@node WARCs
@section WARCs management

To view WARC files, you have to load them in daemon. Responses will be
transparently replaced from those WARCs for corresponding URIs.

There is no strict validation or checking of WARCs correctness at all!
But built-in WARC support seems to be good enough for various sources.
Uncompressed, @command{gzip} (multiple streams and single stream are
supported) and @command{zstd} compressed ones are supported.

Searching in compressed files is @strong{slow} -- every request will
lead to decompression of the file from the very beginning, so keeping
uncompressed WARCs on compressed ZFS dataset is much more preferable.
@command{tofuproxy} does not take advantage of multistream gzip files.

@itemize

@item
Load WARCs:

@example
$ tee fifos/add-warcs < warcs.txt
smth.warc-00000.warc.gz
smth.warc-00001.warc.gz
smth.warc-00002.warc.gz
another.warc
@end example

@item
Visit the URI you know, that exists in those WARCs, or go to
@url{http://warc/}, to view full list of known loaded URIs from
those WARCs.

@item
Pay attention that order of WARCs loading is important! WARC can be
segmented and single response can be split on multiple WARC files.
Each following WARC files will overwrite possibly already existing URIs.

@item
To list and delete loaded known WARCs:

@example
$ cat fifos/list-warcs
smth.warc-00000.warc.gz 154
smth.warc-00001.warc.gz 13
smth.warc-00002.warc.gz 0
another.warc 123
$ echo another.warc > fifos/del-warcs
@end example

One possibility that @file{smth.warc-00002.warc.gz} has no URIs is that
it contains continuation segmented records.

@end itemize

Loading of WARC involves its whole reading and remembering where is each
URI response is located. You can @code{echo SAVE > fifos/add-warcs} to
save in-memory index to the disk as @file{....warc.idx.gob} file. During
the next load, if that file exists, it is used as index immediately,
without expensive WARC reading.

@code{redo warc-extract.cmd} builds @command{warc-extract.cmd} utility,
that uses exactly the same code for parsing WARCs. It can be used to
check if WARCs can be successfully loaded, to list all URIs after, to
extract some specified URI and to pre-generate @file{.idx.gob} indexes.

@example
$ warc-extract.cmd -idx \
    smth.warc-00000.warc.gz \
    smth.warc-00001.warc.gz \
    smth.warc-00002.warc.gz
$ warc-extract.cmd -uri http://some/uri \
    smth.warc-00000.warc.gz \
    smth.warc-00001.warc.gz \
    smth.warc-00002.warc.gz
@end example

@url{https://www.gnu.org/software/wget/, GNU Wget} can be easily used to
create WARCs:

@example
$ wget ... [--page-requisites] [--recursive] \
    --no-warc-keep-log --no-warc-digests [--warc-max-size=XXX] \
    --warc-file smth.warc ...
@end example