fix: remove temp files on error in Compactor.writeNewFiles (#26074)

Compactor.writeNewFiles should delete
temporary files created on iterations
before an error halts the compaction.

closes https://github.com/influxdata/influxdb/issues/26073

tsdb/engine/tsm1/compact.go

@@ -1085,6 +1085,17 @@ func (c *Compactor) RemoveTmpFiles(files []string) error {
 	return errors.Join(errs...)
 }
 
+func (c *Compactor) RemoveTmpFilesOnErr(files []string, originalErrs ...error) error {
+	removeErr := c.RemoveTmpFiles(files)
+	if removeErr == nil {
+		return errors.Join(originalErrs...)
+	} else if errJoin, ok := removeErr.(interface{ Unwrap() []error }); ok {
+		return errors.Join(append(originalErrs, errJoin.Unwrap()...)...)
+	} else {
+		return errors.Join(append(originalErrs, removeErr)...)
+	}
+}
+
 // writeNewFiles writes from the iterator into new TSM files, rotating
 // to a new file once it has reached the max TSM file size.
 func (c *Compactor) writeNewFiles(generation, sequence int, src []string, iter KeyIterator, throttle bool, logger *zap.Logger) ([]string, error) {
@@ -1113,7 +1124,8 @@ func (c *Compactor) writeNewFiles(generation, sequence int, src []string, iter K
 			// If the file only contained tombstoned entries, then it would be a 0 length
 			// file that we can drop.
 			if err := os.RemoveAll(fileName); err != nil {
-				return nil, err
+				// Only return an error if we couldn't remove the temp files
+				return nil, c.RemoveTmpFilesOnErr(files, err)
 			}
 			break
 		} else if errors.As(err, &eInProgress) {
@@ -1124,27 +1136,14 @@ func (c *Compactor) writeNewFiles(generation, sequence int, src []string, iter K
 				// planner keeps track of which files are assigned to compaction plans now.
 				logger.Warn("file exists, compaction in progress already", zap.String("output_file", fileName))
 			}
-			return nil, err
-		} else if err != nil {
-			var errs []error
-			errs = append(errs, err)
 			// We hit an error and didn't finish the compaction.  Abort.
 			// Remove any tmp files we already completed
-			// discard later errors to return the first one from the write() call
-			for _, f := range files {
-				err = os.RemoveAll(f)
-				if err != nil {
-					errs = append(errs, err)
-				}
-			}
-			// Remove the temp file
-			// discard later errors to return the first one from the write() call
-			err = os.RemoveAll(fileName)
-			if err != nil {
-				errs = append(errs, err)
-			}
-
-			return nil, errors.Join(errs...)
+			return nil, c.RemoveTmpFilesOnErr(files, err)
+		} else if err != nil {
+			// We hit an error and didn't finish the compaction.  Abort.
+			// Remove any tmp files we already completed, as well as the current
+			// file we were writing to.
+			return nil, c.RemoveTmpFilesOnErr(files, err, os.RemoveAll(fileName))
 		}
 
 		files = append(files, fileName)