1 files changed, 92 insertions, 0 deletions
diff --git a/innobase/include/read0read.h b/innobase/include/read0read.h
new file mode 100644
index 00000000000..dea952c8547
--- /dev/null
+++ b/innobase/include/read0read.h
@@ -0,0 +1,92 @@
+/******************************************************
+Cursor read
+
+(c) 1997 Innobase Oy
+
+Created 2/16/1997 Heikki Tuuri
+*******************************************************/
+
+#ifndef read0read_h
+#define read0read_h
+
+#include "univ.i"
+
+
+#include "ut0byte.h"
+#include "ut0lst.h"
+#include "trx0trx.h"
+#include "read0types.h"
+
+/*************************************************************************
+Opens a read view where exactly the transactions serialized before this
+point in time are seen in the view. */
+
+read_view_t*
+read_view_open_now(
+/*===============*/
+				/* out, own: read view struct */
+	trx_t*		cr_trx,	/* in: creating transaction, or NULL */
+	mem_heap_t*	heap);	/* in: memory heap from which allocated */
+/*************************************************************************
+Makes a copy of the oldest existing read view, or opens a new. The view
+must be closed with ..._close. */
+
+read_view_t*
+read_view_oldest_copy_or_open_new(
+/*==============================*/
+				/* out, own: read view struct */
+	trx_t*		cr_trx,	/* in: creating transaction, or NULL */
+	mem_heap_t*	heap);	/* in: memory heap from which allocated */
+/*************************************************************************
+Closes a read view. */
+
+void
+read_view_close(
+/*============*/
+	read_view_t*	view);	/* in: read view */
+/*************************************************************************
+Checks if a read view sees the specified transaction. */
+UNIV_INLINE
+ibool
+read_view_sees_trx_id(
+/*==================*/
+				/* out: TRUE if sees */
+	read_view_t*	view,	/* in: read view */
+	dulint		trx_id);	/* in: trx id */
+
+
+/* Read view lists the trx ids of those transactions for which a consistent
+read should not see the modifications to the database. */
+
+struct read_view_struct{
+	ibool	can_be_too_old;	/* TRUE if the system has had to purge old
+				versions which this read view should be able
+				to access: the read view can bump into the
+				DB_MISSING_HISTORY error */
+	dulint	low_limit_no;	/* The view does not need to see the undo
+				logs for transactions whose transaction number
+				is strictly smaller (<) than this value: they
+				can be removed in purge if not needed by other
+				views */
+	dulint	low_limit_id;	/* The read should not see any transaction
+				with trx id >= this value */
+	dulint	up_limit_id;	/* The read should see all trx ids which
+				are strictly smaller (<) than this value */
+	ulint	n_trx_ids;	/* Number of cells in the trx_ids array */
+	dulint*	trx_ids;	/* Additional trx ids which the read should
+				not see: typically, these are the active
+				transactions at the time when the read is
+				serialized, except the reading transaction
+				itself; the trx ids in this array are in a
+				descending order */
+	trx_t*	creator;	/* Pointer to the creating transaction, or
+				NULL if used in purge */
+	UT_LIST_NODE_T(read_view_t) view_list;
+				/* List of read views in trx_sys */
+};
+
+#ifndef UNIV_NONINL
+#include "read0read.ic"
+#endif
+
+#endif