iSQL

Clone of ibrowse 1 and emysql 2 for pipelined mysql requests. Performs load balancing of requests among multiple mysql connections with pipelining. Has interface similar to ibrowse. Alpha version.

Usage

-include("isql.hrl").
-include("ems.hrl").

init() ->
    application:start(isql).

sql_init() ->
    SQLEntity = #sql_entity{
                    host = "localhost", port = 3306,
                    username = "virtan", password = "virtan.com",
                    database = "life", encoding = utf8
                },
    isql:set_max_sessions(SQLEntity, 2),
    isql:set_max_pipeline_size(SQLEntity, 10),
    SQLEntity.

sql_execute(SQLEntity, SQL) ->
    case isql:send_req(SQLEntity, SQL) of
        {ok, #result_packet{rows = Rows}} -> {ok, Rows};
        {ok, #ok_packet{affected_rows = Affected}} -> {ok, Affected};
        {ok, #error_packet{msg = Reason}} -> {error, Reason};
        {error, _} = Error -> Error
    end.

compile_sql(QueryBinary, Args) ->
    Sd = binary:split(QueryBinary, <<"?">>, [global]),
    case {length(Sd), length(Args)} of
        {N, M} when N == M + 1 ->
            Args1 = [ems_util:encode(A, true) || A <- Args],
            iolist_to_binary(lists:zipwith(fun(A, B) -> [B, A] end, Sd, [<<>> | Args1]));
        _ ->
            throw(sql_wrong_number_of_arguments)
    end.

test() ->
    init(),
    SQLEntity = sql_init(),
    SQL = compile_sql(<<"select * from data where id = ? and age < ?">>, ["a123", 21]),
    {ok, [[<<"a123">>, <<"Valya">>, 20],
          [<<"a123">>, <<"Kolya">>, 1]]} = sql_execute(SQLEntity, SQL),
    {ok, 1} = sql_execute(SQLEntity,
                "insert into data(id, name, age) values('a123', 'Igor', 35)"),
    {error, "You have an error in your SQL syntax" ++ _} =
            sql_execute(SQLEntity, "insert into nonexistent(id), values(1)"),
    {error, {conn_failed, eacces}} =
            sql_execute(SQLEntity#sql_entity{host = "255.255.255.255"},
                "select 2").

It's recommended to use SafetyValve 3 to control overall load of database server.

sql_init(Supervisor, SVConfig) ->
    SQLEntity = #sql_entity{
                    host = "localhost", port = 3306,
                    username = "virtan", password = "virtan.com",
                    database = "life", encoding = utf8
                },
    isql:set_max_sessions(SQLEntity, 2),
    isql:set_max_pipeline_size(SQLEntity, 10),
    {ok, _} = supervisor:start_child(Supervisor, {life_sv,
                {sv_queue, start_link, [life_sv, sv_queue:parse_configuration(SVConfig)]},
                permanent, 10000, worker, [sv_queue]}),
    SQLEntity.

sql_execute(SQLEntity, SQL) ->
    case sv_run(life_sv, fun() -> isql:send_req(SQLEntity, SQL) end) of
        {ok, {ok, #result_packet{rows = Rows}}} -> {ok, Rows};
        {ok, {ok, #ok_packet{affected_rows = Affected}}} -> {ok, Affected};
        {ok, {ok, #error_packet{msg = Reason}}} -> {error, Reason};
        {ok, {error, _} = Error} -> Error;
        {error, _} = Error -> Error
    end.

Author

Igor Milyakov [[email protected]] 4

License

The MIT License (MIT)

Copyright (c) 2013 Igor Milyakov [email protected]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.