A fix and a test case for Bug#9643 " CURSOR_TYPE_SCROLLABLE dos not work"

- check on the client the unsupported feature and return 
an error message if it's been requested.
Additionally added API support for STMT_ATTR_PREFETCH_ROWS.
Post-review fixes.


include/errmsg.h:
  Add a new error code for "Not implemented" client-side error message.
include/mysql.h:
  Add a statement attribute STMT_ATTR_PREFETCH_ROWS - unsigned long
  number of rows to fetch per one COM_FETCH command, used when there
  is a read-only cursor.
  Note, that we don't break compatibility by adding this new member
  because MYSQL_STMT is always allocated inside the client library by
  mysql_stmt_init.
libmysql/errmsg.c:
  Text for the error message CR_NOT_IMPLEMENTED
libmysql/libmysql.c:
  Implement support for STMT_ATTR_PREFETCH_ROWS
  Return an error message on attempt to set an attribute of a prepared
  statement which is not implemented yet. We probably should be doing
  it in the server: currently the server just ignores unknown attributes.
tests/mysql_client_test.c:
  A test case for Bug#9643 "CURSOR_TYPE_SCROLLABLE dos not work"
  - check that an error message is returned for CURSOR_TYPE_SCROLLABLE.
  Additionally, check setting of STMT_ATTR_PREFETCH_ROWS.

include/errmsg.h

@@ -96,6 +96,7 @@ extern const char *client_errors[];	/* Error messages */
 #define CR_NO_DATA                              2051
 #define CR_NO_STMT_METADATA                     2052
 #define CR_NO_RESULT_SET                        2053
-#define CR_ERROR_LAST  /*Copy last error nr:*/  2053
+#define CR_NOT_IMPLEMENTED                      2054
+#define CR_ERROR_LAST  /*Copy last error nr:*/  2054
 /* Add error numbers before CR_ERROR_LAST and change it accordingly. */
 

include/mysql.h

@@ -663,6 +663,7 @@ typedef struct st_mysql_stmt
                                   unsigned char **row);
   unsigned long	 stmt_id;	       /* Id for prepared statement */
   unsigned long  flags;                /* i.e. type of cursor to open */
+  unsigned long  prefetch_rows;        /* number of rows per one COM_FETCH */
   /*
     Copied from mysql->server_status after execute/fetch to know
     server-side cursor status for this statement.
@@ -701,7 +702,12 @@ enum enum_stmt_attr_type
     unsigned long with combination of cursor flags (read only, for update,
     etc)
   */
-  STMT_ATTR_CURSOR_TYPE
+  STMT_ATTR_CURSOR_TYPE,
+  /*
+    Amount of rows to retrieve from server per one fetch if using cursors.
+    Accepts unsigned long attribute in the range 1 - ulong_max
+  */
+  STMT_ATTR_PREFETCH_ROWS
 };
 
 

libmysql/errmsg.c

@@ -81,6 +81,7 @@ const char *client_errors[]=
   "Attempt to read column without prior row fetch",
   "Prepared statement contains no metadata",
   "Attempt to read a row while there is no result set associated with the statement",
+  "This feature is not implemented yet",
   ""
 };
 
@@ -143,6 +144,7 @@ const char *client_errors[]=
   "Attempt to read column without prior row fetch",
   "Prepared statement contains no metadata",
   "Attempt to read a row while there is no result set associated with the statement",
+  "This feature is not implemented yet",
   ""
 };
 
@@ -203,6 +205,7 @@ const char *client_errors[]=
   "Attempt to read column without prior row fetch",
   "Prepared statement contains no metadata",
   "Attempt to read a row while there is no result set associated with the statement",
+  "This feature is not implemented yet",
   ""
 };
 #endif

libmysql/libmysql.c

@@ -1703,6 +1703,9 @@ myodbc_remove_escape(MYSQL *mysql,char *name)
 
 /******************* Declarations ***********************************/
 
+/* Default number of rows fetched per one COM_FETCH command. */
+
+#define DEFAULT_PREFETCH_ROWS 1UL
 
 /*
   These functions are called by function pointer MYSQL_STMT::read_row_func.
@@ -1728,6 +1731,7 @@ static my_bool setup_one_fetch_function(MYSQL_BIND *bind, MYSQL_FIELD *field);
 
 #define RESET_SERVER_SIDE 1
 #define RESET_LONG_DATA 2
+#define RESET_STORE_RESULT 4
 
 static my_bool reset_stmt_handle(MYSQL_STMT *stmt, uint flags);
 
@@ -1968,6 +1972,7 @@ mysql_stmt_init(MYSQL *mysql)
   stmt->state= MYSQL_STMT_INIT_DONE;
   stmt->mysql= mysql;
   stmt->read_row_func= stmt_read_row_no_data;
+  stmt->prefetch_rows= DEFAULT_PREFETCH_ROWS;
   /* The rest of statement members was bzeroed inside malloc */
 
   DBUG_RETURN(stmt);
@@ -2026,7 +2031,7 @@ mysql_stmt_prepare(MYSQL_STMT *stmt, const char *query, ulong length)
     /* This is second prepare with another statement */
     char buff[MYSQL_STMT_HEADER];               /* 4 bytes - stmt id */
 
-    if (reset_stmt_handle(stmt, RESET_LONG_DATA))
+    if (reset_stmt_handle(stmt, RESET_LONG_DATA | RESET_STORE_RESULT))
       DBUG_RETURN(1);
     /*
       These members must be reset for API to
@@ -2681,7 +2686,7 @@ stmt_read_row_from_cursor(MYSQL_STMT *stmt, unsigned char **row)
     result->rows= 0;
     /* Send row request to the server */
     int4store(buff, stmt->stmt_id);
-    int4store(buff + 4, 1); /* number of rows to fetch */
+    int4store(buff + 4, stmt->prefetch_rows); /* number of rows to fetch */
     if (cli_advanced_command(mysql, COM_FETCH, buff, sizeof(buff),
                              NullS, 0, 1))
     {
@@ -2739,12 +2744,29 @@ my_bool STDCALL mysql_stmt_attr_set(MYSQL_STMT *stmt,
     stmt->update_max_length= value ? *(const my_bool*) value : 0;
     break;
   case STMT_ATTR_CURSOR_TYPE:
-    stmt->flags= value ? *(const unsigned long *) value : 0;
+  {
+    ulong cursor_type;
+    cursor_type= value ? *(ulong*) value : 0UL;
+    if (cursor_type > (ulong) CURSOR_TYPE_READ_ONLY)
+      goto err_not_implemented;
+    stmt->flags= cursor_type;
+    break;
+  }
+  case STMT_ATTR_PREFETCH_ROWS:
+  {
+    ulong prefetch_rows= value ? *(ulong*) value : DEFAULT_PREFETCH_ROWS;
+    if (value == 0)
+      return TRUE;
+    stmt->prefetch_rows= prefetch_rows;
     break;
+  }
   default:
-    return TRUE;
+    goto err_not_implemented;
   }
   return FALSE;
+err_not_implemented:
+  set_stmt_error(stmt, CR_NOT_IMPLEMENTED, unknown_sqlstate);
+  return TRUE;
 }
 
 
@@ -2821,7 +2843,7 @@ int STDCALL mysql_stmt_execute(MYSQL_STMT *stmt)
     DBUG_RETURN(1);
   }
 
-  if (reset_stmt_handle(stmt, 0))
+  if (reset_stmt_handle(stmt, RESET_STORE_RESULT))
     DBUG_RETURN(1);
   /*
     No need to check for stmt->state: if the statement wasn't
@@ -4826,7 +4848,11 @@ static my_bool reset_stmt_handle(MYSQL_STMT *stmt, uint flags)
     MYSQL_DATA *result= &stmt->result;
     my_bool has_cursor= stmt->read_row_func == stmt_read_row_from_cursor;
 
-    if (result->data)
+    /*
+      Reset stored result set if so was requested or it's a part
+      of cursor fetch.
+    */
+    if (result->data && (has_cursor || (flags & RESET_STORE_RESULT)))
     {
       /* Result buffered */
       free_root(&result->alloc, MYF(MY_KEEP_PREALLOC));
@@ -4885,7 +4911,7 @@ my_bool STDCALL mysql_stmt_free_result(MYSQL_STMT *stmt)
   DBUG_ENTER("mysql_stmt_free_result");
 
   /* Free the client side and close the server side cursor if there is one */
-  DBUG_RETURN(reset_stmt_handle(stmt, RESET_LONG_DATA));
+  DBUG_RETURN(reset_stmt_handle(stmt, RESET_LONG_DATA | RESET_STORE_RESULT));
 }
 
 /********************************************************************

tests/mysql_client_test.c

@@ -13075,6 +13075,68 @@ static void test_bug9478()
 }
 
 
+/*
+  Error message is returned for unsupported features.
+  Test also cursors with non-default PREFETCH_ROWS
+*/
+
+static void test_bug9643()
+{
+  MYSQL_STMT *stmt;
+  MYSQL_BIND bind[1];
+  int32 a;
+  int rc;
+  const char *stmt_text;
+  int num_rows= 0;
+  ulong type;
+  ulong prefetch_rows= 5;
+
+  myheader("test_bug9643");
+
+  mysql_query(mysql, "drop table if exists t1");
+  mysql_query(mysql, "create table t1 (id integer not null primary key)");
+  rc= mysql_query(mysql, "insert into t1 (id) values "
+                         " (1), (2), (3), (4), (5), (6), (7), (8), (9)");
+  myquery(rc);
+
+  stmt= mysql_stmt_init(mysql);
+  /* Not implemented in 5.0 */
+  type= (ulong) CURSOR_TYPE_SCROLLABLE;
+  rc= mysql_stmt_attr_set(stmt, STMT_ATTR_CURSOR_TYPE, (void*) &type);
+  DIE_UNLESS(rc);
+  if (! opt_silent)
+    printf("Got error (as expected): %s\n", mysql_stmt_error(stmt));
+
+  type= (ulong) CURSOR_TYPE_READ_ONLY;
+  rc= mysql_stmt_attr_set(stmt, STMT_ATTR_CURSOR_TYPE, (void*) &type);
+  check_execute(stmt, rc);
+  rc= mysql_stmt_attr_set(stmt, STMT_ATTR_PREFETCH_ROWS,
+                          (void*) &prefetch_rows);
+  check_execute(stmt, rc);
+  stmt_text= "select * from t1";
+  rc= mysql_stmt_prepare(stmt, stmt_text, strlen(stmt_text));
+  check_execute(stmt, rc);
+
+  bzero(bind, sizeof(bind));
+  bind[0].buffer_type= MYSQL_TYPE_LONG;
+  bind[0].buffer= (void*) &a;
+  bind[0].buffer_length= sizeof(a);
+  mysql_stmt_bind_result(stmt, bind);
+
+  rc= mysql_stmt_execute(stmt);
+  check_execute(stmt, rc);
+
+  while ((rc= mysql_stmt_fetch(stmt)) == 0)
+    ++num_rows;
+  DIE_UNLESS(num_rows == 9);
+
+  rc= mysql_stmt_close(stmt);
+  DIE_UNLESS(rc == 0);
+
+  rc= mysql_query(mysql, "drop table t1");
+  myquery(rc);
+}
+
 /*
   Read and parse arguments and MySQL options from my.cnf
 */
@@ -13306,6 +13368,7 @@ static struct my_tests_st my_tests[]= {
   { "test_bug9159", test_bug9159 },
   { "test_bug9520", test_bug9520 },
   { "test_bug9478", test_bug9478 },
+  { "test_bug9643", test_bug9643 },
   { 0, 0 }
 };