Simplify InnoDB startup.

InnoDB needs to collect transactions from the persistent data files
in trx_rseg_array_init() before trx_lists_init_at_db_start() is
executed. But there is no need to create purge_sys->purge_queue
separately from purge_sys.

trx_sys_init_at_db_start(): Change the return type to void.
Remove the direct call to trx_rseg_array_init(). It will be called
by trx_lists_init_at_db_start(), which we are calling.
Initialize the purge system read view.

trx_lists_init_at_db_start(): Call trx_purge_sys_create(), which will
invoke trx_rseg_array_init() to read the undo log segments.

trx_purge_sys_create(): Remove the parameters. Do not initialize
the purge system read view, because trx_sys->rw_trx_list has not
been recovered yet. The purge_sys->view will be initialized at
the end of trx_sys_init_at_db_start().

trx_rseg_array_init(): Remove the parameter. Use purge_sys->purge_queue
directly.

innobase_start_or_create_for_mysql(): Remove the local variable
purge_queue. Do not call trx_purge_sys_create(), because it will be
called by trx_sys_init_at_db_start().

storage/innobase/include/trx0purge.h

@@ -54,19 +54,12 @@ trx_purge_get_log_from_hist(
 /*========================*/
 	fil_addr_t	node_addr);	/*!< in: file address of the history
 					list node of the log */
-/********************************************************************//**
-Creates the global purge system control structure and inits the history
-mutex. */
+/** Create the global purge system data structure. */
 void
-trx_purge_sys_create(
-/*=================*/
-	ulint		n_purge_threads,/*!< in: number of purge threads */
-	purge_pq_t*	purge_queue);	/*!< in/own: UNDO log min binary heap*/
-/********************************************************************//**
-Frees the global purge system control structure. */
+trx_purge_sys_create();
+/** Free the global purge system data structure. */
 void
-trx_purge_sys_close(void);
-/*======================*/
+trx_purge_sys_close();
 /************************************************************************
 Adds the update undo log as the first log in the history list. Removes the
 update undo log segment from the rseg slot if it is too big for reuse. */

storage/innobase/include/trx0rseg.h

@@ -117,13 +117,9 @@ trx_rseg_header_create(
 	ulint			rseg_slot_no,
 	mtr_t*			mtr);
 
-/*********************************************************************//**
-Creates the memory copies for rollback segments and initializes the
-rseg array in trx_sys at a database startup. */
+/** Initialize the rollback segments in memory at database startup. */
 void
-trx_rseg_array_init(
-/*================*/
-	purge_pq_t*	purge_queue);	/*!< in: rseg queue */
+trx_rseg_array_init();
 
 /** Free a rollback segment in memory. */
 void

storage/innobase/include/trx0sys.h

 /*****************************************************************************
 
 Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2017, MariaDB Corporation.
 
 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
@@ -61,13 +62,9 @@ bool
 trx_sys_hdr_page(
 	const page_id_t&	page_id);
 
-/*****************************************************************//**
-Creates and initializes the central memory structures for the transaction
-system. This is called when the database is started.
-@return min binary heap of rsegs to purge */
-purge_pq_t*
-trx_sys_init_at_db_start(void);
-/*==========================*/
+/** Initialize the transaction system main-memory data structures. */
+void trx_sys_init_at_db_start();
+
 /*****************************************************************//**
 Creates the trx_sys instance and initializes purge_queue and mutex. */
 void

storage/innobase/include/trx0trx.h

@@ -143,15 +143,9 @@ trx_disconnect_plain(trx_t*	trx);
 void
 trx_disconnect_prepared(trx_t*	trx);
 
-/****************************************************************//**
-Creates trx objects for transactions and initializes the trx list of
-trx_sys at database start. Rollback segment and undo log lists must
-already exist when this function is called, because the lists of
-transactions to be rolled back or cleaned up are built based on the
-undo log lists. */
+/** Initialize (resurrect) transactions at startup. */
 void
-trx_lists_init_at_db_start(void);
-/*============================*/
+trx_lists_init_at_db_start();
 
 /*************************************************************//**
 Starts the transaction if it is not yet started. */

storage/innobase/srv/srv0start.cc

@@ -1449,7 +1449,6 @@ innobase_start_or_create_for_mysql(void)
 	dberr_t		err		= DB_SUCCESS;
 	ulint		srv_n_log_files_found = srv_n_log_files;
 	mtr_t		mtr;
-	purge_pq_t*	purge_queue;
 	char		logfilename[10000];
 	char*		logfile0	= NULL;
 	size_t		dirnamelen;
@@ -2137,13 +2136,7 @@ innobase_start_or_create_for_mysql(void)
 		All the remaining rollback segments will be created later,
 		after the double write buffer has been created. */
 		trx_sys_create_sys_pages();
-
-		purge_queue = trx_sys_init_at_db_start();
-
-		/* The purge system needs to create the purge view and
-		therefore requires that the trx_sys is inited. */
-
-		trx_purge_sys_create(srv_n_purge_threads, purge_queue);
+		trx_sys_init_at_db_start();
 
 		err = dict_create();
 
@@ -2228,7 +2221,7 @@ innobase_start_or_create_for_mysql(void)
 		}
 
 		/* This must precede recv_apply_hashed_log_recs(true). */
-		purge_queue = trx_sys_init_at_db_start();
+		trx_sys_init_at_db_start();
 
 		if (srv_force_recovery < SRV_FORCE_NO_LOG_REDO) {
 			/* Apply the hashed log records to the
@@ -2309,16 +2302,10 @@ innobase_start_or_create_for_mysql(void)
 					" a startup if you are trying to"
 					" recover a badly corrupt database.";
 
-				UT_DELETE(purge_queue);
 				return(srv_init_abort(DB_ERROR));
 			}
 		}
 
-		/* The purge system needs to create the purge view and
-		therefore requires that the trx_sys is inited. */
-
-		trx_purge_sys_create(srv_n_purge_threads, purge_queue);
-
 		/* recv_recovery_from_checkpoint_finish needs trx lists which
 		are initialized in trx_sys_init_at_db_start(). */
 

storage/innobase/trx/trx0purge.cc

@@ -208,16 +208,9 @@ trx_purge_graph_build(
 	return(fork);
 }
 
-/********************************************************************//**
-Creates the global purge system control structure and inits the history
-mutex. */
+/** Create the global purge system data structure. */
 void
-trx_purge_sys_create(
-/*=================*/
-	ulint		n_purge_threads,	/*!< in: number of purge
-						threads */
-	purge_pq_t*	purge_queue)		/*!< in, own: UNDO log min
-						binary heap */
+trx_purge_sys_create()
 {
 	purge_sys = static_cast<trx_purge_t*>(
 		ut_zalloc_nokey(sizeof(*purge_sys)));
@@ -232,15 +225,18 @@ trx_purge_sys_create(
 	new (&purge_sys->done) purge_iter_t;
 #endif /* UNIV_DEBUG */
 
-	/* Take ownership of purge_queue, we are responsible for freeing it. */
-	purge_sys->purge_queue = purge_queue;
+	purge_sys->purge_queue = UT_NEW_NOKEY(purge_pq_t());
+	ut_a(purge_sys->purge_queue != NULL);
+	if (srv_force_recovery < SRV_FORCE_NO_UNDO_LOG_SCAN) {
+		trx_rseg_array_init();
+	}
 
 	rw_lock_create(trx_purge_latch_key,
 		       &purge_sys->latch, SYNC_PURGE_LATCH);
 
 	mutex_create(LATCH_ID_PURGE_SYS_PQ, &purge_sys->pq_mutex);
 
-	ut_a(n_purge_threads > 0);
+	ut_a(srv_n_purge_threads > 0);
 
 	purge_sys->sess = sess_open();
 
@@ -257,22 +253,16 @@ trx_purge_sys_create(
 	purge_sys->trx->op_info = "purge trx";
 
 	purge_sys->query = trx_purge_graph_build(
-		purge_sys->trx, n_purge_threads);
+		purge_sys->trx, srv_n_purge_threads);
 
 	new(&purge_sys->view) ReadView();
 
-	trx_sys->mvcc->clone_oldest_view(&purge_sys->view);
-
-	purge_sys->view_active = true;
-
 	purge_sys->rseg_iter = UT_NEW_NOKEY(TrxUndoRsegsIterator(purge_sys));
 }
 
-/************************************************************************
-Frees the global purge system control structure. */
+/** Free the global purge system data structure. */
 void
-trx_purge_sys_close(void)
-/*======================*/
+trx_purge_sys_close()
 {
 	que_graph_free(purge_sys->query);
 

storage/innobase/trx/trx0rseg.cc

@@ -262,18 +262,11 @@ trx_rseg_mem_create(
 	return(rseg);
 }
 
-/********************************************************************
-Creates the memory copies for the rollback segments and initializes the
-rseg array in trx_sys at a database startup. */
-static
+/** Initialize the rollback segments in memory at database startup. */
 void
-trx_rseg_create_instance(
-/*=====================*/
-	purge_pq_t*	purge_queue)	/*!< in/out: rseg queue */
+trx_rseg_array_init()
 {
-	ulint		i;
-
-	for (i = 0; i < TRX_SYS_N_RSEGS; i++) {
+	for (ulint i = 0; i < TRX_SYS_N_RSEGS; i++) {
 		ulint	page_no;
 
 		mtr_t	mtr;
@@ -303,7 +296,7 @@ trx_rseg_create_instance(
 
 			rseg = trx_rseg_mem_create(
 				i, space, page_no, page_size,
-				purge_queue, rseg_array, &mtr);
+				purge_sys->purge_queue, rseg_array, &mtr);
 
 			ut_a(rseg->id == i);
 		} else {
@@ -380,19 +373,6 @@ trx_rseg_create(
 	return(rseg);
 }
 
-/*********************************************************************//**
-Creates the memory copies for rollback segments and initializes the
-rseg array in trx_sys at a database startup. */
-void
-trx_rseg_array_init(
-/*================*/
-	purge_pq_t*	purge_queue)	/*!< in: rseg queue */
-{
-	trx_sys->rseg_history_len = 0;
-
-	trx_rseg_create_instance(purge_queue);
-}
-
 /********************************************************************
 Get the number of unique rollback tablespaces in use except space id 0.
 The last space id will be the sentinel value ULINT_UNDEFINED. The array

storage/innobase/trx/trx0sys.cc

@@ -60,7 +60,7 @@ struct file_format_t {
 };
 
 /** The transaction system */
-trx_sys_t*		trx_sys		= NULL;
+trx_sys_t*		trx_sys;
 
 /** List of animal names representing file format. */
 static const char*	file_format_name_map[] = {
@@ -578,29 +578,14 @@ trx_sysf_create(
 	ut_a(page_no == FSP_FIRST_RSEG_PAGE_NO);
 }
 
-/*****************************************************************//**
-Creates and initializes the central memory structures for the transaction
-system. This is called when the database is started.
-@return min binary heap of rsegs to purge */
-purge_pq_t*
-trx_sys_init_at_db_start(void)
-/*==========================*/
+/** Initialize the transaction system main-memory data structures. */
+void
+trx_sys_init_at_db_start()
 {
-	purge_pq_t*	purge_queue;
 	trx_sysf_t*	sys_header;
 	ib_uint64_t	rows_to_undo	= 0;
 	const char*	unit		= "";
 
-	/* We create the min binary heap here and pass ownership to
-	purge when we init the purge sub-system. Purge is responsible
-	for freeing the binary heap. */
-	purge_queue = UT_NEW_NOKEY(purge_pq_t());
-	ut_a(purge_queue != NULL);
-
-	if (srv_force_recovery < SRV_FORCE_NO_UNDO_LOG_SCAN) {
-		trx_rseg_array_init(purge_queue);
-	}
-
 	/* VERY important: after the database is started, max_trx_id value is
 	divisible by TRX_SYS_TRX_ID_WRITE_MARGIN, and the 'if' in
 	trx_sys_get_new_trx_id will evaluate to TRUE when the function
@@ -661,7 +646,9 @@ trx_sys_init_at_db_start(void)
 
 	trx_sys_mutex_exit();
 
-	return(purge_queue);
+	trx_sys->mvcc->clone_oldest_view(&purge_sys->view);
+
+	purge_sys->view_active = true;
 }
 
 /*****************************************************************//**

storage/innobase/trx/trx0trx.cc

@@ -1007,17 +1007,15 @@ trx_resurrect_update(
 	}
 }
 
-/****************************************************************//**
-Creates trx objects for transactions and initializes the trx list of
-trx_sys at database start. Rollback segment and undo log lists must
-already exist when this function is called, because the lists of
-transactions to be rolled back or cleaned up are built based on the
-undo log lists. */
+/** Initialize (resurrect) transactions at startup. */
 void
-trx_lists_init_at_db_start(void)
-/*============================*/
+trx_lists_init_at_db_start()
 {
 	ut_a(srv_is_being_started);
+	ut_ad(!srv_was_started);
+	ut_ad(!purge_sys);
+
+	trx_purge_sys_create();
 
 	/* Look from the rollback segments if there exist undo logs for
 	transactions. */