fix: return and respect cursor errors (#24791)

ArrayCursors were ignoring errors, which led to panics when nil
cursors were operated on. This fix passes errors back up the stack
and uses them to enforce healthy cursor creation.

Closes #24789
---------
Co-authored-by: Stuart Carnie <[email protected]>

cmd/influx_tools/internal/storage/resultset.go

@@ -72,13 +72,14 @@ func (ci *CursorIterator) Next() bool {
 	}
 
 	var shard tsdb.CursorIterator
+	var err error
 	ci.cur = nil
-	for ci.cur == nil && len(ci.itrs) > 0 {
+	for ci.cur == nil && len(ci.itrs) > 0 && err == nil {
 		shard, ci.itrs = ci.itrs[0], ci.itrs[1:]
-		ci.cur, _ = shard.Next(ci.ctx, &ci.req)
+		ci.cur, err = shard.Next(ci.ctx, &ci.req)
 	}
 
-	return ci.cur != nil
+	return ci.cur != nil && err == nil
 }
 
 func (ci *CursorIterator) Cursor() tsdb.Cursor {

storage/reads/array_cursor.gen.go

@@ -335,13 +335,15 @@ func (c *floatMultiShardArrayCursor) nextArrayCursor() bool {
 
 	var itr cursors.CursorIterator
 	var cur cursors.Cursor
-	for cur == nil && len(c.itrs) > 0 {
+	var err error
+	for cur == nil && len(c.itrs) > 0 && err == nil {
 		itr, c.itrs = c.itrs[0], c.itrs[1:]
-		cur, _ = itr.Next(c.ctx, c.req)
+		cur, err = itr.Next(c.ctx, c.req)
 	}
 
+	c.err = err
 	var ok bool
-	if cur != nil {
+	if cur != nil && err == nil {
 		var next cursors.FloatArrayCursor
 		next, ok = cur.(cursors.FloatArrayCursor)
 		if !ok {
@@ -1340,13 +1342,15 @@ func (c *integerMultiShardArrayCursor) nextArrayCursor() bool {
 
 	var itr cursors.CursorIterator
 	var cur cursors.Cursor
-	for cur == nil && len(c.itrs) > 0 {
+	var err error
+	for cur == nil && len(c.itrs) > 0 && err == nil {
 		itr, c.itrs = c.itrs[0], c.itrs[1:]
-		cur, _ = itr.Next(c.ctx, c.req)
+		cur, err = itr.Next(c.ctx, c.req)
 	}
 
+	c.err = err
 	var ok bool
-	if cur != nil {
+	if cur != nil && err == nil {
 		var next cursors.IntegerArrayCursor
 		next, ok = cur.(cursors.IntegerArrayCursor)
 		if !ok {
@@ -2345,13 +2349,15 @@ func (c *unsignedMultiShardArrayCursor) nextArrayCursor() bool {
 
 	var itr cursors.CursorIterator
 	var cur cursors.Cursor
-	for cur == nil && len(c.itrs) > 0 {
+	var err error
+	for cur == nil && len(c.itrs) > 0 && err == nil {
 		itr, c.itrs = c.itrs[0], c.itrs[1:]
-		cur, _ = itr.Next(c.ctx, c.req)
+		cur, err = itr.Next(c.ctx, c.req)
 	}
 
+	c.err = err
 	var ok bool
-	if cur != nil {
+	if cur != nil && err == nil {
 		var next cursors.UnsignedArrayCursor
 		next, ok = cur.(cursors.UnsignedArrayCursor)
 		if !ok {
@@ -3350,13 +3356,15 @@ func (c *stringMultiShardArrayCursor) nextArrayCursor() bool {
 
 	var itr cursors.CursorIterator
 	var cur cursors.Cursor
-	for cur == nil && len(c.itrs) > 0 {
+	var err error
+	for cur == nil && len(c.itrs) > 0 && err == nil {
 		itr, c.itrs = c.itrs[0], c.itrs[1:]
-		cur, _ = itr.Next(c.ctx, c.req)
+		cur, err = itr.Next(c.ctx, c.req)
 	}
 
+	c.err = err
 	var ok bool
-	if cur != nil {
+	if cur != nil && err == nil {
 		var next cursors.StringArrayCursor
 		next, ok = cur.(cursors.StringArrayCursor)
 		if !ok {
@@ -3777,13 +3785,15 @@ func (c *booleanMultiShardArrayCursor) nextArrayCursor() bool {
 
 	var itr cursors.CursorIterator
 	var cur cursors.Cursor
-	for cur == nil && len(c.itrs) > 0 {
+	var err error
+	for cur == nil && len(c.itrs) > 0 && err == nil {
 		itr, c.itrs = c.itrs[0], c.itrs[1:]
-		cur, _ = itr.Next(c.ctx, c.req)
+		cur, err = itr.Next(c.ctx, c.req)
 	}
 
+	c.err = err
 	var ok bool
-	if cur != nil {
+	if cur != nil && err == nil {
 		var next cursors.BooleanArrayCursor
 		next, ok = cur.(cursors.BooleanArrayCursor)
 		if !ok {

storage/reads/array_cursor.gen.go.tmpl

@@ -282,13 +282,15 @@ func (c *{{.name}}MultiShardArrayCursor) nextArrayCursor() bool {
 
 	var itr cursors.CursorIterator
 	var cur cursors.Cursor
-	for cur == nil && len(c.itrs) > 0 {
+	var err error
+	for cur == nil && len(c.itrs) > 0 && err == nil {
 		itr, c.itrs = c.itrs[0], c.itrs[1:]
-		cur, _ = itr.Next(c.ctx, c.req)
+		cur, err = itr.Next(c.ctx, c.req)
 	}
 
+	c.err = err
 	var ok bool
-	if cur != nil {
+	if cur != nil && err == nil {
 		var next cursors.{{.Name}}ArrayCursor
 		next, ok = cur.(cursors.{{.Name}}ArrayCursor)
 		if !ok {

storage/reads/array_cursor.go

@@ -117,12 +117,13 @@ func (m *multiShardArrayCursors) createCursor(row SeriesRow) cursors.Cursor {
 
 	var shard cursors.CursorIterator
 	var cur cursors.Cursor
+	var err error
 	for cur == nil && len(row.Query) > 0 {
 		shard, row.Query = row.Query[0], row.Query[1:]
-		cur, _ = shard.Next(m.ctx, &m.req)
+		cur, err = shard.Next(m.ctx, &m.req)
 	}
 
-	if cur == nil {
+	if cur == nil || err != nil {
 		return nil
 	}