            // with this lua_State will report error regardless of whether the
-            // chunk runs successfully. Get a new lua_State().
-            initLuaState();
-            return { -1, stringize(LLError::Log::classname(error), ": ", error.what()) };
+            // multiple entries on the stack
+            try
+            {
+                for (int index = 1; index <= result.first; ++index)
+                {
+                    result.second.append(lua_tollsd(mState, index));
+                }
+            }
+            catch (const std::exception& error)
+            {
+                // see above comments regarding lua_State's error status
+                initLuaState();
+                return { -1, stringize(LLError::Log::classname(error), ": ", error.what()) };
+            }
         }
-        // pop the result we claimed
-        lua_settop(mState, 0);
-        return result;
     }
+    // pop everything
+    lua_settop(mState, 0);
 
-    // multiple entries on the stack
-    try
-    {
-        for (int index = 1; index <= result.first; ++index)
+    // If we ran a script that loaded the fiber module, finish up with a call
+    // to fiber.run(). That allows a script to kick off some number of fibers,
+    // do some work on the main thread and then fall off the end of the script
+    // without explicitly appending a call to fiber.run(). run() ensures the
+    // rest of the fibers run to completion (or error).
+    luaL_checkstack(mState, 4, nullptr);
+    // Push _MODULES table on stack
+    luaL_findtable(mState, LUA_REGISTRYINDEX, "_MODULES", 1);
+    int index = lua_gettop(mState);
+    bool found = false;
+    // Did this chunk already require('fiber')? To find out, we must search
+    // the _MODULES table, because our require() implementation uses the
+    // pathname of the module file as the key. Push nil key to start.
+    lua_pushnil(mState);
+    while (lua_next(mState, index) != 0)
+    {
+        // key is at index -2, value at index -1
+        // "While traversing a table, do not call lua_tolstring directly on a
+        // key, unless you know that the key is actually a string. Recall that
+        // lua_tolstring changes the value at the given index; this confuses
+        // the next call to lua_next."
+        // https://www.lua.org/manual/5.1/manual.html#lua_next
+        if (lua_type(mState, -2) == LUA_TSTRING &&
+            std::filesystem::path(lua_tostdstring(mState, -2)).stem() == "fiber")
         {
-            result.second.append(lua_tollsd(mState, index));
+            found = true;
+            break;
         }
+        // pop value so key is at top for lua_next()
+        lua_pop(mState, 1);
     }
-    catch (const std::exception& error)
+    if (found)
     {
-        // see above comments regarding lua_State's error status
-        initLuaState();
-        return { -1, stringize(LLError::Log::classname(error), ": ", error.what()) };
+        // okay, index -1 is a table loaded from a file 'fiber.xxx' --
+        // does it have a function named 'run'?
+        auto run_type{ lua_getfield(mState, -1, "run") };
+        if (run_type == LUA_TFUNCTION)
+        {
+            // there's a fiber.run() function sitting on the top of the stack
+            // -- call it with no arguments, discarding anything it returns
+            LL_DEBUGS("Lua") << "Calling fiber.run()" << LL_ENDL;
+            if (! checkLua(desc, lua_pcall(mState, 0, 0, 0)))
+                return { -1, mError };
+        }
     }
-    // pop everything
+    // pop everything again
     lua_settop(mState, 0);
     return result;
 }
diff --git a/indra/newview/scripts/lua/ErrorQueue.lua b/indra/newview/scripts/lua/ErrorQueue.lua
index a6d4470044..076742815a 100644
--- a/indra/newview/scripts/lua/ErrorQueue.lua
+++ b/indra/newview/scripts/lua/ErrorQueue.lua
@@ -3,18 +3,22 @@
 -- raise that error.
 
 local WaitQueue = require('WaitQueue')
+-- local debug = require('printf')
+local function debug(...) end
 
 local ErrorQueue = WaitQueue:new()
 
 function ErrorQueue:Error(message)
     -- Setting Error() is a marker, like closing the queue. Once we reach the
     -- error, every subsequent Dequeue() call will raise the same error.
+    debug('Setting self._closed to %q', message)
     self._closed = message
     self:_wake_waiters()
 end
 
 function ErrorQueue:Dequeue()
     local value = WaitQueue.Dequeue(self)
+    debug('ErrorQueue:Dequeue: base Dequeue() got %s', value)
     if value ~= nil then
         -- queue not yet closed, show caller
         return value
diff --git a/indra/newview/scripts/lua/WaitQueue.lua b/indra/newview/scripts/lua/WaitQueue.lua
index 00766ccae7..a34dbef4d7 100644
--- a/indra/newview/scripts/lua/WaitQueue.lua
+++ b/indra/newview/scripts/lua/WaitQueue.lua
@@ -2,8 +2,12 @@
 -- the Dequeue() operation blocks the calling coroutine until some other
 -- coroutine Enqueue()s a new value.
 
+local fiber = require('fiber')
 local Queue = require('Queue')
 
+-- local debug = print_debug
+local function debug(...) end
+
 local WaitQueue = Queue:new()
 
 function WaitQueue:new()
@@ -32,26 +36,20 @@ function WaitQueue:_wake_waiters()
     -- cases. With multiple consumers, if more than one is trying to
     -- Dequeue() from an empty WaitQueue, we'll have multiple waiters.
     -- Unlike OS threads, with cooperative concurrency it doesn't make sense
-    -- to "notify all": we need resume only one of the waiting Dequeue()
-    -- callers. But since resuming that caller might entail either Enqueue()
-    -- or Dequeue() calls, recheck every time around to see if we must resume
-    -- another waiting coroutine.
-    while not self:IsEmpty() and #self._waiters > 0 do
+    -- to "notify all": we need wake only one of the waiting Dequeue()
+    -- callers.
+    if ((not self:IsEmpty()) or self._closed) and next(self._waiters) then
         -- Pop the oldest waiting coroutine instead of the most recent, for
         -- more-or-less round robin fairness. But skip any coroutines that
         -- have gone dead in the meantime.
         local waiter = table.remove(self._waiters, 1)
-        while waiter and coroutine.status(waiter) ~= "suspended" do
+        while waiter and fiber.status(waiter) == "dead" do
             waiter = table.remove(self._waiters, 1)
         end
         -- do we still have at least one waiting coroutine?
         if waiter then
             -- don't pass the head item: let the resumed coroutine retrieve it
-            local ok, message = coroutine.resume(waiter)
-            -- if resuming that waiter encountered an error, don't swallow it
-            if not ok then
-                error(message)
-            end
+            fiber.wake(waiter)
         end
     end
 end
@@ -62,18 +60,17 @@ function WaitQueue:Dequeue()
         -- the queue while there are still items left, and we want the
         -- consumer(s) to retrieve those last few items.
         if self._closed then
+            debug('WaitQueue:Dequeue(): closed')
             return nil
         end
-        local coro = coroutine.running()
-        if coro == nil then
-            error("WaitQueue:Dequeue() trying to suspend main coroutine")
-        end
+        debug('WaitQueue:Dequeue(): waiting')
         -- add the running coroutine to the list of waiters
-        table.insert(self._waiters, coro)
+        table.insert(self._waiters, fiber.running())
         -- then let somebody else run
-        coroutine.yield()
+        fiber.wait()
     end
     -- here we're sure this queue isn't empty
+    debug('WaitQueue:Dequeue() calling Queue.Dequeue()')
     return Queue.Dequeue(self)
 end
 
diff --git a/indra/newview/scripts/lua/fiber.lua b/indra/newview/scripts/lua/fiber.lua
new file mode 100644
index 0000000000..7dc67f510c
--- /dev/null
+++ b/indra/newview/scripts/lua/fiber.lua
@@ -0,0 +1,331 @@
+-- Organize Lua coroutines into fibers.
+
+-- In this usage, the difference between coroutines and fibers is that fibers
+-- have a scheduler. Yielding a fiber means allowing other fibers, plural, to
+-- run: it's more than just returning control to the specific Lua thread that
+-- resumed the running coroutine.
+
+-- fiber.launch() creates a new fiber ready to run.
+-- fiber.status() reports (augmented) status of the passed fiber: instead of
+-- 'suspended', it returns either 'ready' or 'waiting'
+-- fiber.yield() allows other fibers to run, but leaves the calling fiber
+-- ready to run.
+-- fiber.wait() marks the running fiber not ready, and resumes other fibers.
+-- fiber.wake() marks the designated suspended fiber ready to run, but does
+-- not yet resume it.
+-- fiber.run() runs all current fibers until all have terminated (successfully
+-- or with an error).
+
+local printf = require 'printf'
+-- local debug = printf
+local function debug(...) end
+local coro = require 'coro'
+
+local fiber = {}
+
+-- The tables in which we track fibers must have weak keys so dead fibers
+-- can be garbage-collected.
+local weak_values = {__mode='v'}
+local weak_keys   = {__mode='k'}
+
+-- Track each current fiber as being either ready to run or not ready
+-- (waiting). wait() moves the running fiber from ready to waiting; wake()
+-- moves the designated fiber from waiting back to ready.
+-- The ready table is used as a list so yield() can go round robin.
+local ready   = setmetatable({'main'}, weak_keys)
+-- The waiting table is used as a set because order doesn't matter.
+local waiting = setmetatable({}, weak_keys)
+
+-- Every fiber has a name, for diagnostic purposes. Names must be unique.
+-- A colliding name will be suffixed with an integer.
+-- Predefine 'main' with our marker so nobody else claims that name.
+local names  = setmetatable({main='main'}, weak_keys)
+local byname = setmetatable({main='main'}, weak_values)
+-- each colliding name has its own distinct suffix counter
+local suffix = {}
+
+-- Specify a nullary idle() callback to be called whenever there are no ready
+-- fibers but there are waiting fibers. The idle() callback is responsible for
+-- changing zero or more waiting fibers to ready fibers by calling
+-- fiber.wake(), although a given call may leave them all still waiting.
+-- When there are no ready fibers, it's a good idea for the idle() function to
+-- return control to a higher-level execution agent. Simply returning without
+-- changing any fiber's status will spin the CPU.
+-- The idle() callback can return non-nil to exit fiber.run() with that value.
+function fiber._idle()
+    error('fiber.yield(): you must first call set_idle(nullary idle() function)')
+end
+
+function fiber.set_idle(func)
+    fiber._idle = func
+end
+
+-- Launch a new Lua fiber, ready to run.
+function fiber.launch(name, func, ...)
+    local args = table.pack(...)
+    local co = coroutine.create(function() func(table.unpack(args)) end)
+    -- a new fiber is ready to run
+    table.insert(ready, co)
+    local namekey = name
+    while byname[namekey] do
+        if not suffix[name] then
+            suffix[name] = 1
+        end
+        suffix[name] += 1
+        namekey = name .. tostring(suffix[name])
+    end
+    -- found a namekey not yet in byname: set it
+    byname[namekey] = co
+    -- and remember it as this fiber's name
+    names[co] = namekey
+--  debug('launch(%s)', namekey)
+--  debug('byname[%s] = %s', namekey, tostring(byname[namekey]))
+--  debug('names[%s] = %s', tostring(co), names[co])
+--  debug('ready[-1] = %s', tostring(ready[#ready]))
+end
+
+-- for debugging
+function fiber.print_all()
+    print('Ready fibers:' .. if next(ready) then '' else ' none')
+    for _, co in pairs(ready) do
+        printf('  %s: %s', fiber.get_name(co), fiber.status(co))
+    end
+    print('Waiting fibers:' .. if next(waiting) then '' else ' none')
+    for co in pairs(waiting) do
+        printf('  %s: %s', fiber.get_name(co), fiber.status(co))
+    end
+end
+
+-- return either the running coroutine or, if called from the main thread,
+-- 'main'
+function fiber.running()
+    return coroutine.running() or 'main'
+end
+
+-- Query a fiber's name (nil for the running fiber)
+function fiber.get_name(co)
+    return names[co or fiber.running()] or 'unknown'
+end
+
+-- Query status of the passed fiber
+function fiber.status(co)
+    local running = coroutine.running()
+    if (not co) or co == running then
+        -- silly to ask the status of the running fiber: it's 'running'
+        return 'running'
+    end
+    if co ~= 'main' then
+        -- for any coroutine but main, consult coroutine.status()
+        local status = coroutine.status(co)
+        if status ~= 'suspended' then
+            return status
+        end
+        -- here co is suspended, answer needs further refinement
+    else
+        -- co == 'main'
+        if not running then
+            -- asking about 'main' from the main fiber
+            return 'running'
+        end
+        -- asking about 'main' from some other fiber, so presumably main is suspended
+    end
+    -- here we know co is suspended -- but is it ready to run?
+    if waiting[co] then
+        return 'waiting'
+    end
+    -- not waiting should imply ready: sanity check
+    if table.find(ready, co) then
+        return 'ready'
+    end
+    -- Calls within yield() between popping the next ready fiber and
+    -- re-appending it to the list are in this state. Once we're done
+    -- debugging yield(), we could reinstate either of the below.
+--  error(string.format('fiber.status(%s) is stumped', fiber.get_name(co)))
+--  print(string.format('*** fiber.status(%s) is stumped', fiber.get_name(co)))
+    return '(unknown)'
+end
+
+-- change the running fiber's status to waiting
+local function set_waiting()
+    -- if called from the main fiber, inject a 'main' marker into the list
+    co = fiber.running()
+    -- delete from ready list
+    local i = table.find(ready, co)
+    if i then
+        table.remove(ready, i)
+    end
+    -- add to waiting list
+    waiting[co] = true
+end
+
+-- Suspend the current fiber until some other fiber calls fiber.wake() on it
+function fiber.wait()
+    set_waiting()
+    -- now yield to other fibers
+    fiber.yield()
+end
+
+-- Mark a suspended fiber as being ready to run
+function fiber.wake(co)
+    if not waiting[co] then
+        error(string.format('fiber.wake(%s) but status=%s, ready=%s, waiting=%s',
+                            names[co], fiber.status(co), ready[co], waiting[co]))
+    end
+    -- delete from waiting list
+    waiting[co] = nil
+    -- add to end of ready list
+    table.insert(ready, co)
+    -- but don't yet resume it: that happens next time we reach yield()
+end
+
+-- pop and return the next not-dead fiber in the ready list, or nil if none remain
+local function live_ready_iter()
+    -- don't write
+    -- for co in table.remove, ready, 1
+    -- because it would keep passing a new second parameter!
+    for co in function() return table.remove(ready, 1) end do
+        debug('%s live_ready_iter() sees %s, status %s',
+              fiber.get_name(), fiber.get_name(co), fiber.status(co))
+        -- keep removing the head entry until we find one that's not dead,
+        -- discarding any dead coroutines along the way
+        if co == 'main' or coroutine.status(co) ~= 'dead' then
+            debug('%s live_ready_iter() returning %s',
+                  fiber.get_name(), fiber.get_name(co))
+            return co
+        end
+    end
+    debug('%s live_ready_iter() returning nil', fiber.get_name())
+    return nil
+end
+
+-- prune the set of waiting fibers
+local function prune_waiting()
+    for waiter in pairs(waiting) do
+        if waiter ~= 'main' and coroutine.status(waiter) == 'dead' then
+            waiting[waiter] = nil
+        end
+    end
+end
+
+-- Run other ready fibers, leaving this one ready, returning after a cycle.
+-- Returns:
+-- * true, nil if there remain other live fibers, whether ready or waiting,
+--   but it's our turn to run
+-- * false, nil if this is the only remaining fiber
+-- * nil,   x   if configured idle() callback returns non-nil x
+local function scheduler()
+    -- scheduler() is asymmetric because Lua distinguishes the main thread
+    -- from other coroutines. The main thread can't yield; it can only resume
+    -- other coroutines. So although an arbitrary coroutine could resume still
+    -- other arbitrary coroutines, it could NOT resume the main thread because
+    -- the main thread can't yield. Therefore, scheduler() delegates its real
+    -- processing to the main thread. If called from a coroutine, pass control
+    -- back to the main thread.
+    if coroutine.running() then
+        -- seize the opportunity to make sure the viewer isn't shutting down
+--      check_stop()
+        -- this is a real coroutine, yield normally to main thread
+        coroutine.yield()
+        -- main certainly still exists
+        return true
+    end
+
+    -- This is the main fiber: coroutine.yield() doesn't work.
+    -- Instead, resume each of the ready fibers.
+    -- Prune the set of waiting fibers after every time fiber business logic
+    -- runs (i.e. other fibers might have terminated or hit error), such as
+    -- here on entry.
+    prune_waiting()
+    local others, idle_stop
+    repeat
+        for co in live_ready_iter do
+            -- seize the opportunity to make sure the viewer isn't shutting down
+--          check_stop()
+            -- before we re-append co, is it the only remaining entry?
+            others = next(ready)
+            -- co is live, re-append it to the ready list
+            table.insert(ready, co)
+            if co == 'main' then
+                -- Since we know the caller is the main fiber, it's our turn.
+                -- Tell caller if there are other ready or waiting fibers.
+                return others or next(waiting)
+            end
+            -- not main, but some other ready coroutine:
+            -- use coro.resume() so we'll propagate any error encountered
+            coro.resume(co)
+            prune_waiting()
+        end
+        -- Here there are no ready fibers. Are there any waiting fibers?
+        if not next(waiting) then
+            return false
+        end
+        -- there are waiting fibers: call consumer's configured idle() function
+        idle_stop = fiber._idle()
+        if idle_stop ~= nil then
+            return nil, idle_stop
+        end
+        prune_waiting()
+        -- loop "forever", that is, until:
+        -- * main is ready, or
+        -- * there are neither ready fibers nor waiting fibers, or
+        -- * fiber._idle() returned non-nil
+    until false
+end
+
+-- Let other fibers run. This is useful in either of two cases:
+-- * fiber.wait() calls this to run other fibers while this one is waiting.
+--   fiber.yield() (and therefore fiber.wait()) works from the main thread as
+--   well as from explicitly-launched fibers, without the caller having to
+--   care.
+-- * A long-running fiber that doesn't often call fiber.wait() should sprinkle
+--   in fiber.yield() calls to interleave processing on other fibers.
+function fiber.yield()
+    -- The difference between this and fiber.run() is that fiber.yield()
+    -- assumes its caller has work to do. yield() returns to its caller as
+    -- soon as scheduler() pops this fiber from the ready list. fiber.run()
+    -- continues looping until all other fibers have terminated, or the
+    -- set_idle() callback tells it to stop.
+    local others, idle_done = scheduler()
+    -- scheduler() returns either if we're ready, or if idle_done ~= nil.
+    if idle_done ~= nil then
+        -- Returning normally from yield() means the caller can carry on with
+        -- its pending work. But in this case scheduler() returned because the
+        -- configured set_idle() function interrupted it -- not because we're
+        -- actually ready. Don't return normally.
+        error('fiber.set_idle() interrupted yield() with: ' .. tostring(idle_done))
+    end
+    -- We're ready! Just return to caller. In this situation we don't care
+    -- whether there are other ready fibers.
+end
+
+-- Run fibers until all but main have terminated: return nil.
+-- Or until configured idle() callback returns x ~= nil: return x.
+function fiber.run()
+    -- A fiber calling run() is not also doing other useful work. Remove the
+    -- calling fiber from the ready list. Otherwise yield() would keep seeing
+    -- that our caller is ready and return to us, instead of realizing that
+    -- all coroutines are waiting and call idle(). But don't say we're
+    -- waiting, either, because then when all other fibers have terminated
+    -- we'd call idle() forever waiting for something to make us ready again.
+    local i = table.find(ready, fiber.running())
+    if i then
+        table.remove(ready, i)
+    end
+    local others, idle_done
+    repeat
+        debug('%s calling fiber.run() calling scheduler()', fiber.get_name())
+        others, idle_done = scheduler()
+        debug("%s fiber.run()'s scheduler() returned %s, %s", fiber.get_name(),
+              tostring(others), tostring(idle_done))
+    until (not others)
+    debug('%s fiber.run() done', fiber.get_name())
+    -- For whatever it's worth, put our own fiber back in the ready list.
+    table.insert(ready, fiber.running())
+    -- Once there are no more waiting fibers, and the only ready fiber is
+    -- us, return to caller. All previously-launched fibers are done. Possibly
+    -- the chunk is done, or the chunk may decide to launch a new batch of
+    -- fibers.
+    return idle_done
+end
+
+return fiber
diff --git a/indra/newview/scripts/lua/leap.lua b/indra/newview/scripts/lua/leap.lua
index 81728e7230..77f3a3e116 100644
--- a/indra/newview/scripts/lua/leap.lua
+++ b/indra/newview/scripts/lua/leap.lua
@@ -38,7 +38,10 @@
 --    leap.process(). process() won't notice until the next event from the
 --    viewer, though.
 
+local fiber = require('fiber')
 local ErrorQueue = require('ErrorQueue')
+-- local debug = require('printf')
+local function debug(...) end 
 
 local leap = {}
 
@@ -68,11 +71,13 @@ leap._reply, leap._command = get_event_pumps()
 -- later one. That means that no incoming event will ever be given to
 -- the old WaitForReqid object. Any coroutine waiting on the discarded
 -- WaitForReqid object would therefore wait forever.
-leap._pending = {}
+-- these are weak values tables
+local weak_values = {__mode='v'}
+leap._pending = setmetatable({}, weak_values)
 -- Our consumer will instantiate some number of WaitFor subclass objects.
 -- As these are traversed in descending priority order, we must keep
 -- them in a list.
-leap._waitfors = {}
+leap._waitfors = setmetatable({}, weak_values)
 -- It has been suggested that we should use UUIDs as ["reqid"] values,
 -- since UUIDs are guaranteed unique. However, as the "namespace" for
 -- ["reqid"] values is our very own _reply pump, we can get away with
@@ -91,15 +96,13 @@ function leap.cmdpump()
     return leap._command
 end
 
--- local inspect = require('inspect')
-
 -- Fire and forget. Send the specified request LLSD, expecting no reply.
 -- In fact, should the request produce an eventual reply, it will be
 -- treated as an unsolicited event.
 -- 
 -- See also request(), generate().
 function leap.send(pump, data, reqid)
---  print_debug('leap.send('..pump..', '..inspect(data)..', '..reqid..') entry')
+    debug('leap.send(%s, %s, %s) entry', pump, data, reqid)
     local data = data
     if type(data) == 'table' then
         data = table.clone(data)
@@ -108,10 +111,26 @@ function leap.send(pump, data, reqid)
             data['reqid'] = reqid
         end
     end
---  print_debug('leap.send('..pump..', '..inspect(data)..') calling post_on()')
+    debug('leap.send(%s, %s) calling post_on()', pump, data)
     post_on(pump, data)
 end
 
+-- common setup code shared by request() and generate()
+local function requestSetup(pump, data)
+    -- invent a new, unique reqid
+    leap._reqid += 1
+    local reqid = leap._reqid
+    -- Instantiate a new WaitForReqid object. The priority is irrelevant
+    -- because, unlike the WaitFor base class, WaitForReqid does not
+    -- self-register on our leap._waitfors list. Instead, capture the new
+    -- WaitForReqid object in leap._pending so dispatch() can find it.
+    leap._pending[reqid] = leap.WaitForReqid:new(reqid)
+    -- Pass reqid to send() to stamp it into (a copy of) the request data.
+    debug('requestSetup(%s, %s)', pump, data)
+    leap.send(pump, data, reqid)
+    return reqid
+end
+
 -- Send the specified request LLSD, expecting exactly one reply. Block
 -- the calling coroutine until we receive that reply.
 -- 
@@ -131,39 +150,20 @@ end
 --
 -- See also send(), generate().
 function leap.request(pump, data)
-    local reqid = leap._requestSetup(pump, data)
+    local reqid = requestSetup(pump, data)
     local waitfor = leap._pending[reqid]
---  print_debug('leap.request('..tostring(pump)..', '..inspect(data)..') about to wait on '..
---              tostring(waitfor))
+    debug('leap.request(%s, %s) about to wait on %s', pump, data, tostring(waitfor))
     local ok, response = pcall(waitfor.wait, waitfor)
---  print_debug('leap.request('..tostring(pump)..', '..inspect(data)..') got '..
---              tostring(ok)..': '..inspect(response))
+    debug('leap.request(%s, %s) got %s: %s', pump, data, ok, response)
     -- kill off temporary WaitForReqid object, even if error
     leap._pending[reqid] = nil
     if ok then
-        response.reqid = nil
         return response
     else
         error(response)
     end
 end
 
--- common setup code shared by request() and generate()
-function leap._requestSetup(pump, data)
-    -- invent a new, unique reqid
-    leap._reqid += 1
-    local reqid = leap._reqid
-    -- Instantiate a new WaitForReqid object. The priority is irrelevant
-    -- because, unlike the WaitFor base class, WaitForReqid does not
-    -- self-register on our leap._waitfors list. Instead, capture the new
-    -- WaitForReqid object in leap._pending so _dispatch() can find it.
-    leap._pending[reqid] = leap.WaitForReqid:new(reqid)
-    -- Pass reqid to send() to stamp it into (a copy of) the request data.
---  print_debug('leap._requestSetup('..tostring(pump)..', '..inspect(data)..')')
-    leap.send(pump, data, reqid)
-    return reqid
-end
-
 -- Send the specified request LLSD, expecting an arbitrary number of replies.
 -- Each one is yielded on receipt. If you omit checklast, this is an infinite
 -- generator; it's up to the caller to recognize when the last reply has been
@@ -178,7 +178,7 @@ function leap.generate(pump, data, checklast)
     -- Invent a new, unique reqid. Arrange to handle incoming events
     -- bearing that reqid. Stamp the outbound request with that reqid, and
     -- send it.
-    local reqid = leap._requestSetup(pump, data)
+    local reqid = requestSetup(pump, data)
     local waitfor = leap._pending[reqid]
     local ok, response
     repeat
@@ -186,7 +186,6 @@ function leap.generate(pump, data, checklast)
         if not ok then
             break
         end
-        response.reqid = nil
         coroutine.yield(response)
     until checklast and checklast(response)
     -- If we break the above loop, whether or not due to error, clean up.
@@ -196,78 +195,79 @@ function leap.generate(pump, data, checklast)
     end
 end
 
--- Kick off response processing. The calling script must create and resume one
--- or more coroutines to perform viewer requests using send(), request() or
--- generate() before calling this function to handle responses.
---
--- While waiting for responses from the viewer, the C++ coroutine running the
--- calling Lua script is blocked: no other Lua coroutine is running.
-function leap.process()
-    leap._done = false
-    local ok, pump, data
-    while not leap._done do
---      print_debug('leap.process() calling get_event_next()')
-        ok, pump, data = pcall(get_event_next)
---      print_debug('leap.process() got '..tostring(ok)..': '..pump..', '..inspect(data))
-        -- ok false means get_event_next() raised a Lua error
-        -- data nil means get_event_next() returned (pump, LLSD()) to indicate done
-        if not (ok and data) then
-            break
-        end
-        leap._dispatch(pump, data)
-    end
---  print_debug('leap.process() done')
+local function cleanup(message)
     -- we're done: clean up all pending coroutines
-    -- if ok, then we're just done.
-    -- if not ok, then 'pump' is actually the error message.
-    message = if ok then 'done' else pump
     for i, waitfor in pairs(leap._pending) do
-        waitfor:_exception(message)
+        waitfor:close()
     end
     for i, waitfor in pairs(leap._waitfors) do
-        waitfor:_exception(message)
-    end
-    -- now that we're done with cleanup, propagate the error we caught above
-    if not ok then
-        error(pump)
+        waitfor:close()
     end
 end
 
-function leap.done()
-    leap._done = true
+-- Handle an incoming (pump, data) event with no recognizable ['reqid']
+local function unsolicited(pump, data)
+    -- we maintain waitfors in descending priority order, so the first waitfor
+    -- to claim this event is the one with the highest priority
+    for i, waitfor in pairs(leap._waitfors) do
+        debug('unsolicited() checking %s', waitfor.name)
+        if waitfor:handle(pump, data) then
+            return
+        end
+    end
+    print_debug(string.format('unsolicited(%s, %s) discarding unclaimed event', pump, data))
 end
 
 -- Route incoming (pump, data) event to the appropriate waiting coroutine.
-function leap._dispatch(pump, data)
+local function dispatch(pump, data)
     local reqid = data['reqid']
     -- if the response has no 'reqid', it's not from request() or generate()
     if reqid == nil then
-        return leap._unsolicited(pump, data)
+        return unsolicited(pump, data)
     end
     -- have reqid; do we have a WaitForReqid?
     local waitfor = leap._pending[reqid]
     if waitfor == nil then
-        return leap._unsolicited(pump, data)
+        return unsolicited(pump, data)
     end
     -- found the right WaitForReqid object, let it handle the event
-    data['reqid'] = nil
-    waitfor:_handle(pump, data)
+    waitfor:handle(pump, data)
 end
 
--- Handle an incoming (pump, data) event with no recognizable ['reqid']
-function leap._unsolicited(pump, data)
-    -- we maintain waitfors in descending priority order, so the first waitfor
-    -- to claim this event is the one with the highest priority
-    for i, waitfor in pairs(leap._waitfors) do
-        if waitfor:_handle(pump, data) then
-            return
-        end
+-- We configure fiber.set_idle() function. fiber.yield() calls the configured
+-- idle callback whenever there are waiting fibers but no ready fibers. In
+-- our case, that means it's time to fetch another incoming viewer event.
+fiber.set_idle(function ()
+    -- If someone has called leap.done(), then tell fiber.yield() to break loop.
+    if leap._done then
+        cleanup('done')
+        return 'done'
+    end
+    debug('leap.idle() calling get_event_next()')
+    local ok, pump, data = pcall(get_event_next)
+    debug('leap.idle() got %s: %s, %s', ok, pump, data)
+    -- ok false means get_event_next() raised a Lua error, pump is message
+    if not ok then
+        cleanup(pump)
+        error(pump)
+    end
+    -- data nil means get_event_next() returned (pump, LLSD()) to indicate done
+    if not data then
+        cleanup('end')
+        return 'end'
     end
---  print_debug('_unsolicited(', pump, ', ', data, ') discarding unclaimed event')
+    -- got a real pump, data pair 
+    dispatch(pump, data)
+    -- return to fiber.yield(): any incoming message might result in one or
+    -- more fibers becoming ready
+end)
+
+function leap.done()
+    leap._done = true
 end
 
 -- called by WaitFor.enable()
-function leap._registerWaitFor(waitfor)
+local function registerWaitFor(waitfor)
     table.insert(leap._waitfors, waitfor)
     -- keep waitfors sorted in descending order of specified priority
     table.sort(leap._waitfors,
@@ -275,7 +275,7 @@ function leap._registerWaitFor(waitfor)
 end
 
 -- called by WaitFor.disable()
-function leap._unregisterWaitFor(waitfor)
+local function unregisterWaitFor(waitfor)
     for i, w in pairs(leap._waitfors) do
         if w == waitfor then
             leap._waitfors[i] = nil
@@ -322,8 +322,13 @@ end
 -- --------------------------------- WaitFor ---------------------------------
 leap.WaitFor = { _id=0 }
 
+function leap.WaitFor.tostring(self)
+    -- Lua (sub)classes have no name; can't prefix with that
+    return self.name
+end
+
 function leap.WaitFor:new(priority, name)
-    local obj = setmetatable({}, self)
+    local obj = setmetatable({__tostring=leap.WaitFor.tostring}, self)
     self.__index = self
 
     obj.priority = priority
@@ -343,16 +348,11 @@ function leap.WaitFor:new(priority, name)
     return obj
 end
 
-function leap.WaitFor.tostring(self)
-    -- Lua (sub)classes have no name; can't prefix with that
-    return self.name
-end
-
 -- Re-enable a disable()d WaitFor object. New WaitFor objects are
 -- enable()d by default.
 function leap.WaitFor:enable()
     if not self._registered then
-        leap._registerWaitFor(self)
+        registerWaitFor(self)
         self._registered = true
     end
 end
@@ -360,7 +360,7 @@ end
 -- Disable an enable()d WaitFor object.
 function leap.WaitFor:disable()
     if self._registered then
-        leap._unregisterWaitFor(self)
+        unregisterWaitFor(self)
         self._registered = false
     end
 end
@@ -368,18 +368,12 @@ end
 -- Block the calling coroutine until a suitable unsolicited event (one
 -- for which filter() returns the event) arrives.
 function leap.WaitFor:wait()
---  print_debug(self.name .. ' about to wait')
-    item = self._queue:Dequeue()
---  print_debug(self.name .. ' got ', item)
+    debug('%s about to wait', self.name)
+    local item = self._queue:Dequeue()
+    debug('%s got %s', self.name, item)
     return item
 end
 
--- Loop over wait() calls.
-function leap.WaitFor:iterate()
-    -- on each iteration, call self.wait(self)
-    return self.wait, self, nil
-end
-
 -- Override filter() to examine the incoming event in whatever way
 -- makes sense.
 -- 
@@ -395,9 +389,10 @@ function leap.WaitFor:filter(pump, data)
     error('You must override the WaitFor.filter() method')
 end
 
--- called by leap._unsolicited() for each WaitFor in leap._waitfors
-function leap.WaitFor:_handle(pump, data)
-    item = self:filter(pump, data)
+-- called by unsolicited() for each WaitFor in leap._waitfors
+function leap.WaitFor:handle(pump, data)
+    local item = self:filter(pump, data)
+    debug('%s.filter() returned %s', self.name, item)
     -- if this item doesn't pass the filter, we're not interested
     if not item then
         return false
@@ -407,13 +402,18 @@ function leap.WaitFor:_handle(pump, data)
     return true
 end
 
--- called by WaitFor:_handle() for an accepted event
+-- called by WaitFor:handle() for an accepted event
 function leap.WaitFor:process(item)
     self._queue:Enqueue(item)
 end
 
+-- called by cleanup() at end
+function leap.WaitFor:close()
+    self._queue:close()
+end
+
 -- called by leap.process() when get_event_next() raises an error
-function leap.WaitFor:_exception(message)
+function leap.WaitFor:exception(message)
     print_warning(self.name .. ' error: ' .. message)
     self._queue:Error(message)
 end
diff --git a/indra/newview/scripts/lua/printf.lua b/indra/newview/scripts/lua/printf.lua
new file mode 100644
index 0000000000..584cd4f391
--- /dev/null
+++ b/indra/newview/scripts/lua/printf.lua
@@ -0,0 +1,19 @@
+-- printf(...) is short for print(string.format(...))
+
+local inspect = require 'inspect'
+
+local function printf(...)
+    -- string.format() only handles numbers and strings.
+    -- Convert anything else to string using the inspect module.
+    local args = {}
+    for _, arg in pairs(table.pack(...)) do
+        if type(arg) == 'number' or type(arg) == 'string' then
+            table.insert(args, arg)
+        else
+            table.insert(args, inspect(arg))
+        end
+    end
+    print(string.format(table.unpack(args)))
+end
+
+return printf
diff --git a/indra/newview/tests/llluamanager_test.cpp b/indra/newview/tests/llluamanager_test.cpp
index 069e10e9cf..872d7827fe 100644
--- a/indra/newview/tests/llluamanager_test.cpp
+++ b/indra/newview/tests/llluamanager_test.cpp
@@ -105,10 +105,8 @@ namespace tut
     void from_lua(const std::string& desc, const std::string_view& construct, const LLSD& expect)
     {
         LLSD fromlua;
-        LLEventStream replypump("testpump");
-        LLTempBoundListener conn(
-            replypump.listen("llluamanager_test",
-                             listener([&fromlua](const LLSD& data){ fromlua = data; })));
+        LLStreamListener pump("testpump",
+                              listener([&fromlua](const LLSD& data){ fromlua = data; }));
         const std::string lua(stringize(
             "data = ", construct, "\n"
             "post_on('testpump', data)\n"
@@ -137,11 +135,9 @@ namespace tut
     {
         set_test_name("test post_on(), get_event_pumps(), get_event_next()");
         StringVec posts;
-        LLEventStream replypump("testpump");
-        LLTempBoundListener conn(
-            replypump.listen("test<3>",
-                             listener([&posts](const LLSD& data)
-                             { posts.push_back(data.asString()); })));
+        LLStreamListener pump("testpump",
+                              listener([&posts](const LLSD& data)
+                              { posts.push_back(data.asString()); }));
         const std::string lua(
             "-- test post_on,get_event_pumps,get_event_next\n"
             "post_on('testpump', 'entry')\n"
@@ -180,7 +176,7 @@ namespace tut
 
     void round_trip(const std::string& desc, const LLSD& send, const LLSD& expect)
     {
-        LLEventMailDrop replypump("testpump");
+        LLEventMailDrop testpump("testpump");
         const std::string lua(
             "-- test LLSD round trip\n"
             "replypump, cmdpump = get_event_pumps()\n"
@@ -194,7 +190,7 @@ namespace tut
         // 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{ llcoro::suspendUntilEventOn(replypump).asString() };
+        auto luapump{ llcoro::suspendUntilEventOn(testpump).asString() };
         LLEventPumps::instance().post(luapump, send);
         // The C++ coroutine running the Lua script is now ready to run. Run
         // it so it will echo the LLSD back to us.
@@ -307,27 +303,60 @@ namespace tut
     template<> template<>
     void object::test<5>()
     {
-        set_test_name("test leap.lua");
+        set_test_name("leap.request() from main thread");
         const std::string lua(
-            "-- test leap.lua\n"
+            "-- leap.request() from main thread\n"
             "\n"
+            "leap = require 'leap'\n"
+            "\n"
+            "return {\n"
+            "    a=leap.request('echo', {data='a'}).data,\n"
+            "    b=leap.request('echo', {data='b'}).data\n"
+            "}\n"
+        );
+
+        LLStreamListener pump(
+            "echo",
+            listener([](const LLSD& data)
+            {
+                LL_DEBUGS("Lua") << "echo pump got: " << data << LL_ENDL;
+                sendReply(data, data);
+            }));
+
+        LuaState L;
+        auto [count, result] = LLLUAmanager::waitScriptLine(L, lua);
+        ensure_equals("Lua script didn't return item", count, 1);
+        ensure_equals("echo failed", result, llsd::map("a", "a", "b", "b"));
+    }
+
+    template<> template<>
+    void object::test<6>()
+    {
+        set_test_name("interleave leap.request() responses");
+        const std::string lua(
+            "-- interleave leap.request() responses\n"
+            "\n"
+            "fiber = require('fiber')\n"
             "leap = require('leap')\n"
-            "coro = require('coro')\n"
+            "-- debug = require('printf')\n"
+            "local function debug(...) end\n"
             "\n"
             "-- negative priority ensures catchall is always last\n"
             "catchall = leap.WaitFor:new(-1, 'catchall')\n"
             "function catchall:filter(pump, data)\n"
+            "    debug('catchall:filter(%s, %s)', pump, data)\n"
             "    return data\n"
             "end\n"
             "\n"
             "-- but first, catch events with 'special' key\n"
             "catch_special = leap.WaitFor:new(2, 'catch_special')\n"
             "function catch_special:filter(pump, data)\n"
+            "    debug('catch_special:filter(%s, %s)', pump, data)\n"
             "    return if data['special'] ~= nil then data else nil\n"
             "end\n"
             "\n"
             "function drain(waitfor)\n"
-            "    print(waitfor.name .. ' start')\n"
+            "    debug('%s start', waitfor.name)\n"
             "    -- It seems as though we ought to be able to code this loop\n"
             "    -- over waitfor:wait() as:\n"
             "    -- for item in waitfor.wait, waitfor do\n"
@@ -335,40 +364,37 @@ namespace tut
             "    -- the coroutine call stack, which prohibits coroutine.yield():\n"
             "    -- 'attempt to yield across metamethod/C-call boundary'\n"
             "    -- So we resort to two different calls to waitfor:wait().\n"
-            "    item = waitfor:wait()\n"
+            "    local item = waitfor:wait()\n"
             "    while item do\n"
-            "        print(waitfor.name .. ' caught', item)\n"
+            "        debug('%s caught %s', waitfor.name, item)\n"
             "        item = waitfor:wait()\n"
             "    end\n"
-            "    print(waitfor.name .. ' done')\n"
+            "    debug('%s done', waitfor.name)\n"
             "end\n"
             "\n"
             "function requester(name)\n"
-            "    print('requester('..name..') start')\n"
-            "    response = leap.request('testpump', {name=name})\n"
-            "    print('requester('..name..') got '..tostring(response))\n"
+            "    debug('requester(%s) start', name)\n"
+            "    local response = leap.request('testpump', {name=name})\n"
+            "    debug('requester(%s) got %s', name, response)\n"
             "    -- verify that the correct response was dispatched to this coroutine\n"
             "    assert(response.name == name)\n"
             "end\n"
             "\n"
-            "coro.launch(drain, catchall)\n"
-            "coro.launch(drain, catch_special)\n"
-            "coro.launch(requester, 'a')\n"
-            "coro.launch(requester, 'b')\n"
-            "\n"
-            "leap.process()\n"
+            "-- fiber.print_all()\n"
+            "fiber.launch('catchall', drain, catchall)\n"
+            "fiber.launch('catch_special', drain, catch_special)\n"
+            "fiber.launch('requester(a)', requester, 'a')\n"
+            "fiber.launch('requester(b)', requester, 'b')\n"
         );
 
         LLSD requests;
-        LLEventStream pump("testpump", false);
-        LLTempBoundListener conn{
-            pump.listen("test<5>()",
-                        listener([&requests](const LLSD& data)
-                        {
-                            LL_DEBUGS("Lua") << "testpump got: " << data << LL_ENDL;
-                            requests.append(data);
-                        }))
-        };
+        LLStreamListener pump(
+            "testpump",
+            listener([&requests](const LLSD& data)
+            {
+                LL_DEBUGS("Lua") << "testpump got: " << data << LL_ENDL;
+                requests.append(data);
+            }));
 
         LuaState L;
         auto future = LLLUAmanager::startScriptLine(L, lua);