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authorGuilhem Bichot <guilhem@mysql.com>2009-08-07 12:16:00 +0200
committerGuilhem Bichot <guilhem@mysql.com>2009-08-07 12:16:00 +0200
commit7ceb29ff17047a268d8e8670478f6e1669939904 (patch)
tree65b42f5cb11f29ea5b4414ff075ccafd48569ad6 /storage/innobase/read
parent7fa1449eac29401b3d1f3fb4980149e9e562a705 (diff)
downloadmariadb-git-7ceb29ff17047a268d8e8670478f6e1669939904.tar.gz
Renamed storage/innodb_plugin to storage/innobase, so that 1) it's the same
layout as we always had in trees containing only the builtin 2) win\configure.js WITH_INNOBASE_STORAGE_ENGINE still works. storage/innobase/CMakeLists.txt: fix to new directory name (and like 5.1) storage/innobase/Makefile.am: fix to new directory name (and like 5.1) storage/innobase/handler/ha_innodb.cc: fix to new directory name (and like 5.1) storage/innobase/plug.in: fix to new directory name (and like 5.1)
Diffstat (limited to 'storage/innobase/read')
-rw-r--r--storage/innobase/read/read0read.c540
1 files changed, 540 insertions, 0 deletions
diff --git a/storage/innobase/read/read0read.c b/storage/innobase/read/read0read.c
new file mode 100644
index 00000000000..85adae4ddff
--- /dev/null
+++ b/storage/innobase/read/read0read.c
@@ -0,0 +1,540 @@
+/*****************************************************************************
+
+Copyright (c) 1997, 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
+
+*****************************************************************************/
+
+/**************************************************//**
+@file read/read0read.c
+Cursor read
+
+Created 2/16/1997 Heikki Tuuri
+*******************************************************/
+
+#include "read0read.h"
+
+#ifdef UNIV_NONINL
+#include "read0read.ic"
+#endif
+
+#include "srv0srv.h"
+#include "trx0sys.h"
+
+/*
+-------------------------------------------------------------------------------
+FACT A: Cursor read view on a secondary index sees only committed versions
+-------
+of the records in the secondary index or those versions of rows created
+by transaction which created a cursor before cursor was created even
+if transaction which created the cursor has changed that clustered index page.
+
+PROOF: We must show that read goes always to the clustered index record
+to see that record is visible in the cursor read view. Consider e.g.
+following table and SQL-clauses:
+
+create table t1(a int not null, b int, primary key(a), index(b));
+insert into t1 values (1,1),(2,2);
+commit;
+
+Now consider that we have a cursor for a query
+
+select b from t1 where b >= 1;
+
+This query will use secondary key on the table t1. Now after the first fetch
+on this cursor if we do a update:
+
+update t1 set b = 5 where b = 2;
+
+Now second fetch of the cursor should not see record (2,5) instead it should
+see record (2,2).
+
+We also should show that if we have delete t1 where b = 5; we still
+can see record (2,2).
+
+When we access a secondary key record maximum transaction id is fetched
+from this record and this trx_id is compared to up_limit_id in the view.
+If trx_id in the record is greater or equal than up_limit_id in the view
+cluster record is accessed. Because trx_id of the creating
+transaction is stored when this view was created to the list of
+trx_ids not seen by this read view previous version of the
+record is requested to be built. This is build using clustered record.
+If the secondary key record is delete marked it's corresponding
+clustered record can be already be purged only if records
+trx_id < low_limit_no. Purge can't remove any record deleted by a
+transaction which was active when cursor was created. But, we still
+may have a deleted secondary key record but no clustered record. But,
+this is not a problem because this case is handled in
+row_sel_get_clust_rec() function which is called
+whenever we note that this read view does not see trx_id in the
+record. Thus, we see correct version. Q. E. D.
+
+-------------------------------------------------------------------------------
+FACT B: Cursor read view on a clustered index sees only committed versions
+-------
+of the records in the clustered index or those versions of rows created
+by transaction which created a cursor before cursor was created even
+if transaction which created the cursor has changed that clustered index page.
+
+PROOF: Consider e.g.following table and SQL-clauses:
+
+create table t1(a int not null, b int, primary key(a));
+insert into t1 values (1),(2);
+commit;
+
+Now consider that we have a cursor for a query
+
+select a from t1 where a >= 1;
+
+This query will use clustered key on the table t1. Now after the first fetch
+on this cursor if we do a update:
+
+update t1 set a = 5 where a = 2;
+
+Now second fetch of the cursor should not see record (5) instead it should
+see record (2).
+
+We also should show that if we have execute delete t1 where a = 5; after
+the cursor is opened we still can see record (2).
+
+When accessing clustered record we always check if this read view sees
+trx_id stored to clustered record. By default we don't see any changes
+if record trx_id >= low_limit_id i.e. change was made transaction
+which started after transaction which created the cursor. If row
+was changed by the future transaction a previous version of the
+clustered record is created. Thus we see only committed version in
+this case. We see all changes made by committed transactions i.e.
+record trx_id < up_limit_id. In this case we don't need to do anything,
+we already see correct version of the record. We don't see any changes
+made by active transaction except creating transaction. We have stored
+trx_id of creating transaction to list of trx_ids when this view was
+created. Thus we can easily see if this record was changed by the
+creating transaction. Because we already have clustered record we can
+access roll_ptr. Using this roll_ptr we can fetch undo record.
+We can now check that undo_no of the undo record is less than undo_no of the
+trancaction which created a view when cursor was created. We see this
+clustered record only in case when record undo_no is less than undo_no
+in the view. If this is not true we build based on undo_rec previous
+version of the record. This record is found because purge can't remove
+records accessed by active transaction. Thus we see correct version. Q. E. D.
+-------------------------------------------------------------------------------
+FACT C: Purge does not remove any delete marked row that is visible
+-------
+to cursor view.
+
+TODO: proof this
+
+*/
+
+/*********************************************************************//**
+Creates a read view object.
+@return own: read view struct */
+UNIV_INLINE
+read_view_t*
+read_view_create_low(
+/*=================*/
+ ulint n, /*!< in: number of cells in the trx_ids array */
+ mem_heap_t* heap) /*!< in: memory heap from which allocated */
+{
+ read_view_t* view;
+
+ view = mem_heap_alloc(heap, sizeof(read_view_t));
+
+ view->n_trx_ids = n;
+ view->trx_ids = mem_heap_alloc(heap, n * sizeof *view->trx_ids);
+
+ return(view);
+}
+
+/*********************************************************************//**
+Makes a copy of the oldest existing read view, with the exception that also
+the creating trx of the oldest view is set as not visible in the 'copied'
+view. Opens a new view if no views currently exist. The view must be closed
+with ..._close. This is used in purge.
+@return own: read view struct */
+UNIV_INTERN
+read_view_t*
+read_view_oldest_copy_or_open_new(
+/*==============================*/
+ trx_id_t cr_trx_id, /*!< in: trx_id of creating
+ transaction, or ut_dulint_zero
+ used in purge */
+ mem_heap_t* heap) /*!< in: memory heap from which
+ allocated */
+{
+ read_view_t* old_view;
+ read_view_t* view_copy;
+ ibool needs_insert = TRUE;
+ ulint insert_done = 0;
+ ulint n;
+ ulint i;
+
+ ut_ad(mutex_own(&kernel_mutex));
+
+ old_view = UT_LIST_GET_LAST(trx_sys->view_list);
+
+ if (old_view == NULL) {
+
+ return(read_view_open_now(cr_trx_id, heap));
+ }
+
+ n = old_view->n_trx_ids;
+
+ if (!ut_dulint_is_zero(old_view->creator_trx_id)) {
+ n++;
+ } else {
+ needs_insert = FALSE;
+ }
+
+ view_copy = read_view_create_low(n, heap);
+
+ /* Insert the id of the creator in the right place of the descending
+ array of ids, if needs_insert is TRUE: */
+
+ i = 0;
+ while (i < n) {
+ if (needs_insert
+ && (i >= old_view->n_trx_ids
+ || ut_dulint_cmp(old_view->creator_trx_id,
+ read_view_get_nth_trx_id(old_view, i))
+ > 0)) {
+
+ read_view_set_nth_trx_id(view_copy, i,
+ old_view->creator_trx_id);
+ needs_insert = FALSE;
+ insert_done = 1;
+ } else {
+ read_view_set_nth_trx_id(view_copy, i,
+ read_view_get_nth_trx_id(
+ old_view,
+ i - insert_done));
+ }
+
+ i++;
+ }
+
+ view_copy->creator_trx_id = cr_trx_id;
+
+ view_copy->low_limit_no = old_view->low_limit_no;
+ view_copy->low_limit_id = old_view->low_limit_id;
+
+
+ if (n > 0) {
+ /* The last active transaction has the smallest id: */
+ view_copy->up_limit_id = read_view_get_nth_trx_id(
+ view_copy, n - 1);
+ } else {
+ view_copy->up_limit_id = old_view->up_limit_id;
+ }
+
+ UT_LIST_ADD_LAST(view_list, trx_sys->view_list, view_copy);
+
+ return(view_copy);
+}
+
+/*********************************************************************//**
+Opens a read view where exactly the transactions serialized before this
+point in time are seen in the view.
+@return own: read view struct */
+UNIV_INTERN
+read_view_t*
+read_view_open_now(
+/*===============*/
+ trx_id_t cr_trx_id, /*!< in: trx_id of creating
+ transaction, or ut_dulint_zero
+ used in purge */
+ mem_heap_t* heap) /*!< in: memory heap from which
+ allocated */
+{
+ read_view_t* view;
+ trx_t* trx;
+ ulint n;
+
+ ut_ad(mutex_own(&kernel_mutex));
+
+ view = read_view_create_low(UT_LIST_GET_LEN(trx_sys->trx_list), heap);
+
+ view->creator_trx_id = cr_trx_id;
+ view->type = VIEW_NORMAL;
+ view->undo_no = ut_dulint_zero;
+
+ /* No future transactions should be visible in the view */
+
+ view->low_limit_no = trx_sys->max_trx_id;
+ view->low_limit_id = view->low_limit_no;
+
+ n = 0;
+ trx = UT_LIST_GET_FIRST(trx_sys->trx_list);
+
+ /* No active transaction should be visible, except cr_trx */
+
+ while (trx) {
+ if (ut_dulint_cmp(trx->id, cr_trx_id) != 0
+ && (trx->conc_state == TRX_ACTIVE
+ || trx->conc_state == TRX_PREPARED)) {
+
+ read_view_set_nth_trx_id(view, n, trx->id);
+
+ n++;
+
+ /* NOTE that a transaction whose trx number is <
+ trx_sys->max_trx_id can still be active, if it is
+ in the middle of its commit! Note that when a
+ transaction starts, we initialize trx->no to
+ ut_dulint_max. */
+
+ if (ut_dulint_cmp(view->low_limit_no, trx->no) > 0) {
+
+ view->low_limit_no = trx->no;
+ }
+ }
+
+ trx = UT_LIST_GET_NEXT(trx_list, trx);
+ }
+
+ view->n_trx_ids = n;
+
+ if (n > 0) {
+ /* The last active transaction has the smallest id: */
+ view->up_limit_id = read_view_get_nth_trx_id(view, n - 1);
+ } else {
+ view->up_limit_id = view->low_limit_id;
+ }
+
+
+ UT_LIST_ADD_FIRST(view_list, trx_sys->view_list, view);
+
+ return(view);
+}
+
+/*********************************************************************//**
+Closes a read view. */
+UNIV_INTERN
+void
+read_view_close(
+/*============*/
+ read_view_t* view) /*!< in: read view */
+{
+ ut_ad(mutex_own(&kernel_mutex));
+
+ UT_LIST_REMOVE(view_list, trx_sys->view_list, view);
+}
+
+/*********************************************************************//**
+Closes a consistent read view for MySQL. This function is called at an SQL
+statement end if the trx isolation level is <= TRX_ISO_READ_COMMITTED. */
+UNIV_INTERN
+void
+read_view_close_for_mysql(
+/*======================*/
+ trx_t* trx) /*!< in: trx which has a read view */
+{
+ ut_a(trx->global_read_view);
+
+ mutex_enter(&kernel_mutex);
+
+ read_view_close(trx->global_read_view);
+
+ mem_heap_empty(trx->global_read_view_heap);
+
+ trx->read_view = NULL;
+ trx->global_read_view = NULL;
+
+ mutex_exit(&kernel_mutex);
+}
+
+/*********************************************************************//**
+Prints a read view to stderr. */
+UNIV_INTERN
+void
+read_view_print(
+/*============*/
+ const read_view_t* view) /*!< in: read view */
+{
+ ulint n_ids;
+ ulint i;
+
+ if (view->type == VIEW_HIGH_GRANULARITY) {
+ fprintf(stderr,
+ "High-granularity read view undo_n:o %lu %lu\n",
+ (ulong) ut_dulint_get_high(view->undo_no),
+ (ulong) ut_dulint_get_low(view->undo_no));
+ } else {
+ fprintf(stderr, "Normal read view\n");
+ }
+
+ fprintf(stderr, "Read view low limit trx n:o %lu %lu\n",
+ (ulong) ut_dulint_get_high(view->low_limit_no),
+ (ulong) ut_dulint_get_low(view->low_limit_no));
+
+ fprintf(stderr, "Read view up limit trx id " TRX_ID_FMT "\n",
+ TRX_ID_PREP_PRINTF(view->up_limit_id));
+
+ fprintf(stderr, "Read view low limit trx id " TRX_ID_FMT "\n",
+ TRX_ID_PREP_PRINTF(view->low_limit_id));
+
+ fprintf(stderr, "Read view individually stored trx ids:\n");
+
+ n_ids = view->n_trx_ids;
+
+ for (i = 0; i < n_ids; i++) {
+ fprintf(stderr, "Read view trx id " TRX_ID_FMT "\n",
+ TRX_ID_PREP_PRINTF(
+ read_view_get_nth_trx_id(view, i)));
+ }
+}
+
+/*********************************************************************//**
+Create a high-granularity consistent cursor view for mysql to be used
+in cursors. In this consistent read view modifications done by the
+creating transaction after the cursor is created or future transactions
+are not visible. */
+UNIV_INTERN
+cursor_view_t*
+read_cursor_view_create_for_mysql(
+/*==============================*/
+ trx_t* cr_trx) /*!< in: trx where cursor view is created */
+{
+ cursor_view_t* curview;
+ read_view_t* view;
+ mem_heap_t* heap;
+ trx_t* trx;
+ ulint n;
+
+ ut_a(cr_trx);
+
+ /* Use larger heap than in trx_create when creating a read_view
+ because cursors are quite long. */
+
+ heap = mem_heap_create(512);
+
+ curview = (cursor_view_t*) mem_heap_alloc(heap, sizeof(cursor_view_t));
+ curview->heap = heap;
+
+ /* Drop cursor tables from consideration when evaluating the need of
+ auto-commit */
+ curview->n_mysql_tables_in_use = cr_trx->n_mysql_tables_in_use;
+ cr_trx->n_mysql_tables_in_use = 0;
+
+ mutex_enter(&kernel_mutex);
+
+ curview->read_view = read_view_create_low(
+ UT_LIST_GET_LEN(trx_sys->trx_list), curview->heap);
+
+ view = curview->read_view;
+ view->creator_trx_id = cr_trx->id;
+ view->type = VIEW_HIGH_GRANULARITY;
+ view->undo_no = cr_trx->undo_no;
+
+ /* No future transactions should be visible in the view */
+
+ view->low_limit_no = trx_sys->max_trx_id;
+ view->low_limit_id = view->low_limit_no;
+
+ n = 0;
+ trx = UT_LIST_GET_FIRST(trx_sys->trx_list);
+
+ /* No active transaction should be visible */
+
+ while (trx) {
+
+ if (trx->conc_state == TRX_ACTIVE
+ || trx->conc_state == TRX_PREPARED) {
+
+ read_view_set_nth_trx_id(view, n, trx->id);
+
+ n++;
+
+ /* NOTE that a transaction whose trx number is <
+ trx_sys->max_trx_id can still be active, if it is
+ in the middle of its commit! Note that when a
+ transaction starts, we initialize trx->no to
+ ut_dulint_max. */
+
+ if (ut_dulint_cmp(view->low_limit_no, trx->no) > 0) {
+
+ view->low_limit_no = trx->no;
+ }
+ }
+
+ trx = UT_LIST_GET_NEXT(trx_list, trx);
+ }
+
+ view->n_trx_ids = n;
+
+ if (n > 0) {
+ /* The last active transaction has the smallest id: */
+ view->up_limit_id = read_view_get_nth_trx_id(view, n - 1);
+ } else {
+ view->up_limit_id = view->low_limit_id;
+ }
+
+ UT_LIST_ADD_FIRST(view_list, trx_sys->view_list, view);
+
+ mutex_exit(&kernel_mutex);
+
+ return(curview);
+}
+
+/*********************************************************************//**
+Close a given consistent cursor view for mysql and restore global read view
+back to a transaction read view. */
+UNIV_INTERN
+void
+read_cursor_view_close_for_mysql(
+/*=============================*/
+ trx_t* trx, /*!< in: trx */
+ cursor_view_t* curview)/*!< in: cursor view to be closed */
+{
+ ut_a(curview);
+ ut_a(curview->read_view);
+ ut_a(curview->heap);
+
+ /* Add cursor's tables to the global count of active tables that
+ belong to this transaction */
+ trx->n_mysql_tables_in_use += curview->n_mysql_tables_in_use;
+
+ mutex_enter(&kernel_mutex);
+
+ read_view_close(curview->read_view);
+ trx->read_view = trx->global_read_view;
+
+ mutex_exit(&kernel_mutex);
+
+ mem_heap_free(curview->heap);
+}
+
+/*********************************************************************//**
+This function sets a given consistent cursor view to a transaction
+read view if given consistent cursor view is not NULL. Otherwise, function
+restores a global read view to a transaction read view. */
+UNIV_INTERN
+void
+read_cursor_set_for_mysql(
+/*======================*/
+ trx_t* trx, /*!< in: transaction where cursor is set */
+ cursor_view_t* curview)/*!< in: consistent cursor view to be set */
+{
+ ut_a(trx);
+
+ mutex_enter(&kernel_mutex);
+
+ if (UNIV_LIKELY(curview != NULL)) {
+ trx->read_view = curview->read_view;
+ } else {
+ trx->read_view = trx->global_read_view;
+ }
+
+ mutex_exit(&kernel_mutex);
+}