New disk cache eviction algorithm.

net/disk_cache/rankings.cc

Index: net/disk_cache/rankings.cc
===================================================================
--- net/disk_cache/rankings.cc	(revision 11078)
+++ net/disk_cache/rankings.cc	(working copy)
@@ -174,14 +174,14 @@
 
 namespace disk_cache {
 
-bool Rankings::Init(BackendImpl* backend) {
+bool Rankings::Init(BackendImpl* backend, bool count_lists) {
   DCHECK(!init_);
   if (init_)
     return false;
 
   backend_ = backend;
-
   control_data_ = backend_->GetLruData();
+  count_lists_ = count_lists;
 
   ReadHeads();
   ReadTails();
@@ -281,6 +281,7 @@
 
   // The last thing to do is move our head to point to a node already stored.
   WriteHead(list);
+  IncrementCounter(list);
   GenerateCrash(ON_INSERT_4);
 }
 
@@ -377,6 +378,7 @@
   prev.Store();
   GenerateCrash(ON_REMOVE_8);
   node->Store();
+  DecrementCounter(list);
   UpdateIterators(&next);
   UpdateIterators(&prev);
 }
@@ -747,4 +749,22 @@
   }
 }
 
+void Rankings::IncrementCounter(List list) {
+  if (!count_lists_)
+    return;
+
+  DCHECK(control_data_->sizes[list] < kint32max);
+  if (control_data_->sizes[list] < kint32max)
+    control_data_->sizes[list]++;
+}
+
+void Rankings::DecrementCounter(List list) {
+  if (!count_lists_)
+    return;
+
+  DCHECK(control_data_->sizes[list] > 0);
+  if (control_data_->sizes[list] > 0)
+    control_data_->sizes[list]--;
+}
+
 }  // namespace disk_cache