* refactor NewSegmentsRangeReader to take multi WAL ranges
In case of an error when checkpointing the WAL the error doesn't show
the exact WAL index that is corrupter. this is because it uses
MultiReader to read multiply WAL files.
This refactoring allows the NewSegmentsRangeReader to take more than a
single WAL range and it reads all of the ranges by iterating each one.
this changes the logs from
create checkpoint: read segments: corruption after 4841144384 bytes:...
to
create checkpoint: read segments: corruption in segment
data/wal/00017351 at 123142208: ...
Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>
Create checkpoints from a sequence of WAL segments while filtering
out obsolete data. The checkpoint format is again a sequence of WAL
segments, which allows us to reuse the serialization format and
implementation.
Signed-off-by: Fabian Reinartz <freinartz@google.com>
