Disk cache: Go back to regular evictions if we are falling behind.

If the cache is under load we try to avoid evictions, or at least reduce
the frequency of evictions. This CL alters that logic so that when the
size of the cache grows too much above the desired limit we go back to
non throttled evictions.

BUG=none
TEST=none
Review URL: https://codereview.chromium.org/11961008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@177708 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 7 insertions, 1 deletions

diff --git a/net/disk_cache/eviction.cc b/net/disk_cache/eviction.cc
index 1a4a0f1..2086bd3 100644
--- a/net/disk_cache/eviction.cc
+++ b/net/disk_cache/eviction.cc
@@ -57,6 +57,10 @@ int LowWaterAdjust(int high_water) {
   return high_water - kCleanUpMargin;
 }
 
+bool FallingBehind(int current_size, int max_size) {
+  return current_size > max_size - kCleanUpMargin * 20;
+}
+
 }  // namespace
 
 namespace disk_cache {
@@ -219,8 +223,10 @@ void Eviction::DelayedTrim() {
 }
 
 bool Eviction::ShouldTrim() {
-  if (trim_delays_ < kMaxDelayedTrims && backend_->IsLoaded())
+  if (!FallingBehind(header_->num_bytes, max_size_) &&
+      trim_delays_ < kMaxDelayedTrims && backend_->IsLoaded()) {
     return false;
+  }
 
   UMA_HISTOGRAM_COUNTS("DiskCache.TrimDelays", trim_delays_);
   trim_delays_ = 0;