[net] Move host_cache files from net/base to net/dns

TBR=sky

BUG=70818

Review URL: https://chromiumcodereview.appspot.com/13818025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@193455 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 122 insertions, 0 deletions

diff --git a/net/dns/host_cache.cc b/net/dns/host_cache.cc
new file mode 100644
index 0000000..9c45bad
--- /dev/null
+++ b/net/dns/host_cache.cc
@@ -0,0 +1,122 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/dns/host_cache.h"
+
+#include "base/logging.h"
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
+#include "base/string_number_conversions.h"
+#include "net/base/net_errors.h"
+
+namespace net {
+
+//-----------------------------------------------------------------------------
+
+HostCache::Entry::Entry(int error, const AddressList& addrlist,
+                        base::TimeDelta ttl)
+    : error(error),
+      addrlist(addrlist),
+      ttl(ttl) {
+  DCHECK(ttl >= base::TimeDelta());
+}
+
+HostCache::Entry::Entry(int error, const AddressList& addrlist)
+    : error(error),
+      addrlist(addrlist),
+      ttl(base::TimeDelta::FromSeconds(-1)) {
+}
+
+HostCache::Entry::~Entry() {
+}
+
+//-----------------------------------------------------------------------------
+
+HostCache::HostCache(size_t max_entries)
+    : entries_(max_entries) {
+}
+
+HostCache::~HostCache() {
+}
+
+const HostCache::Entry* HostCache::Lookup(const Key& key,
+                                          base::TimeTicks now) {
+  DCHECK(CalledOnValidThread());
+  if (caching_is_disabled())
+    return NULL;
+
+  return entries_.Get(key, now);
+}
+
+void HostCache::Set(const Key& key,
+                    const Entry& entry,
+                    base::TimeTicks now,
+                    base::TimeDelta ttl) {
+  DCHECK(CalledOnValidThread());
+  if (caching_is_disabled())
+    return;
+
+  entries_.Put(key, entry, now, now + ttl);
+}
+
+void HostCache::clear() {
+  DCHECK(CalledOnValidThread());
+  entries_.Clear();
+}
+
+size_t HostCache::size() const {
+  DCHECK(CalledOnValidThread());
+  return entries_.size();
+}
+
+size_t HostCache::max_entries() const {
+  DCHECK(CalledOnValidThread());
+  return entries_.max_entries();
+}
+
+// Note that this map may contain expired entries.
+const HostCache::EntryMap& HostCache::entries() const {
+  DCHECK(CalledOnValidThread());
+  return entries_;
+}
+
+// static
+scoped_ptr<HostCache> HostCache::CreateDefaultCache() {
+  // Cache capacity is determined by the field trial.
+#if defined(ENABLE_BUILT_IN_DNS)
+  const size_t kDefaultMaxEntries = 1000;
+#else
+  const size_t kDefaultMaxEntries = 100;
+#endif
+  const size_t kSaneMaxEntries = 1 << 20;
+  size_t max_entries = 0;
+  base::StringToSizeT(base::FieldTrialList::FindFullName("HostCacheSize"),
+                      &max_entries);
+  if ((max_entries == 0) || (max_entries > kSaneMaxEntries))
+    max_entries = kDefaultMaxEntries;
+  return make_scoped_ptr(new HostCache(max_entries));
+}
+
+void HostCache::EvictionHandler::Handle(
+    const Key& key,
+    const Entry& entry,
+    const base::TimeTicks& expiration,
+    const base::TimeTicks& now,
+    bool on_get) const {
+  if (on_get) {
+    DCHECK(now >= expiration);
+    UMA_HISTOGRAM_CUSTOM_TIMES("DNS.CacheExpiredOnGet", now - expiration,
+        base::TimeDelta::FromSeconds(1), base::TimeDelta::FromDays(1), 100);
+    return;
+  }
+  if (expiration > now) {
+    UMA_HISTOGRAM_CUSTOM_TIMES("DNS.CacheEvicted", expiration - now,
+        base::TimeDelta::FromSeconds(1), base::TimeDelta::FromDays(1), 100);
+  } else {
+    UMA_HISTOGRAM_CUSTOM_TIMES("DNS.CacheExpired", now - expiration,
+        base::TimeDelta::FromSeconds(1), base::TimeDelta::FromDays(1), 100);
+  }
+}
+
+}  // namespace net