TODO list for agedu
===================
-Before it's non-embarrassingly releasable:
-
- - more flexible running modes
- + combined scan+dump mode which doesn't even generate an index
- file (nearly indistinguishable from find(1))
- + load mode which reads a dump from standard input and builds
- the index (need to nail down a perfectly general dump format)
- + at least some ability to chain actions within the same run:
- "agedu -s dirname -w" would seem handy.
-
- - work out what to do about atimes on directories in the absence of
- the Linux syscall magic
- * one option is to read them during the scan and reinstate them
- after each recursion pop. Race-condition prone.
- * marking them in a distinctive colour in the reports is another
- option.
- * a third option is simply to ignore space taken up by
- directories in the first place; inaccurate but terribly simple.
- * incidentally, sometimes open(...,O_NOATIME) will fail, and
- then we have to fall back to ordinary open. Be prepared to do
- this, which probably means getting rid of the icky macro
- hackery in du.c and turning it into a more sensible run-time
- abstraction layer.
-
- - polish the plain-text output to make it look more like du
- + configurable recursive output depth
- + show the right bits last
-
- - figure out what to do about scans starting in the root directory
- + Currently we end up with a double leading slash on the
- pathnames, which is ugly, and we also get a zero-length href
- in between those slashes which means the web interface doesn't
- let you click back up to the top level at all.
- + One big problem here is that a lot of the code assumes that
- you can find the extent of a pathname by searching for "foo"
- and "foo^A", trusting that anything inside the directory will
- begin "foo/". So I'd need to consistently fix this everywhere
- so that a trailing slash is disregarded while doing it, but
- not actually removed.
- + The text output gets it all wrong.
- + The HTML output is fiddly even at the design stage: where
- would I _ideally_ put the link to click on to get back to /?
- It's unclear!
-
- - cross-Unix portability:
- + use autoconf
- * configure use of stat64
- * configure use of /proc/net/tcp
- * configure use of /dev/random
- * configure use of Linux syscall magic replacing readdir
- + later glibcs have fdopendir, hooray! So we can use that
- too, if it's available and O_NOATIME is too.
- * what do we do elsewhere about _GNU_SOURCE?
-
- - prepare a little in advance for a potential future Windows port:
- + store the separator character in the index file when writing
- it, and be prepared to cope on reading if it isn't a slash
- + store literal byte sizes in all the size fields, instead of
- Unixoid 512-byte sectors
-
- - man page, licence.
-
-Future directions:
+ - we could still be using more of the information coming from
+ autoconf. Our config.h is defining a whole bunch of HAVE_FOOs for
+ particular functions (e.g. HAVE_INET_NTOA, HAVE_MEMCHR,
+ HAVE_FNMATCH). We could usefully supply alternatives for some of
+ these functions (e.g. cannibalise the PuTTY wildcard matcher for
+ use in the absence of fnmatch, switch to vanilla truncate() in
+ the absence of ftruncate); where we don't have alternative code,
+ it would perhaps be polite to throw an error at configure time
+ rather than allowing the subsequent build to fail.
+ + however, I don't see anything here that looks very
+ controversial; IIRC it's all in POSIX, for one thing. So more
+ likely this should simply wait until somebody complains.
- IPv6 support in the HTTP server
+ * of course, Linux magic auth can still work in this context; we
+ merely have to be prepared to open one of /proc/net/tcp or
+ /proc/net/tcp6 as appropriate.
- run-time configuration in the HTTP server
* I think this probably works by having a configuration form, or
straight to terminfo: generate lines of attribute-interleaved
text and display them, so we only really need the sequences
"go here and display stuff", "scroll up", "scroll down".
- + I think the attribute-interleaved text might be possible to do
- cunningly, as well: we autodetect a basically VT-style
- terminal, and add 256-colour sequences on the end. So, for
- instance, we might set ANSI-yellow foreground, set ANSI-red
- background, _then_ set both foreground and background to the
- appropriate xterm 256-colour, and then display some
- appropriate character which would have given the right blend
- of the ANSI-16 fore and background colours. Then the same
- display code should gracefully degrade in the face of a
- terminal which doesn't support xterm-256.
- * current best plan is to simulate the xterm-256 shading from
- 0/5 to 5/5 by doing space, colon and hash in colour A on
- colour B background, then hash, colon and space in B on A
- background.
+ Infrastructure work before doing any of this would be to split
html.c into two: one part to prepare an abstract data
structure describing an HTML-like report (in particular, all
- http://msdn.microsoft.com/en-us/library/ms724290.aspx suggest
modern Windowses support atime-equivalents, so a Windows port is
- possible in principle. Would need to modify the current structure
- a lot, to abstract away (at least) memory-mapping of files,
- details of disk scan procedure, networking for httpd. Unclear
- what the right UI would be on Windows, too; command-line exactly
- as now might be considered just a _little_ unfriendly. Or perhaps
- not.
+ possible in principle.
+ + For a full Windows port, would need to modify the current
+ structure a lot, to abstract away (at least) memory-mapping of
+ files, details of disk scan procedure, networking for httpd.
+ Unclear what the right UI would be on Windows, too;
+ command-line exactly as now might be considered just a
+ _little_ unfriendly. Or perhaps not.
+ * Disk scan procedure: the FindFirstFile / FindNextFile
+ functions to scan a directory automatically return the file
+ times along with the filenames, so there's no need to stat
+ them later. Would want to fiddle the shape of the
+ abstraction layer to reflect this.
+ + Alternatively, a much easier approach would be to write a
+ Windows version of just the --scan-dump mode, which does a
+ filesystem scan via the Windows API and generates a valid
+ agedu dump file on standard output. Then one would simply feed
+ that over the network connection of one's choice to the rest
+ of agedu running on Unix as usual.
+
+ - it might conceivably be useful to support a choice of indexing
+ strategies. The current "continuous index" mechanism' tradeoff of
+ taking O(N log N) space in order to be able to support any age
+ cutoff you like is not going to be ideal for everybody. A second
+ more conventional "discrete index" mechanism which allows the
+ user to specify a number of fixed cutoffs and just indexes each
+ directory on those alone would undoubtedly be a useful thing for
+ large-scale users. This will require considerable thought about
+ how to make the indexers pluggable at both index-generation time
+ and query time.
+ * however, now we have the cut-down version of the continuous
+ index, the space saving is less compelling.
~mdw / sgt / agedu / blobdiff