http: create header field names as internalized strings

src/node_http_common.h

@@ -16,6 +16,8 @@ class Environment;
 #define DEFAULT_MAX_HEADER_LIST_PAIRS 128u
 #define DEFAULT_MAX_HEADER_LENGTH 8192
 
+constexpr size_t kMaxInternalizedHeaderNameLength = 64;
+
 #define HTTP_SPECIAL_HEADERS(V)                                               \
   V(STATUS, ":status")                                                        \
   V(METHOD, ":method")                                                        \
@@ -432,7 +434,7 @@ class NgRcBufPointer : public MemoryRetainer {
         return v8::String::Empty(env->isolate());
       }
 
-      if (ptr.IsInternalizable() && len < 64) {
+      if (ptr.IsInternalizable() && len < kMaxInternalizedHeaderNameLength) {
         v8::MaybeLocal<v8::String> ret = GetInternalizedString(env, ptr);
         ptr.reset();
         return ret;

src/node_http_parser.cc

@@ -28,6 +28,7 @@
 #include "llhttp.h"
 #include "memory_tracker-inl.h"
 #include "node_external_reference.h"
+#include "node_http_common.h"
 #include "stream_base-inl.h"
 #include "v8.h"
 
@@ -65,6 +66,7 @@ using v8::Isolate;
 using v8::Local;
 using v8::LocalVector;
 using v8::MaybeLocal;
+using v8::NewStringType;
 using v8::Number;
 using v8::Object;
 using v8::ObjectTemplate;
@@ -233,6 +235,18 @@ struct StringPtr {
       return String::Empty(env->isolate());
   }
 
+  Local<String> ToInternalizedString(Environment* env) const {
+    // Only internalize short names to avoid pressuring the string table.
+    if (size_ != 0 && size_ < kMaxInternalizedHeaderNameLength) {
+      return String::NewFromOneByte(env->isolate(),
+                                    reinterpret_cast<const uint8_t*>(str_),
+                                    NewStringType::kInternalized,
+                                    size_)
+          .ToLocalChecked();
+    }
+    return ToString(env);
+  }
+
   // Strip trailing OWS (SPC or HTAB) from string.
   Local<String> ToTrimmedString(Environment* env) {
     while (size_ > 0 && IsOWS(str_[size_ - 1])) {
@@ -940,7 +954,8 @@ class Parser : public AsyncWrap, public StreamListener {
     Local<Value> headers_v[kMaxHeaderFieldsCount * 2];
 
     for (size_t i = 0; i < num_values_; ++i) {
-      headers_v[i * 2] = fields_[i].ToString(env());
+      // Field names repeat across requests, so internalize them.
+      headers_v[i * 2] = fields_[i].ToInternalizedString(env());
       headers_v[i * 2 + 1] = values_[i].ToTrimmedString(env());
     }