Disk cache: Report more info from the current experiment.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/119218

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17772 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 43 insertions, 19 deletions

diff --git a/net/disk_cache/backend_impl.cc b/net/disk_cache/backend_impl.cc
index f22f741..63db6b1 100644
--- a/net/disk_cache/backend_impl.cc
+++ b/net/disk_cache/backend_impl.cc
@@ -136,20 +136,19 @@ bool DelayedCacheCleanup(const std::wstring& full_path) {
   return true;
 }
 
-// Sets |stored_value| for the current experiment. Returns false if the files
+// Sets |current_group| for the current experiment. Returns false if the files
 // should be discarded.
-bool InitExperiment(int* stored_value) {
-  if (*stored_value <= 2) {
+bool InitExperiment(int* current_group) {
+  if (*current_group <= 2) {
     // Not taking part of this experiment.
-    *stored_value = 5;
-    return true;
-  }
-
-  if (*stored_value < 5) {
+    *current_group = 5;
+  } else if (*current_group < 5) {
     // Discard current cache for groups 3 and 4.
     return false;
   }
 
+  UMA_HISTOGRAM_CACHE_ERROR("DiskCache.Experiment", *current_group);
+
   // Current experiment already set.
   return true;
 }
@@ -231,6 +230,7 @@ bool BackendImpl::Init() {
 
 #ifdef USE_NEW_EVICTION
   new_eviction_ = true;
+  user_flags_ |= kNewEviction;
 #endif
 
   bool create_files = false;
@@ -566,6 +566,7 @@ bool BackendImpl::SetMaxSize(int max_bytes) {
   if (!max_bytes)
     return true;
 
+  user_flags_ |= kMaxSize;
   max_size_ = max_bytes;
   return true;
 }
@@ -788,10 +789,6 @@ void BackendImpl::CriticalError(int error) {
   LogStats();
   ReportError(error);
 
-  // Reset the mask_ if it was not given by the user.
-  if (static_cast<int>(mask_) == data_->header.table_len - 1)
-    mask_ = 0;
-
   // Setting the index table length to an invalid value will force re-creation
   // of the cache files.
   data_->header.table_len = 1;
@@ -843,14 +840,17 @@ void BackendImpl::DecrementIoCount() {
 }
 
 void BackendImpl::SetUnitTestMode() {
+  user_flags_ |= kUnitTestMode;
   unit_test_ = true;
 }
 
 void BackendImpl::SetUpgradeMode() {
+  user_flags_ |= kUpgradeMode;
   read_only_ = true;
 }
 
 void BackendImpl::SetNewEviction() {
+  user_flags_ |= kNewEviction;
   new_eviction_ = true;
 }
 
@@ -988,9 +988,12 @@ void BackendImpl::RestartCache() {
 
 void BackendImpl::PrepareForRestart() {
   // Reset the mask_ if it was not given by the user.
-  if (static_cast<int>(mask_) == data_->header.table_len - 1)
+  if (!(user_flags_ & kMask))
     mask_ = 0;
 
+  if (!(user_flags_ & kNewEviction))
+    new_eviction_ = false;
+
   data_->header.crash = 0;
   index_ = NULL;
   data_ = NULL;
diff --git a/net/disk_cache/backend_impl.h b/net/disk_cache/backend_impl.h
index 7270b30..a061feb 100644
--- a/net/disk_cache/backend_impl.h
+++ b/net/disk_cache/backend_impl.h
@@ -17,6 +17,14 @@
 
 namespace disk_cache {
 
+enum BackendFlags {
+  kMask = 1,
+  kMaxSize = 1 << 1,
+  kUnitTestMode = 1 << 2,
+  kUpgradeMode = 1 << 3,
+  kNewEviction = 1 << 4
+};
+
 // This class implements the Backend interface. An object of this
 // class handles the operations of the cache for a particular profile.
 class BackendImpl : public Backend {
@@ -24,14 +32,14 @@ class BackendImpl : public Backend {
  public:
   explicit BackendImpl(const std::wstring& path)
       : path_(path), block_files_(path), mask_(0), max_size_(0),
-        cache_type_(net::DISK_CACHE), uma_report_(0), init_(false),
-        restarted_(false), unit_test_(false), read_only_(false),
+        cache_type_(net::DISK_CACHE), uma_report_(0), user_flags_(0),
+        init_(false), restarted_(false), unit_test_(false), read_only_(false),
         new_eviction_(false), first_timer_(true) {}
   // mask can be used to limit the usable size of the hash table, for testing.
   BackendImpl(const std::wstring& path, uint32 mask)
       : path_(path), block_files_(path), mask_(mask), max_size_(0),
-        cache_type_(net::DISK_CACHE), uma_report_(0), init_(false),
-        restarted_(false), unit_test_(false), read_only_(false),
+        cache_type_(net::DISK_CACHE), uma_report_(0), user_flags_(kMask),
+        init_(false), restarted_(false), unit_test_(false), read_only_(false),
         new_eviction_(false), first_timer_(true) {}
   ~BackendImpl();
 
@@ -235,6 +243,7 @@ class BackendImpl : public Backend {
   int num_pending_io_;  // Number of pending IO operations.
   net::CacheType cache_type_;
   int uma_report_;  // Controls transmision of UMA data.
+  uint32 user_flags_;  // Flags set by the user.
   bool init_;  // controls the initialization of the system.
   bool restarted_;
   bool unit_test_;
diff --git a/net/disk_cache/eviction.cc b/net/disk_cache/eviction.cc
index dab707d..cae5702 100644
--- a/net/disk_cache/eviction.cc
+++ b/net/disk_cache/eviction.cc
@@ -146,10 +146,22 @@ void Eviction::ReportTrimTimes(EntryImpl* entry) {
       ReportListStats();
     }
 
-    if (header_->create_time && !header_->lru.filled) {
+    if (header_->lru.filled)
+      return;
+
+    header_->lru.filled = 1;
+
+    if (header_->create_time) {
       // This is the first entry that we have to evict, generate some noise.
-      header_->lru.filled = 1;
       backend_->FirstEviction();
+    } else {
+      // This is an old file, but we may want more reports from this user so
+      // lets save some create_time.
+      Time::Exploded old = {0};
+      old.year = 2009;
+      old.month = 3;
+      old.day_of_month = 1;
+      header_->create_time = Time::FromLocalExploded(old).ToInternalValue();
     }
   }
 }