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%%%----------------------------------------------------------------------
%%% File : ejabberd_odbc.erl
%%% Author : Alexey Shchepin <alexey@sevcom.net>
%%% Purpose : Serve ODBC connection
%%% Created : 8 Dec 2004 by Alexey Shchepin <alexey@sevcom.net>
%%% Id : $Id$
%%%----------------------------------------------------------------------
-module(ejabberd_odbc).
-author('alexey@sevcom.net').
-vsn('$Revision$ ').
-behaviour(gen_server).
%% External exports
-export([start/1, start_link/1,
sql_query/2,
sql_query_t/1,
sql_transaction/2,
escape/1,
escape_like/1]).
%% gen_server callbacks
-export([init/1,
handle_call/3,
handle_cast/2,
code_change/3,
handle_info/2,
terminate/2]).
-include("ejabberd.hrl").
-record(state, {db_ref, db_type}).
-define(STATE_KEY, ejabberd_odbc_state).
-define(MAX_TRANSACTION_RESTARTS, 10).
-define(MYSQL_PORT, 3306).
%%%----------------------------------------------------------------------
%%% API
%%%----------------------------------------------------------------------
start(Host) ->
gen_server:start(ejabberd_odbc, [Host], []).
start_link(Host) ->
gen_server:start_link(ejabberd_odbc, [Host], []).
sql_query(Host, Query) ->
gen_server:call(ejabberd_odbc_sup:get_random_pid(Host),
{sql_query, Query}, 60000).
%% SQL transaction based on a list of queries
%% This function automatically
sql_transaction(Host, Queries) when is_list(Queries) ->
F = fun() ->
lists:foreach(fun(Query) ->
sql_query_t(Query)
end,
Queries)
end,
sql_transaction(Host, F);
%% SQL transaction, based on a erlang anonymous function (F = fun)
sql_transaction(Host, F) ->
gen_server:call(ejabberd_odbc_sup:get_random_pid(Host),
{sql_transaction, F}, 60000).
%% This function is intended to be used from inside an sql_transaction:
sql_query_t(Query) ->
State = get(?STATE_KEY),
QRes = sql_query_internal(State, Query),
case QRes of
{error, "No SQL-driver information available."} ->
% workaround for odbc bug
{updated, 0};
{error, _} ->
throw(aborted);
Rs when is_list(Rs) ->
case lists:keymember(error, 1, Rs) of
true ->
throw(aborted);
_ ->
QRes
end;
_ ->
QRes
end.
%% Escape character that will confuse an SQL engine
escape(S) when is_list(S) ->
[odbc_queries:escape(C) || C <- S].
%% Escape character that will confuse an SQL engine
%% Percent and underscore only need to be escaped for pattern matching like
%% statement
escape_like(S) when is_list(S) ->
[escape_like(C) || C <- S];
escape_like($%) -> "\\%";
escape_like($_) -> "\\_";
escape_like(C) -> odbc_queries:escape(C).
%%%----------------------------------------------------------------------
%%% Callback functions from gen_server
%%%----------------------------------------------------------------------
%%----------------------------------------------------------------------
%% Func: init/1
%% Returns: {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%%----------------------------------------------------------------------
init([Host]) ->
SQLServer = ejabberd_config:get_local_option({odbc_server, Host}),
case SQLServer of
{pgsql, Server, DB, Username, Password} ->
pgsql_connect(Server, DB, Username, Password);
{mysql, Server, DB, Username, Password} ->
mysql_connect(Server, DB, Username, Password);
_ when is_list(SQLServer) ->
odbc_connect(SQLServer)
end.
%%----------------------------------------------------------------------
%% Func: handle_call/3
%% Returns: {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} | (terminate/2 is called)
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_call({sql_query, Query}, _From, State) ->
Reply = sql_query_internal(State, Query),
{reply, Reply, State};
handle_call({sql_transaction, F}, _From, State) ->
Reply = execute_transaction(State, F, ?MAX_TRANSACTION_RESTARTS),
{reply, Reply, State};
handle_call(_Request, _From, State) ->
Reply = ok,
{reply, Reply, State}.
%%----------------------------------------------------------------------
%% Func: handle_cast/2
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
handle_cast(_Msg, State) ->
{noreply, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%----------------------------------------------------------------------
%% Func: handle_info/2
%% Returns: {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State} (terminate/2 is called)
%%----------------------------------------------------------------------
%% We receive the down signal when we loose the MySQL connection (we are
%% monitoring the connection)
%% => We exit and let the supervisor restart the connection.
handle_info({'DOWN', _MonitorRef, process, _Pid, _Info}, State) ->
{stop, connection_dropped, State};
handle_info(_Info, State) ->
{noreply, State}.
%%----------------------------------------------------------------------
%% Func: terminate/2
%% Purpose: Shutdown the server
%% Returns: any (ignored by gen_server)
%%----------------------------------------------------------------------
terminate(_Reason, _State) ->
ok.
%%%----------------------------------------------------------------------
%%% Internal functions
%%%----------------------------------------------------------------------
sql_query_internal(State, Query) ->
case State#state.db_type of
odbc ->
odbc:sql_query(State#state.db_ref, Query);
pgsql ->
pgsql_to_odbc(pgsql:squery(State#state.db_ref, Query));
mysql ->
mysql_to_odbc(mysql_conn:fetch(State#state.db_ref, Query, self()))
end.
execute_transaction(_State, _F, 0) ->
{aborted, restarts_exceeded};
execute_transaction(State, F, NRestarts) ->
put(?STATE_KEY, State),
sql_query_internal(State, "begin;"),
case catch F() of
aborted ->
execute_transaction(State, F, NRestarts - 1);
{'EXIT', Reason} ->
sql_query_internal(State, "rollback;"),
{aborted, Reason};
Res ->
sql_query_internal(State, "commit;"),
{atomic, Res}
end.
%% == pure ODBC code
%% part of init/1
%% Open an ODBC database connection
odbc_connect(SQLServer) ->
case odbc:connect(SQLServer,[{scrollable_cursors, off}]) of
{ok, Ref} ->
erlang:monitor(process, Ref),
{ok, #state{db_ref = Ref, db_type = odbc}};
{error, Reason} ->
?ERROR_MSG("ODBC connection (~s) failed: ~p~n",
[SQLServer, Reason]),
%% If we can't connect we wait for 30 seconds before retrying
timer:sleep(30000),
{stop, odbc_connection_failed}
end.
%% == Native PostgreSQL code
%% part of init/1
%% Open a database connection to PostgreSQL
pgsql_connect(Server, DB, Username, Password) ->
case pgsql:connect(Server, DB, Username, Password) of
{ok, Ref} ->
{ok, #state{db_ref = Ref, db_type = pgsql}};
{error, Reason} ->
?ERROR_MSG("PostgreSQL connection failed: ~p~n", [Reason]),
%% If we can't connect we wait for 30 seconds before retrying
timer:sleep(30000),
{stop, pgsql_connection_failed}
end.
%% Convert PostgreSQL query result to Erlang ODBC result formalism
pgsql_to_odbc({ok, PGSQLResult}) ->
case PGSQLResult of
[Item] ->
pgsql_item_to_odbc(Item);
Items ->
[pgsql_item_to_odbc(Item) || Item <- Items]
end.
pgsql_item_to_odbc({"SELECT", Rows, Recs}) ->
{selected,
[element(1, Row) || Row <- Rows],
[list_to_tuple(Rec) || Rec <- Recs]};
pgsql_item_to_odbc("INSERT " ++ OIDN) ->
[_OID, N] = string:tokens(OIDN, " "),
{updated, list_to_integer(N)};
pgsql_item_to_odbc("DELETE " ++ N) ->
{updated, list_to_integer(N)};
pgsql_item_to_odbc({error, Error}) ->
{error, Error};
pgsql_item_to_odbc(_) ->
{updated,undefined}.
%% == Native MySQL code
%% part of init/1
%% Open a database connection to MySQL
mysql_connect(Server, DB, Username, Password) ->
NoLogFun = fun(_Level,_Format,_Argument) -> ok end,
case mysql_conn:start(Server, ?MYSQL_PORT, Username, Password, DB, NoLogFun) of
{ok, Ref} ->
erlang:monitor(process, Ref),
{ok, #state{db_ref = Ref, db_type = mysql}};
{error, Reason} ->
?ERROR_MSG("MySQL connection failed: ~p~n", [Reason]),
%% If we can't connect we wait for 30 seconds before retrying
timer:sleep(30000),
{stop, mysql_connection_failed}
end.
%% Convert MySQL query result to Erlang ODBC result formalism
mysql_to_odbc({updated, MySQLRes}) ->
{updated, mysql:get_result_affected_rows(MySQLRes)};
mysql_to_odbc({data, MySQLRes}) ->
mysql_item_to_odbc(mysql:get_result_field_info(MySQLRes),
mysql:get_result_rows(MySQLRes));
mysql_to_odbc({error, MySQLRes}) ->
{error, mysql:get_result_reason(MySQLRes)}.
%% When tabular data is returned, convert it to the ODBC formalism
mysql_item_to_odbc(Columns, Recs) ->
%% For now, there is a bug and we do not get the correct value from MySQL
%% module:
{selected,
[element(2, Column) || Column <- Columns],
[list_to_tuple(Rec) || Rec <- Recs]}.
|
