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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/dns_config_service.h"
#include <string>
#include "base/check_op.h"
#include "base/metrics/histogram_macros.h"
#include "base/notreached.h"
namespace net {
// static
const base::TimeDelta DnsConfigService::kInvalidationTimeout =
base::TimeDelta::FromMilliseconds(150);
DnsConfigService::DnsConfigService()
: watch_failed_(false),
have_config_(false),
have_hosts_(false),
need_update_(false),
last_sent_empty_(true) {
DETACH_FROM_SEQUENCE(sequence_checker_);
}
DnsConfigService::~DnsConfigService() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}
void DnsConfigService::ReadConfig(const CallbackType& callback) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(!callback.is_null());
DCHECK(callback_.is_null());
callback_ = callback;
ReadNow();
}
void DnsConfigService::WatchConfig(const CallbackType& callback) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(!callback.is_null());
DCHECK(callback_.is_null());
callback_ = callback;
watch_failed_ = !StartWatching();
ReadNow();
}
void DnsConfigService::RefreshConfig() {
// Overridden on supported platforms.
NOTREACHED();
}
void DnsConfigService::InvalidateConfig() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
base::TimeTicks now = base::TimeTicks::Now();
if (!last_invalidate_config_time_.is_null()) {
UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.ConfigNotifyInterval",
now - last_invalidate_config_time_);
}
last_invalidate_config_time_ = now;
if (!have_config_)
return;
have_config_ = false;
StartTimer();
}
void DnsConfigService::InvalidateHosts() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
base::TimeTicks now = base::TimeTicks::Now();
if (!last_invalidate_hosts_time_.is_null()) {
UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.HostsNotifyInterval",
now - last_invalidate_hosts_time_);
}
last_invalidate_hosts_time_ = now;
if (!have_hosts_)
return;
have_hosts_ = false;
StartTimer();
}
void DnsConfigService::OnConfigRead(const DnsConfig& config) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(config.IsValid());
bool changed = false;
if (!config.EqualsIgnoreHosts(dns_config_)) {
dns_config_.CopyIgnoreHosts(config);
need_update_ = true;
changed = true;
}
if (!changed && !last_sent_empty_time_.is_null()) {
UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.UnchangedConfigInterval",
base::TimeTicks::Now() - last_sent_empty_time_);
}
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.ConfigChange", changed);
have_config_ = true;
if (have_hosts_ || watch_failed_)
OnCompleteConfig();
}
void DnsConfigService::OnHostsRead(const DnsHosts& hosts) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
bool changed = false;
if (hosts != dns_config_.hosts) {
dns_config_.hosts = hosts;
need_update_ = true;
changed = true;
}
if (!changed && !last_sent_empty_time_.is_null()) {
UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.UnchangedHostsInterval",
base::TimeTicks::Now() - last_sent_empty_time_);
}
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HostsChange", changed);
have_hosts_ = true;
if (have_config_ || watch_failed_)
OnCompleteConfig();
}
void DnsConfigService::StartTimer() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (last_sent_empty_) {
DCHECK(!timer_.IsRunning());
return; // No need to withdraw again.
}
timer_.Stop();
// Give it a short timeout to come up with a valid config. Otherwise withdraw
// the config from the receiver. The goal is to avoid perceivable network
// outage (when using the wrong config) but at the same time avoid
// unnecessary Job aborts in HostResolverImpl. The signals come from multiple
// sources so it might receive multiple events during a config change.
timer_.Start(FROM_HERE, kInvalidationTimeout, this,
&DnsConfigService::OnTimeout);
}
void DnsConfigService::OnTimeout() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(!last_sent_empty_);
// Indicate that even if there is no change in On*Read, we will need to
// update the receiver when the config becomes complete.
need_update_ = true;
// Empty config is considered invalid.
last_sent_empty_ = true;
last_sent_empty_time_ = base::TimeTicks::Now();
callback_.Run(DnsConfig());
}
void DnsConfigService::OnCompleteConfig() {
timer_.Stop();
if (!need_update_)
return;
need_update_ = false;
last_sent_empty_ = false;
if (watch_failed_) {
// If a watch failed, the config may not be accurate, so report empty.
callback_.Run(DnsConfig());
} else {
callback_.Run(dns_config_);
}
}
} // namespace net
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