Misc trx_sys scalability fixes

trx_erase_lists(): trx->read_view is owned by current thread and thus
doesn't need trx_sys.mutex protection for reading it's value. Move
trx->read_view check out of mutex

trx_start_low(): moved assertion out of mutex.

Call ReadView::creator_trx_id() directly: allows to inline this one-line
method.

storage/innobase/include/read0read.h

@@ -80,11 +80,6 @@ class MVCC {
 		return(view != NULL && !(intptr_t(view) & 0x1));
 	}
 
-	/**
-	Set the view creator transaction id. Note: This shouldbe set only
-	for views created by RW transactions. */
-	static void set_view_creator_trx_id(ReadView* view, trx_id_t id);
-
 private:
 
 	/**

storage/innobase/include/read0types.h

@@ -239,6 +239,18 @@ class ReadView {
 		return(m_ids.empty());
 	}
 
+	/**
+	Set the creator transaction id, existing id must be 0.
+
+	Note: This shouldbe set only for views created by RW
+	transactions. Caller must own trx_sys.mutex. */
+	void creator_trx_id(trx_id_t id)
+	{
+		ut_ad(id > 0);
+		ut_ad(m_creator_trx_id == 0);
+		m_creator_trx_id = id;
+	}
+
 #ifdef UNIV_DEBUG
 	/**
 	@param rhs		view to compare with
@@ -278,14 +290,6 @@ class ReadView {
 	m_trx_ids too and adjust the m_up_limit_id *, if required */
 	inline void copy_complete();
 
-	/**
-	Set the creator transaction id, existing id must be 0 */
-	void creator_trx_id(trx_id_t id)
-	{
-		ut_ad(m_creator_trx_id == 0);
-		m_creator_trx_id = id;
-	}
-
 	friend class MVCC;
 
 private:

storage/innobase/read/read0read.cc

@@ -769,17 +769,3 @@ MVCC::view_close(ReadView*& view, bool own_mutex)
 		view = NULL;
 	}
 }
-
-/**
-Set the view creator transaction id. Note: This shouldbe set only
-for views created by RW transactions.
-@param view		Set the creator trx id for this view
-@param id		Transaction id to set */
-
-void
-MVCC::set_view_creator_trx_id(ReadView* view, trx_id_t id)
-{
-	ut_ad(id > 0);
-	ut_ad(mutex_own(&trx_sys.mutex));
-	view->creator_trx_id(id);
-}

storage/innobase/trx/trx0trx.cc

@@ -1169,21 +1169,16 @@ trx_start_low(
 	if (!trx->read_only
 	    && (trx->mysql_thd == 0 || read_write || trx->ddl)) {
 
-		trx->rsegs.m_redo.rseg = trx_assign_rseg_low();
-
 		/* Temporary rseg is assigned only if the transaction
 		updates a temporary table */
-
-		mutex_enter(&trx_sys.mutex);
-
-		trx->id = trx_sys.get_new_trx_id();
-
-		trx_sys.rw_trx_ids.push_back(trx->id);
-
+		trx->rsegs.m_redo.rseg = trx_assign_rseg_low();
 		ut_ad(trx->rsegs.m_redo.rseg != 0
 		      || srv_read_only_mode
 		      || srv_force_recovery >= SRV_FORCE_NO_TRX_UNDO);
 
+		mutex_enter(&trx_sys.mutex);
+		trx->id = trx_sys.get_new_trx_id();
+		trx_sys.rw_trx_ids.push_back(trx->id);
 		mutex_exit(&trx_sys.mutex);
 		trx_sys.rw_trx_hash.insert(trx);
 
@@ -1541,15 +1536,13 @@ trx_erase_lists(
 {
 	ut_ad(trx->id > 0);
 
-	if (trx->read_only || trx->rsegs.m_redo.rseg == NULL) {
-
+	if (trx->rsegs.m_redo.rseg && trx->read_view) {
+		ut_ad(!trx->read_only);
 		mutex_enter(&trx_sys.mutex);
+		trx_sys.mvcc.view_close(trx->read_view, true);
 	} else {
 
 		mutex_enter(&trx_sys.mutex);
-		if (trx->read_view != NULL) {
-			trx_sys.mvcc.view_close(trx->read_view, true);
-		}
 	}
 
 	if (serialised) {
@@ -2759,12 +2752,11 @@ trx_set_rw_mode(
 
 	mutex_enter(&trx_sys.mutex);
 	trx->id = trx_sys.get_new_trx_id();
-
 	trx_sys.rw_trx_ids.push_back(trx->id);
 
 	/* So that we can see our own changes. */
 	if (MVCC::is_view_active(trx->read_view)) {
-		MVCC::set_view_creator_trx_id(trx->read_view, trx->id);
+		trx->read_view->creator_trx_id(trx->id);
 	}
 	mutex_exit(&trx_sys.mutex);
 	trx_sys.rw_trx_hash.insert(trx);