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9a204593e1
xmpp.chapril.org-ejabberd/src/odbc/ejabberd_odbc.erl
Badlop 9a204593e1 Merge 2425 from trunk: fix keepalive query, broken by r2092. 
SVN Revision: 2435
2009-08-06 21:57:53 +00:00

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%%%----------------------------------------------------------------------
%%% File : ejabberd_odbc.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Serve ODBC connection
%%% Created : 8 Dec 2004 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2009 ProcessOne
%%%
%%% 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; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% 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
%%%
%%%----------------------------------------------------------------------
-module(ejabberd_odbc).
-author('alexey@process-one.net').
-behaviour(gen_server).
%% External exports
-export([start/1, start_link/2,
sql_query/2,
sql_query_t/1,
sql_transaction/2,
sql_bloc/2,
escape/1,
escape_like/1,
keep_alive/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(NESTING_KEY, ejabberd_odbc_nesting_level).
-define(TOP_LEVEL_TXN, 0).
-define(MAX_TRANSACTION_RESTARTS, 10).
-define(PGSQL_PORT, 5432).
-define(MYSQL_PORT, 3306).
-define(TRANSACTION_TIMEOUT, 60000).
-define(KEEPALIVE_TIMEOUT, 60000).
-define(KEEPALIVE_QUERY, "SELECT 1;").
%%%----------------------------------------------------------------------
%%% API
%%%----------------------------------------------------------------------
start(Host) ->
gen_server:start(ejabberd_odbc, [Host], []).
start_link(Host, StartInterval) ->
gen_server:start_link(ejabberd_odbc, [Host, StartInterval], []).
sql_query(Host, Query) ->
sql_call(Host, {sql_query, Query}).
%% 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) when is_function(F) ->
sql_call(Host, {sql_transaction, F}).
%% SQL bloc, based on a erlang anonymous function (F = fun)
sql_bloc(Host, F) ->
sql_call(Host, {sql_bloc, F}).
sql_call(Host, Msg) ->
case get(?STATE_KEY) of
undefined ->
gen_server:call(ejabberd_odbc_sup:get_random_pid(Host),
{sql_cmd, Msg}, ?TRANSACTION_TIMEOUT);
_State ->
nested_op(Msg)
end.
%% This function is intended to be used from inside an sql_transaction:
sql_query_t(Query) ->
QRes = sql_query_internal(Query),
case QRes of
{error, Reason} ->
throw({aborted, Reason});
Rs when is_list(Rs) ->
case lists:keysearch(error, 1, Rs) of
{value, {error, Reason}} ->
throw({aborted, Reason});
_ ->
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(S) when is_binary(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, StartInterval]) ->
case ejabberd_config:get_local_option({odbc_keepalive_interval, Host}) of
KeepaliveInterval when is_integer(KeepaliveInterval) ->
timer:apply_interval(KeepaliveInterval*1000, ?MODULE, keep_alive, [self()]);
undefined ->
ok;
_Other ->
?ERROR_MSG("Wrong odbc_keepalive_interval definition '~p' for host ~p.~n", [_Other, Host])
end,
SQLServer = ejabberd_config:get_local_option({odbc_server, Host}),
case SQLServer of
%% Default pgsql port
{pgsql, Server, DB, Username, Password} ->
pgsql_connect(Server, ?PGSQL_PORT, DB, Username, Password, StartInterval);
{pgsql, Server, Port, DB, Username, Password} when is_integer(Port) ->
pgsql_connect(Server, Port, DB, Username, Password, StartInterval);
%% Default mysql port
{mysql, Server, DB, Username, Password} ->
mysql_connect(Server, ?MYSQL_PORT, DB, Username, Password, StartInterval);
{mysql, Server, Port, DB, Username, Password} when is_integer(Port) ->
mysql_connect(Server, Port, DB, Username, Password, StartInterval);
_ when is_list(SQLServer) ->
odbc_connect(SQLServer, StartInterval)
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_cmd, Command}, _From, State) ->
put(?NESTING_KEY, ?TOP_LEVEL_TXN),
put(?STATE_KEY, State),
abort_on_driver_error(outer_op(Command));
handle_call(Request, {Who, _Ref}, State) ->
?WARNING_MSG("Unexpected call ~p from ~p.", [Request, Who]),
{reply, ok, 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) ->
case State#state.db_type of
mysql ->
% old versions of mysql driver don't have the stop function
% so the catch
catch mysql_conn:stop(State#state.db_ref);
_ ->
ok
end,
ok.
%%%----------------------------------------------------------------------
%%% Internal functions
%%%----------------------------------------------------------------------
%% Only called by handle_call, only handles top level operations.
%% @spec outer_op(Op) -> {error, Reason} | {aborted, Reason} | {atomic, Result}
outer_op({sql_query, Query}) ->
sql_query_internal(Query);
outer_op({sql_transaction, F}) ->
outer_transaction(F, ?MAX_TRANSACTION_RESTARTS, "");
outer_op({sql_bloc, F}) ->
execute_bloc(F).
%% Called via sql_query/transaction/bloc from client code when inside a
%% nested operation
nested_op({sql_query, Query}) ->
%% XXX - use sql_query_t here insted? Most likely would break
%% callers who expect {error, _} tuples (sql_query_t turns
%% these into throws)
sql_query_internal(Query);
nested_op({sql_transaction, F}) ->
NestingLevel = get(?NESTING_KEY),
if NestingLevel =:= ?TOP_LEVEL_TXN ->
%% First transaction inside a (series of) sql_blocs
outer_transaction(F, ?MAX_TRANSACTION_RESTARTS, "");
true ->
%% Transaction inside a transaction
inner_transaction(F)
end;
nested_op({sql_bloc, F}) ->
execute_bloc(F).
%% Never retry nested transactions - only outer transactions
inner_transaction(F) ->
PreviousNestingLevel = get(?NESTING_KEY),
case get(?NESTING_KEY) of
?TOP_LEVEL_TXN ->
{backtrace, T} = process_info(self(), backtrace),
?ERROR_MSG("inner transaction called at outer txn level. Trace: ~s", [T]),
erlang:exit(implementation_faulty);
_N -> ok
end,
put(?NESTING_KEY, PreviousNestingLevel + 1),
Result = (catch F()),
put(?NESTING_KEY, PreviousNestingLevel),
case Result of
{aborted, Reason} ->
{aborted, Reason};
{'EXIT', Reason} ->
{'EXIT', Reason};
{atomic, Res} ->
{atomic, Res};
Res ->
{atomic, Res}
end.
outer_transaction(F, NRestarts, _Reason) ->
PreviousNestingLevel = get(?NESTING_KEY),
case get(?NESTING_KEY) of
?TOP_LEVEL_TXN ->
ok;
_N ->
{backtrace, T} = process_info(self(), backtrace),
?ERROR_MSG("outer transaction called at inner txn level. Trace: ~s", [T]),
erlang:exit(implementation_faulty)
end,
sql_query_internal("begin;"),
put(?NESTING_KEY, PreviousNestingLevel + 1),
Result = (catch F()),
put(?NESTING_KEY, PreviousNestingLevel),
case Result of
{aborted, Reason} when NRestarts > 0 ->
%% Retry outer transaction upto NRestarts times.
sql_query_internal("rollback;"),
outer_transaction(F, NRestarts - 1, Reason);
{aborted, Reason} when NRestarts =:= 0 ->
%% Too many retries of outer transaction.
?ERROR_MSG("SQL transaction restarts exceeded~n"
"** Restarts: ~p~n"
"** Last abort reason: ~p~n"
"** Stacktrace: ~p~n"
"** When State == ~p",
[?MAX_TRANSACTION_RESTARTS, Reason,
erlang:get_stacktrace(), get(?STATE_KEY)]),
sql_query_internal("rollback;"),
{aborted, Reason};
{'EXIT', Reason} ->
%% Abort sql transaction on EXIT from outer txn only.
sql_query_internal("rollback;"),
{aborted, Reason};
Res ->
%% Commit successful outer txn
sql_query_internal("commit;"),
{atomic, Res}
end.
execute_bloc(F) ->
%% We don't alter ?NESTING_KEY here as only SQL transactions alter txn nesting
case catch F() of
{aborted, Reason} ->
{aborted, Reason};
{'EXIT', Reason} ->
{aborted, Reason};
Res ->
{atomic, Res}
end.
sql_query_internal(Query) ->
State = get(?STATE_KEY),
Res = 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 ->
?DEBUG("MySQL, Send query~n~p~n", [Query]),
R = mysql_to_odbc(mysql_conn:fetch(State#state.db_ref, Query, self())),
?INFO_MSG("MySQL, Received result~n~p~n", [R]),
R
end,
case Res of
{error, "No SQL-driver information available."} ->
% workaround for odbc bug
{updated, 0};
_Else -> Res
end.
%% Generate the OTP callback return tuple depending on the driver result.
abort_on_driver_error({error, "query timed out"} = Reply) ->
%% mysql driver error
{stop, timeout, Reply, get(?STATE_KEY)};
abort_on_driver_error({error, "Failed sending data on socket"++_} = Reply) ->
%% mysql driver error
{stop, closed, Reply, get(?STATE_KEY)};
abort_on_driver_error(Reply) ->
{reply, Reply, get(?STATE_KEY)}.
%% == pure ODBC code
%% part of init/1
%% Open an ODBC database connection
odbc_connect(SQLServer, StartInterval) ->
application:start(odbc),
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 before retrying
timer:sleep(StartInterval),
{stop, odbc_connection_failed}
end.
%% == Native PostgreSQL code
%% part of init/1
%% Open a database connection to PostgreSQL
pgsql_connect(Server, Port, DB, Username, Password, StartInterval) ->
case pgsql:connect(Server, DB, Username, Password, Port) of
{ok, Ref} ->
erlang:monitor(process, 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 before retrying
timer:sleep(StartInterval),
{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("UPDATE " ++ 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, Port, DB, Username, Password, StartInterval) ->
case mysql_conn:start(Server, Port, Username, Password, DB, fun log/3) of
{ok, Ref} ->
erlang:monitor(process, Ref),
mysql_conn:fetch(Ref, ["set names 'utf8';"], self()),
{ok, #state{db_ref = Ref, db_type = mysql}};
{error, Reason} ->
?ERROR_MSG("MySQL connection failed: ~p~nWaiting ~p seconds before retrying...~n",
[Reason, StartInterval div 1000]),
%% If we can't connect we wait before retrying
timer:sleep(StartInterval),
{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}) when is_list(MySQLRes) ->
{error, 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]}.
% perform a harmless query on all opened connexions to avoid connexion close.
keep_alive(PID) ->
gen_server:call(PID, {sql_cmd, {sql_query, ?KEEPALIVE_QUERY}},
?KEEPALIVE_TIMEOUT).
% log function used by MySQL driver
log(Level, Format, Args) ->
case Level of
debug ->
?DEBUG(Format, Args);
normal ->
?INFO_MSG(Format, Args);
error ->
?ERROR_MSG(Format, Args)
end.
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