Hi
We have a problem with the (ODBC) persistent database connection. We
have found that every PHP-session, using the same dsn, user and
password, are getting the same persistent connection by a reasonable
chance.
Also meaning that if a database transaction was not finished, other
PHP-session can do a rollback or commit of that transaction.
Due to resource problems with (temporarily) connections the persistent
connections are used, so we do. But "leftovers" of database transactions
were not intended.
Also if one want to open an another connection in one PHP-session the
result is the same connection. (E.g. we use a DB-log-file to log errors
en warning, so you don't want to do a rollback on the DB-log-file, in
peculiar.)
To overcome these problems one has to tag the connections. I suggest to
use a new parameter on ODBC_(p)connect: Tag, a string parameter. If used
it tries to re-connect to the connection with the same tag, if not
existing it creates a new-connection.
For example the tag parameter is filled with the session_ID() to ensure
that a connection is bounded to one PHP-session. But also an extension
on this value is possible: (Session_ID() + 'Log') or (Session_ID() +
'Data').
And if somebody does not uses this tag parameter, it works in the old
way, so these solution is downwards compatible.
So the adjusted description will be:
resource odbc_pconnect (string $dsn , string $user , string $password [,
int $cursor_type [, string $tag ] ] )
Eg ODBC_pconnect( $dns, $user,, $password, SQL_CUR_DEFAULT,
Session_ID()+ 'LOG')
The change of the PHP source of the function odbc_do_connect is minimal:
void odbc_do_connect(INTERNAL_FUNCTION_PARAMETERS, int persistent) {
char *db = NULL;
char *uid = NULL;
char *pwd = NULL;
char *tag = NULL;
zval **pv_db, **pv_uid, **pv_pwd, **pv_opt, **pv_tag;
odbc_connection *db_conn;
char *hashed_details;
int hashed_len, cur_opt;
/* Now an optional 4th parameter specifying the cursor type
* defaulting to the cursors default
*/
switch(ZEND_NUM_ARGS()) {
case 3:
if (zend_get_parameters_ex(3, &pv_db, &pv_uid,
&pv_pwd) == FAILURE) {
WRONG_PARAM_COUNT;
}
/* Use Default: Probably a better way to do this
*/
cur_opt = SQL_CUR_DEFAULT;
tag = '';
break;
case 4:
if (zend_get_parameters_ex(4, &pv_db, &pv_uid,
&pv_pwd, &pv_opt) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_long_ex(pv_opt);
cur_opt = Z_LVAL_PP(pv_opt);
/* Confirm the cur_opt range */
if (! (cur_opt == SQL_CUR_USE_IF_NEEDED ||
cur_opt == SQL_CUR_USE_ODBC ||
cur_opt == SQL_CUR_USE_DRIVER ||
cur_opt == SQL_CUR_DEFAULT) ) {
php_error_docref(NULL TSRMLS_CC,
E_WARNING, "Invalid Cursor type (%d)", cur_opt);
RETURN_FALSE;
}
tag = '';
break;
case 5:
if (zend_get_parameters_ex(5, &pv_db, &pv_uid,
&pv_pwd, &pv_opt, &pv_tag) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_long_ex(pv_opt);
cur_opt = Z_LVAL_PP(pv_opt);
/* Confirm the cur_opt range */
if (! (cur_opt == SQL_CUR_USE_IF_NEEDED ||
cur_opt == SQL_CUR_USE_ODBC ||
cur_opt == SQL_CUR_USE_DRIVER ||
cur_opt == SQL_CUR_DEFAULT) ) {
php_error_docref(NULL TSRMLS_CC,
E_WARNING, "Invalid Cursor type (%d)", cur_opt);
RETURN_FALSE;
}
convert_to_string_ex(pv_tag);
tag = Z_STRVAL_PP(pv_tag);
break;
default:
WRONG_PARAM_COUNT;
break;
}
convert_to_string_ex(pv_db);
convert_to_string_ex(pv_uid);
convert_to_string_ex(pv_pwd);
db = Z_STRVAL_PP(pv_db);
uid = Z_STRVAL_PP(pv_uid);
pwd = Z_STRVAL_PP(pv_pwd);
if (ODBCG(allow_persistent) <= 0) {
persistent = 0;
}
hashed_len = spprintf(&hashed_details, 0, "%s_%s_%s_%s_%d_%s",
ODBC_TYPE, db, uid, pwd, cur_opt, tag);
Gomar Bijl
Software Engineer BU400
CAL Consult
Phone +31 (0) 318 - 691 300
Fax +31 (0) 318 - 691 301
Direct +31 (0) 318 - 691 366
E-mail gomar.bijl@cal-consult.nl
KvK nr. 09078710
Software for logistics www.cal-consult.nl <http://www.cal-consult.nl/
Hi
We have a problem with the (ODBC) persistent database connection. We
have found that every PHP-session, using the same dsn, user and
password, are getting the same persistent connection by a reasonable
chance.
Also meaning that if a database transaction was not finished, other
PHP-session can do a rollback or commit of that transaction.
Right, I presume you are aware of the documentation on this topic,
which affects all rdbms extensions. Just to be sure here is the link:
http://php.net/manual/en/features.persistent-connections.php
To overcome these problems one has to tag the connections. I suggest
to
use a new parameter on ODBC_(p)connect: Tag, a string parameter. If
used
it tries to re-connect to the connection with the same tag, if not
existing it creates a new-connection.
For example the tag parameter is filled with thesession_ID()to
ensure
that a connection is bounded to one PHP-session. But also an extension
on this value is possible: (Session_ID() + 'Log') or (Session_ID() +
'Data').
And if somebody does not uses this tag parameter, it works in the old
way, so these solution is downwards compatible.
Several extensions offer a "new_link" optional boolean parameter to
ensure that a new connection is returned if there is already an
existing connection in this request:
http://php.net/mysql_connect
IIRC this "feature" (returning an existing connection link of a
section connection is made to the same server in the same request) is
not present in all extensions, but since ext/mysql was sort of a
template for many extensions, I think a lot of developers copied this
behavior. Note that this parameter is not available in the pconnect
alternatives.
ideally the odbc extension should do a "change user", which would
clean up all the session specific stuff inside the connection (next to
open transactions, there are other stuff like date formats etc that
could also be set). i am not however sure if this feature exists in
all rdbms. afaik the mysql developers are looking to implement this
into mysqlnd.
either way, any solution should try to be consistent across all
affected extensions.
regards,
Lukas Kahwe Smith
mls@pooteeweet.org