global.set has been implemented, but not diff xmit for globals

luprex/cpp/core/world-accessor.cpp

@@ -1,6 +1,7 @@
 
 #include "world.hpp"
 #include "pprint.hpp"
+#include "serializelua.hpp"
 #include <cmath>
 #include <iostream>
 
@@ -854,3 +855,171 @@ LuaDefine(http_post, "request",
     "|See doc(http.clientrequest) and doc(http.clientresponse).") {
     return lfn_http_request(L, "POST");
 }
+
+void global_set(LuaStack &LS0, const eng::string &gvar, LuaSlot value) {
+    lua_State *L = LS0.state();
+    World *w = World::fetch_global_pointer(L);
+    LuaVar globaldb, copy;
+    LuaStack LS(L, globaldb, copy);
+
+    // Serialize then deserialize the data, to produce a copy.
+    StreamBuffer sb;
+    eng::string error = serialize_lua(LS, value, &sb);
+    if (!error.empty()) {
+        luaL_error(L, "%s", error.c_str());
+        return;
+    }
+    eng::string serialized(sb.view());
+    error = deserialize_lua(LS, copy, &sb);
+    if (!error.empty()) {
+        luaL_error(L, "%s", error.c_str());
+        return;
+    }
+
+    // Store the copy in the globalDB.
+    LS.rawget(globaldb, LuaRegistry, "globaldb");
+    LS.rawset(globaldb, gvar, copy);
+
+    // Store the serialized blob in the master model.
+    w->gvar_to_serial_.emplace(gvar, serialized);
+
+    // In an authoritative model only, update the assignment counters.
+    if (w->is_authoritative()) {
+        int64_t newassign = w->next_gvar_assign_++;
+        auto oldassigniter = w->gvar_to_assign_.find(gvar);
+        if (oldassigniter != w->gvar_to_assign_.end()) {
+            int64_t oldassign = oldassigniter->second;
+            w->assign_to_gvar_.erase(oldassign);
+        }
+        w->assign_to_gvar_.emplace(newassign, gvar);
+        w->gvar_to_assign_[gvar] = newassign;
+    }
+    LS.result();
+}
+
+LuaDefine(global_set, "varname, value",
+    "|Store data in the global data table."
+    "|"
+    "|The variable name must be a string which is a valid"
+    "|lua identifier."
+    "|"
+    "|You can store global data using global.set, then you can"
+    "|retrieve it using global.get.  You can also retrieve data using"
+    "|gv.varname, which is just shorthand for global.get.  You may not"
+    "|store data using gv.varname=value, this yields the error 'Use "
+    "|global.set to store data in the global data table.'"
+    "|"
+    "|Values stored using global.set are transmitted to all"
+    "|connected clients immediately.  When a new client connects,"
+    "|he will receive all the global data."
+    "|"
+    "|The global data table is not the same thing as the lua "
+    "|environment table.  Trying to store data in the lua environment"
+    "|table will seem to work, at first, but the data will not get"
+    "|difference transmitted, and will eventually be cleared and lost."
+    "|Therefore, it is essential that global data be stored in the"
+    "|global data table (using global.set) instead of in the lua"
+    "|environment table."
+    "|"
+    "|There are certain restrictions on the values that you store."
+    "|Only data that can be serialized according to doc(table.serialize)"
+    "|can be stored."
+    "|"
+    "|When you store the value, it is immediately serialized and then"
+    "|deserialized again, and the deserialized copy is stored in the"
+    "|variable."
+    "|"
+//    "|When you call global.get, you obtain the copy.  Any attempt to"
+//    "|mutate the copy will fail with this lua error message: 'Tables"
+//    "|returned by global.get are immutable.'  This rule prevents'"
+//    "|aliasing between global data and other data structures."
+    "|") {
+    LuaArg varname;
+    LuaArg value;
+    LuaStack LS(L, varname, value);
+
+    // Check the varname argument.
+    eng::string gvar = LS.ckstring(varname);
+    if (!sv::is_lua_id(gvar)) {
+        luaL_error(L, "variable name must be a valid lua identifier: %s", gvar.c_str());
+        return LS.result();
+    }
+
+    global_set(LS, gvar, value);
+    return LS.result();
+}
+
+LuaDefine(global_get, "varname", 
+    "|Get data stored using global.set"
+    "|"
+    "|See doc(global.set) for information on how to store global data."
+    "|"
+    "|Do not mutate data returned by global.get: doing so will produce"
+    "|unpredictable results.  Instead, using global.set to mutate global"
+    "|variables."
+    "|") {
+    LuaArg varname;
+    LuaRet value;
+    LuaVar globaldb;
+    LuaStack LS(L, varname, value, globaldb);
+    LS.rawget(globaldb, LuaRegistry, "globaldb");
+    LS.rawget(value, globaldb, varname);
+    return LS.result();
+}
+
+LuaDefine(global_once, "varname",
+    "|For a given string, returns true exactly once"
+    "|"
+    "|The semantics and difference transmission behavior of global.once"
+    "|are identical to the semantics of global.set, since global.once"
+    "|uses global.set under the covers."
+    "|") {
+    LuaArg varname;
+    LuaRet result;
+    LuaVar globaldb, flag;
+    LuaStack LS(L, varname, flag, result, globaldb);
+
+    // Check the varname argument.
+    eng::string gvar = LS.ckstring(varname);
+    if (!sv::is_lua_id(gvar)) {
+        luaL_error(L, "variable name must be a valid lua identifier: %s", gvar.c_str());
+        return LS.result();
+    }
+    gvar += ":once";
+
+    LS.rawget(globaldb, LuaRegistry, "globaldb");
+    LS.rawget(flag, globaldb, gvar);
+
+    if (!LS.isnil(flag)) {
+        LS.set(result, false);
+        return LS.result();
+    }
+
+    LS.set(result, true);
+    global_set(LS, gvar, result);
+    return LS.result();
+}
+
+LuaDefine(global_clearonce, "varname",
+    "|Reset the specified once-flag"
+    "|"
+    "|The semantics and difference transmission behavior of global.clearonce"
+    "|are identical to the semantics of global.set, since global.once"
+    "|uses global.set under the covers."
+    "|") {
+    LuaArg varname;
+    LuaVar null;
+    LuaStack LS(L, varname, null);
+
+    // Check the varname argument.
+    eng::string gvar = LS.ckstring(varname);
+    if (!sv::is_lua_id(gvar)) {
+        luaL_error(L, "variable name must be a valid lua identifier: %s", gvar.c_str());
+        return LS.result();
+    }
+    gvar += ":once";
+
+    LS.set(null, LuaNil);
+    global_set(LS, gvar, null);
+    return LS.result();
+}