[net/dns] Reland of 218616 (Simultaneous A/AAAA queries).

net/dns/host_resolver_impl.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 NET_DNS_HOST_RESOLVER_IMPL_H_
 #define NET_DNS_HOST_RESOLVER_IMPL_H_
 
 #include <map>
 
 #include "base/basictypes.h"
@@ skipping 139 matching lines @@
   friend class HostResolverImplTest;
   class Job;
   class ProcTask;
   class LoopbackProbeJob;
   class DnsTask;
   class Request;
   typedef HostCache::Key Key;
   typedef std::map<Key, Job*> JobMap;
   typedef ScopedVector<Request> RequestsList;
 
+  // Number of consecutive failures of DnsTask (with successful fallback to
+  // ProcTask) before the DnsClient is disabled until the next DNS change.
+  static const unsigned kMaximumDnsFailures;
+
   // Helper used by |Resolve()| and |ResolveFromCache()|.  Performs IP
   // literal, cache and HOSTS lookup (if enabled), returns OK if successful,
   // ERR_NAME_NOT_RESOLVED if either hostname is invalid or IP literal is
   // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache and HOSTS.
   int ResolveHelper(const Key& key,
                     const RequestInfo& info,
                     AddressList* addresses,
                     const BoundNetLog& request_net_log);
 
   // Tries to resolve |key| as an IP, returns true and sets |net_error| if
@@ skipping 31 matching lines @@
                    const HostCache::Entry& entry,
                    base::TimeDelta ttl);
 
   // Removes |job| from |jobs_|, only if it exists.
   void RemoveJob(Job* job);
 
   // Aborts all in progress jobs with ERR_NETWORK_CHANGED and notifies their
   // requests. Might start new jobs.
   void AbortAllInProgressJobs();
 
+  // Aborts all in progress DnsTasks. In-progress jobs will fall back to
+  // ProcTasks. Might start new jobs, if any jobs were taking up two dispatcher
+  // slots.
+  void AbortDnsTasks();
+
   // Attempts to serve each Job in |jobs_| from the HOSTS file if we have
   // a DnsClient with a valid DnsConfig.
   void TryServingAllJobsFromHosts();
 
   // NetworkChangeNotifier::IPAddressObserver:
   virtual void OnIPAddressChanged() OVERRIDE;
 
   // NetworkChangeNotifier::DNSObserver:
   virtual void OnDNSChanged() OVERRIDE;
 
   // True if have a DnsClient with a valid DnsConfig.
   bool HaveDnsConfig() const;
 
   // Called when a host name is successfully resolved and DnsTask was run on it
   // and resulted in |net_error|.
   void OnDnsTaskResolve(int net_error);
 
-  // Allows the tests to catch slots leaking out of the dispatcher.
-  size_t num_running_jobs_for_tests() const {
+  // Allows the tests to catch slots leaking out of the dispatcher.  One
+  // HostResolverImpl::Job could occupy multiple PrioritizedDispatcher job
+  // slots.
+  size_t num_running_dispatcher_jobs_for_tests() const {
     return dispatcher_.num_running_jobs();
   }
 
   // Cache of host resolution results.
   scoped_ptr<HostCache> cache_;
 
   // Map from HostCache::Key to a Job.
   JobMap jobs_;
 
   // Starts Jobs according to their priority and the configured limits.
@@ skipping 37 matching lines @@
 
   // Allow fallback to ProcTask if DnsTask fails.
   bool fallback_to_proctask_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_RESOLVER_IMPL_H_