Disk cache: Make sure that we don't keep looping trying

to evict entries from the cache.

Also, consider the number of requests and returned data
when deciding if the cache is under load, and not just the
number of pending operations.

BUG=68894
TEST=none
Review URL: http://codereview.chromium.org/8392020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@107425 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 38 insertions, 33 deletions

diff --git a/net/disk_cache/eviction.cc b/net/disk_cache/eviction.cc
index fa0425d..07028ed 100644
--- a/net/disk_cache/eviction.cc
+++ b/net/disk_cache/eviction.cc
@@ -114,8 +114,9 @@ void Eviction::TrimCache(bool empty) {
   trimming_ = true;
   TimeTicks start = TimeTicks::Now();
   Rankings::ScopedRankingsBlock node(rankings_);
-  Rankings::ScopedRankingsBlock next(rankings_,
-      rankings_->GetPrev(node.get(), Rankings::NO_USE));
+  Rankings::ScopedRankingsBlock next(
+      rankings_, rankings_->GetPrev(node.get(), Rankings::NO_USE));
+  int deleted_entries = 0;
   int target_size = empty ? 0 : max_size_;
   while ((header_->num_bytes > target_size || test_mode_) && next.get()) {
     // The iterator could be invalidated within EvictEntry().
@@ -127,28 +128,26 @@ void Eviction::TrimCache(bool empty) {
       // This entry is not being used by anybody.
       // Do NOT use node as an iterator after this point.
       rankings_->TrackRankingsBlock(node.get(), false);
-      if (!EvictEntry(node.get(), empty, Rankings::NO_USE) && !test_mode_)
-        continue;
+      if (EvictEntry(node.get(), empty, Rankings::NO_USE) && !test_mode_)
+        deleted_entries++;
 
-      if (!empty) {
-        backend_->OnEvent(Stats::TRIM_ENTRY);
-        if (test_mode_)
-          break;
-
-        if ((TimeTicks::Now() - start).InMilliseconds() > 20) {
-          MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
-              &Eviction::TrimCache, ptr_factory_.GetWeakPtr(), false));
-          break;
-        }
-      }
+      if (!empty && test_mode_)
+        break;
+    }
+    if (!empty && (deleted_entries > 20 ||
+                   (TimeTicks::Now() - start).InMilliseconds() > 20)) {
+      MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
+          &Eviction::TrimCache, ptr_factory_.GetWeakPtr(), false));
+      break;
     }
   }
 
   if (empty) {
     CACHE_UMA(AGE_MS, "TotalClearTimeV1", 0, start);
   } else {
-    CACHE_UMA(AGE_MS, "TotalTrimTimeV1", backend_->GetSizeGroup(), start);
+    CACHE_UMA(AGE_MS, "TotalTrimTimeV1", 0, start);
   }
+  CACHE_UMA(COUNTS, "TrimItemsV1", 0, deleted_entries);
 
   trimming_ = false;
   Trace("*** Trim Cache end ***");
@@ -269,6 +268,8 @@ bool Eviction::EvictEntry(CacheRankingsBlock* node, bool empty,
   ReportTrimTimes(entry);
   if (empty || !new_eviction_) {
     entry->DoomImpl();
+    if (!empty)
+      backend_->OnEvent(Stats::TRIM_ENTRY);
   } else {
     entry->DeleteEntryData(false);
     EntryStore* info = entry->entry()->Data();
@@ -317,8 +318,9 @@ void Eviction::TrimCacheV2(bool empty) {
     list = 0;
 
   Rankings::ScopedRankingsBlock node(rankings_);
-
+  int deleted_entries = 0;
   int target_size = empty ? 0 : max_size_;
+
   for (; list < kListsToSearch; list++) {
     while ((header_->num_bytes > target_size || test_mode_) &&
            next[list].get()) {
@@ -332,18 +334,17 @@ void Eviction::TrimCacheV2(bool empty) {
         // This entry is not being used by anybody.
         // Do NOT use node as an iterator after this point.
         rankings_->TrackRankingsBlock(node.get(), false);
-        if (!EvictEntry(node.get(), empty, static_cast<Rankings::List>(list)) &&
-            !test_mode_)
-          continue;
+        if (EvictEntry(node.get(), empty, static_cast<Rankings::List>(list)))
+          deleted_entries++;
 
         if (!empty && test_mode_)
           break;
-
-        if (!empty && (TimeTicks::Now() - start).InMilliseconds() > 20) {
-          MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
-              &Eviction::TrimCache, ptr_factory_.GetWeakPtr(), false));
-          break;
-        }
+      }
+      if (!empty && (deleted_entries > 20 ||
+                     (TimeTicks::Now() - start).InMilliseconds() > 20)) {
+        MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
+            &Eviction::TrimCache, ptr_factory_.GetWeakPtr(), false));
+        break;
       }
     }
     if (!empty)
@@ -361,8 +362,9 @@ void Eviction::TrimCacheV2(bool empty) {
   if (empty) {
     CACHE_UMA(AGE_MS, "TotalClearTimeV2", 0, start);
   } else {
-    CACHE_UMA(AGE_MS, "TotalTrimTimeV2", backend_->GetSizeGroup(), start);
+    CACHE_UMA(AGE_MS, "TotalTrimTimeV2", 0, start);
   }
+  CACHE_UMA(COUNTS, "TrimItemsV2", 0, deleted_entries);
 
   Trace("*** Trim Cache end ***");
   trimming_ = false;
@@ -470,14 +472,16 @@ void Eviction::TrimDeleted(bool empty) {
 
   TimeTicks start = TimeTicks::Now();
   Rankings::ScopedRankingsBlock node(rankings_);
-  Rankings::ScopedRankingsBlock next(rankings_,
-    rankings_->GetPrev(node.get(), Rankings::DELETED));
-  bool deleted = false;
+  Rankings::ScopedRankingsBlock next(
+    rankings_, rankings_->GetPrev(node.get(), Rankings::DELETED));
+  int deleted_entries = 0;
   while (next.get() &&
-         (empty || (TimeTicks::Now() - start).InMilliseconds() < 20)) {
+         (empty || (deleted_entries < 20 &&
+                    (TimeTicks::Now() - start).InMilliseconds() < 20))) {
     node.reset(next.release());
     next.reset(rankings_->GetPrev(node.get(), Rankings::DELETED));
-    deleted |= RemoveDeletedNode(node.get());
+    if (RemoveDeletedNode(node.get()))
+      deleted_entries++;
     if (test_mode_)
       break;
   }
@@ -488,13 +492,14 @@ void Eviction::TrimDeleted(bool empty) {
   // lists intact.
   int max_length = in_experiment_ ? header_->num_entries * 2 / 5 :
                                     header_->num_entries / 4;
-  if (deleted && !empty && !test_mode_ &&
+  if (deleted_entries && !empty && !test_mode_ &&
       header_->lru.sizes[Rankings::DELETED] > max_length) {
     MessageLoop::current()->PostTask(FROM_HERE,
         base::Bind(&Eviction::TrimDeleted, ptr_factory_.GetWeakPtr(), false));
   }
 
   CACHE_UMA(AGE_MS, "TotalTrimDeletedTime", 0, start);
+  CACHE_UMA(COUNTS, "TrimDeletedItems", 0, deleted_entries);
   Trace("*** Trim Deleted end ***");
   return;
 }