net: measure theoretical delay of waiting for DNS cert information.

net/socket/ssl_host_info.cc

 // Copyright (c) 2010 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/socket/ssl_host_info.h"
 
 #include "base/metrics/histogram.h"
 #include "base/pickle.h"
 #include "base/string_piece.h"
 #include "net/base/dns_util.h"
@@ skipping 58 matching lines @@
 }
 
 const SSLHostInfo::State& SSLHostInfo::state() const {
   return state_;
 }
 
 SSLHostInfo::State* SSLHostInfo::mutable_state() {
   return &state_;
 }
 
+void SSLHostInfo::set_cert_verification_finished_time() {
+#if defined(OS_LINUX)
+  if (dnsrr_resolver_ && dns_handle_ == DnsRRResolver::kInvalidHandle) {
+    // We have completed the DNS lookup already. Therefore, waiting for the DNS
+    // lookup would cause no delay.
+    UMA_HISTOGRAM_TIMES("Net.SSLHostInfoDNSLookupDelayMs", base::TimeDelta());
+  } else {
+    // The actual delay will be calculated when the DNS lookup finishes, in
+    // DnsComplete.
+    cert_verification_finished_time_ = base::TimeTicks::Now();
+  }
+#endif
+}
+
 bool SSLHostInfo::Parse(const std::string& data) {
   State* state = mutable_state();
 
   state->Clear();
   cert_verification_complete_ = false;
 
   bool r = ParseInner(data);
   if (!r)
     state->Clear();
   return r;
@@ skipping 128 matching lines @@
     callback->Run(rv);
   }
 }
 
 void SSLHostInfo::DnsComplete(int rv) {
   dns_handle_ = DnsRRResolver::kInvalidHandle;
   delete dns_callback_;
   dns_callback_ = NULL;
 
   const base::TimeTicks now = base::TimeTicks::Now();
-  const base::TimeDelta elapsed = now - dns_lookup_start_time_;
+  base::TimeDelta elapsed = now - dns_lookup_start_time_;
   UMA_HISTOGRAM_TIMES("Net.SSLHostInfoDNSLookup", elapsed);
+
+  if (!cert_verification_finished_time_.is_null()) {
+    elapsed = now - cert_verification_finished_time_;
+    UMA_HISTOGRAM_TIMES("Net.SSLHostInfoDNSLookupDelayMs", elapsed);
+  }
 }
 
+
 SSLHostInfoFactory::~SSLHostInfoFactory() {}
 
 }  // namespace net