Load files sequentially

#1

We have files with historical and incremental data sent to us by a customer. I have to load all these files sequentially to make sure the data in historical files does not update the latest incremental changes.

Eg: I have a folder
"S3 bucket name/Source Collection/"
And files in it as
C3_Canonical_Histroical_20171201.csv (Historical)
C3_Canonical_Incremental_20180101.csv
C3_Canonical_Incremental_20180102.csv
C3_Canonical_Incremental_20180103.csv

When I start loading all these files using SourceFile.processAll(), I cannot guarantee sequential processing. Is there a way I can do that?