一个支持主从，事务以及连接池功能的mysql-proxy脚本

看了点例子，根据mysql-proxy里的keepalive例子修改了一个支持主从分离，事务到主库，非事务查询到从库，以及连接断开时自动回滚的脚本，分享一下。

--[[ $%BEGINLICENSE%$ Copyright (C) 2007-2008 MySQL AB, 2008 Sun Microsystems, Inc This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA $%ENDLICENSE%$ --]] --[[ --]] --- -- a flexible statement based load balancer with connection pooling -- -- * build a connection pool of min_idle_connections for each backend and -- maintain its size -- * reusing a server-side connection when it is idling -- --- config -- -- connection pool local min_idle_connections = 4 local max_idle_connections = 8 -- debug local is_debug = true --- end of config --- -- read/write splitting sends all non-transactional SELECTs to the slaves -- -- is_in_transaction tracks the state of the transactions local is_in_transaction = 0 --- -- get a connection to a backend -- -- as long as we don't have enough connections in the pool, create new connections -- function connect_server() -- make sure that we connect to each backend at least ones to -- keep the connections to the servers alive -- -- on read_query we can switch the backends again to another backend if is_debug then print() print("[connect_server] ") end local least_idle_conns_ndx = 0 local least_idle_conns = 0 for i = 1, #proxy.global.backends do local s = proxy.global.backends[i] local pool = s.pool -- we don't have a username yet, try to find a connections which is idling local cur_idle = pool.users[""].cur_idle_connections if cur_idle == nil then cur_idle = 0 end if is_debug then print(" [".. i .."].connected_clients = " .. s.connected_clients) print(" [".. i .."].idling_connections = " .. cur_idle) print(" [".. i .."].type = " .. s.type) print(" [".. i .."].state = " .. s.state) end if s.state ~= proxy.BACKEND_STATE_DOWN then -- try to connect to each backend once at least if cur_idle == 0 then proxy.connection.backend_ndx = i if is_debug then print(" [".. i .."] open new connection") end return end -- try to open at least min_idle_connections if least_idle_conns_ndx == 0 or ( cur_idle < min_idle_connections and cur_idle < least_idle_conns ) then least_idle_conns_ndx = i least_idle_conns = s.idling_connections if least_idle_conns == nil then least_idle_conns = 0 end end end end if least_idle_conns_ndx > 0 then proxy.connection.backend_ndx = least_idle_conns_ndx end if proxy.connection.backend_ndx > 0 then local s = proxy.global.backends[proxy.connection.backend_ndx] local pool = s.pool -- we don't have a username yet, try to find a connections which is idling local cur_idle = pool.users[""].cur_idle_connections if cur_idle >= min_idle_connections then -- we have 4 idling connections in the pool, that's good enough if is_debug then print(" using pooled connection from: " .. proxy.connection.backend_ndx) end return proxy.PROXY_IGNORE_RESULT end end if is_debug then print(" opening new connection on: " .. proxy.connection.backend_ndx) end -- open a new connection end --- -- put the successfully authed connection into the connection pool -- -- @param auth the context information for the auth -- -- auth.packet is the packet function read_auth_result( auth ) if auth.packet:byte() == proxy.MYSQLD_PACKET_OK then -- auth was fine, disconnect from the server proxy.connection.backend_ndx = 0 elseif auth.packet:byte() == proxy.MYSQLD_PACKET_EOF then -- we received either a -- -- * MYSQLD_PACKET_ERR and the auth failed or -- * MYSQLD_PACKET_EOF which means a OLD PASSWORD (4.0) was sent print("(read_auth_result) ... not ok yet"); elseif auth.packet:byte() == proxy.MYSQLD_PACKET_ERR then -- auth failed end end --- -- read/write splitting function read_query( packet ) if is_debug then print("[read_query]") print(" authed backend = " .. proxy.connection.backend_ndx) print(" used db = " .. proxy.connection.client.default_db) end if packet:byte() == proxy.COM_QUIT then -- don't send COM_QUIT to the backend. We manage the connection -- in all aspects. proxy.response = { type = proxy.MYSQLD_PACKET_OK, } if is_in_transaction then print(" transaction on, rollback now") proxy.queries.append(1, string:char(proxy.COM_QUERY) .. "ROLLBACK", { resultset_is_needed = false}) end return proxy.PROXY_SEND_RESULT end if proxy.connection.backend_ndx == 0 then if is_debug then print(" no connection, select now") end is_master = true if packet:byte() == proxy.COM_QUERY then command = packet:sub(2, 7) print(" command:" .. command) if string.lower(command) == "select" then print(" session not in transaction, select go to slave") is_master = false end end -- we don't have a backend right now -- -- let's pick a master as a good default for i = 1, #proxy.global.backends do local s = proxy.global.backends[i] local pool = s.pool -- we don't have a username yet, try to find a connections which is idling local cur_idle = pool.users[proxy.connection.client.username].cur_idle_connections if cur_idle > 0 and s.state ~= proxy.BACKEND_STATE_DOWN then if s.type == proxy.BACKEND_TYPE_RW and is_master == true then proxy.connection.backend_ndx = i break elseif s.type == proxy.BACKEND_TYPE_RO and is_master == false then proxy.connection.backend_ndx = i break end end end end if is_debug then print(" connection:" .. proxy.connection.backend_ndx) end if true or proxy.connection.client.default_db and proxy.connection.client.default_db ~= proxy.connection.server.default_db then -- sync the client-side default_db with the server-side default_db proxy.queries:append(2, string.char(proxy.COM_INIT_DB) .. proxy.connection.client.default_db, { resultset_is_needed = true }) end proxy.queries:append(1, packet, { resultset_is_needed = true }) return proxy.PROXY_SEND_QUERY end --- -- as long as we are in a transaction keep the connection -- otherwise release it so another client can use it function read_query_result( inj ) local res = assert(inj.resultset) local flags = res.flags if inj.id ~= 1 then -- ignore the result of the USE <default_db> return proxy.PROXY_IGNORE_RESULT end is_in_transaction = flags.in_trans if not is_in_transaction then -- release the backend proxy.connection.backend_ndx = 0 end end --- -- close the connections if we have enough connections in the pool -- -- @return nil - close connection -- IGNORE_RESULT - store connection in the pool function disconnect_client() if is_debug then print("[disconnect_client]") end if proxy.connection.backend_ndx == 0 then -- currently we don't have a server backend assigned -- -- pick a server which has too many idling connections and close one for i = 1, #proxy.global.backends do local s = proxy.global.backends[i] local pool = s.pool -- we don't have a username yet, try to find a connections which is idling local cur_idle = pool.users[proxy.connection.client.username].cur_idle_connections if s.state ~= proxy.BACKEND_STATE_DOWN and cur_idle > max_idle_connections then -- try to disconnect a backend proxy.connection.backend_ndx = i if is_debug then print(" [".. i .."] closing connection, idling: " .. cur_idle) end return end end end end