1 files changed, 114 insertions, 0 deletions
diff --git a/dnsdist-lbpolicies.hh b/dnsdist-lbpolicies.hh
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+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+struct dnsdist_ffi_servers_list_t;
+struct dnsdist_ffi_server_t;
+struct dnsdist_ffi_dnsquestion_t;
+
+struct DownstreamState;
+
+struct PerThreadPoliciesState;
+
+class ServerPolicy
+{
+public:
+  template <class T> using NumberedVector = std::vector<std::pair<unsigned int, T> >;
+  using NumberedServerVector = NumberedVector<shared_ptr<DownstreamState>>;
+  typedef std::function<shared_ptr<DownstreamState>(const NumberedServerVector& servers, const DNSQuestion*)> policyfunc_t;
+  typedef std::function<unsigned int(dnsdist_ffi_servers_list_t* servers, dnsdist_ffi_dnsquestion_t* dq)> ffipolicyfunc_t;
+
+  ServerPolicy(const std::string& name_, policyfunc_t policy_, bool isLua_): d_name(name_), d_policy(policy_), d_isLua(isLua_)
+  {
+  }
+
+  ServerPolicy(const std::string& name_, ffipolicyfunc_t policy_): d_name(name_), d_ffipolicy(policy_), d_isLua(true), d_isFFI(true)
+  {
+  }
+
+  /* create a per-thread FFI policy */
+  ServerPolicy(const std::string& name_, const std::string& code);
+
+  ServerPolicy()
+  {
+  }
+
+  std::shared_ptr<DownstreamState> getSelectedBackend(const ServerPolicy::NumberedServerVector& servers, DNSQuestion& dq) const;
+
+  const std::string& getName() const
+  {
+    return d_name;
+  }
+
+  std::string toString() const {
+    return string("ServerPolicy") + (d_isLua ? " (Lua)" : "") + " \"" + d_name + "\"";
+  }
+
+private:
+  struct PerThreadState
+  {
+    LuaContext d_luaContext;
+    std::unordered_map<std::string, ffipolicyfunc_t> d_policies;
+    bool d_initialized{false};
+  };
+
+  const ffipolicyfunc_t& getPerThreadPolicy() const;
+  static thread_local PerThreadState t_perThreadState;
+
+
+public:
+  std::string d_name;
+  std::string d_perThreadPolicyCode;
+
+  policyfunc_t d_policy;
+  ffipolicyfunc_t d_ffipolicy;
+
+  bool d_isLua{false};
+  bool d_isFFI{false};
+  bool d_isPerThread{false};
+};
+
+struct ServerPool;
+
+using pools_t = map<std::string, std::shared_ptr<ServerPool>>;
+std::shared_ptr<ServerPool> getPool(const pools_t& pools, const std::string& poolName);
+std::shared_ptr<ServerPool> createPoolIfNotExists(pools_t& pools, const string& poolName);
+void setPoolPolicy(pools_t& pools, const string& poolName, std::shared_ptr<ServerPolicy> policy);
+void addServerToPool(pools_t& pools, const string& poolName, std::shared_ptr<DownstreamState> server);
+void removeServerFromPool(pools_t& pools, const string& poolName, std::shared_ptr<DownstreamState> server);
+
+const std::shared_ptr<ServerPolicy::NumberedServerVector> getDownstreamCandidates(const map<std::string,std::shared_ptr<ServerPool>>& pools, const std::string& poolName);
+
+std::shared_ptr<DownstreamState> firstAvailable(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
+
+std::shared_ptr<DownstreamState> leastOutstanding(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
+std::shared_ptr<DownstreamState> wrandom(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
+std::shared_ptr<DownstreamState> whashed(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
+std::shared_ptr<DownstreamState> whashedFromHash(const ServerPolicy::NumberedServerVector& servers, size_t hash);
+std::shared_ptr<DownstreamState> chashed(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
+std::shared_ptr<DownstreamState> chashedFromHash(const ServerPolicy::NumberedServerVector& servers, size_t hash);
+std::shared_ptr<DownstreamState> roundrobin(const ServerPolicy::NumberedServerVector& servers, const DNSQuestion* dq);
+
+extern double g_consistentHashBalancingFactor;
+extern double g_weightedBalancingFactor;
+extern uint32_t g_hashperturb;
+extern bool g_roundrobinFailOnNoServer;