Store in memory cookies in a hash set instead of a list.

chrome/browser/browsing_data/canonical_cookie_hash.h

+// 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.
+
+// Provides utility structures for inserting a CanonicalCookie into a hash set.
+// Two cookies are considered equal if their names, domains, and paths are
+// equivalent.
+
+#ifndef CHROME_BROWSER_BROWSING_DATA_CANONICAL_COOKIE_HASH_H_
+#define CHROME_BROWSER_BROWSING_DATA_CANONICAL_COOKIE_HASH_H_
+
+#if defined(COMPILER_MSVC)
+#include <functional>
+#endif  // COMPILER_MSVC
+
+#include "base/containers/hash_tables.h"
+#include "net/cookies/canonical_cookie.h"
+
+namespace canonical_cookie {
+
+// Returns a fast hash of a cookie, based on its name, domain, and path.
+size_t FastHash(const net::CanonicalCookie& cookie);
+
+#if defined(COMPILER_MSVC)
+struct CanonicalCookieTraits {
+  static const size_t bucket_size = 4;
+
+  // Returns a hash of |cookie|.
+  size_t operator()(const net::CanonicalCookie& cookie) const {
+    return FastHash(cookie);
+  }
+
+  // The 'less' operator on cookies. We need to create a total ordering. We
+  // order lexigraphically, first by name, then path, then domain. Name is most
+  // likely to be distinct, so it is compared first, and domain is least likely
+  // to be distinct, so it is compared last.
+  bool operator()(const net::CanonicalCookie& cookie1,
+                  const net::CanonicalCookie& cookie2) const {
+    std::less<std::string> less_than;
+    if (less_than(cookie1.Name(), cookie2.Name()))
+      return true;
+    if (less_than(cookie2.Name(), cookie1.Name()))
+      return false;
+    if (less_than(cookie1.Path(), cookie2.Path()))
+      return true;
+    if (less_than(cookie2.Path(), cookie1.Path()))
+      return false;
+    if (less_than(cookie1.Domain(), cookie2.Domain()))
+      return true;
+    if (less_than(cookie2.Domain(), cookie1.Domain()))
+      return false;
+
+    // The cookies are equivalent.
+    return false;
+  }
+};
+
+typedef base::hash_set<net::CanonicalCookie, CanonicalCookieTraits>
+    CookieHashSet;
+
+#else  // COMPILER_MSVC
+
+struct CanonicalCookieHasher {
+  std::size_t operator()(const net::CanonicalCookie& cookie) const {
+    return FastHash(cookie);
+  }
+};
+
+struct CanonicalCookieComparer {
+  bool operator()(const net::CanonicalCookie& cookie1,
+                  const net::CanonicalCookie& cookie2) const {
+    return cookie1.Name() == cookie2.Name() &&
+           cookie1.Domain() == cookie2.Domain() &&
+           cookie1.Path() == cookie2.Path();
+  }
+};
+
+typedef base::hash_set<net::CanonicalCookie,
+                       CanonicalCookieHasher,
+                       CanonicalCookieComparer> CookieHashSet;
+
+#endif  // COMPILER_MSVC
+
+};  // namespace canonical_cookie
+
+#endif  // CHROME_BROWSER_BROWSING_DATA_CANONICAL_COOKIE_HASH_H_