Implement MySQL framework to support consistent read views in (6fd13aaa) · Commits · Software / OSDI20 Artifacts / mariadb

innobase/include/read0read.h

+40 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,35 @@ read_view_print(
		/============/
		read_view_t* view); /* in: read view */

		/*************************************************************************
		Create a consistent cursor view for mysql to be used in cursors. In this
		consistent read view modifications done by the creating transaction or future
		transactions are not visible. */

		cursor_view_t*
		read_cursor_view_create_for_mysql(
		/==============================/
		trx_t* cr_trx);/* in: trx where cursor view is created */

		/*************************************************************************
		Close a given consistent cursor view for and restore global read view
		back to a transaction. */

		void
		read_cursor_view_close_for_mysql(
		/=============================/
		trx_t* trx, /* in: trx */
		cursor_view_t* curview); /* in: cursor view to be closed */
		/*************************************************************************
		This function sets a given consistent cursor view to a transaction
		read view if given consistent cursor view is not null. Otherwice, function
		restores a global read view to a transaction read view. */

		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 */

		/* Read view lists the trx ids of those transactions for which a consistent
		read should not see the modifications to the database. */
		@@ -100,6 +129,17 @@ struct read_view_struct{
		/* List of read views in trx_sys */
		};

		/* Implement InnoDB framework to support consistent read views in
		cursors. This struct holds both heap where consistent read view
		is allocated and pointer to a read view. */

		struct cursor_view_struct{
		mem_heap_t* heap;
		/* Memory heap for the cursor view */
		read_view_t* read_view;
		/* Consistent read view of the cursor*/
		};

		#ifndef UNIV_NONINL
		#include "read0read.ic"
		#endif

innobase/include/read0types.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -10,5 +10,6 @@ Created 2/16/1997 Heikki Tuuri
		#define read0types_h

		typedef struct read_view_struct read_view_t;
		typedef struct cursor_view_struct cursor_view_t;

		#endif

innobase/include/trx0trx.h

+13 −2

Original line number	Diff line number	Diff line
		@@ -602,8 +602,19 @@ struct trx_struct{
		UT_LIST_BASE_NODE_T(lock_t)
		trx_locks; /* locks reserved by the transaction */
		/------------------------------/
		mem_heap_t* read_view_heap; /* memory heap for the read view */
		read_view_t* read_view; /* consistent read view or NULL */
		mem_heap_t* global_read_view_heap;
		/* memory heap for the global read
		view */
		read_view_t* global_read_view;
		/* consistent read view used in the
		transaction is stored here if
		transaction is using a consistent
		read view associated to a cursor */
		read_view_t* read_view; /* consistent read view used in the
		transaction or NULL, this read view
		can be normal read view associated
		to a transaction or read view
		associated to a cursor */
		/------------------------------/
		UT_LIST_BASE_NODE_T(trx_named_savept_t)
		trx_savepoints; /* savepoints set with SAVEPOINT ...,

innobase/read/read0read.c

+138 −3

Original line number	Diff line number	Diff line
		@@ -212,15 +212,16 @@ read_view_close_for_mysql(
		/======================/
		trx_t* trx) /* in: trx which has a read view */
		{
		ut_a(trx->read_view);
		ut_a(trx->global_read_view);

		mutex_enter(&kernel_mutex);

		read_view_close(trx->read_view);
		read_view_close(trx->global_read_view);

		mem_heap_empty(trx->read_view_heap);
		mem_heap_empty(trx->global_read_view_heap);

		trx->read_view = NULL;
		trx->global_read_view = NULL;

		mutex_exit(&kernel_mutex);
		}
		@@ -258,3 +259,137 @@ read_view_print(
		(ulong) ut_dulint_get_low(read_view_get_nth_trx_id(view, i)));
		}
		}

		/*************************************************************************
		Create a consistent cursor view for mysql to be used in cursors. In this
		consistent read view modifications done by the creating transaction or future
		transactions are not visible. */

		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;

		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 = cr_trx;

		/* 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;

		view->can_be_too_old = FALSE;

		n = 0;
		trx = UT_LIST_GET_FIRST(trx_sys->trx_list);

		/* No active transaction should be visible, not even cr_trx !*/

		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 and restore global read view
		back to a transaction. */

		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);

		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. Otherwice, function
		restores a global read view to a transaction read view. */

		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);
		}

innobase/row/row0sel.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -4083,6 +4083,11 @@ row_search_for_mysql(
		}

		func_exit:
		/* Restore a global read view back to transaction. This forces
		MySQL always to set cursor view before fetch if it is used. */

		trx->read_view = trx->global_read_view;

		trx->op_info = "";
		if (UNIV_LIKELY_NULL(heap)) {
		mem_heap_free(heap);
		@@ -4136,7 +4141,8 @@ row_search_check_if_query_cache_permitted(
		&& !trx->read_view) {

		trx->read_view = read_view_open_now(trx,
		trx->read_view_heap);
		trx->global_read_view_heap);
		trx->global_read_view = trx->read_view;
		}
		}