services/proxy_resolver/proxy_host_resolver_cache.h

   1 // Copyright 2021 The Chromium Authors
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SERVICES_PROXY_RESOLVER_PROXY_HOST_RESOLVER_CACHE_H_
   6 #define SERVICES_PROXY_RESOLVER_PROXY_HOST_RESOLVER_CACHE_H_
   7
   8 #include <list>
   9 #include <map>
  10 #include <string>
  11 #include <tuple>
  12 #include <vector>
  13
  14 #include "base/time/time.h"
  15 #include "net/base/ip_address.h"
  16 #include "net/base/network_anonymization_key.h"
  17
  18 namespace proxy_resolver {
  19
  20 // Simple cache for proxy host resolutions. Maintains cached entries for up to
  21 // `kTtl`, and evicts oldest entries when filled past capacity.
  22 class ProxyHostResolverCache {
  23  public:
  24   static constexpr auto kTtl = base::Seconds(5);
  25
  26   explicit ProxyHostResolverCache(size_t max_entries = 500u);
  27   ~ProxyHostResolverCache();
  28   ProxyHostResolverCache(const ProxyHostResolverCache&) = delete;
  29   ProxyHostResolverCache& operator=(const ProxyHostResolverCache&) = delete;
  30
  31   void StoreEntry(std::string hostname,
  32                   net::NetworkAnonymizationKey network_anonymization_key,
  33                   bool is_ex_operation,
  34                   std::vector<net::IPAddress> results);
  35
  36   // Returns `nullptr` if entry not found or expired. Erases from cache if
  37   // expired.
  38   const std::vector<net::IPAddress>* LookupEntry(
  39       std::string hostname,
  40       net::NetworkAnonymizationKey network_anonymization_key,
  41       bool is_ex_operation);
  42
  43   size_t GetSizeForTesting() const;
  44
  45  private:
  46   struct Key {
  47     bool operator<(const Key& other) const {
  48       return std::tie(hostname, network_anonymization_key, is_ex_operation) <
  49              std::tie(other.hostname, other.network_anonymization_key,
  50                       other.is_ex_operation);
  51     }
  52
  53     std::string hostname;
  54     net::NetworkAnonymizationKey network_anonymization_key;
  55     bool is_ex_operation;
  56   };
  57
  58   using ExpirationList = std::list<const Key*>;
  59
  60   struct Entry {
  61     Entry(std::vector<net::IPAddress> results,
  62           base::TimeTicks expiration,
  63           ExpirationList::iterator expiration_list_it);
  64     ~Entry();
  65     Entry(Entry&&);
  66     Entry& operator=(Entry&&);
  67
  68     std::vector<net::IPAddress> results;
  69     base::TimeTicks expiration;
  70     ExpirationList::iterator expiration_list_it;
  71   };
  72
  73   using EntryMap = std::map<Key, Entry>;
  74
  75   // Removes oldest entry iff `max_entries_` exceeded.
  76   void RemoveOldestEntry();
  77
  78   size_t max_entries_;
  79   EntryMap entries_;
  80
  81   // List of `const Key*`s in expiration order starting from the earliest to
  82   // expire.
  83   ExpirationList expiration_list_;
  84 };
  85
  86 }  // namespace proxy_resolver
  87
  88 #endif  // SERVICES_PROXY_RESOLVER_PROXY_HOST_RESOLVER_CACHE_H_