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// 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_macros.h"
#include "base/strings/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
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