Lua - use native tables to improve code compatibility (#672)

* Make keys and argv as native lua tables

* clean up logic

* fix test

* make tables readonly

* format

* improve test

* significantly improve coverage

* fix dispose logic

* correctly wire in number return values from lua to garnet calls

* Fix fast-path where set arguments were ignored.

Author: badrishc

benchmark/BDN.benchmark/Resp/RespLuaRunnerStress.cs

@@ -10,7 +10,7 @@ namespace BDN.benchmark.Resp
     public unsafe class RespLuaRunnerStress
     {
         LuaRunner r1, r2, r3, r4;
-        readonly string[] keys = ["key1", "key2"];
+        readonly string[] keys = ["key1"];
 
         [GlobalSetup]
         public void GlobalSetup()
@@ -36,7 +36,7 @@ public void GlobalCleanup()
 
         [Benchmark]
         public void BasicLua1()
-            => r1.RunVoid();
+            => r1.Run();
 
         [Benchmark]
         public void BasicLua2()

libs/common/RespReadUtils.cs

@@ -856,7 +856,7 @@ public static bool ReadStringArrayResponseWithLengthHeader(out string[] result,
             {
                 if (*ptr == '$')
                 {
-                    if (!ReadStringWithLengthHeader(out result[i], ref ptr, end))
+                    if (!ReadStringResponseWithLengthHeader(out result[i], ref ptr, end))
                         return false;
                 }
                 else if (*ptr == '+')

libs/server/ArgSlice/ScratchBufferManager.cs

@@ -253,6 +253,7 @@ public ArgSlice FormatCommandAsResp(string cmd, object[] args, Lua state)
                         }
                         scratchBufferOffset = (int)(ptr - scratchBufferHead);
                     }
+                    t.Dispose();
                 }
                 else if (item is long i)
                 {

libs/server/Lua/LuaCommands.cs

@@ -194,36 +194,72 @@ private unsafe bool ExecuteScript(int count, LuaRunner scriptRunner)
         {
             try
             {
-                object scriptResult = scriptRunner.Run(count, parseState);
-                if (scriptResult != null)
+                var scriptResult = scriptRunner.Run(count, parseState);
+                WriteObject(scriptResult);
+            }
+            catch (LuaScriptException ex)
+            {
+                logger?.LogError(ex.InnerException ?? ex, "Error executing Lua script callback");
+                while (!RespWriteUtils.WriteError("ERR " + (ex.InnerException ?? ex).Message, ref dcurr, dend))
+                    SendAndReset();
+                return true;
+            }
+            catch (Exception ex)
+            {
+                logger?.LogError(ex, "Error executing Lua script");
+                while (!RespWriteUtils.WriteError("ERR " + ex.Message, ref dcurr, dend))
+                    SendAndReset();
+                return true;
+            }
+            return true;
+        }
+
+        void WriteObject(object scriptResult)
+        {
+            if (scriptResult != null)
+            {
+                if (scriptResult is string s)
                 {
-                    if (scriptResult is string s)
-                    {
-                        while (!RespWriteUtils.WriteAsciiBulkString(s, ref dcurr, dend))
-                            SendAndReset();
-                    }
-                    else if ((scriptResult as byte?) != null && (byte)scriptResult == 36) //equals to $
-                    {
-                        while (!RespWriteUtils.WriteDirect((byte[])scriptResult, ref dcurr, dend))
-                            SendAndReset();
-                    }
-                    else if (scriptResult as Int64? != null)
-                    {
-                        while (!RespWriteUtils.WriteInteger((Int64)scriptResult, ref dcurr, dend))
-                            SendAndReset();
-                    }
-                    else if (scriptResult as ArgSlice? != null)
+                    while (!RespWriteUtils.WriteAsciiBulkString(s, ref dcurr, dend))
+                        SendAndReset();
+                }
+                else if ((scriptResult as byte?) != null && (byte)scriptResult == 36) //equals to $
+                {
+                    while (!RespWriteUtils.WriteDirect((byte[])scriptResult, ref dcurr, dend))
+                        SendAndReset();
+                }
+                else if (scriptResult is bool b)
+                {
+                    if (b)
                     {
-                        while (!RespWriteUtils.WriteBulkString(((ArgSlice)scriptResult).ToArray(), ref dcurr, dend))
+                        while (!RespWriteUtils.WriteInteger(1, ref dcurr, dend))
                             SendAndReset();
                     }
-                    else if (scriptResult as Object[] != null)
+                    else
                     {
-                        // Two objects one boolean value and the result from the Lua Call
-                        while (!RespWriteUtils.WriteAsciiBulkString((scriptResult as Object[])[1].ToString().AsSpan(), ref dcurr, dend))
+                        while (!RespWriteUtils.WriteDirect(CmdStrings.RESP_ERRNOTFOUND, ref dcurr, dend))
                             SendAndReset();
                     }
-                    else if (scriptResult is LuaTable luaTable)
+                }
+                else if (scriptResult is long l)
+                {
+                    while (!RespWriteUtils.WriteInteger(l, ref dcurr, dend))
+                        SendAndReset();
+                }
+                else if (scriptResult is ArgSlice a)
+                {
+                    while (!RespWriteUtils.WriteBulkString(a.ReadOnlySpan, ref dcurr, dend))
+                        SendAndReset();
+                }
+                else if (scriptResult is object[] o)
+                {
+                    // Two objects one boolean value and the result from the Lua Call
+                    while (!RespWriteUtils.WriteAsciiBulkString(o[1].ToString().AsSpan(), ref dcurr, dend))
+                        SendAndReset();
+                }
+                else if (scriptResult is LuaTable luaTable)
+                {
+                    try
                     {
                         var retVal = luaTable["err"];
                         if (retVal != null)
@@ -241,36 +277,31 @@ private unsafe bool ExecuteScript(int count, LuaRunner scriptRunner)
                             }
                             else
                             {
-                                throw new LuaScriptException("Unknown LuaTable return type", "");
+                                int count = luaTable.Values.Count;
+                                while (!RespWriteUtils.WriteArrayLength(count, ref dcurr, dend))
+                                    SendAndReset();
+                                foreach (var value in luaTable.Values)
+                                {
+                                    WriteObject(value);
+                                }
                             }
                         }
                     }
-                    else
+                    finally
                     {
-                        throw new LuaScriptException("Unknown return type", "");
+                        luaTable.Dispose();
                     }
                 }
                 else
                 {
-                    while (!RespWriteUtils.WriteDirect(CmdStrings.RESP_ERRNOTFOUND, ref dcurr, dend))
-                        SendAndReset();
+                    throw new LuaScriptException("Unknown return type", "");
                 }
             }
-            catch (LuaScriptException ex)
-            {
-                logger?.LogError(ex.InnerException ?? ex, "Error executing Lua script callback");
-                while (!RespWriteUtils.WriteError("ERR " + (ex.InnerException ?? ex).Message, ref dcurr, dend))
-                    SendAndReset();
-                return true;
-            }
-            catch (Exception ex)
+            else
             {
-                logger?.LogError(ex, "Error executing Lua script");
-                while (!RespWriteUtils.WriteError("ERR " + ex.Message, ref dcurr, dend))
+                while (!RespWriteUtils.WriteDirect(CmdStrings.RESP_ERRNOTFOUND, ref dcurr, dend))
                     SendAndReset();
-                return true;
             }
-            return true;
         }
     }
 }