fs: cache context lookup in vectored io loops

Author: mertcanaltin

src/node_file.cc

@@ -2391,9 +2391,10 @@ static void WriteBuffers(const FunctionCallbackInfo<Value>& args) {
 
   MaybeStackBuffer<uv_buf_t> iovs(chunks->Length());
 
+  Local<Context> context = env->context();
   for (uint32_t i = 0; i < iovs.length(); i++) {
     Local<Value> chunk;
-    if (!chunks->Get(env->context(), i).ToLocal(&chunk)) return;
+    if (!chunks->Get(context, i).ToLocal(&chunk)) return;
     CHECK(Buffer::HasInstance(chunk));
     iovs[i] = uv_buf_init(Buffer::Data(chunk), Buffer::Length(chunk));
   }
@@ -2776,9 +2777,10 @@ static void ReadBuffers(const FunctionCallbackInfo<Value>& args) {
   MaybeStackBuffer<uv_buf_t> iovs(buffers->Length());
 
   // Init uv buffers from ArrayBufferViews
+  Local<Context> context = env->context();
   for (uint32_t i = 0; i < iovs.length(); i++) {
     Local<Value> buffer;
-    if (!buffers->Get(env->context(), i).ToLocal(&buffer)) return;
+    if (!buffers->Get(context, i).ToLocal(&buffer)) return;
     CHECK(Buffer::HasInstance(buffer));
     iovs[i] = uv_buf_init(Buffer::Data(buffer), Buffer::Length(buffer));
   }