pdns/dnsdist-lbpolicies.hh

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #pragma once
  23
  24 struct dnsdist_ffi_servers_list_t;
  25 struct dnsdist_ffi_server_t;
  26 struct dnsdist_ffi_dnsquestion_t;
  27
  28 struct DownstreamState;
  29
  30 struct ServerPolicy
  31 {
  32   template <class T> using NumberedVector = std::vector<std::pair<unsigned int, T> >;
  33   using NumberedServerVector = NumberedVector<shared_ptr<DownstreamState>>;
  34   typedef std::function<shared_ptr<DownstreamState>(const NumberedServerVector& servers, const DNSQuestion*)> policyfunc_t;
  35   typedef std::function<unsigned int(dnsdist_ffi_servers_list_t* servers, dnsdist_ffi_dnsquestion_t* dq)> ffipolicyfunc_t;
  36
  37   ServerPolicy(const std::string& name_, policyfunc_t policy_, bool isLua_): name(name_), policy(policy_), isLua(isLua_)
  38   {
  39   }
  40   ServerPolicy(const std::string& name_, ffipolicyfunc_t policy_): name(name_), ffipolicy(policy_), isLua(true), isFFI(true)
  41   {
  42   }
  43   ServerPolicy()
  44   {
  45   }
  46
  47   string name;
  48   policyfunc_t policy;
  49   ffipolicyfunc_t ffipolicy;
  50   bool isLua{false};
  51   bool isFFI{false};
  52
  53   std::string toString() const {
  54     return string("ServerPolicy") + (isLua ? " (Lua)" : "") + " \"" + name + "\"";
  55   }
  56 };
  57
  58 struct ServerPool;
  59
  60 using pools_t=map<std::string,std::shared_ptr<ServerPool>>;
  61 std::shared_ptr<ServerPool> getPool(const pools_t& pools, const std::string& poolName);
  62 std::shared_ptr<ServerPool> createPoolIfNotExists(pools_t& pools, const string& poolName);
  63 void setPoolPolicy(pools_t& pools, const string& poolName, std::shared_ptr<ServerPolicy> policy);
  64 void addServerToPool(pools_t& pools, const string& poolName, std::shared_ptr<DownstreamState> server);
  65 void removeServerFromPool(pools_t& pools, const string& poolName, std::shared_ptr<DownstreamState> server);
  66
  67 ServerPolicy::NumberedServerVector getDownstreamCandidates(const map<std::string,std::shared_ptr<ServerPool>>& pools, const std::string& poolName);
  68
  69 std::shared_ptr<DownstreamState> firstAvailable(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
  70
  71 std::shared_ptr<DownstreamState> leastOutstanding(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
  72 std::shared_ptr<DownstreamState> wrandom(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
  73 std::shared_ptr<DownstreamState> whashed(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
  74 std::shared_ptr<DownstreamState> whashedFromHash(const ServerPolicy::NumberedServerVector& servers, size_t hash);
  75 std::shared_ptr<DownstreamState> chashed(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
  76 std::shared_ptr<DownstreamState> chashedFromHash(const ServerPolicy::NumberedServerVector& servers, size_t hash);
  77 std::shared_ptr<DownstreamState> roundrobin(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
  78 std::shared_ptr<DownstreamState> getSelectedBackendFromPolicy(const ServerPolicy& policy, const ServerPolicy::NumberedServerVector& servers, DNSQuestion& dq);
  79
  80 extern double g_consistentHashBalancingFactor;
  81 extern double g_weightedBalancingFactor;
  82 extern uint32_t g_hashperturb;
  83 extern bool g_roundrobinFailOnNoServer;