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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;
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