sql: rationalize the txnAborted event

The connection state machine returns an event to the connExecutor -
txnAborted - telling it to clean up some state. This event was
confusingly returned both when entering the Aborted state and sometimes
when leaving it.
This patch replaces txnAborted with a txnRollback event which is
returned strictly on rollback. Entering the Aborted state no longer
triggers this event; it triggers no event. This is in preparation for
broader support for savepoints, which want to enter the Aborted state
without much fuss.

Release note: None

pkg/sql/conn_executor.go

@@ -863,7 +863,7 @@ func (ex *connExecutor) close(ctx context.Context, closeType closeType) {
 
 	ev := noEvent
 	if _, noTxn := ex.machine.CurState().(stateNoTxn); !noTxn {
-		ev = txnAborted
+		ev = txnRollback
 	}
 
 	if closeType == normalClose {
@@ -1195,7 +1195,7 @@ func (ex *connExecutor) resetExtraTxnState(
 	}
 
 	switch ev {
-	case txnCommit, txnAborted:
+	case txnCommit, txnRollback:
 		// After txn is finished, we need to call onTxnFinish (if it's non-nil).
 		if ex.extraTxnState.onTxnFinish != nil {
 			ex.extraTxnState.onTxnFinish(ev)
@@ -2201,7 +2201,7 @@ func (ex *connExecutor) txnStateTransitionsApplyWrapper(
 		ex.extraTxnState.tables.waitForCacheToDropDatabases(ex.Ctx())
 
 		fallthrough
-	case txnRestart, txnAborted:
+	case txnRestart, txnRollback:
 		if err := ex.resetExtraTxnState(ex.Ctx(), ex.server.dbCache, advInfo.txnEvent); err != nil {
 			return advanceInfo{}, err
 		}

pkg/sql/conn_fsm.go

@@ -158,7 +158,7 @@ func (e eventTxnFinishPayload) toEvent() txnEvent {
 	if e.commit {
 		return txnCommit
 	}
-	return txnAborted
+	return txnRollback
 }
 
 type eventTxnRestart struct{}
@@ -323,7 +323,7 @@ var TxnStateTransitions = fsm.Compile(fsm.Pattern{
 			Action: func(args fsm.Args) error {
 				ts := args.Extended.(*txnState)
 				ts.mu.txn.CleanupOnError(ts.Ctx, args.Payload.(payloadWithError).errorCause())
-				ts.setAdvanceInfo(skipBatch, noRewind, txnAborted)
+				ts.setAdvanceInfo(skipBatch, noRewind, noEvent)
 				ts.txnAbortCount.Inc(1)
 				return nil
 			},
@@ -350,7 +350,7 @@ var TxnStateTransitions = fsm.Compile(fsm.Pattern{
 			Action: func(args fsm.Args) error {
 				ts := args.Extended.(*txnState)
 				ts.mu.txn.CleanupOnError(ts.Ctx, args.Payload.(payloadWithError).errorCause())
-				ts.setAdvanceInfo(skipBatch, noRewind, txnAborted)
+				ts.setAdvanceInfo(skipBatch, noRewind, noEvent)
 				ts.txnAbortCount.Inc(1)
 				return nil
 			},
@@ -471,7 +471,7 @@ var TxnStateTransitions = fsm.Compile(fsm.Pattern{
 			Action: func(args fsm.Args) error {
 				ts := args.Extended.(*txnState)
 				ts.mu.txn.CleanupOnError(ts.Ctx, args.Payload.(eventNonRetriableErrPayload).err)
-				ts.setAdvanceInfo(skipBatch, noRewind, txnAborted)
+				ts.setAdvanceInfo(skipBatch, noRewind, noEvent)
 				ts.txnAbortCount.Inc(1)
 				return nil
 			},
@@ -508,7 +508,7 @@ func cleanupAndFinish(args fsm.Args) error {
 	ts := args.Extended.(*txnState)
 	ts.mu.txn.CleanupOnError(ts.Ctx, args.Payload.(payloadWithError).errorCause())
 	ts.finishSQLTxn()
-	ts.setAdvanceInfo(skipBatch, noRewind, txnAborted)
+	ts.setAdvanceInfo(skipBatch, noRewind, txnRollback)
 	return nil
 }
 
@@ -553,14 +553,14 @@ func (ts *txnState) finishTxn(payload eventTxnFinishPayload) error {
 var BoundTxnStateTransitions = fsm.Compile(fsm.Pattern{
 	stateOpen{ImplicitTxn: fsm.False, RetryIntent: fsm.False}: {
 		// We accept eventNonRetriableErr with both IsCommit={True, fsm.False}, even
-		// those this state machine does not support COMMIT statements because
+		// though this state machine does not support COMMIT statements because
 		// connExecutor.close() sends an eventNonRetriableErr{IsCommit: fsm.True} event.
 		eventNonRetriableErr{IsCommit: fsm.Any}: {
 			Next: stateInternalError{},
 			Action: func(args fsm.Args) error {
 				ts := args.Extended.(*txnState)
 				ts.finishSQLTxn()
-				ts.setAdvanceInfo(skipBatch, noRewind, txnAborted)
+				ts.setAdvanceInfo(skipBatch, noRewind, txnRollback)
 				return nil
 			},
 		},
@@ -569,7 +569,7 @@ var BoundTxnStateTransitions = fsm.Compile(fsm.Pattern{
 			Action: func(args fsm.Args) error {
 				ts := args.Extended.(*txnState)
 				ts.finishSQLTxn()
-				ts.setAdvanceInfo(skipBatch, noRewind, txnAborted)
+				ts.setAdvanceInfo(skipBatch, noRewind, txnRollback)
 				return nil
 			},
 		},

pkg/sql/txn_state.go

@@ -370,12 +370,8 @@ const (
 	// This event is produced both when entering the CommitWait state and also
 	// when leaving it.
 	txnCommit
-	// txnAborted means that the transaction will not commit. This doesn't mean
-	// that the SQL txn is necessarily "finished" - the connection might be in the
-	// Aborted state.
-	// This event is produced both when entering the Aborted state and sometimes
-	// when leaving it.
-	txnAborted
+	// txnRollback means that the transaction has rolled back.
+	txnRollback
 	// txnRestart means that the transaction is restarting. The iteration
 	// of the txn just finished will not commit.
 	txnRestart

pkg/sql/txn_state_test.go

@@ -484,7 +484,7 @@ func TestTransitions(t *testing.T) {
 			expState: stateNoTxn{},
 			expAdv: expAdvance{
 				expCode: skipBatch,
-				expEv:   txnAborted,
+				expEv:   txnRollback,
 			},
 			// Expect nil txn.
 			expTxn: nil,
@@ -501,7 +501,7 @@ func TestTransitions(t *testing.T) {
 			expState:  stateNoTxn{},
 			expAdv: expAdvance{
 				expCode: skipBatch,
-				expEv:   txnAborted,
+				expEv:   txnRollback,
 			},
 			// Expect nil txn.
 			expTxn: nil,
@@ -524,7 +524,7 @@ func TestTransitions(t *testing.T) {
 			expState: stateAborted{RetryIntent: fsm.False},
 			expAdv: expAdvance{
 				expCode: skipBatch,
-				expEv:   txnAborted,
+				expEv:   noEvent,
 			},
 			expTxn: &expKVTxn{},
 		},
@@ -546,7 +546,7 @@ func TestTransitions(t *testing.T) {
 			expState: stateNoTxn{},
 			expAdv: expAdvance{
 				expCode: skipBatch,
-				expEv:   txnAborted,
+				expEv:   txnRollback,
 			},
 			// Expect the txn to have been cleared.
 			expTxn: nil,
@@ -563,7 +563,7 @@ func TestTransitions(t *testing.T) {
 			expState:  stateAborted{RetryIntent: fsm.False},
 			expAdv: expAdvance{
 				expCode: skipBatch,
-				expEv:   txnAborted,
+				expEv:   noEvent,
 			},
 			expTxn: &expKVTxn{},
 		},
@@ -616,7 +616,7 @@ func TestTransitions(t *testing.T) {
 			expState:  stateNoTxn{},
 			expAdv: expAdvance{
 				expCode: advanceOne,
-				expEv:   txnAborted,
+				expEv:   txnRollback,
 			},
 			expTxn: nil,
 		},
@@ -674,7 +674,7 @@ func TestTransitions(t *testing.T) {
 			expState:  stateNoTxn{},
 			expAdv: expAdvance{
 				expCode: advanceOne,
-				expEv:   txnAborted,
+				expEv:   txnRollback,
 			},
 			expTxn: nil,
 		},
@@ -704,7 +704,7 @@ func TestTransitions(t *testing.T) {
 			expState:  stateAborted{RetryIntent: fsm.True},
 			expAdv: expAdvance{
 				expCode: skipBatch,
-				expEv:   txnAborted,
+				expEv:   noEvent,
 			},
 			expTxn: &expKVTxn{},
 		},