Avoid learning about subresources of old navigations

Track all navigatinos, and keep a list of 
navigatinos in the last 10 seconds.  If it was
older than 10 seconds, any preconnection based
on that navigation would be reset for lack
of use.


r=willchan
bug=83094
Review URL: http://codereview.chromium.org/6960001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@87640 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 38 insertions, 1 deletions

diff --git a/chrome/browser/net/connect_interceptor.h b/chrome/browser/net/connect_interceptor.h
index b0b15f1..c1f6177 100644
--- a/chrome/browser/net/connect_interceptor.h
+++ b/chrome/browser/net/connect_interceptor.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -8,6 +8,9 @@
 
 #include "net/url_request/url_request.h"
 
+#include "base/gtest_prod_util.h"
+#include "base/memory/mru_cache.h"
+
 namespace chrome_browser_net {
 
 //------------------------------------------------------------------------------
@@ -29,6 +32,40 @@ class ConnectInterceptor : public net::URLRequest::Interceptor {
                                                      const GURL& location);
 
  private:
+  // Provide access to local class TimedCache for testing.
+  FRIEND_TEST(ConnectInterceptorTest, TimedCacheRecall);
+  FRIEND_TEST(ConnectInterceptorTest, TimedCacheEviction);
+
+  // Define a LRU cache that recalls all navigations within the last N seconds.
+  // When we learn about subresources to possibly preconnect to, it would be a
+  // waste to preconnect when the original navigation was too long ago.  Any
+  // connected, but unused TCP/IP connection, will generally be reset by the
+  // server if it is not used quickly (i.e., GET or POST is sent).
+  class TimedCache {
+   public:
+    explicit TimedCache(const base::TimeDelta& max_duration);
+
+    // Evicts any entries that have been in the FIFO "too long," and then checks
+    // to see if the given url is (still) in the FIFO cache.
+    bool WasRecentlySeen(const GURL& url);
+
+    // Adds the given url to the cache, where it will remain for max_duration_.
+    void SetRecentlySeen(const GURL& url);
+
+   private:
+    // Our cache will be keyed on a URL (actually, just a scheme/host/port).
+    // We will always track the time it was last added to the FIFO cache by
+    // remembering a TimeTicks value.
+    typedef base::MRUCache<GURL, base::TimeTicks> UrlMruTimedCache;
+    UrlMruTimedCache mru_cache_;
+
+    // The longest time an entry can persist in the cache, and still be found.
+    const base::TimeDelta max_duration_;
+
+    DISALLOW_COPY_AND_ASSIGN(TimedCache);
+  };
+  TimedCache timed_cache_;
+
   DISALLOW_COPY_AND_ASSIGN(ConnectInterceptor);
 };