Avoid string construction overhead for lookup-only HpackEntry objects.

net/spdy/hpack/hpack_entry.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/spdy/hpack/hpack_entry.h"
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 
 namespace net {
 
 using base::StringPiece;
 
 const size_t HpackEntry::kSizeOverhead = 32;
 
 HpackEntry::HpackEntry(StringPiece name,
                        StringPiece value,
                        bool is_static,
                        size_t insertion_index)
     : name_(name.data(), name.size()),
       value_(value.data(), value.size()),
+      name_ref_(name_),
+      value_ref_(value_),
       insertion_index_(insertion_index),
       type_(is_static ? STATIC : DYNAMIC) {}
 
 HpackEntry::HpackEntry(StringPiece name, StringPiece value)
-    : name_(name.data(), name.size()),
-      value_(value.data(), value.size()),
-      insertion_index_(0),
-      type_(LOOKUP) {}
+    : name_ref_(name), value_ref_(value), insertion_index_(0), type_(LOOKUP) {}
 
 HpackEntry::HpackEntry() : insertion_index_(0), type_(LOOKUP) {}
 
+HpackEntry::HpackEntry(const HpackEntry& other)
+    : insertion_index_(other.insertion_index_), type_(other.type_) {
+  if (type_ == LOOKUP) {
+    name_ref_ = other.name_ref_;
+    value_ref_ = other.value_ref_;
+  } else {
+    name_ = other.name_;
+    value_ = other.value_;
+    name_ref_.set(name_.data(), name_.size());
+    value_ref_.set(value_.data(), value_.size());
+  }
+}
+
+HpackEntry& HpackEntry::operator=(const HpackEntry& other) {
+  insertion_index_ = other.insertion_index_;
+  type_ = other.type_;
+  if (type_ == LOOKUP) {
+    name_ref_ = other.name_ref_;
+    value_ref_ = other.value_ref_;
+    return *this;
+  }
+  name_ = other.name_;
+  value_ = other.value_;
+  name_ref_.set(name_.data(), name_.size());
+  value_ref_.set(value_.data(), value_.size());
+  return *this;
+}
+
 HpackEntry::~HpackEntry() {}
 
 // static
 size_t HpackEntry::Size(StringPiece name, StringPiece value) {
   return name.size() + value.size() + kSizeOverhead;
 }
+
 size_t HpackEntry::Size() const {
   return Size(name(), value());
 }
 
 std::string HpackEntry::GetDebugString() const {
-  return "{ name: \"" + name_ + "\", value: \"" + value_ + "\", " +
-         (IsStatic() ? "static" : "dynamic") + " }";
+  return "{ name: \"" + name_ref_.as_string() + "\", value: \"" +
+         value_ref_.as_string() + "\", index: " +
+         base::SizeTToString(insertion_index_) +
+         (IsStatic() ? " static" : (IsLookup() ? " lookup" : " dynamic")) +
+         " }";
 }
 
 }  // namespace net