mysql-proxy实现读写分离脚本

sunny03

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function set_error(errmsg)
　　proxy.response = {
　　type = proxy.MYSQLD_PACKET_ERR,
　　errmsg = errmsg or "error"
　　}
　　
end
　　

　　
function read_query(packet)
　　if packet:byte() ~= proxy.COM_QUERY then
　　set_error("[admin] we only handle text-based queries (COM_QUERY)")
　　return proxy.PROXY_SEND_RESULT
　　end
　　

　　local query = packet:sub(2)
　　

　　local rows = { }
　　local fields = { }
　　

　　if query:lower() == "select * from backends" then
　　fields = {
　　{ name = "backend_ndx",
　　type = proxy.MYSQL_TYPE_LONG },
　　

　　{ name = "address",
　　type = proxy.MYSQL_TYPE_STRING },
　　{ name = "state",
　　type = proxy.MYSQL_TYPE_STRING },
　　{ name = "type",
　　type = proxy.MYSQL_TYPE_STRING },
　　{ name = "uuid",
　　type = proxy.MYSQL_TYPE_STRING },
　　{ name = "connected_clients",
　　type = proxy.MYSQL_TYPE_LONG },
　　}
　　

　　for i = 1, #proxy.global.backends do
　　local states = {
　　"unknown",
　　"up",
　　"down"
　　}
　　local types = {
　　"unknown",
　　"rw",
　　"ro"
　　}
　　local b = proxy.global.backends
　　

　　rows[#rows + 1] = {
　　i,
　　b.dst.name,          -- configured backend address
　　states[b.state + 1], -- the C-id is pushed down starting at 0
　　types[b.type + 1],   -- the C-id is pushed down starting at 0
　　b.uuid,              -- the MySQL Server's UUID if it is managed
　　b.connected_clients  -- currently connected clients
　　}
　　end
　　elseif query:lower() == "select * from help" then
　　fields = {
　　{ name = "command",
　　type = proxy.MYSQL_TYPE_STRING },
　　{ name = "description",
　　type = proxy.MYSQL_TYPE_STRING },
　　}
　　rows[#rows + 1] = { "SELECT * FROM help", "shows this help" }
　　rows[#rows + 1] = { "SELECT * FROM backends", "lists the backends and their state" }
　　else
　　set_error("use 'SELECT * FROM help' to see the supported commands")
　　return proxy.PROXY_SEND_RESULT
　　end
　　

　　proxy.response = {
　　type = proxy.MYSQLD_PACKET_OK,
　　resultset = {
　　fields = fields,
　　rows = rows
　　}
　　}
　　return proxy.PROXY_SEND_RESULT
　　
end