chore: potential optimisations

Author: niranjannitesh

cpp/msgpack.hpp

@@ -5,8 +5,6 @@
 #include <vector>
 #include <jsi/jsi.h>
 #include "cmp.h"
-#include <iostream>
-#include <sstream>
 
 using namespace facebook;
 
@@ -99,11 +97,18 @@ static bool mp_reader(cmp_ctx_t *ctx, void *data, size_t limit)
 
 struct MessagePackWriter
 {
-  std::stringstream stream;
+  std::vector<uint8_t> data;
+
+  MessagePackWriter()
+  {
+    data.reserve(1024);
+  }
 
   size_t write(void *data, size_t count)
   {
-    stream.write(static_cast<const char *>(data), count);
+    size_t prev_size = this->data.size();
+    this->data.resize(prev_size + count);
+    std::move(static_cast<const uint8_t *>(data), static_cast<const uint8_t *>(data) + count, this->data.data() + prev_size);
     return count;
   }
 };
@@ -114,14 +119,14 @@ static size_t mp_writer(cmp_ctx_t *ctx, const void *data, size_t count)
   return mp->write(const_cast<void *>(data), count);
 }
 
-std::vector<uint8_t> write(jsi::Runtime &rt, const jsi::Value &value)
+void write(jsi::Runtime &rt, const jsi::Value &value, std::vector<uint8_t> &data)
 {
   MessagePackWriter writer;
   std::unique_ptr<cmp_ctx_s> ctx(new cmp_ctx_s);
   cmp_init(ctx.get(), &writer, mp_reader, NULL, mp_writer);
   writeValue(ctx.get(), rt, value);
-  const std::string &data = writer.stream.str();
-  return std::vector<uint8_t>(data.begin(), data.end());
+  writer.data.shrink_to_fit();
+  data.swap(writer.data);
 }
 
 jsi::Value readValue(cmp_ctx_t *ctx, jsi::Runtime &rt)

cpp/react-native-msgpack.hpp

@@ -12,15 +12,16 @@ void install(jsi::Runtime &rt)
                         const jsi::Value *args,
                         size_t count) -> jsi::Value
   {
-    auto data = write(rt, std::move(args[0]));
+    std::vector<uint8_t> data;
+    write(rt, args[0], data);
     auto size = data.size();
     jsi::ArrayBuffer arrayBuffer =
         rt.global()
             .getPropertyAsFunction(rt, "ArrayBuffer")
             .callAsConstructor(rt, static_cast<int>(size))
             .asObject(rt)
             .getArrayBuffer(rt);
-    std::memcpy(arrayBuffer.data(rt), data.data(), size);
+    std::memcpy(arrayBuffer.data(rt), std::move(data).data(), size);
     auto typedArray = rt.global()
                           .getPropertyAsFunction(rt, "Uint8Array")
                           .callAsConstructor(rt, std::move(arrayBuffer))