[net] Measure DNS.CacheEvicted and DNS.CacheExpired.
On every eviction from HostCache record the time left to expiration
(DNS.CacheEvicted) or time since expiration (DNS.CacheExpired).
A distinction is made for evictions on Lookup (DNS.CacheExpiredOnGet).
Review URL: https://chromiumcodereview.appspot.com/11359053
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166781 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/net/base/expiring_cache.h b/net/base/expiring_cache.h
index fe2fc65..ee3fc3f 100644
--- a/net/base/expiring_cache.h
+++ b/net/base/expiring_cache.h
@@ -14,6 +14,19 @@
namespace net {
+template <typename KeyType,
+ typename ValueType,
+ typename ExpirationType>
+class NoopEvictionHandler {
+ public:
+ void Handle(const KeyType& key,
+ const ValueType& value,
+ const ExpirationType& expiration,
+ const ExpirationType& now,
+ bool onGet) const {
+ }
+};
+
// Cache implementation where all entries have an explicit expiration policy. As
// new items are added, expired items will be removed first.
// The template types have the following requirements:
@@ -54,7 +67,10 @@
template <typename KeyType,
typename ValueType,
typename ExpirationType,
- typename ExpirationCompare>
+ typename ExpirationCompare,
+ typename EvictionHandler = NoopEvictionHandler<KeyType,
+ ValueType,
+ ExpirationType> >
class ExpiringCache {
private:
// Intentionally violate the C++ Style Guide so that EntryMap is known to be
@@ -113,7 +129,7 @@
// Immediately remove expired entries.
if (!expiration_comp_(now, it->second.second)) {
- entries_.erase(it);
+ Evict(it, now, true);
return NULL;
}
@@ -163,7 +179,7 @@
typename EntryMap::iterator it;
for (it = entries_.begin(); it != entries_.end(); ) {
if (!expiration_comp_(now, it->second.second)) {
- entries_.erase(it++);
+ Evict(it++, now, false);
} else {
++it;
}
@@ -175,15 +191,24 @@
// If the cache is still too full, start deleting items 'randomly'.
for (it = entries_.begin();
it != entries_.end() && entries_.size() >= max_entries_;) {
- entries_.erase(it++);
+ Evict(it++, now, false);
}
}
+ void Evict(typename EntryMap::iterator it,
+ const ExpirationType& now,
+ bool on_get) {
+ eviction_handler_.Handle(it->first, it->second.first, it->second.second,
+ now, on_get);
+ entries_.erase(it);
+ }
+
// Bound on total size of the cache.
size_t max_entries_;
EntryMap entries_;
ExpirationCompare expiration_comp_;
+ EvictionHandler eviction_handler_;
DISALLOW_COPY_AND_ASSIGN(ExpiringCache);
};
