1 files changed, 230 insertions, 0 deletions
diff --git a/src/rgw/rgw_lua_background.h b/src/rgw/rgw_lua_background.h
new file mode 100644
index 000000000..e1271bceb
--- /dev/null
+++ b/src/rgw/rgw_lua_background.h
@@ -0,0 +1,230 @@
+#pragma once
+#include "common/dout.h"
+#include "rgw_common.h"
+#include <string>
+#include <unordered_map>
+#include <variant>
+#include "rgw_lua_utils.h"
+#include "rgw_realm_reloader.h"
+
+namespace rgw::lua {
+
+//Interval between each execution of the script is set to 5 seconds
+constexpr const int INIT_EXECUTE_INTERVAL = 5;
+
+//Writeable meta table named RGW with mutex protection
+using BackgroundMapValue = std::variant<std::string, long long int, double, bool>;
+using BackgroundMap  = std::unordered_map<std::string, BackgroundMapValue>;
+
+inline void pushvalue(lua_State* L, const std::string& value) {
+  pushstring(L, value);
+}
+
+inline void pushvalue(lua_State* L, long long value) {
+  lua_pushinteger(L, value);
+}
+
+inline void pushvalue(lua_State* L, double value) {
+  lua_pushnumber(L, value);
+}
+
+inline void pushvalue(lua_State* L, bool value) {
+  lua_pushboolean(L, value);
+}
+
+
+struct RGWTable : EmptyMetaTable {
+
+  static const char* INCREMENT;
+  static const char* DECREMENT;
+
+  static std::string TableName() {return "RGW";}
+  static std::string Name() {return TableName() + "Meta";}
+  
+  static int increment_by(lua_State* L);
+
+  static int IndexClosure(lua_State* L) {
+    const auto map = reinterpret_cast<BackgroundMap*>(lua_touserdata(L, lua_upvalueindex(FIRST_UPVAL)));
+    auto& mtx = *reinterpret_cast<std::mutex*>(lua_touserdata(L, lua_upvalueindex(SECOND_UPVAL)));
+    const char* index = luaL_checkstring(L, 2);
+
+    if (strcasecmp(index, INCREMENT) == 0) {
+      lua_pushlightuserdata(L, map);
+      lua_pushlightuserdata(L, &mtx);
+      lua_pushboolean(L, false /*increment*/);
+      lua_pushcclosure(L, increment_by, THREE_UPVALS);
+      return ONE_RETURNVAL;
+    } 
+    if (strcasecmp(index, DECREMENT) == 0) {
+      lua_pushlightuserdata(L, map);
+      lua_pushlightuserdata(L, &mtx);
+      lua_pushboolean(L, true /*decrement*/);
+      lua_pushcclosure(L, increment_by, THREE_UPVALS);
+      return ONE_RETURNVAL;
+    }
+
+    std::lock_guard l(mtx);
+
+    const auto it = map->find(std::string(index));
+    if (it == map->end()) {
+      lua_pushnil(L);
+    } else {
+      std::visit([L](auto&& value) { pushvalue(L, value); }, it->second);
+    }
+    return ONE_RETURNVAL;
+  }
+
+  static int LenClosure(lua_State* L) {
+    const auto map = reinterpret_cast<BackgroundMap*>(lua_touserdata(L, lua_upvalueindex(FIRST_UPVAL)));
+    auto& mtx = *reinterpret_cast<std::mutex*>(lua_touserdata(L, lua_upvalueindex(SECOND_UPVAL)));
+
+    std::lock_guard l(mtx);
+
+    lua_pushinteger(L, map->size());
+
+    return ONE_RETURNVAL;
+  }
+
+  static int NewIndexClosure(lua_State* L) {
+    const auto map = reinterpret_cast<BackgroundMap*>(lua_touserdata(L, lua_upvalueindex(FIRST_UPVAL)));
+    auto& mtx = *reinterpret_cast<std::mutex*>(lua_touserdata(L, lua_upvalueindex(SECOND_UPVAL)));
+    const auto index = luaL_checkstring(L, 2);
+    
+    if (strcasecmp(index, INCREMENT) == 0 || strcasecmp(index, DECREMENT) == 0) {
+        return luaL_error(L, "increment/decrement are reserved function names for RGW");
+    }
+
+    std::unique_lock l(mtx);
+
+    size_t len;
+    BackgroundMapValue value;
+    const int value_type = lua_type(L, 3);
+
+    switch (value_type) {
+      case LUA_TNIL:
+        map->erase(std::string(index));
+        return NO_RETURNVAL;
+      case LUA_TBOOLEAN:
+        value = static_cast<bool>(lua_toboolean(L, 3));
+        len = sizeof(bool);
+        break;
+      case LUA_TNUMBER:
+         if (lua_isinteger(L, 3)) {
+          value = lua_tointeger(L, 3);
+          len = sizeof(long long int);
+         } else {
+          value = lua_tonumber(L, 3);
+          len = sizeof(double);
+         }
+         break;
+      case LUA_TSTRING:
+      {
+        const auto str = lua_tolstring(L, 3, &len);
+        value = std::string{str, len};
+        break;
+      }
+      default:
+        l.unlock();
+        return luaL_error(L, "unsupported value type for RGW table");
+    }
+
+    if (len + strnlen(index, MAX_LUA_VALUE_SIZE)
+      > MAX_LUA_VALUE_SIZE) {
+      return luaL_error(L, "Lua maximum size of entry limit exceeded");
+    } else if (map->size() > MAX_LUA_KEY_ENTRIES) {
+      l.unlock();
+      return luaL_error(L, "Lua max number of entries limit exceeded");
+    } else {
+      map->insert_or_assign(index, value);
+    }
+
+    return NO_RETURNVAL;
+  }
+
+  static int PairsClosure(lua_State* L) {
+    auto map = reinterpret_cast<BackgroundMap*>(lua_touserdata(L, lua_upvalueindex(FIRST_UPVAL)));
+    ceph_assert(map);
+    lua_pushlightuserdata(L, map);
+    lua_pushcclosure(L, stateless_iter, ONE_UPVAL); // push the stateless iterator function
+    lua_pushnil(L);                                 // indicate this is the first call
+    // return stateless_iter, nil
+
+    return TWO_RETURNVALS;
+  }
+  
+  static int stateless_iter(lua_State* L) {
+    // based on: http://lua-users.org/wiki/GeneralizedPairsAndIpairs
+    auto map = reinterpret_cast<BackgroundMap*>(lua_touserdata(L, lua_upvalueindex(FIRST_UPVAL)));
+    typename BackgroundMap::const_iterator next_it;
+    if (lua_isnil(L, -1)) {
+      next_it = map->begin();
+    } else {
+      const char* index = luaL_checkstring(L, 2);
+      const auto it = map->find(std::string(index));
+      ceph_assert(it != map->end());
+      next_it = std::next(it);
+    }
+
+    if (next_it == map->end()) {
+      // index of the last element was provided
+      lua_pushnil(L);
+      lua_pushnil(L);
+      // return nil, nil
+    } else {
+      pushstring(L, next_it->first);
+      std::visit([L](auto&& value) { pushvalue(L, value); }, next_it->second);
+      // return key, value
+    }
+
+    return TWO_RETURNVALS;
+  }
+};
+
+class Background : public RGWRealmReloader::Pauser {
+
+private:
+  BackgroundMap rgw_map;
+  bool stopped = false;
+  bool started = false;
+  bool paused = false;
+  int execute_interval;
+  const DoutPrefix dp;
+  std::unique_ptr<rgw::sal::LuaManager> lua_manager; 
+  CephContext* const cct;
+  const std::string luarocks_path;
+  std::thread runner;
+  mutable std::mutex table_mutex;
+  std::mutex cond_mutex;
+  std::mutex pause_mutex;
+  std::condition_variable cond;
+  static const BackgroundMapValue empty_table_value;
+
+  void run();
+
+protected:
+  std::string rgw_script;
+  virtual int read_script();
+
+public:
+  Background(rgw::sal::Driver* driver,
+      CephContext* cct,
+      const std::string& luarocks_path,
+      int execute_interval = INIT_EXECUTE_INTERVAL);
+
+    virtual ~Background() = default;
+    void start();
+    void shutdown();
+    void create_background_metatable(lua_State* L);
+    const BackgroundMapValue& get_table_value(const std::string& key) const;
+    template<typename T>
+    void put_table_value(const std::string& key, T value) {
+      std::unique_lock cond_lock(table_mutex);
+      rgw_map[key] = value;
+    }
+    
+    void pause() override;
+    void resume(rgw::sal::Driver* _driver) override;
+};
+
+} //namepsace rgw::lua
+