Serialize and deserialize HostCache for persistence

net/dns/host_cache.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_CACHE_H_
 #define NET_DNS_HOST_CACHE_H_
 
 #include <stddef.h>
 
 #include <functional>
+#include <map>
 #include <memory>
 #include <string>
 #include <tuple>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time/time.h"
 #include "net/base/address_family.h"
 #include "net/base/address_list.h"
 #include "net/base/expiring_cache.h"
 #include "net/base/net_export.h"
 #include "net/dns/dns_util.h"
 
+namespace base {
+class ListValue;
+}
+
 namespace net {
 
 // Cache used by HostResolver to map hostnames to their resolved result.
 class NET_EXPORT HostCache : NON_EXPORTED_BASE(public base::NonThreadSafe) {
  public:
   struct Key {
     Key(const std::string& hostname, AddressFamily address_family,
         HostResolverFlags host_resolver_flags)
         : hostname(hostname),
           address_family(address_family),
@@ skipping 48 matching lines @@
     int network_changes() const { return network_changes_; }
 
    private:
     friend class HostCache;
 
     Entry(const Entry& entry,
           base::TimeTicks now,
           base::TimeDelta ttl,
           int network_changes);
 
+    Entry(int error,
+          const AddressList& addresses,
+          base::TimeTicks expires,
+          int network_changes);
+
     int total_hits() const { return total_hits_; }
     int stale_hits() const { return stale_hits_; }
 
     bool IsStale(base::TimeTicks now, int network_changes) const;
     void CountHit(bool hit_is_stale);
     void GetStaleness(base::TimeTicks now,
                       int network_changes,
                       EntryStaleness* out) const;
 
     // The resolve results for this entry.
@@ skipping 45 matching lines @@
     eviction_callback_ = callback;
   }
 
   // Empties the cache.
   void clear();
 
   // Clears hosts matching |host_filter| from the cache.
   void ClearForHosts(
       const base::Callback<bool(const std::string&)>& host_filter);
 
+  // Returns the contents of the cache represented as a base::ListValue for
+  // serialization.
+  std::unique_ptr<base::ListValue> GetAsListValue(bool include_staleness) const;
+  // Takes a base::ListValue representing cache entries and stores them in the
+  // cache, skipping any that already have entries. Returns true on success,
+  // false on failure.
+  bool RestoreFromListValue(base::ListValue& old_cache);
+
   // Returns the number of entries in the cache.
   size_t size() const;
 
   // Following are used by net_internals UI.
   size_t max_entries() const;
   int network_changes() const { return network_changes_; }
   const EntryMap& entries() const { return entries_; }
 
   // Creates a default cache.
   static std::unique_ptr<HostCache> CreateDefaultCache();
@@ skipping 16 matching lines @@
   void RecordLookup(LookupOutcome outcome,
                     base::TimeTicks now,
                     const Entry* entry);
   void RecordErase(EraseReason reason, base::TimeTicks now, const Entry& entry);
   void RecordEraseAll(EraseReason reason, base::TimeTicks now);
 
   // Returns true if this HostCache can contain no entries.
   bool caching_is_disabled() const { return max_entries_ == 0; }
 
   void EvictOneEntry(base::TimeTicks now);
+  // Helper to insert an Entry into the cache.
+  void AddEntry(const Key& key, const Entry& entry);
 
   // Map from hostname (presumably in lowercase canonicalized format) to
   // a resolved result entry.
   EntryMap entries_;
   size_t max_entries_;
   int network_changes_;
   EvictionCallback eviction_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(HostCache);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_HOST_CACHE_H_