Display DNS probe results.

chrome/browser/net/dns_probe_service.h

 // 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.
 
 #ifndef CHROME_BROWSER_NET_DNS_PROBE_SERVICE_H_
 #define CHROME_BROWSER_NET_DNS_PROBE_SERVICE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
-#include "chrome/browser/net/dns_probe_job.h"
+#include "chrome/browser/net/dns_probe_runner.h"
 #include "chrome/common/net/net_error_info.h"
 #include "net/base/network_change_notifier.h"
 
 namespace net {
+class DnsClient;
 struct DnsConfig;
 }
 
 namespace chrome_browser_net {
 
-class DnsProbeService : public net::NetworkChangeNotifier::IPAddressObserver {
+// Probes the system and public DNS servers to determine the (probable) cause
+// of a recent DNS-related page load error.  Coalesces multiple probe requests
+// (perhaps from multiple tabs) and caches the results.
+//
+// Uses a single DNS attempt per config, and doesn't randomize source ports.
+class DnsProbeService : public net::NetworkChangeNotifier::DNSObserver {
  public:
-  typedef base::Callback<void(chrome_common_net::DnsProbeResult result)>
-      CallbackType;
+  typedef base::Callback<void(chrome_common_net::DnsProbeStatus result)>
+      ProbeCallback;
 
   DnsProbeService();
   virtual ~DnsProbeService();
 
-  void ProbeDns(const CallbackType& callback);
+  void ProbeDns(const ProbeCallback& callback);
 
-  // NetworkChangeNotifier::IPAddressObserver implementation:
-  virtual void OnIPAddressChanged() OVERRIDE;
+  // NetworkChangeNotifier::DNSObserver implementation:
+  virtual void OnDNSChanged() OVERRIDE;
 
- protected:
-  // This can be called by tests to pretend the cached reuslt has expired.
-  void ExpireResults();
+  void SetSystemClientForTesting(scoped_ptr<net::DnsClient> system_client);
+  void SetPublicClientForTesting(scoped_ptr<net::DnsClient> public_client);
+  void ExpireResultForTesting();
 
  private:
   enum State {
     STATE_NO_RESULTS,
     STATE_PROBE_RUNNING,
     STATE_RESULTS_CACHED,
   };
 
+  enum ProbeType {
+    SYSTEM,
+    PUBLIC
+  };
+
+  void SetSystemClientToCurrentConfig();
+  void SetPublicClientToGooglePublicDns();
+
+  // Sets the DnsClients used by |system_runner_| and |public_runner_|.
+  void SetSystemClient(scoped_ptr<net::DnsClient> system_client);
+  void SetPublicClient(scoped_ptr<net::DnsClient> public_client);
+
+  // Starts a probe (runs system and public probes).
   void StartProbes();
-  void OnProbesComplete();
+  void OnProbeComplete(ProbeType type, DnsProbeRunner::Result result);
+  // Examines |system_result_| and |public_result_| and returns an overall
+  // result for why a DNS query may have failed.
+  chrome_common_net::DnsProbeStatus EvaluateResults() const;
+  // Histograms the results of a just-finished probe.
+  void HistogramProbes() const;
+  // Calls all |pending_callbacks_| with the |cached_result_|.
   void CallCallbacks();
+  // Clears a cached probe result.
+  void ExpireResult();

[szym, 2013/06/13 20:50:48]

nit: Suggest to name it ClearResult, FlushResult, AbandonResult, ForgetResult to
make it obvious that this is an unconditional action rather than "if expired,
remove it".

[Deprecated (see juliatuttle), 2013/06/18 19:36:37]

Done.

 
-  void OnProbeJobComplete(DnsProbeJob* job, DnsProbeJob::Result result);
-  chrome_common_net::DnsProbeResult EvaluateResults() const;
-  void HistogramProbes() const;
+  bool ResultsExpired() const;
 
-  // These are expected to be overridden by tests to return mock jobs.
-  virtual scoped_ptr<DnsProbeJob> CreateSystemProbeJob(
-      const DnsProbeJob::CallbackType& job_callback);
-  virtual scoped_ptr<DnsProbeJob> CreatePublicProbeJob(
-      const DnsProbeJob::CallbackType& job_callback);
+  State state_;
+  std::vector<ProbeCallback> pending_callbacks_;
+  base::Time probe_start_time_;
+  chrome_common_net::DnsProbeStatus cached_result_;
 
-  scoped_ptr<DnsProbeJob> CreateProbeJob(
-      const net::DnsConfig& dns_config,
-      const DnsProbeJob::CallbackType& job_callback);
-  void GetSystemDnsConfig(net::DnsConfig* config);
-  void GetPublicDnsConfig(net::DnsConfig* config);
-  bool ResultsExpired();
-
-  scoped_ptr<DnsProbeJob> system_job_;
-  scoped_ptr<DnsProbeJob> public_job_;
-  DnsProbeJob::Result system_result_;
-  DnsProbeJob::Result public_result_;
-  std::vector<CallbackType> callbacks_;
-  State state_;
-  chrome_common_net::DnsProbeResult result_;
-  base::Time probe_start_time_;
-  // How many DNS request attempts the probe jobs will make before giving up
-  // (Overrides the attempts field in the system DnsConfig.)
-  const int dns_attempts_;
-  // How many nameservers the system config has.
-  int system_nameserver_count_;
-  // Whether the only system nameserver is 127.0.0.1.
-  bool system_is_localhost_;
+  // DnsProbeRunners for the system DNS configuration and a public DNS server.
+  DnsProbeRunner system_runner_;
+  DnsProbeRunner public_runner_;
+  // Results most recently returned by |system_runner_| and |public_runner_|.
+  DnsProbeRunner::Result system_result_;
+  DnsProbeRunner::Result public_result_;
 
   DISALLOW_COPY_AND_ASSIGN(DnsProbeService);
 };
 
 }  // namespace chrome_browser_net
 
 #endif  // CHROME_BROWSER_NET_DNS_PROBE_SERVICE_H_