Added HostResolverImpl::fallback_to_proctask_ to vary according to AsyncDnsNoFallback group in AsynDns finch trial. Fixed use-after-delete issue.
patch from issue 16881005
BUG=224248
TEST=net_unittests --gtest_filter=HostResolverImplDnsTest.NoFallbackToProcTask
TEST=net_unittests --gtest_filter=HostResolverImplDnsTest.OnDnsTaskFailureAbortedJob
Review URL: https://chromiumcodereview.appspot.com/18136002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@209054 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/net/dns/host_resolver_impl.cc b/net/dns/host_resolver_impl.cc
index 6c41181..25e5ded 100644
--- a/net/dns/host_resolver_impl.cc
+++ b/net/dns/host_resolver_impl.cc
@@ -243,6 +243,20 @@
base::TimeDelta::FromDays(1), 100);
}
+bool ConfigureAsyncDnsNoFallbackFieldTrial() {
+ const bool kDefault = false;
+
+ // Configure the AsyncDns field trial as follows:
+ // groups AsyncDnsNoFallbackA and AsyncDnsNoFallbackB: return true,
+ // groups AsyncDnsA and AsyncDnsB: return false,
+ // groups SystemDnsA and SystemDnsB: return false,
+ // otherwise (trial absent): return default.
+ std::string group_name = base::FieldTrialList::FindFullName("AsyncDns");
+ if (!group_name.empty())
+ return StartsWithASCII(group_name, "AsyncDnsNoFallback", false);
+ return kDefault;
+}
+
//-----------------------------------------------------------------------------
AddressList EnsurePortOnAddressList(const AddressList& list, uint16 port) {
@@ -1475,19 +1489,60 @@
void StartDnsTask() {
DCHECK(resolver_->HaveDnsConfig());
+ base::TimeTicks start_time = base::TimeTicks::Now();
dns_task_.reset(new DnsTask(
resolver_->dns_client_.get(),
key_,
- base::Bind(&Job::OnDnsTaskComplete, base::Unretained(this),
- base::TimeTicks::Now()),
+ base::Bind(&Job::OnDnsTaskComplete, base::Unretained(this), start_time),
net_log_));
int rv = dns_task_->Start();
- if (rv != ERR_IO_PENDING) {
- DCHECK_NE(OK, rv);
+ if (rv == ERR_IO_PENDING)
+ return; // Complete asynchronously.
+ DCHECK_NE(OK, rv);
+ base::TimeDelta duration = base::TimeTicks::Now() - start_time;
+ if (resolver_->fallback_to_proctask_) {
+ DNS_HISTOGRAM("AsyncDNS.ResolveFail", duration);
dns_task_error_ = rv;
dns_task_.reset();
StartProcTask();
+ } else {
+ // We could be running within Resolve(), so make sure to complete
+ // asynchronously.
+ base::MessageLoopProxy::current()->PostTask(
+ FROM_HERE,
+ base::Bind(&Job::OnDnsTaskFailure,
+ base::Unretained(this),
+ dns_task_->AsWeakPtr(),
+ duration,
+ rv));
+ }
+ }
+
+ // Called if DnsTask fails. It is posted from StartDnsTask, so Job may be
+ // deleted before this callback. In this case dns_task is deleted as well,
+ // so we use it as indicator whether Job is still valid.
+ void OnDnsTaskFailure(const base::WeakPtr<DnsTask>& dns_task,
+ base::TimeDelta duration,
+ int net_error) {
+ DNS_HISTOGRAM("AsyncDNS.ResolveFail", duration);
+
+ if (dns_task == NULL)
+ return;
+
+ dns_task_error_ = net_error;
+
+ // TODO(szym): Run ServeFromHosts now if nsswitch.conf says so.
+ // http://crbug.com/117655
+
+ // TODO(szym): Some net errors indicate lack of connectivity. Starting
+ // ProcTask in that case is a waste of time.
+ if (resolver_->fallback_to_proctask_) {
+ dns_task_.reset();
+ StartProcTask();
+ } else {
+ UmaAsyncDnsResolveStatus(RESOLVE_STATUS_FAIL);
+ CompleteRequestsWithError(net_error);
}
}
@@ -1500,17 +1555,7 @@
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (net_error != OK) {
- DNS_HISTOGRAM("AsyncDNS.ResolveFail", duration);
-
- dns_task_error_ = net_error;
- dns_task_.reset();
-
- // TODO(szym): Run ServeFromHosts now if nsswitch.conf says so.
- // http://crbug.com/117655
-
- // TODO(szym): Some net errors indicate lack of connectivity. Starting
- // ProcTask in that case is a waste of time.
- StartProcTask();
+ OnDnsTaskFailure(dns_task_->AsWeakPtr(), duration, net_error);
return;
}
DNS_HISTOGRAM("AsyncDNS.ResolveSuccess", duration);
@@ -1704,7 +1749,8 @@
num_dns_failures_(0),
ipv6_probe_monitoring_(false),
resolved_known_ipv6_hostname_(false),
- additional_resolver_flags_(0) {
+ additional_resolver_flags_(0),
+ fallback_to_proctask_(true) {
DCHECK_GE(dispatcher_.num_priorities(), static_cast<size_t>(NUM_PRIORITIES));
@@ -1734,6 +1780,8 @@
NetworkChangeNotifier::GetDnsConfig(&dns_config);
received_dns_config_ = dns_config.IsValid();
}
+
+ fallback_to_proctask_ = !ConfigureAsyncDnsNoFallbackFieldTrial();
}
HostResolverImpl::~HostResolverImpl() {
