On Mon, 2012-07-09 at 16:49 +0400, Alexey Zakhlestin wrote:
> On 09.07.2012, at 14:17, Johannes Schlüter wrote:
>
> > an example like this:
> >
> > $pdo = new PDO("mysql:...");
> > $select = $pdo->prepare("SELECT * FROM t WHERE id = ?");
> > /* do something ... connection break in between */
> > $delete = $pdo->prepare("DELETE FROM t WHERE id = ?");
> > $select->execute([1]);
> >
> > This will in fact do a DELETE, not a SELECT as the statement handle
> > effectively is nothing but a per-connection counted unsigned long.
>
> Well, this sounds like a bug
>
> Prepared statements should become invalid once connection is lost and
> further attempts to execute them should lead to exception
Nothing PHP can do about.*) The reconnect, if requested, happens
silently. I've attached a simple test program (warning: not a good
example for libmysql usage, missing some error handling, leaking
everything etc.) demonstrating this behavior. Compile it using something
like
gcc `mysql_config --cflags --libs` mysql_reconnect_ps.c
after editing username and password for your setup. If you comment out
the mysql_kill() call the first statement will be executed, if you leave
it as is the second will be executed.
johannes
*) Well there's one thing PHP could do - check the thread-id for every
operation, if it changed there was a reconnect -- but better not use
silent reconnects at all ...
#include <unistd.h>
#include <mysql.h>
#include <stdio.h>
void main() {
MYSQL_STMT *stmt1, *stmt2;
my_bool my_true = 1;
MYSQL *mysql = mysql_init(NULL);
mysql_options(mysql, MYSQL_OPT_RECONNECT, &my_true);
if (!mysql_real_connect(mysql, "localhost", "USER", "PASS", "test", 0,
NULL, 0 )) {
fprintf(stderr, "mysql_real_connect() failed: %s",
mysql_error(mysql));
return;
}
stmt1 = mysql_stmt_init(mysql);
mysql_stmt_prepare(stmt1, "SELECT 1", sizeof("SELECT 1")-1);
mysql_kill(mysql, mysql_thread_id(mysql));
stmt2 = mysql_stmt_init(mysql);
mysql_stmt_prepare(stmt2, "SELECT 2 UNION SELECT 3", sizeof("SELECT 2
UNION SELECT 3")-1);
if (mysql_stmt_execute(stmt1))
{
fprintf(stderr, "Error: %s\n", mysql_stmt_error(stmt1));
return;
}
mysql_stmt_store_result(stmt1);
printf("got %i rows\n", mysql_stmt_num_rows(stmt1));
}
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