Having a next-random cursor open could block transactions or checkpoints

because the cursor.reset method failed with not-supported.   Two fixes:
explicitly change next-random cursors to call the underlying reset method,
they're btree handles so it makes sense for them.  Additionally, make the
default cursor.reset method be a no-op rather than a not-supported error,
bulk cursors don't want to block transactions/checkpoints either.

6 files changed, 30 insertions, 7 deletions

diff --git a/dist/s_string.ok b/dist/s_string.ok
index 97661ce02d9..678f31e7b1b 100644
--- a/dist/s_string.ok
+++ b/dist/s_string.ok
@@ -501,6 +501,7 @@ nhex
 nl
 nlpo
 nocase
+noop
 nop
 notfound
 notset
diff --git a/src/cursor/cur_file.c b/src/cursor/cur_file.c
index 988dfcf12b0..05ff4b24e39 100644
--- a/src/cursor/cur_file.c
+++ b/src/cursor/cur_file.c
@@ -338,12 +338,13 @@ __wt_curfile_create(WT_SESSION_IMPL *session,
 
 	/*
 	 * random_retrieval
-	 * Random retrieval cursors only support next and close.
+	 * Random retrieval cursors only support next, reset and close.
 	 */
 	WT_ERR(__wt_config_gets_defno(session, cfg, "next_random", &cval));
 	if (cval.val != 0) {
 		__wt_cursor_set_notsup(cursor);
 		cursor->next = __curfile_next_random;
+		cursor->reset = __curfile_reset;
 	}
 
 	/* __wt_cursor_init is last so we don't have to clean up on error. */
diff --git a/src/cursor/cur_std.c b/src/cursor/cur_std.c
index 2f571625432..fd9422ed5c3 100644
--- a/src/cursor/cur_std.c
+++ b/src/cursor/cur_std.c
@@ -19,18 +19,37 @@ __wt_cursor_notsup(WT_CURSOR *cursor)
 	return (ENOTSUP);
 }
 
+/* 
+ * __wt_cursor_noop --
+ *	Cursor noop.
+ */
+int
+__wt_cursor_noop(WT_CURSOR *cursor)
+{
+	WT_UNUSED(cursor);
+
+	return (0);
+}
+
 /*
  * __wt_cursor_set_notsup --
- *	Set all of the cursor methods (except for close), to not-supported.
+ *	Reset the cursor methods to not-supported.
  */
 void
 __wt_cursor_set_notsup(WT_CURSOR *cursor)
 {
+	/*
+	 * Set all of the cursor methods (except for close and reset), to fail.
+	 * Close is unchanged so the cursor can be discarded, reset defaults to
+	 * a no-op because session transactional operations reset all of the
+	 * cursors in a session, and random cursors shouldn't block transactions
+	 * or checkpoints.
+	 */
 	cursor->compare =
 	    (int (*)(WT_CURSOR *, WT_CURSOR *, int *))__wt_cursor_notsup;
 	cursor->next = __wt_cursor_notsup;
 	cursor->prev = __wt_cursor_notsup;
-	cursor->reset = __wt_cursor_notsup;
+	cursor->reset = __wt_cursor_noop;
 	cursor->search = __wt_cursor_notsup;
 	cursor->search_near = (int (*)(WT_CURSOR *, int *))__wt_cursor_notsup;
 	cursor->insert = __wt_cursor_notsup;
@@ -458,7 +477,7 @@ __wt_cursor_init(WT_CURSOR *cursor,
 	if (cursor->prev == NULL)
 		cursor->prev = __wt_cursor_notsup;
 	if (cursor->reset == NULL)
-		cursor->reset = __wt_cursor_notsup;
+		cursor->reset = __wt_cursor_noop;
 	if (cursor->search == NULL)
 		cursor->search = __cursor_search;
 	if (cursor->search_near == NULL)
diff --git a/src/cursor/cur_table.c b/src/cursor/cur_table.c
index 61c68246a4e..85024e5ce95 100644
--- a/src/cursor/cur_table.c
+++ b/src/cursor/cur_table.c
@@ -783,12 +783,13 @@ __wt_curtable_open(WT_SESSION_IMPL *session,
 
 	/*
 	 * random_retrieval
-	 * Random retrieval cursors only support next and close.
+	 * Random retrieval cursors only support next, reset and close.
 	 */
 	WT_ERR(__wt_config_gets_defno(session, cfg, "next_random", &cval));
 	if (cval.val != 0) {
 		__wt_cursor_set_notsup(cursor);
 		cursor->next = __curtable_next_random;
+		cursor->reset = __curtable_reset;
 	}
 
 	STATIC_ASSERT(offsetof(WT_CURSOR_TABLE, iface) == 0);
diff --git a/src/include/extern.h b/src/include/extern.h
index 3d8c663ee9e..ea1cb091fe7 100644
--- a/src/include/extern.h
+++ b/src/include/extern.h
@@ -617,6 +617,7 @@ extern int __wt_curstat_open(WT_SESSION_IMPL *session,
     const char *cfg[],
     WT_CURSOR **cursorp);
 extern int __wt_cursor_notsup(WT_CURSOR *cursor);
+extern int __wt_cursor_noop(WT_CURSOR *cursor);
 extern void __wt_cursor_set_notsup(WT_CURSOR *cursor);
 extern int __wt_cursor_kv_not_set(WT_CURSOR *cursor, int key);
 extern int __wt_cursor_get_key(WT_CURSOR *cursor, ...);
diff --git a/test/suite/test_cursor_random.py b/test/suite/test_cursor_random.py
index 073a114344d..63c4d2a04b9 100644
--- a/test/suite/test_cursor_random.py
+++ b/test/suite/test_cursor_random.py
@@ -37,7 +37,7 @@ class test_cursor_random(wttest.WiredTigerTestCase):
         ]
 
     # Check that opening a random cursor on a row-store returns not-supported
-    # for every method except for next, and next returns not-found.
+    # for every method except for next and reset, and next returns not-found.
     def test_cursor_random_column(self):
         uri = self.type + 'random'
         self.session.create(uri, 'key_format=' + self.fmt + ',value_format=S')
@@ -45,7 +45,6 @@ class test_cursor_random(wttest.WiredTigerTestCase):
         self.assertRaises(
             wiredtiger.WiredTigerError, lambda: cursor.compare(cursor))
         self.assertRaises(wiredtiger.WiredTigerError, lambda: cursor.prev())
-        self.assertRaises(wiredtiger.WiredTigerError, lambda: cursor.reset())
         self.assertRaises(wiredtiger.WiredTigerError, lambda: cursor.search())
         self.assertRaises(
             wiredtiger.WiredTigerError, lambda: cursor.search_near())
@@ -53,6 +52,7 @@ class test_cursor_random(wttest.WiredTigerTestCase):
         self.assertRaises(wiredtiger.WiredTigerError, lambda: cursor.update())
         self.assertRaises(wiredtiger.WiredTigerError, lambda: cursor.remove())
 
+        cursor.reset()
         self.assertTrue(cursor.next(), wiredtiger.WT_NOTFOUND)
         cursor.close()