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

11 files changed, 269 insertions, 120 deletions

diff --git a/indra/newview/llluamanager.cpp b/indra/newview/llluamanager.cpp
index be332a7244..82be85a153 100644
--- a/indra/newview/llluamanager.cpp
+++ b/indra/newview/llluamanager.cpp
@@ -28,6 +28,7 @@
 #include "llviewerprecompiledheaders.h"
 #include "llluamanager.h"
 
+#include "fsyspath.h"
 #include "llcoros.h"
 #include "llerror.h"
 #include "lleventcoro.h"
@@ -37,7 +38,6 @@
 #include "stringize.h"
 
 #include <boost/algorithm/string/replace.hpp>
-#include <filesystem>
 
 #include "luau/luacode.h"
 #include "luau/lua.h"
@@ -122,7 +122,7 @@ lua_function(post_on, "post_on(pumpname, data): post specified data to specified
     std::string pumpname{ lua_tostdstring(L, 1) };
     LLSD data{ lua_tollsd(L, 2) };
     lua_pop(L, 2);
-    LL_INFOS("Lua") << "post_on('" << pumpname << "', " << data << ")" << LL_ENDL;
+    LL_DEBUGS("Lua") << "post_on('" << pumpname << "', " << data << ")" << LL_ENDL;
     LLEventPumps::instance().obtain(pumpname).post(data);
     return 0;
 }
@@ -314,19 +314,12 @@ void LLRequireResolver::resolveRequire(lua_State *L, std::string path)
 }
 
 LLRequireResolver::LLRequireResolver(lua_State *L, const std::string& path) :
-    mPathToResolve(path),
+    mPathToResolve(fsyspath(path).lexically_normal()),
     L(L)
 {
-    //Luau lua_Debug and lua_getinfo() are different compared to default Lua:
-    //see https://github.com/luau-lang/luau/blob/80928acb92d1e4b6db16bada6d21b1fb6fa66265/VM/include/lua.h
-    lua_Debug ar;
-    lua_getinfo(L, 1, "s", &ar);
-    mSourceChunkname = ar.source;
+    mSourceDir = lluau::source_path(L).parent_path();
 
-    std::filesystem::path fs_path(mPathToResolve);
-    mPathToResolve = fs_path.lexically_normal().string();
-
-    if (fs_path.is_absolute())
+    if (mPathToResolve.is_absolute())
         luaL_argerrorL(L, 1, "cannot require a full path");
 }
 
@@ -358,8 +351,8 @@ private:
 // push the loaded module or throw a Lua error
 void LLRequireResolver::findModule()
 {
-    // If mPathToResolve is absolute, this replaces mSourceChunkname.parent_path.
-    auto absolutePath = (std::filesystem::path((mSourceChunkname)).parent_path() / mPathToResolve).u8string();
+    // If mPathToResolve is absolute, this replaces mSourceDir.
+    auto absolutePath = (mSourceDir / mPathToResolve).u8string();
 
     // Push _MODULES table on stack for checking and saving to the cache
     luaL_findtable(L, LUA_REGISTRYINDEX, "_MODULES", 1);
@@ -375,30 +368,30 @@ void LLRequireResolver::findModule()
 
     // not already cached - prep error message just in case
     auto fail{
-        [L=L, path=mPathToResolve]()
+        [L=L, path=mPathToResolve.u8string()]()
         { luaL_error(L, "could not find require('%s')", path.data()); }};
 
-    if (std::filesystem::path(mPathToResolve).is_absolute())
+    if (mPathToResolve.is_absolute())
     {
         // no point searching known directories for an absolute path
         fail();
     }
 
-    std::vector<std::string> lib_paths
+    std::vector<fsyspath> lib_paths
     {
         gDirUtilp->getExpandedFilename(LL_PATH_SCRIPTS, "lua"),
 #ifdef LL_TEST
         // Build-time tests don't have the app bundle - use source tree.
-        std::filesystem::path(__FILE__).parent_path() / "scripts" / "lua",
+        fsyspath(__FILE__).parent_path() / "scripts" / "lua",
 #endif
     };
 
     for (const auto& path : lib_paths)
     {
-        std::string absolutePathOpt = (std::filesystem::path(path) / mPathToResolve).u8string();
+        std::string absolutePathOpt = (path / mPathToResolve).u8string();
 
         if (absolutePathOpt.empty())
-            luaL_error(L, "error requiring module '%s'", mPathToResolve.data());
+            luaL_error(L, "error requiring module '%s'", mPathToResolve.u8string().data());
 
         if (findModuleImpl(absolutePathOpt))
             return;
@@ -457,12 +450,14 @@ void LLRequireResolver::runModule(const std::string& desc, const std::string& co
     // Module needs to run in a new thread, isolated from the rest.
     // Note: we create ML on main thread so that it doesn't inherit environment of L.
     lua_State *GL = lua_mainthread(L);
-    lua_State *ML = lua_newthread(GL);
+//  lua_State *ML = lua_newthread(GL);
+    // Try loading modules on Lua's main thread instead.
+    lua_State *ML = GL;
     // lua_newthread() pushed the new thread object on GL's stack. Move to L's.
-    lua_xmove(GL, L, 1);
+//  lua_xmove(GL, L, 1);
 
     // new thread needs to have the globals sandboxed
-    luaL_sandboxthread(ML);
+//  luaL_sandboxthread(ML);
 
     {
         // If loadstring() returns (! LUA_OK) then there's an error message on
@@ -472,7 +467,9 @@ void LLRequireResolver::runModule(const std::string& desc, const std::string& co
         {
             // luau uses Lua 5.3's version of lua_resume():
             // run the coroutine on ML, "from" L, passing no arguments.
-            int status = lua_resume(ML, L, 0);
+//          int status = lua_resume(ML, L, 0);
+            // we expect one return value
+            int status = lua_pcall(ML, 0, 1, 0);
 
             if (status == LUA_OK)
             {
@@ -494,9 +491,12 @@ void LLRequireResolver::runModule(const std::string& desc, const std::string& co
     }
     // There's now a return value (string error message or module) on top of ML.
     // Move return value to L's stack.
-    lua_xmove(ML, L, 1);
+    if (ML != L)
+    {
+        lua_xmove(ML, L, 1);
+    }
     // remove ML from L's stack
-    lua_remove(L, -2);
+//  lua_remove(L, -2);
 //  // DON'T call lua_close(ML)! Since ML is only a thread of L, corrupts L too!    
 //  lua_close(ML);
 }
diff --git a/indra/newview/llluamanager.h b/indra/newview/llluamanager.h
index a297d14502..3c00450179 100644
--- a/indra/newview/llluamanager.h
+++ b/indra/newview/llluamanager.h
@@ -27,6 +27,7 @@
 #ifndef LL_LLLUAMANAGER_H
 #define LL_LLLUAMANAGER_H
 
+#include "fsyspath.h"
 #include "llcoros.h"
 #include "llsd.h"
 #include <functional>
@@ -88,8 +89,8 @@ class LLRequireResolver
     static void resolveRequire(lua_State *L, std::string path);
 
  private:
-    std::string mPathToResolve;
-    std::string mSourceChunkname;
+    fsyspath mPathToResolve;
+    fsyspath mSourceDir;
 
     LLRequireResolver(lua_State *L, const std::string& path);
 
diff --git a/indra/newview/scripts/lua/ErrorQueue.lua b/indra/newview/scripts/lua/ErrorQueue.lua
index 076742815a..6ed1c10d5c 100644
--- a/indra/newview/scripts/lua/ErrorQueue.lua
+++ b/indra/newview/scripts/lua/ErrorQueue.lua
@@ -3,22 +3,22 @@
 -- raise that error.
 
 local WaitQueue = require('WaitQueue')
--- local debug = require('printf')
-local function debug(...) end
+-- local dbg = require('printf')
+local function dbg(...) 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)
+    dbg('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)
+    dbg('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/Queue.lua b/indra/newview/scripts/lua/Queue.lua
index b0a5a87f87..5ab2a8a72c 100644
--- a/indra/newview/scripts/lua/Queue.lua
+++ b/indra/newview/scripts/lua/Queue.lua
@@ -1,6 +1,12 @@
 -- from https://create.roblox.com/docs/luau/queues#implementing-queues,
 -- amended per https://www.lua.org/pil/16.1.html
 
+-- While coding some scripting in Lua
+-- I found that I needed a queua
+-- I thought of linked list
+-- But had to resist
+-- For fear it might be too obscua. 
+
 local Queue = {}
 
 function Queue:new()
diff --git a/indra/newview/scripts/lua/WaitQueue.lua b/indra/newview/scripts/lua/WaitQueue.lua
index 1fbcc50847..ad4fdecf43 100644
--- a/indra/newview/scripts/lua/WaitQueue.lua
+++ b/indra/newview/scripts/lua/WaitQueue.lua
@@ -5,8 +5,8 @@
 local fiber = require('fiber')
 local Queue = require('Queue')
 
--- local debug = LL.print_debug
-local function debug(...) end
+-- local dbg = require('printf')
+local function dbg(...) end
 
 local WaitQueue = Queue:new()
 
@@ -60,17 +60,18 @@ 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')
+            dbg('WaitQueue:Dequeue(): closed')
             return nil
         end
-        debug('WaitQueue:Dequeue(): waiting')
+        dbg('WaitQueue:Dequeue(): waiting')
         -- add the running coroutine to the list of waiters
+        dbg('WaitQueue:Dequeue() running %s', tostring(coroutine.running() or 'main'))
         table.insert(self._waiters, fiber.running())
         -- then let somebody else run
         fiber.wait()
     end
     -- here we're sure this queue isn't empty
-    debug('WaitQueue:Dequeue() calling Queue.Dequeue()')
+    dbg('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
index aebf27357f..9057e6c890 100644
--- a/indra/newview/scripts/lua/fiber.lua
+++ b/indra/newview/scripts/lua/fiber.lua
@@ -17,8 +17,8 @@
 -- or with an error).
 
 local printf = require 'printf'
--- local debug = printf
-local function debug(...) end
+-- local dbg = printf
+local function dbg(...) end
 local coro = require 'coro'
 
 local fiber = {}
@@ -78,22 +78,28 @@ function fiber.launch(name, func, ...)
     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]))
+--  dbg('launch(%s)', namekey)
+--  dbg('byname[%s] = %s', namekey, tostring(byname[namekey]))
+--  dbg('names[%s] = %s', tostring(co), names[co])
+--  dbg('ready[-1] = %s', tostring(ready[#ready]))
 end
 
 -- for debugging
-function fiber.print_all()
-    print('Ready fibers:' .. if next(ready) then '' else ' none')
+function format_all()
+    output = {}
+    table.insert(output, 'Ready fibers:' .. if next(ready) then '' else ' none')
     for _, co in pairs(ready) do
-        printf('  %s: %s', fiber.get_name(co), fiber.status(co))
+        table.insert(output, string.format('  %s: %s', fiber.get_name(co), fiber.status(co)))
     end
-    print('Waiting fibers:' .. if next(waiting) then '' else ' none')
+    table.insert(output, 'Waiting fibers:' .. if next(waiting) then '' else ' none')
     for co in pairs(waiting) do
-        printf('  %s: %s', fiber.get_name(co), fiber.status(co))
+        table.insert(output, string.format('  %s: %s', fiber.get_name(co), fiber.status(co)))
     end
+    return table.concat(output, '\n')
+end
+
+function fiber.print_all()
+    print(format_all())
 end
 
 -- return either the running coroutine or, if called from the main thread,
@@ -160,6 +166,7 @@ end
 
 -- Suspend the current fiber until some other fiber calls fiber.wake() on it
 function fiber.wait()
+    dbg('Fiber %q waiting', fiber.get_name())
     set_waiting()
     -- now yield to other fibers
     fiber.yield()
@@ -175,26 +182,27 @@ function fiber.wake(co)
     waiting[co] = nil
     -- add to end of ready list
     table.insert(ready, co)
+    dbg('Fiber %q ready', fiber.get_name(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
+    -- 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',
+        dbg('%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',
+            dbg('%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())
+    dbg('%s live_ready_iter() returning nil', fiber.get_name())
     return nil
 end
 
@@ -214,6 +222,7 @@ end
 -- * false, nil if this is the only remaining fiber
 -- * nil,   x   if configured idle() callback returns non-nil x
 local function scheduler()
+    dbg('scheduler():\n%s', format_all())
     -- 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
@@ -311,12 +320,12 @@ function fiber.run()
     end
     local others, idle_done
     repeat
-        debug('%s calling fiber.run() calling scheduler()', fiber.get_name())
+        dbg('%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(),
+        dbg("%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())
+    dbg('%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
diff --git a/indra/newview/scripts/lua/leap.lua b/indra/newview/scripts/lua/leap.lua
index a60819d493..d19273e8bc 100644
--- a/indra/newview/scripts/lua/leap.lua
+++ b/indra/newview/scripts/lua/leap.lua
@@ -40,25 +40,25 @@
 
 local fiber = require('fiber')
 local ErrorQueue = require('ErrorQueue')
--- local debug = require('printf')
-local function debug(...) end 
+local function dbg(...) end 
+-- local dbg = require('printf')
 
 local leap = {}
 
--- _reply: string name of reply LLEventPump. Any events the viewer posts to
+-- reply: string name of reply LLEventPump. Any events the viewer posts to
 -- this pump will be queued for get_event_next(). We usually specify it as the
 -- reply pump for requests to internal viewer services.
--- _command: string name of command LLEventPump. post_to(_command, ...)
+-- command: string name of command LLEventPump. post_to(command, ...)
 -- engages LLLeapListener operations such as listening on a specified other
 -- LLEventPump, etc.
-leap._reply, leap._command = LL.get_event_pumps()
+local reply, command = LL.get_event_pumps()
 -- Dict of features added to the LEAP protocol since baseline implementation.
 -- Before engaging a new feature that might break an older viewer, we can
 -- check for the presence of that feature key. This table is solely about the
 -- LEAP protocol itself, the way we communicate with the viewer. To discover
 -- whether a given listener exists, or supports a particular operation, use
--- _command's "getAPI" operation.
--- For Lua, _command's "getFeatures" operation suffices?
+-- command's "getAPI" operation.
+-- For Lua, command's "getFeatures" operation suffices?
 -- leap._features = {}
 
 -- Each outstanding request() or generate() call has a corresponding
@@ -67,20 +67,25 @@ leap._reply, leap._command = LL.get_event_pumps()
 -- we can look up the appropriate WaitForReqid object more efficiently
 -- in a dict than by tossing such objects into the usual waitfors list.
 -- Note: the ["reqid"] must be unique, otherwise we could end up
--- replacing an earlier WaitForReqid object in self.pending with a
+-- replacing an earlier WaitForReqid object in pending with a
 -- 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.
--- these are weak values tables
-local weak_values = {__mode='v'}
-leap._pending = setmetatable({}, weak_values)
+-- pending is NOT a weak table because the caller of request() or generate()
+-- never sees the WaitForReqid object. pending holds the only reference, so
+-- it should NOT be garbage-collected.
+pending = {}
 -- 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 = setmetatable({}, weak_values)
+-- Anyone who instantiates a WaitFor subclass object should retain a reference
+-- to it. Once the consuming script drops the reference, allow Lua to
+-- garbage-collect the WaitFor despite its entry in waitfors.
+local weak_values = {__mode='v'}
+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
+-- ["reqid"] values is our very own reply pump, we can get away with
 -- an integer.
 leap._reqid = 0
 -- break leap.process() loop
@@ -88,12 +93,12 @@ leap._done = false
 
 -- get the name of the reply pump
 function leap.replypump()
-    return leap._reply
+    return reply
 end
 
 -- get the name of the command pump
 function leap.cmdpump()
-    return leap._command
+    return command
 end
 
 -- Fire and forget. Send the specified request LLSD, expecting no reply.
@@ -102,16 +107,15 @@ end
 -- 
 -- See also request(), generate().
 function leap.send(pump, data, reqid)
-    debug('leap.send(%s, %s, %s) entry', pump, data, reqid)
     local data = data
     if type(data) == 'table' then
         data = table.clone(data)
-        data['reply'] = leap._reply
+        data['reply'] = reply
         if reqid ~= nil then
             data['reqid'] = reqid
         end
     end
-    debug('leap.send(%s, %s) calling post_on()', pump, data)
+    dbg('leap.send(%s, %s) calling post_on()', pump, data)
     LL.post_on(pump, data)
 end
 
@@ -122,13 +126,14 @@ local function requestSetup(pump, data)
     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)
+    -- self-register on our waitfors list. Instead, capture the new
+    -- WaitForReqid object in pending so dispatch() can find it.
+    local waitfor = leap.WaitForReqid:new(reqid)
+    pending[reqid] = waitfor
     -- Pass reqid to send() to stamp it into (a copy of) the request data.
-    debug('requestSetup(%s, %s)', pump, data)
+    dbg('requestSetup(%s, %s)', pump, data)
     leap.send(pump, data, reqid)
-    return reqid
+    return reqid, waitfor
 end
 
 -- Send the specified request LLSD, expecting exactly one reply. Block
@@ -150,13 +155,12 @@ end
 --
 -- See also send(), generate().
 function leap.request(pump, data)
-    local reqid = requestSetup(pump, data)
-    local waitfor = leap._pending[reqid]
-    debug('leap.request(%s, %s) about to wait on %s', pump, data, tostring(waitfor))
+    local reqid, waitfor = requestSetup(pump, data)
+    dbg('leap.request(%s, %s) about to wait on %s', pump, data, tostring(waitfor))
     local ok, response = pcall(waitfor.wait, waitfor)
-    debug('leap.request(%s, %s) got %s: %s', pump, data, ok, response)
+    dbg('leap.request(%s, %s) got %s: %s', pump, data, ok, response)
     -- kill off temporary WaitForReqid object, even if error
-    leap._pending[reqid] = nil
+    pending[reqid] = nil
     if ok then
         return response
     else
@@ -178,8 +182,7 @@ 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 = requestSetup(pump, data)
-    local waitfor = leap._pending[reqid]
+    local reqid, waitfor = requestSetup(pump, data)
     local ok, response
     repeat
         ok, response = pcall(waitfor.wait, waitfor)
@@ -189,7 +192,7 @@ function leap.generate(pump, data, checklast)
         coroutine.yield(response)
     until checklast and checklast(response)
     -- If we break the above loop, whether or not due to error, clean up.
-    leap._pending[reqid] = nil
+    pending[reqid] = nil
     if not ok then
         error(response)
     end
@@ -197,10 +200,10 @@ end
 
 local function cleanup(message)
     -- we're done: clean up all pending coroutines
-    for i, waitfor in pairs(leap._pending) do
+    for i, waitfor in pairs(pending) do
         waitfor:close()
     end
-    for i, waitfor in pairs(leap._waitfors) do
+    for i, waitfor in pairs(waitfors) do
         waitfor:close()
     end
 end
@@ -209,8 +212,8 @@ end
 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)
+    for i, waitfor in pairs(waitfors) do
+        dbg('unsolicited() checking %s', waitfor.name)
         if waitfor:handle(pump, data) then
             return
         end
@@ -226,7 +229,7 @@ local function dispatch(pump, data)
         return unsolicited(pump, data)
     end
     -- have reqid; do we have a WaitForReqid?
-    local waitfor = leap._pending[reqid]
+    local waitfor = pending[reqid]
     if waitfor == nil then
         return unsolicited(pump, data)
     end
@@ -243,9 +246,9 @@ fiber.set_idle(function ()
         cleanup('done')
         return 'done'
     end
-    debug('leap.idle() calling get_event_next()')
+    dbg('leap.idle() calling get_event_next()')
     local ok, pump, data = pcall(LL.get_event_next)
-    debug('leap.idle() got %s: %s, %s', ok, pump, data)
+    dbg('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)
@@ -268,17 +271,17 @@ end
 
 -- called by WaitFor.enable()
 local function registerWaitFor(waitfor)
-    table.insert(leap._waitfors, waitfor)
+    table.insert(waitfors, waitfor)
     -- keep waitfors sorted in descending order of specified priority
-    table.sort(leap._waitfors,
+    table.sort(waitfors,
                function (lhs, rhs) return lhs.priority > rhs.priority end)
 end
 
 -- called by WaitFor.disable()
 local function unregisterWaitFor(waitfor)
-    for i, w in pairs(leap._waitfors) do
+    for i, w in pairs(waitfors) do
         if w == waitfor then
-            leap._waitfors[i] = nil
+            waitfors[i] = nil
             break
         end
     end
@@ -368,9 +371,9 @@ end
 -- Block the calling coroutine until a suitable unsolicited event (one
 -- for which filter() returns the event) arrives.
 function leap.WaitFor:wait()
-    debug('%s about to wait', self.name)
+    dbg('%s about to wait', self.name)
     local item = self._queue:Dequeue()
-    debug('%s got %s', self.name, item)
+    dbg('%s got %s', self.name, item)
     return item
 end
 
@@ -389,10 +392,10 @@ function leap.WaitFor:filter(pump, data)
     error('You must override the WaitFor.filter() method')
 end
 
--- called by unsolicited() for each WaitFor in leap._waitfors
+-- called by unsolicited() for each WaitFor in waitfors
 function leap.WaitFor:handle(pump, data)
     local item = self:filter(pump, data)
-    debug('%s.filter() returned %s', self.name, item)
+    dbg('%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
@@ -423,8 +426,8 @@ leap.WaitForReqid = leap.WaitFor:new()
 
 function leap.WaitForReqid:new(reqid)
     -- priority is meaningless, since this object won't be added to the
-    -- priority-sorted ViewerClient.waitfors list. Use the reqid as the
-    -- debugging name string.
+    -- priority-sorted waitfors list. Use the reqid as the debugging name
+    -- string.
     local obj = leap.WaitFor:new(nil, 'WaitForReqid(' .. reqid .. ')')
     setmetatable(obj, self)
     self.__index = self
diff --git a/indra/newview/scripts/lua/startup.lua b/indra/newview/scripts/lua/startup.lua
new file mode 100644
index 0000000000..4311bb9a60
--- /dev/null
+++ b/indra/newview/scripts/lua/startup.lua
@@ -0,0 +1,101 @@
+-- query, wait for or mandate a particular viewer startup state
+
+-- During startup, the viewer steps through a sequence of numbered (and named)
+-- states. This can be used to detect when, for instance, the login screen is
+-- displayed, or when the viewer has finished logging in and is fully
+-- in-world.
+
+local fiber = require 'fiber'
+local leap = require 'leap'
+local inspect = require 'inspect'
+local function dbg(...) end
+-- local dbg = require 'printf'
+
+-- ---------------------------------------------------------------------------
+-- Get the list of startup states from the viewer.
+local bynum = leap.request('LLStartUp', {op='getStateTable'})['table']
+
+local byname = setmetatable(
+    {},
+    -- set metatable to throw an error if you look up invalid state name
+    {__index=function(t, k)
+         local v = t[k]
+         if v then
+             return v
+         end
+         error(string.format('startup module passed invalid state %q', k), 2)
+    end})
+
+-- derive byname as a lookup table to find the 0-based index for a given name
+for i, name in pairs(bynum) do
+    -- the viewer's states are 0-based, not 1-based like Lua indexes
+    byname[name] = i - 1
+end
+-- dbg('startup states: %s', inspect(byname))
+
+-- specialize a WaitFor to track the viewer's startup state
+local startup_pump = 'StartupState'
+local waitfor = leap.WaitFor:new(0, startup_pump)
+function waitfor:filter(pump, data)
+    if pump == self.name then
+        return data
+    end
+end
+
+function waitfor:process(data)
+    -- keep updating startup._state for interested parties
+    startup._state = data.str
+    dbg('startup updating state to %q', data.str)
+    -- now pass data along to base-class method to queue
+    leap.WaitFor.process(self, data)
+end
+
+-- listen for StartupState events
+leap.request(leap.cmdpump(),
+             {op='listen', source=startup_pump, listener='startup.lua', tweak=true})
+-- poke LLStartUp to make sure we get an event
+leap.send('LLStartUp', {op='postStartupState'})
+
+-- ---------------------------------------------------------------------------
+startup = {}
+
+-- wait for response from postStartupState
+while not startup._state do
+    dbg('startup.state() waiting for first StartupState event')
+    waitfor:wait()
+end
+
+-- return a list of all known startup states
+function startup.list()
+    return bynum
+end
+
+-- report whether state with string name 'left' is before string name 'right'
+function startup.before(left, right)
+    return byname[left] < byname[right]
+end
+
+-- report the viewer's current startup state
+function startup.state()
+    return startup._state
+end
+
+-- error if script is called before specified state string name
+function startup.ensure(state)
+    if startup.before(startup.state(), state) then
+        -- tell error() to pretend this error was thrown by our caller
+        error('must not be called before startup state ' .. state, 2)
+    end
+end
+
+-- block calling fiber until viewer has reached state with specified string name
+function startup.wait(state)
+    dbg('startup.wait(%q)', state)
+    while startup.before(startup.state(), state) do
+        local item = waitfor:wait()
+        dbg('startup.wait(%q) sees %s', state, item)
+    end
+end
+
+return startup
+
diff --git a/indra/newview/scripts/lua/test_luafloater_demo.lua b/indra/newview/scripts/lua/test_luafloater_demo.lua
index c375a2abc7..ab638dcdd1 100644
--- a/indra/newview/scripts/lua/test_luafloater_demo.lua
+++ b/indra/newview/scripts/lua/test_luafloater_demo.lua
@@ -1,10 +1,16 @@
-XML_FILE_PATH = "luafloater_demo.xml"
+XML_FILE_PATH = LL.abspath("luafloater_demo.xml")
+
+scriptparts = string.split(LL.source_path(), '/')
+scriptname = scriptparts[#scriptparts]
+print('Running ' .. scriptname)
 
 leap = require 'leap'
 fiber = require 'fiber'
+startup = require 'startup'
 
 --event pump for sending actions to the floater
-COMMAND_PUMP_NAME = ""
+local COMMAND_PUMP_NAME = ""
+local reqid
 --table of floater UI events
 event_list=leap.request("LLFloaterReg", {op="getFloaterEvents"}).events
 
@@ -41,24 +47,29 @@ function handleEvents(event_data)
     end
   elseif event_data.event == _event("floater_close") then
     LL.print_warning("Floater was closed")
-    leap.done()
+    return false
   end
+  return true
 end
 
+startup.wait('STATE_LOGIN_WAIT')
 local key = {xml_path = XML_FILE_PATH, op = "showLuaFloater"}
 --sign for additional events for defined control {<control_name>= {action1, action2, ...}}
 key.extra_events={show_time_lbl = {_event("right_mouse_down"), _event("double_click")}}
-COMMAND_PUMP_NAME = leap.request("LLFloaterReg", key).command_name
+local resp = leap.request("LLFloaterReg", key)
+COMMAND_PUMP_NAME = resp.command_name
+reqid = resp.reqid
 
 catch_events = leap.WaitFor:new(-1, "all_events")
 function catch_events:filter(pump, data)
-  return data
+  if data.reqid == reqid then
+    return data
+  end
 end
 
 function process_events(waitfor)
   event_data = waitfor:wait()
-  while event_data do
-    handleEvents(event_data)
+  while event_data and handleEvents(event_data) do
     event_data = waitfor:wait()
   end
 end
diff --git a/indra/newview/scripts/lua/test_luafloater_gesture_list.lua b/indra/newview/scripts/lua/test_luafloater_gesture_list.lua
index 6d4a8e0cad..3d9a9b0ad4 100644
--- a/indra/newview/scripts/lua/test_luafloater_gesture_list.lua
+++ b/indra/newview/scripts/lua/test_luafloater_gesture_list.lua
@@ -1,11 +1,17 @@
-XML_FILE_PATH = "luafloater_gesture_list.xml"
+XML_FILE_PATH = LL.abspath("luafloater_gesture_list.xml")
+
+scriptparts = string.split(LL.source_path(), '/')
+scriptname = scriptparts[#scriptparts]
+print('Running ' .. scriptname)
 
 leap = require 'leap'
 fiber = require 'fiber'
 LLGesture = require 'LLGesture'
+startup = require 'startup'
 
 --event pump for sending actions to the floater
-COMMAND_PUMP_NAME = ""
+local COMMAND_PUMP_NAME = ""
+local reqid
 --table of floater UI events
 event_list=leap.request("LLFloaterReg", {op="getFloaterEvents"}).events
 
@@ -22,9 +28,12 @@ end
 
 function handleEvents(event_data)
   if event_data.event == _event("floater_close") then
-    leap.done()
-  elseif event_data.event == _event("post_build") then
+    return false
+  end
+
+  if event_data.event == _event("post_build") then
     COMMAND_PUMP_NAME = event_data.command_name
+    reqid = event_data.reqid
     gestures_uuid = LLGesture.getActiveGestures()
     local action_data = {}
     action_data.action = "add_list_element"
@@ -40,8 +49,10 @@ function handleEvents(event_data)
       LLGesture.startGesture(event_data.value)
     end
   end
+  return true
 end
 
+startup.wait('STATE_STARTED')
 local key = {xml_path = XML_FILE_PATH, op = "showLuaFloater"}
 --receive additional events for defined control {<control_name>= {action1, action2, ...}}
 key.extra_events={gesture_list = {_event("double_click")}}
@@ -49,13 +60,14 @@ handleEvents(leap.request("LLFloaterReg", key))
 
 catch_events = leap.WaitFor:new(-1, "all_events")
 function catch_events:filter(pump, data)
-  return data
+  if data.reqid == reqid then
+    return data
+  end
 end
 
 function process_events(waitfor)
   event_data = waitfor:wait()
-  while event_data do
-    handleEvents(event_data)
+  while event_data and handleEvents(event_data) do
     event_data = waitfor:wait()
   end
 end
diff --git a/indra/newview/scripts/lua/util.lua b/indra/newview/scripts/lua/util.lua
index e3af633ea7..a2191288f6 100644
--- a/indra/newview/scripts/lua/util.lua
+++ b/indra/newview/scripts/lua/util.lua
@@ -2,9 +2,9 @@
 
 local util = {}
 
--- cheap test whether table t is empty
-function util.empty(t)
-    return not next(t)
+-- check if array-like table contains certain value
+function util.contains(t, v)
+    return table.find(t, v) ~= nil
 end
 
 -- reliable count of the number of entries in table t
@@ -17,6 +17,11 @@ function util.count(t)
     return count
 end
 
+-- cheap test whether table t is empty
+function util.empty(t)
+    return not next(t)
+end
+
 -- recursive table equality
 function util.equal(t1, t2)
     if not (type(t1) == 'table' and type(t2) == 'table') then