DNS: Let requests specify a callback for future cache hits

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 <stddef.h>
 #include <stdint.h>
 
@@ skipping 279 matching lines @@
 
   void UpdateDNSConfig(bool config_changed);
 
   // 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);
 
+  void OnCacheEntryEvicted(const HostCache::Key& key,
+                           const HostCache::Entry& entry);
+  void ClearCacheHitCallbacks(const HostCache::Key& key);
+  void MaybeAddCacheHitCallback(const HostCache::Key& key,
+                                const RequestInfo& info);
+  void RunCacheHitCallbacks(const HostCache::Key& key, const RequestInfo& info);
+
   // 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.
   std::unique_ptr<HostCache> cache_;
 
@@ skipping 36 matching lines @@
   HostResolverFlags additional_resolver_flags_;
 
   // Allow fallback to ProcTask if DnsTask fails.
   bool fallback_to_proctask_;
 
   // Task runner used for DNS lookups using the platform resolver, and other
   // blocking operations. Usually just the WorkerPool's task runner for slow
   // tasks, but can be overridden for tests.
   scoped_refptr<base::TaskRunner> worker_task_runner_;
 
+  std::map<const HostCache::Key, std::vector<RequestInfo::CacheHitCallback>>
+      cache_hit_callbacks_;
+
   base::WeakPtrFactory<HostResolverImpl> weak_ptr_factory_;
 
   base::WeakPtrFactory<HostResolverImpl> probe_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 // Resolves a local hostname (such as "localhost" or "localhost6") into
 // IP endpoints with the given port. Returns true if |host| is a local
 // hostname and false otherwise. Special IPv6 names (e.g. "localhost6")
 // will resolve to an IPv6 address only, whereas other names will
 // resolve to both IPv4 and IPv6.
 // This function is only exposed so it can be unit-tested.
 // TODO(tfarina): It would be better to change the tests so this function
 // gets exercised indirectly through HostResolverImpl.
 NET_EXPORT_PRIVATE bool ResolveLocalHostname(base::StringPiece host,
                                              uint16_t port,
                                              AddressList* address_list);
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_RESOLVER_IMPL_H_