Disk Cache: Run another experiment: Increase the number

of deleted entries that we keep around.

I'm doubling the number of deleted entries for about
13% of the dev channed.

I'm also adding a few extra histograms.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/3343010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@59243 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 10 insertions, 2 deletions

diff --git a/net/disk_cache/eviction.cc b/net/disk_cache/eviction.cc
index da7577c..0173c16 100644
--- a/net/disk_cache/eviction.cc
+++ b/net/disk_cache/eviction.cc
@@ -7,7 +7,7 @@
 // only one list in use (Rankings::NO_USE), and elements are sent to the front
 // of the list whenever they are accessed.
 
-// The new (in-development) eviction policy ads re-use as a factor to evict
+// The new (in-development) eviction policy adds re-use as a factor to evict
 // an entry. The story so far:
 
 // Entries are linked on separate lists depending on how often they are used.
@@ -35,6 +35,7 @@
 #include "base/time.h"
 #include "net/disk_cache/backend_impl.h"
 #include "net/disk_cache/entry_impl.h"
+#include "net/disk_cache/experiments.h"
 #include "net/disk_cache/histogram_macros.h"
 #include "net/disk_cache/trace.h"
 
@@ -81,6 +82,7 @@ void Eviction::Init(BackendImpl* backend) {
   delay_trim_ = false;
   trim_delays_ = 0;
   init_ = true;
+  in_experiment_ = (header_->experiment == EXPERIMENT_DELETED_LIST_IN);
 }
 
 void Eviction::Stop() {
@@ -451,8 +453,14 @@ void Eviction::TrimDeleted(bool empty) {
     deleted |= RemoveDeletedNode(node.get());
   }
 
+  // Normally we use 25% for each list. The experiment doubles the number of
+  // deleted entries, so the total number of entries increases by 25%. Using
+  // 40% of that value for deleted entries leaves the size of the other three
+  // lists intact.
+  int max_length = in_experiment_ ? header_->num_entries * 2 / 5 :
+                                    header_->num_entries / 4;
   if (deleted && !empty &&
-      header_->lru.sizes[Rankings::DELETED] > header_->num_entries / 4)
+      header_->lru.sizes[Rankings::DELETED] > max_length)
     MessageLoop::current()->PostTask(FROM_HERE,
         factory_.NewRunnableMethod(&Eviction::TrimDeleted, false));