Import Percona XtraDB into the MariaDB source tree.

1 files changed, 136 insertions, 0 deletions

diff --git a/storage/xtradb/include/buf0rea.h b/storage/xtradb/include/buf0rea.h
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+++ b/storage/xtradb/include/buf0rea.h
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+/*****************************************************************************
+
+Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; version 2 of the License.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+
+*****************************************************************************/
+
+/******************************************************
+The database buffer read
+
+Created 11/5/1995 Heikki Tuuri
+*******************************************************/
+
+#ifndef buf0rea_h
+#define buf0rea_h
+
+#include "univ.i"
+#include "buf0types.h"
+
+/************************************************************************
+High-level function which reads a page asynchronously from a file to the
+buffer buf_pool if it is not already there. Sets the io_fix flag and sets
+an exclusive lock on the buffer frame. The flag is cleared and the x-lock
+released by the i/o-handler thread. Does a random read-ahead if it seems
+sensible. */
+UNIV_INTERN
+ulint
+buf_read_page(
+/*==========*/
+			/* out: number of page read requests issued: this can
+			be > 1 if read-ahead occurred */
+	ulint	space,	/* in: space id */
+	ulint	zip_size,/* in: compressed page size in bytes, or 0 */
+	ulint	offset);/* in: page number */
+/************************************************************************
+Applies linear read-ahead if in the buf_pool the page is a border page of
+a linear read-ahead area and all the pages in the area have been accessed.
+Does not read any page if the read-ahead mechanism is not activated. Note
+that the the algorithm looks at the 'natural' adjacent successor and
+predecessor of the page, which on the leaf level of a B-tree are the next
+and previous page in the chain of leaves. To know these, the page specified
+in (space, offset) must already be present in the buf_pool. Thus, the
+natural way to use this function is to call it when a page in the buf_pool
+is accessed the first time, calling this function just after it has been
+bufferfixed.
+NOTE 1: as this function looks at the natural predecessor and successor
+fields on the page, what happens, if these are not initialized to any
+sensible value? No problem, before applying read-ahead we check that the
+area to read is within the span of the space, if not, read-ahead is not
+applied. An uninitialized value may result in a useless read operation, but
+only very improbably.
+NOTE 2: the calling thread may own latches on pages: to avoid deadlocks this
+function must be written such that it cannot end up waiting for these
+latches!
+NOTE 3: the calling thread must want access to the page given: this rule is
+set to prevent unintended read-aheads performed by ibuf routines, a situation
+which could result in a deadlock if the OS does not support asynchronous io. */
+UNIV_INTERN
+ulint
+buf_read_ahead_linear(
+/*==================*/
+			/* out: number of page read requests issued */
+	ulint	space,	/* in: space id */
+	ulint	zip_size,/* in: compressed page size in bytes, or 0 */
+	ulint	offset);/* in: page number of a page; NOTE: the current thread
+			must want access to this page (see NOTE 3 above) */
+/************************************************************************
+Issues read requests for pages which the ibuf module wants to read in, in
+order to contract the insert buffer tree. Technically, this function is like
+a read-ahead function. */
+UNIV_INTERN
+void
+buf_read_ibuf_merge_pages(
+/*======================*/
+	ibool		sync,		/* in: TRUE if the caller
+					wants this function to wait
+					for the highest address page
+					to get read in, before this
+					function returns */
+	const ulint*	space_ids,	/* in: array of space ids */
+	const ib_int64_t* space_versions,/* in: the spaces must have
+					this version number
+					(timestamp), otherwise we
+					discard the read; we use this
+					to cancel reads if DISCARD +
+					IMPORT may have changed the
+					tablespace size */
+	const ulint*	page_nos,	/* in: array of page numbers
+					to read, with the highest page
+					number the last in the
+					array */
+	ulint		n_stored);	/* in: number of elements
+					in the arrays */
+/************************************************************************
+Issues read requests for pages which recovery wants to read in. */
+UNIV_INTERN
+void
+buf_read_recv_pages(
+/*================*/
+	ibool		sync,		/* in: TRUE if the caller
+					wants this function to wait
+					for the highest address page
+					to get read in, before this
+					function returns */
+	ulint		space,		/* in: space id */
+	ulint		zip_size,	/* in: compressed page size in
+					bytes, or 0 */
+	const ulint*	page_nos,	/* in: array of page numbers
+					to read, with the highest page
+					number the last in the
+					array */
+	ulint		n_stored);	/* in: number of page numbers
+					in the array */
+
+/* The size in pages of the area which the read-ahead algorithms read if
+invoked */
+
+#define	BUF_READ_AHEAD_AREA					\
+	ut_min(64, ut_2_power_up(buf_pool->curr_size / 32))
+
+/* Modes used in read-ahead */
+#define BUF_READ_IBUF_PAGES_ONLY	131
+#define BUF_READ_ANY_PAGE		132
+
+#endif