[net] Make HostResolverImpl::OnIPAddressChange faster by removing blocking on HaveOnlyLoopbackAddre…

net/base/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_BASE_HOST_RESOLVER_IMPL_H_
 #define NET_BASE_HOST_RESOLVER_IMPL_H_
 
 #include <map>
 
 #include "base/basictypes.h"
@@ skipping 96 matching lines @@
   // |job_limits| specifies the maximum number of jobs that the resolver will
   // run at once. This upper-bounds the total number of outstanding
   // DNS transactions (not counting retransmissions and retries).
   //
   // |dns_config_service| will be used to detect changes to DNS configuration
   // and obtain DnsConfig for DnsClient.
   //
   // |dns_client|, if set, will be used to resolve requests.
   //
   // |net_log| must remain valid for the life of the HostResolverImpl.
-  // TODO(szym): change to scoped_ptr<HostCache>.
   HostResolverImpl(scoped_ptr<HostCache> cache,
                    const PrioritizedDispatcher::Limits& job_limits,
                    const ProcTaskParams& proc_params,
                    scoped_ptr<DnsClient> dns_client,
                    NetLog* net_log);
 
   // If any completion callbacks are pending when the resolver is destroyed,
   // the host resolutions are cancelled, and the completion callbacks will not
   // be called.
   virtual ~HostResolverImpl();
@@ skipping 16 matching lines @@
   virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE;
   virtual void ProbeIPv6Support() OVERRIDE;
   virtual HostCache* GetHostCache() OVERRIDE;
   virtual base::Value* GetDnsConfigAsValue() const OVERRIDE;
 
  private:
   friend class HostResolverImplTest;
   class Job;
   class ProcTask;
   class IPv6ProbeJob;
+  class LoopbackProbeJob;
   class DnsTask;
   class Request;
   typedef HostCache::Key Key;
   typedef std::map<Key, Job*> JobMap;
   typedef ScopedVector<Request> RequestsList;
 
   // 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.
@@ skipping 16 matching lines @@
                       const RequestInfo& info,
                       int* net_error,
                       AddressList* addresses);
 
   // If we have a DnsClient with a valid DnsConfig, and |key| is found in the
   // HOSTS file, returns true and fills |addresses|. Otherwise returns false.
   bool ServeFromHosts(const Key& key,
                       const RequestInfo& info,
                       AddressList* addresses);
 
-  // Notifies IPv6ProbeJob not to call back, and discard reference to the job.
-  void DiscardIPv6ProbeJob();
-
   // Callback from IPv6 probe activity.
   void IPv6ProbeSetDefaultAddressFamily(AddressFamily address_family);
 
   // Callback from HaveOnlyLoopbackAddresses probe.
   void SetHaveOnlyLoopbackAddresses(bool result);
 
   // Returns the (hostname, address_family) key to use for |info|, choosing an
   // "effective" address family by inheriting the resolver's default address
   // family when the request leaves it unspecified.
   Key GetEffectiveKeyForRequest(const RequestInfo& info) const;
@@ skipping 41 matching lines @@
   size_t max_queued_jobs_;
 
   // Parameters for ProcTask.
   ProcTaskParams proc_params_;
 
   // Address family to use when the request doesn't specify one.
   AddressFamily default_address_family_;
 
   base::WeakPtrFactory<HostResolverImpl> weak_ptr_factory_;
 
+  base::WeakPtrFactory<HostResolverImpl> probe_weak_ptr_factory_;
+
   // If present, used by DnsTask and ServeFromHosts to resolve requests.
   scoped_ptr<DnsClient> dns_client_;
 
   // True if received valid config from |dns_config_service_|. Temporary, used
   // to measure performance of DnsConfigService: http://crbug.com/125599
   bool received_dns_config_;
 
   // Indicate if probing is done after each network change event to set address
-  // family. When false, explicit setting of address family is used.
+  // family. When false, explicit setting of address family is used and results
+  // of the IPv6 probe job are ignored.
   bool ipv6_probe_monitoring_;
 
-  // The last un-cancelled IPv6ProbeJob (if any).
-  scoped_refptr<IPv6ProbeJob> ipv6_probe_job_;
-
   // Any resolver flags that should be added to a request by default.
   HostResolverFlags additional_resolver_flags_;
 
   NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_IMPL_H_