Make property bindings shared amongst all lua threads

src/app_console/app_console.cpp

@@ -628,8 +628,7 @@ static const char kReplMain[] =
     "repl:run()\n";
 
 int CmdLua(int argc, char** argv) {
-  std::unique_ptr<lua::LuaThread> context{
-      lua::LuaThread::Start(*AppConsole::sServices)};
+  auto context = lua::Registry::instance(*AppConsole::sServices).newThread();
   if (!context) {
     return 1;
   }
@@ -652,8 +651,7 @@ int CmdLua(int argc, char** argv) {
 }
 
 int CmdLuaRun(int argc, char** argv) {
-  std::unique_ptr<lua::LuaThread> context{
-      lua::LuaThread::Start(*AppConsole::sServices)};
+  auto context = lua::Registry::instance(*AppConsole::sServices).newThread();
   if (!context) {
     return 1;
   }

src/lua/bridge.cpp

@@ -22,6 +22,9 @@
 #include "lua_version.hpp"
 #include "lvgl.h"
 
+#include "font/lv_font_loader.h"
+#include "luavgl.h"
+
 #include "event_queue.hpp"
 #include "property.hpp"
 #include "service_locator.hpp"
@@ -32,34 +35,62 @@ int luaopen_linenoise(lua_State* L);
 int luaopen_term_core(lua_State* L);
 }
 
+LV_FONT_DECLARE(font_fusion_12);
+LV_FONT_DECLARE(font_fusion_10);
+
 namespace lua {
 
 [[maybe_unused]] static constexpr char kTag[] = "lua_bridge";
 
 static constexpr char kBridgeKey[] = "bridge";
 
+static auto make_font_cb(const char* name, int size, int weight)
+    -> const lv_font_t* {
+  if (std::string{"fusion"} == name) {
+    if (size == 12) {
+      return &font_fusion_12;
+    }
+    if (size == 10) {
+      return &font_fusion_10;
+    }
+  }
+  return NULL;
+}
+
+static auto delete_font_cb(lv_font_t* font) -> void {}
+
 auto Bridge::Get(lua_State* state) -> Bridge* {
   lua_pushstring(state, kBridgeKey);
   lua_gettable(state, LUA_REGISTRYINDEX);
   return reinterpret_cast<Bridge*>(lua_touserdata(state, -1));
 }
 
-Bridge::Bridge(system_fsm::ServiceLocator& services, lua_State& s)
-    : services_(services), state_(s), bindings_(s) {
-  lua_pushstring(&s, kBridgeKey);
-  lua_pushlightuserdata(&s, this);
-  lua_settable(&s, LUA_REGISTRYINDEX);
+Bridge::Bridge(system_fsm::ServiceLocator& services) : services_(services) {}
+
+auto Bridge::installBaseModules(lua_State* L) -> void {
+  lua_pushstring(L, kBridgeKey);
+  lua_pushlightuserdata(L, this);
+  lua_settable(L, LUA_REGISTRYINDEX);
 
-  luaL_requiref(&s, "linenoise", luaopen_linenoise, true);
-  lua_pop(&s, 1);
+  bindings_.install(L);
 
-  luaL_requiref(&s, "term.core", luaopen_term_core, true);
-  lua_pop(&s, 1);
+  luaL_requiref(L, "linenoise", luaopen_linenoise, true);
+  lua_pop(L, 1);
+
+  luaL_requiref(L, "term.core", luaopen_term_core, true);
+  lua_pop(L, 1);
+
+  RegisterControlsModule(L);
+  RegisterDatabaseModule(L);
+  RegisterQueueModule(L);
+  RegisterVersionModule(L);
+}
 
-  RegisterControlsModule(&s);
-  RegisterDatabaseModule(&s);
-  RegisterQueueModule(&s);
-  RegisterVersionModule(&s);
+auto Bridge::installLvgl(lua_State* L) -> void {
+  luavgl_set_pcall(L, CallProtected);
+  luavgl_set_font_extension(L, make_font_cb, delete_font_cb);
+  luaL_requiref(L, "lvgl", luaopen_lvgl, true);
+  lua_pop(L, 1);
 }
 
 static auto new_property_module(lua_State* state) -> int {
@@ -76,32 +107,33 @@ static auto new_property_module(lua_State* state) -> int {
 template <class... Ts>
 inline constexpr bool always_false_v = false;
 
-auto Bridge::AddPropertyModule(
+auto Bridge::installPropertyModule(
+    lua_State* L,
     const std::string& name,
-    std::vector<std::pair<std::string, std::variant<LuaFunction, Property*>>>
+    std::vector<std::pair<std::string, std::variant<LuaFunction, Property*>>>&
         props) -> void {
   // Create the module (or retrieve it if one with this name already exists)
-  luaL_requiref(&state_, name.c_str(), new_property_module, true);
+  luaL_requiref(L, name.c_str(), new_property_module, true);
 
   for (const auto& prop : props) {
-    lua_pushstring(&state_, prop.first.c_str());
+    lua_pushstring(L, prop.first.c_str());
     std::visit(
         [&](auto&& arg) {
           using T = std::decay_t<decltype(arg)>;
           if constexpr (std::is_same_v<T, LuaFunction>) {
-            bindings_.Register(&state_, arg);
+            bindings_.Register(L, arg);
           } else if constexpr (std::is_same_v<T, Property*>) {
-            bindings_.Register(&state_, arg);
+            bindings_.Register(L, arg);
           } else {
             static_assert(always_false_v<T>, "missing case");
           }
         },
         prop.second);
 
-    lua_settable(&state_, -3);  // metatable.propname = property
+    lua_settable(L, -3);  // metatable.propname = property
   }
 
-  lua_pop(&state_, 1);  // pop the module off the stack
+  lua_pop(L, 1);  // pop the module off the stack
 }
 
 }  // namespace lua

src/lua/include/bridge.hpp

@@ -16,25 +16,38 @@
 
 namespace lua {
 
+/*
+ * Responsible for adding C/C++ module bindings to Lua threads. This class
+ * keeps no thread-specific internal state, and instead uses the LUA_REGISTRY
+ * table of its host threads to store data.
+ */
 class Bridge {
  public:
+  /*
+   * Utility for retrieving the Bridge from a Lua thread in which the Bridge's
+   * bindings have been installed. Use by Lua's C callbacks to access the rest
+   * of the system.
+   */
   static auto Get(lua_State* state) -> Bridge*;
 
-  Bridge(system_fsm::ServiceLocator&, lua_State& s);
+  Bridge(system_fsm::ServiceLocator& s);
 
-  auto AddPropertyModule(
+  system_fsm::ServiceLocator& services() { return services_; }
+
+  auto installBaseModules(lua_State* L) -> void;
+  auto installLvgl(lua_State* L) -> void;
+  auto installPropertyModule(
+      lua_State* L,
       const std::string&,
       std::vector<
-          std::pair<std::string,
-                    std::variant<LuaFunction, Property*>>>)
+          std::pair<std::string, std::variant<LuaFunction, Property*>>>&)
       -> void;
 
-  system_fsm::ServiceLocator& services() { return services_; }
-  PropertyBindings& bindings() { return bindings_; }
+  Bridge(const Bridge&) = delete;
+  Bridge& operator=(const Bridge&) = delete;
 
  private:
   system_fsm::ServiceLocator& services_;
-  lua_State& state_;
   PropertyBindings bindings_;
 };
 

src/lua/include/lua_thread.hpp

@@ -23,8 +23,7 @@ auto CallProtected(lua_State*, int nargs, int nresults) -> int;
 
 class LuaThread {
  public:
-  static auto Start(system_fsm::ServiceLocator&, lv_obj_t* lvgl_root = nullptr)
-      -> LuaThread*;
+  static auto Start(system_fsm::ServiceLocator&) -> LuaThread*;
   ~LuaThread();
 
   auto RunScript(const std::string& path) -> bool;
@@ -32,15 +31,48 @@ class LuaThread {
 
   auto DumpStack() -> void;
 
-  auto bridge() -> Bridge& { return *bridge_; }
   auto state() -> lua_State* { return state_; }
 
+  LuaThread(const LuaThread&) = delete;
+  LuaThread& operator=(const LuaThread&) = delete;
+
  private:
-  LuaThread(std::unique_ptr<Allocator>&, std::unique_ptr<Bridge>&, lua_State*);
+  LuaThread(std::unique_ptr<Allocator>&, lua_State*);
 
   std::unique_ptr<Allocator> alloc_;
-  std::unique_ptr<Bridge> bridge_;
   lua_State* state_;
 };
 
+class Registry {
+ public:
+  static auto instance(system_fsm::ServiceLocator&) -> Registry&;
+
+  auto uiThread() -> std::shared_ptr<LuaThread>;
+  auto newThread() -> std::shared_ptr<LuaThread>;
+
+  auto AddPropertyModule(
+      const std::string&,
+      std::vector<
+          std::pair<std::string, std::variant<LuaFunction, Property*>>>)
+      -> void;
+
+  Registry(const Registry&) = delete;
+  Registry& operator=(const Registry&) = delete;
+
+ private:
+  Registry(system_fsm::ServiceLocator&);
+
+  system_fsm::ServiceLocator& services_;
+  std::unique_ptr<Bridge> bridge_;
+
+  std::shared_ptr<LuaThread> ui_thread_;
+  std::list<std::weak_ptr<LuaThread>> threads_;
+
+  std::vector<
+      std::pair<std::string,
+                std::vector<std::pair<std::string,
+                                      std::variant<LuaFunction, Property*>>>>>
+      modules_;
+};
+
 }  // namespace lua

src/lua/include/property.hpp

@@ -53,7 +53,9 @@ class Property {
 
 class PropertyBindings {
  public:
-  PropertyBindings(lua_State&);
+  PropertyBindings();
+
+  auto install(lua_State*) -> void;
 
   auto Register(lua_State*, Property*) -> void;
   auto Register(lua_State*, LuaFunction) -> void;

src/lua/lua_thread.cpp

@@ -9,22 +9,16 @@
 #include <iostream>
 #include <memory>
 
-#include "lauxlib.h"
-#include "lua.h"
-#include "lua.hpp"
-
-#include "font/lv_font_loader.h"
-#include "luavgl.h"
-
 #include "esp_heap_caps.h"
 #include "esp_log.h"
+#include "lua.hpp"
+
+#include "bridge.hpp"
 #include "event_queue.hpp"
+#include "memory_resource.hpp"
 #include "service_locator.hpp"
 #include "ui_events.hpp"
 
-LV_FONT_DECLARE(font_fusion_12);
-LV_FONT_DECLARE(font_fusion_10);
-
 namespace lua {
 
 [[maybe_unused]] static constexpr char kTag[] = "lua";
@@ -59,23 +53,7 @@ static int lua_panic(lua_State* L) {
   return 0;
 }
 
-static auto make_font_cb(const char* name, int size, int weight)
-    -> const lv_font_t* {
-  if (std::string{"fusion"} == name) {
-    if (size == 12) {
-      return &font_fusion_12;
-    }
-    if (size == 10) {
-      return &font_fusion_10;
-    }
-  }
-  return NULL;
-}
-
-static auto delete_font_cb(lv_font_t* font) -> void {}
-
-auto LuaThread::Start(system_fsm::ServiceLocator& services, lv_obj_t* lvgl_root)
-    -> LuaThread* {
+auto LuaThread::Start(system_fsm::ServiceLocator& services) -> LuaThread* {
   auto alloc = std::make_unique<Allocator>();
   lua_State* state = lua_newstate(lua_alloc, alloc.get());
   if (!state) {
@@ -85,24 +63,11 @@ auto LuaThread::Start(system_fsm::ServiceLocator& services, lv_obj_t* lvgl_root)
   luaL_openlibs(state);
   lua_atpanic(state, lua_panic);
 
-  auto bridge = std::make_unique<Bridge>(services, *state);
-
-  // FIXME: luavgl init should probably be a part of the bridge.
-  if (lvgl_root) {
-    luavgl_set_pcall(state, CallProtected);
-    luavgl_set_font_extension(state, make_font_cb, delete_font_cb);
-    luavgl_set_root(state, lvgl_root);
-    luaL_requiref(state, "lvgl", luaopen_lvgl, true);
-    lua_pop(state, 1);
-  }
-
-  return new LuaThread(alloc, bridge, state);
+  return new LuaThread(alloc, state);
 }
 
-LuaThread::LuaThread(std::unique_ptr<Allocator>& alloc,
-                     std::unique_ptr<Bridge>& bridge,
-                     lua_State* state)
-    : alloc_(std::move(alloc)), bridge_(std::move(bridge)), state_(state) {}
+LuaThread::LuaThread(std::unique_ptr<Allocator>& alloc, lua_State* state)
+    : alloc_(std::move(alloc)), state_(state) {}
 
 LuaThread::~LuaThread() {
   lua_close(state_);
@@ -219,4 +184,51 @@ auto CallProtected(lua_State* s, int nargs, int nresults) -> int {
   return ret;
 }
 
+auto Registry::instance(system_fsm::ServiceLocator& s) -> Registry& {
+  static Registry sRegistry{s};
+  return sRegistry;
+}
+
+Registry::Registry(system_fsm::ServiceLocator& services)
+    : services_(services), bridge_(new Bridge(services)) {}
+
+auto Registry::uiThread() -> std::shared_ptr<LuaThread> {
+  if (!ui_thread_) {
+    ui_thread_ = newThread();
+    bridge_->installLvgl(ui_thread_->state());
+  }
+  return ui_thread_;
+}
+
+auto Registry::newThread() -> std::shared_ptr<LuaThread> {
+  std::shared_ptr<LuaThread> thread{LuaThread::Start(services_)};
+  bridge_->installBaseModules(thread->state());
+  for (auto& module : modules_) {
+    bridge_->installPropertyModule(thread->state(), module.first,
+                                   module.second);
+  }
+  threads_.push_back(thread);
+  return thread;
+}
+
+auto Registry::AddPropertyModule(
+    const std::string& name,
+    std::vector<std::pair<std::string, std::variant<LuaFunction, Property*>>>
+        properties) -> void {
+  modules_.push_back(std::make_pair(name, properties));
+
+  // Any live threads will need to be updated to include the new module.
+  auto it = threads_.begin();
+  while (it != threads_.end()) {
+    auto thread = it->lock();
+    if (!thread) {
+      // Thread has been destroyed; stop tracking it.
+      it = threads_.erase(it);
+    } else {
+      bridge_->installPropertyModule(thread->state(), name, properties);
+      it++;
+    }
+  }
+}
+
 }  // namespace lua

src/lua/property.cpp

@@ -10,10 +10,12 @@
 #include <cmath>
 #include <memory>
 #include <memory_resource>
+#include <sstream>
 #include <string>
 #include <variant>
 
 #include "bluetooth_types.hpp"
+#include "lauxlib.h"
 #include "lua.h"
 #include "lua.hpp"
 #include "lua_thread.hpp"
@@ -76,9 +78,29 @@ static auto property_bind(lua_State* state) -> int {
   return 1;
 }
 
-static const struct luaL_Reg kPropertyBindingFuncs[] = {{"get", property_get},
+static auto property_tostring(lua_State* state) -> int {
+  Property* p = check_property(state);
+  p->PushValue(*state);
+
+  std::stringstream str{};
+  str << "property { " << luaL_tolstring(state, -1, NULL);
+  if (!p->IsTwoWay()) {
+    str << ", read-only";
+  }
+  str << " }";
+
+  lua_settop(state, 0);
+
+  std::string res = str.str();
+  lua_pushlstring(state, res.data(), res.size());
+  return 1;
+}
+
+static const struct luaL_Reg kPropertyBindingFuncs[] = {
+    {"get", property_get},
     {"set", property_set},
     {"bind", property_bind},
+    {"__tostring", property_tostring},
     {NULL, NULL}};
 
 static auto generic_function_cb(lua_State* state) -> int {
@@ -98,45 +120,47 @@ static auto generic_function_cb(lua_State* state) -> int {
   return std::invoke(fn, state);
 }
 
-PropertyBindings::PropertyBindings(lua_State& s) {
-  lua_pushstring(&s, kBinderKey);
-  lua_pushlightuserdata(&s, this);
-  lua_settable(&s, LUA_REGISTRYINDEX);
+PropertyBindings::PropertyBindings() : functions_(&memory::kSpiRamResource) {}
+
+auto PropertyBindings::install(lua_State* L) -> void {
+  lua_pushstring(L, kBinderKey);
+  lua_pushlightuserdata(L, this);
+  lua_settable(L, LUA_REGISTRYINDEX);
 
   // Create the metatable responsible for the Property API.
-  luaL_newmetatable(&s, kPropertyMetatable);
+  luaL_newmetatable(L, kPropertyMetatable);
 
-  lua_pushliteral(&s, "__index");
-  lua_pushvalue(&s, -2);
-  lua_settable(&s, -3);  // metatable.__index = metatable
+  lua_pushliteral(L, "__index");
+  lua_pushvalue(L, -2);
+  lua_settable(L, -3);  // metatable.__index = metatable
 
   // Add our binding funcs (get, set, bind) to the metatable.
-  luaL_setfuncs(&s, kPropertyBindingFuncs, 0);
+  luaL_setfuncs(L, kPropertyBindingFuncs, 0);
 
   // We've finished setting up the metatable, so pop it.
-  lua_pop(&s, 1);
+  lua_pop(L, 1);
 
   // Create a weak table in the registry to hold live bindings.
-  lua_pushstring(&s, kBindingsTable);
-  lua_newtable(&s);  // bindings = {}
+  lua_pushstring(L, kBindingsTable);
+  lua_newtable(L);  // bindings = {}
 
   // Metatable for the weak table. Values are weak.
-  lua_newtable(&s);  // meta = {}
-  lua_pushliteral(&s, "__mode");
-  lua_pushliteral(&s, "v");
-  lua_settable(&s, -3);      // meta.__mode='v'
-  lua_setmetatable(&s, -2);  // setmetatable(bindings, meta)
+  lua_newtable(L);  // meta = {}
+  lua_pushliteral(L, "__mode");
+  lua_pushliteral(L, "v");
+  lua_settable(L, -3);      // meta.__mode='v'
+  lua_setmetatable(L, -2);  // setmetatable(bindings, meta)
 
-  lua_settable(&s, LUA_REGISTRYINDEX);  // REGISTRY[kBindingsTable] = bindings
+  lua_settable(L, LUA_REGISTRYINDEX);  // REGISTRY[kBindingsTable] = bindings
 
   // Create the metatable for C++ functions.
-  luaL_newmetatable(&s, kFunctionMetatable);
+  luaL_newmetatable(L, kFunctionMetatable);
 
-  lua_pushliteral(&s, "__call");
-  lua_pushcfunction(&s, generic_function_cb);
-  lua_settable(&s, -3);  // metatable.__call = metatable
+  lua_pushliteral(L, "__call");
+  lua_pushcfunction(L, generic_function_cb);
+  lua_settable(L, -3);  // metatable.__call = metatable
 
-  lua_pop(&s, 1);  // Clean up the function metatable
+  lua_pop(L, 1);  // Clean up the function metatable
 }
 
 auto PropertyBindings::Register(lua_State* s, Property* prop) -> void {

src/ui/ui_fsm.cpp

@@ -442,27 +442,26 @@ void Lua::entry() {
                                alert_timer_callback);
     sAlertContainer = lv_obj_create(sCurrentScreen->alert());
 
-    sLua.reset(lua::LuaThread::Start(*sServices, sCurrentScreen->content()));
-    sLua->bridge().AddPropertyModule("power",
-                                     {
+    auto& registry = lua::Registry::instance(*sServices);
+    sLua = registry.uiThread();
+    registry.AddPropertyModule("power", {
                                             {"battery_pct", &sBatteryPct},
                                             {"battery_millivolts", &sBatteryMv},
                                             {"plugged_in", &sBatteryCharging},
                                         });
-    sLua->bridge().AddPropertyModule(
-        "bluetooth", {
+    registry.AddPropertyModule("bluetooth",
+                               {
                                    {"enabled", &sBluetoothEnabled},
                                    {"connected", &sBluetoothConnected},
                                    {"paired_device", &sBluetoothPairedDevice},
                                    {"devices", &sBluetoothDevices},
                                });
-    sLua->bridge().AddPropertyModule("playback",
-                                     {
+    registry.AddPropertyModule("playback", {
                                                {"playing", &sPlaybackPlaying},
                                                {"track", &sPlaybackTrack},
                                                {"position", &sPlaybackPosition},
                                            });
-    sLua->bridge().AddPropertyModule(
+    registry.AddPropertyModule(
         "queue",
         {
             {"next", [&](lua_State* s) { return QueueNext(s); }},
@@ -473,7 +472,7 @@ void Lua::entry() {
             {"repeat_track", &sQueueRepeat},
             {"random", &sQueueRandom},
         });
-    sLua->bridge().AddPropertyModule("volume",
+    registry.AddPropertyModule("volume",
                                {
                                    {"current_pct", &sVolumeCurrentPct},
                                    {"current_db", &sVolumeCurrentDb},
@@ -481,30 +480,29 @@ void Lua::entry() {
                                    {"limit_db", &sVolumeLimit},
                                });
 
-    sLua->bridge().AddPropertyModule("display",
+    registry.AddPropertyModule("display",
                                {
                                    {"brightness", &sDisplayBrightness},
                                });
 
-    sLua->bridge().AddPropertyModule("controls",
+    registry.AddPropertyModule("controls",
                                {
                                    {"scheme", &sControlsScheme},
                                    {"scroll_sensitivity", &sScrollSensitivity},
                                });
 
-    sLua->bridge().AddPropertyModule(
+    registry.AddPropertyModule(
         "backstack",
         {
             {"push", [&](lua_State* s) { return PushLuaScreen(s); }},
             {"pop", [&](lua_State* s) { return PopLuaScreen(s); }},
         });
-    sLua->bridge().AddPropertyModule(
+    registry.AddPropertyModule(
         "alerts", {
                       {"show", [&](lua_State* s) { return ShowAlert(s); }},
                       {"hide", [&](lua_State* s) { return HideAlert(s); }},
                   });
-    sLua->bridge().AddPropertyModule("database",
-                                     {
+    registry.AddPropertyModule("database", {
                                                {"updating", &sDatabaseUpdating},
                                            });