Bug#28141: Control C on query waiting on lock causes ERROR 1053 (server shutdown)

If a thread is killed in the server, we throw "shutdown" only if one is actually in
progress; otherwise, we throw "query interrupted".

Control-C in the mysql command-line client is "incremental" now.
First Control-C sends KILL QUERY (when connected to 5.0+ server, otherwise, see next)
Next  Control-C sends KILL CONNECTION
Next  Control-C aborts client.

As the first two steps only pertain to an existing query,
Control-C will abort the client right away if no query is running.

client will give more detailed/consistent feedback on Control-C now.

1 files changed, 19 insertions, 3 deletions

diff --git a/client/mysql.cc b/client/mysql.cc
index 0b8b44b3421..9474e4beccc 100644
--- a/client/mysql.cc
+++ b/client/mysql.cc
@@ -1219,18 +1219,34 @@ sig_handler mysql_sigint(int sig)
   MYSQL *kill_mysql= NULL;
 
   /* terminate if no query being executed, or we already tried interrupting */
-  if (!executing_query || interrupted_query++)
+  if (!executing_query || (interrupted_query == 2))
+  {
+    tee_fprintf(stdout, "Ctrl-C -- exit!\n");
     goto err;
+  }
 
   kill_mysql= mysql_init(kill_mysql);
   if (!mysql_real_connect(kill_mysql,current_host, current_user, opt_password,
                           "", opt_mysql_port, opt_mysql_unix_port,0))
+  {
+    tee_fprintf(stdout, "Ctrl-C -- sorry, cannot connect to server to kill query, giving up ...\n");
     goto err;
+  }
+
+  interrupted_query++;
+
+  /* mysqld < 5 does not understand KILL QUERY, skip to KILL CONNECTION */
+  if ((interrupted_query == 1) && (mysql_get_server_version(&mysql) < 50000))
+    interrupted_query= 2;
+
   /* kill_buffer is always big enough because max length of %lu is 15 */
-  sprintf(kill_buffer, "KILL /*!50000 QUERY */ %lu", mysql_thread_id(&mysql));
+  sprintf(kill_buffer, "KILL %s%lu",
+          (interrupted_query == 1) ? "QUERY " : "",
+          mysql_thread_id(&mysql));
+  tee_fprintf(stdout, "Ctrl-C -- sending \"%s\" to server ...\n", kill_buffer);
   mysql_real_query(kill_mysql, kill_buffer, (uint) strlen(kill_buffer));
   mysql_close(kill_mysql);
-  tee_fprintf(stdout, "Query aborted by Ctrl+C\n");
+  tee_fprintf(stdout, "Ctrl-C -- query aborted.\n");
 
   return;