@node WARCs
-@section WARCs management
+@unnumbered 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.
+Following formats 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.
+@table @asis
+
+@item @file{.warc}
+Ordinary uncompressed WARC. Useful to be stored on transparently
+compressed ZFS dataset.
+
+@item @command{.warc.gz}
+GZIP compressed WARC. Multi-stream (multi-segment) formats are also
+supported and properly indexed.
+
+@item @command{.warc.zst}
+Zstandard compressed WARC, as in
+@url{https://iipc.github.io/warc-specifications/specifications/warc-zstd/, specification}.
+Multi-frame format is properly indexed. Dictionary at the beginning
+is also supported.
+
+It is processed with @command{unzstd} (@file{cmd/zstd/unzstd})
+utility. It eats compressed stream from @code{stdin}, outputs
+decompressed data to @code{stdout}, and prints each frame size with
+corresponding decompressed data size to 3rd file descriptor (if it is
+opened).
+
+@end table
@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.
+save in-memory index to the disk as @file{....idx.gob} files. During
+the next load, if those files exists, they are used as index immediately,
+without expensive WARC parsing.
-@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.
+@code{cmd/warc-extract/warc-extract} utility 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} indices.
@example
-$ warc-extract.cmd -idx \
+$ cmd/warc-extract/warc-extract -idx \
smth.warc-00000.warc.gz \
smth.warc-00001.warc.gz \
smth.warc-00002.warc.gz
-$ warc-extract.cmd -uri http://some/uri \
+$ cmd/warc-extract/warc-extract -uri http://some/uri \
smth.warc-00000.warc.gz \
smth.warc-00001.warc.gz \
smth.warc-00002.warc.gz
@end example
+Following example can be used to create multi-frame @file{.warc.zst}
+from any kind of already existing WARCs. It has better compression ratio
+and much higher decompression speed, than @file{.warc.gz}.
+
+@example
+$ cmd/warc-extract/warc-extract -for-enzstd /path/to.warc.gz |
+ cmd/zstd/enzstd > /path/to.warc.zst
+@end example
+
@url{https://www.gnu.org/software/wget/, GNU Wget} can be easily used to
create WARCs:
--no-warc-keep-log --no-warc-digests [--warc-max-size=XXX] \
--warc-file smth.warc ...
@end example
+
+Or even more simpler @url{https://git.jordan.im/crawl/tree/README.md, crawl}
+utility written on Go too.