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ec5db6409d
Parallelism is achieved by using mysql_send_query on multiple connections without waiting for results, and using IO multiplexing (poll/IOCP) to wait for completions. Refresh libmariadb to pick up CONC-676 (fixes for IOCP use with named pipe)
125 lines
3.4 KiB
C++
125 lines
3.4 KiB
C++
/*
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Copyright (c) 2023, MariaDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335
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USA
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*/
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#pragma once
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#include <mysql.h>
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#include <vector>
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#include <queue>
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#include <string>
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <poll.h>
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#endif
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/*
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Implementation of asynchronous mariadb connection pool.
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This pool consists of set of MYSQL* connections, created by C API
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function. The intention is that all connections have the same state
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same server, by the same user etc.
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The "asynchronous" means the queries are executed on the server
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without waiting for the server reply. The queries are submitted
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with mysql_send_query(), and completions are picked by poll/IOCP.
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*/
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namespace async_pool
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{
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typedef void (*query_completion_handler)(MYSQL *mysql, const char *query, bool success, void *context);
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struct pooled_connection
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#ifdef _WIN32
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: OVERLAPPED
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#endif
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{
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MYSQL *mysql;
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query_completion_handler on_completion=NULL;
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void *context=NULL;
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std::string query;
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bool in_use=false;
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bool release_connection=false;
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#ifdef _WIN32
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bool is_pipe;
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HANDLE handle;
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#else
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int fd;
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#endif
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pooled_connection(MYSQL *mysql);
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};
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struct connection_pool
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{
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private:
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std::vector<pooled_connection> all_connections;
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std::queue<pooled_connection *> free_connections;
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pooled_connection *get_connection();
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void wait_for_completions();
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void complete_query(pooled_connection *c);
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void add_to_pollset(pooled_connection *c);
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#ifdef _WIN32
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HANDLE iocp=nullptr;
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#else
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std::vector<pollfd> pollset;
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#endif
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public:
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~connection_pool();
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/**
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Add connections to the connection pool
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@param con - connections
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@param n_connections - number of connections
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*/
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void init(MYSQL *con[], size_t n_connections);
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/**
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Send query to the connection pool
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Executes query on a connection in the pool, using mysql_send_query
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@param query - query string
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@param on_completion - callback function to be called on completion
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@param context - user context that will be passed to the callback function
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@param release_connecton - if true, the connection should be released to the
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pool after the query is executed. If you execute another
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mysql_send_query() on the same connection, set this to false.
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Note: the function will block if there are no free connections in the pool.
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@return return code of mysql_send_query
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*/
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int execute_async(const char *query, query_completion_handler on_completion, void *context, bool release_connecton=true);
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/** Waits for all outstanding queries to complete.*/
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void wait_all();
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/** Execute callback for each connection in the pool. */
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void for_each_connection(void (*f)(MYSQL *mysql));
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/**
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Closes all connections in pool and frees all resources.
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Does not wait for pending queries to complete
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(use wait_all() for that)
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*/
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int close();
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};
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} // namespace async_pool
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