CONC-184 : provide a function to cancel a current connection

(without invalidating MYSQL struct, without sending KILL)
This apparently is useful for replication handling in the server

include/ma_pvio.h

@@ -105,6 +105,7 @@ struct st_ma_pvio_methods
   my_bool (*is_blocking)(MARIADB_PVIO *pvio);
   my_bool (*is_alive)(MARIADB_PVIO *pvio);
   my_bool (*has_data)(MARIADB_PVIO *pvio, ssize_t *data_len);
+  int(*shutdown)(MARIADB_PVIO *pvio);
 };
 
 /* Function prototypes */

include/mysql.h

@@ -570,6 +570,7 @@ my_socket STDCALL mysql_get_socket(MYSQL *mysql);
 unsigned int STDCALL mysql_get_timeout_value(const MYSQL *mysql);
 unsigned int STDCALL mysql_get_timeout_value_ms(const MYSQL *mysql);
 my_bool STDCALL mariadb_reconnect(MYSQL *mysql);
+int STDCALL mariadb_cancel(MYSQL *mysql);
 
 /* Async API */
 int STDCALL mysql_close_start(MYSQL *sock);

libmariadb/mariadb_lib.c

@@ -3804,6 +3804,24 @@ my_bool STDCALL mariadb_get_info(MYSQL *mysql, enum mariadb_value value, void *a
   return mariadb_get_infov(mysql, value, arg);
 }
 
+/* 
+  Immediately aborts connection, making all subsequent read/write operations fail.
+  Does not invalidate memory used for mysql structure, nor closes any communication
+  channels - mysql_close is still needed.
+  Useful to break long query, in situation  sending KILL is not possible.
+*/
+int STDCALL mariadb_cancel(MYSQL *mysql)
+{
+  if (!mysql || !mysql->net.pvio || !mysql->net.pvio->methods || !mysql->net.pvio->methods->shutdown)
+  {
+    return 1;
+  }
+  else
+  {
+    MARIADB_PVIO *pvio = mysql->net.pvio;
+    return pvio->methods->shutdown(pvio);
+  }
+}
 #undef STDCALL
 /* API functions for usage in dynamic plugins */
 struct st_mariadb_api MARIADB_API=

plugins/pvio/pvio_npipe.c

@@ -45,6 +45,7 @@ int pvio_npipe_fast_send(MARIADB_PVIO *pvio);
 int pvio_npipe_keepalive(MARIADB_PVIO *pvio);
 my_bool pvio_npipe_get_handle(MARIADB_PVIO *pvio, void *handle);
 my_bool pvio_npipe_is_blocking(MARIADB_PVIO *pvio);
+int pvio_npipe_shutdown(MARIADB_PVIO *pvio);
 
 struct st_ma_pvio_methods pvio_npipe_methods= {
   pvio_npipe_set_timeout,
@@ -60,7 +61,8 @@ struct st_ma_pvio_methods pvio_npipe_methods= {
   pvio_npipe_fast_send,
   pvio_npipe_keepalive,
   pvio_npipe_get_handle,
-  pvio_npipe_is_blocking
+  pvio_npipe_is_blocking,
+  pvio_npipe_shutdown
 };
 
 #ifndef HAVE_NPIPE_DYNAMIC
@@ -354,4 +356,13 @@ my_bool pvio_npipe_is_blocking(MARIADB_PVIO *pvio)
   return (flags & PIPE_NOWAIT) ? 0 : 1;
 }
 
+int pvio_npipe_shutdown(MARIADB_PVIO *pvio)
+{
+  HANDLE h;
+  if (pvio_npipe_get_handle(pvio, &h) == 0)
+  {
+    return(CancelIoEx(h, NULL) ? 0 : 1);
+  }
+  return 1;
+}
 #endif

plugins/pvio/pvio_shmem.c

@@ -40,7 +40,7 @@ int pvio_shm_wait_io_or_timeout(MARIADB_PVIO *pvio, my_bool is_read, int timeout
 my_bool pvio_shm_blocking(MARIADB_PVIO *pvio, my_bool value, my_bool *old_value);
 my_bool pvio_shm_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo);
 my_bool pvio_shm_close(MARIADB_PVIO *pvio);
-
+int pvio_shm_shutdown(MARIADB_PVIO *pvio);
 
 struct st_ma_pvio_methods pvio_shm_methods= {
   pvio_shm_set_timeout,
@@ -57,7 +57,9 @@ struct st_ma_pvio_methods pvio_shm_methods= {
   NULL,
   NULL,
   NULL,
-  NULL
+  NULL,
+  NULL,
+  pvio_shm_shutdown
 };
 
 #ifndef HAVE_SHMEM_DYNAMIC
@@ -438,5 +440,11 @@ my_bool pvio_shm_is_blocking(MARIADB_PVIO *pvio)
   return 1;
 }
 
+int pvio_shm_shutdown(MARIADB_PVIO *pvio)
+{
+  PVIO_SHM *pvio_shm= (PVIO_SHM *)pvio->data;
+  if (pvio_shm)
+    return (SetEvent(pvio_shm->event[PVIO_SHM_CONNECTION_CLOSED]) ? 0 : 1);
+}
 #endif
 

plugins/pvio/pvio_socket.c

@@ -76,6 +76,7 @@ my_bool pvio_socket_get_handle(MARIADB_PVIO *pvio, void *handle);
 my_bool pvio_socket_is_blocking(MARIADB_PVIO *pvio);
 my_bool pvio_socket_is_alive(MARIADB_PVIO *pvio);
 my_bool pvio_socket_has_data(MARIADB_PVIO *pvio, ssize_t *data_len);
+int pvio_socket_shutdown(MARIADB_PVIO *pvio);
 
 static int pvio_socket_init(char *unused1, 
                            size_t unused2, 
@@ -99,7 +100,8 @@ struct st_ma_pvio_methods pvio_socket_methods= {
   pvio_socket_get_handle,
   pvio_socket_is_blocking,
   pvio_socket_is_alive,
-  pvio_socket_has_data
+  pvio_socket_has_data,
+  pvio_socket_shutdown
 };
 
 #ifndef HAVE_SOCKET_DYNAMIC
@@ -1023,3 +1025,19 @@ my_bool pvio_socket_has_data(MARIADB_PVIO *pvio, ssize_t *data_len)
   return 0;
 }
 /* }}} */
+
+int pvio_socket_shutdown(MARIADB_PVIO *pvio)
+{
+  int rc = 0;
+  if (pvio && pvio->data)
+  {
+    my_socket s = ((struct st_pvio_socket *)pvio->data)->socket;
+#ifdef _WIN32
+    rc = shutdown(s, SD_BOTH);
+    CancelIoEx((HANDLE)s, NULL);
+#else
+    rc = shutdown(s, SHUT_RDWR);
+#endif
+  }
+  return -1;
+}