transiton to libpqxx & connection pool for central controllers
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4 changed files with 571 additions and 986 deletions
161
controller/ConnectionPool.hpp
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161
controller/ConnectionPool.hpp
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/*
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* Copyright (c)2021 ZeroTier, Inc.
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file in the project's root directory.
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*
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* Change Date: 2025-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2.0 of the Apache License.
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*/
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/****/
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#ifndef ZT_CONNECTION_POOL_H_
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#define ZT_CONNECTION_POOL_H_
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#ifndef _DEBUG
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#define _DEBUG(x)
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#endif
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#include <deque>
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#include <set>
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#include <memory>
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#include <mutex>
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#include <exception>
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#include <string>
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namespace ZeroTier {
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struct ConnectionUnavailable : std::exception {
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char const* what() const throw() {
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return "Unable to allocate connection";
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};
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};
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class Connection {
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public:
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virtual ~Connection() {};
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};
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class ConnectionFactory {
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public:
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virtual ~ConnectionFactory() {};
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virtual std::shared_ptr<Connection> create()=0;
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};
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struct ConnectionPoolStats {
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size_t pool_size;
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size_t borrowed_size;
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};
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template<class T>
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class ConnectionPool {
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public:
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ConnectionPool(size_t max_pool_size, size_t min_pool_size, std::shared_ptr<ConnectionFactory> factory)
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: m_maxPoolSize(max_pool_size)
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, m_minPoolSize(min_pool_size)
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, m_factory(factory)
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{
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while(m_pool.size() < m_minPoolSize){
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m_pool.push_back(m_factory->create());
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}
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};
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ConnectionPoolStats get_stats() {
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std::unique_lock<std::mutex> lock(m_poolMutex);
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ConnectionPoolStats stats;
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stats.pool_size = m_pool.size();
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stats.borrowed_size = m_borrowed.size();
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return stats;
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};
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~ConnectionPool() {
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};
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/**
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* Borrow
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*
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* Borrow a connection for temporary use
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*
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* When done, either (a) call unborrow() to return it, or (b) (if it's bad) just let it go out of scope. This will cause it to automatically be replaced.
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* @retval a shared_ptr to the connection object
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*/
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std::shared_ptr<T> borrow() {
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std::unique_lock<std::mutex> l(m_poolMutex);
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while((m_pool.size() + m_borrowed.size()) < m_minPoolSize) {
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std::shared_ptr<Connection> conn = m_factory->create();
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m_pool.push_back(conn);
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}
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if(m_pool.size()==0){
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if ((m_pool.size() + m_borrowed.size()) <= m_maxPoolSize) {
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try {
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std::shared_ptr<Connection> conn = m_factory->create();
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m_borrowed.insert(conn);
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return std::static_pointer_cast<T>(conn);
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} catch (std::exception &e) {
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throw ConnectionUnavailable();
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}
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} else {
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for(auto it = m_borrowed.begin(); it != m_borrowed.end(); ++it){
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if((*it).unique()) {
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// This connection has been abandoned! Destroy it and create a new connection
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try {
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// If we are able to create a new connection, return it
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_DEBUG("Creating new connection to replace discarded connection");
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std::shared_ptr<Connection> conn = m_factory->create();
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m_borrowed.erase(it);
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m_borrowed.insert(conn);
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return std::static_pointer_cast<T>(conn);
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} catch(std::exception& e) {
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// Error creating a replacement connection
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throw ConnectionUnavailable();
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}
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}
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}
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// Nothing available
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throw ConnectionUnavailable();
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}
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}
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// Take one off the front
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std::shared_ptr<Connection> conn = m_pool.front();
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m_pool.pop_front();
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// Add it to the borrowed list
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m_borrowed.insert(conn);
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return std::static_pointer_cast<T>(conn);
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};
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/**
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* Unborrow a connection
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*
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* Only call this if you are returning a working connection. If the connection was bad, just let it go out of scope (so the connection manager can replace it).
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* @param the connection
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*/
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void unborrow(std::shared_ptr<T> conn) {
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// Lock
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std::unique_lock<std::mutex> lock(m_poolMutex);
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m_borrowed.erase(conn);
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if ((m_pool.size() + m_borrowed.size()) < m_maxPoolSize) {
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m_pool.push_back(conn);
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}
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};
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protected:
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size_t m_maxPoolSize;
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size_t m_minPoolSize;
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std::shared_ptr<ConnectionFactory> m_factory;
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std::deque<std::shared_ptr<Connection> > m_pool;
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std::set<std::shared_ptr<Connection> > m_borrowed;
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std::mutex m_poolMutex;
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};
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}
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#endif
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