TODO list for agedu
===================
-Before it's non-embarrassingly releasable:
+ - stop trying to calculate an upper bound on the index file size.
+ Instead, just mmap it at initial size + delta, and periodically
+ re-mmap it during index building if it grows too big. If we run
+ out of address space, we'll hear about it eventually; and
+ computing upper bounds given the new optimised index tends to be
+ a factor of five out, which is bad because it'll lead to running
+ out of theoretical address space and erroneously reporting
+ failure long before we run out of it for real.
- - sort out the command line syntax
- * I think there should be a unified --mode / -M for every
- running mode, possibly without the one-letter option for the
- diagnostic sorts of things
- * there should be some configurable options:
- + range limits on the age display
- + server address in httpd mode
- + HTTP authentication: specify username and/or password, the
- latter by at least some means which doesn't involve it
- showing up in "ps"
+ - 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.
- - 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.
-
- - make a final decision on the name!
-
- - man page, licence, online help.
-
-Future directions:
+ - 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
* All the same options should have their starting states
configurable on the command line too.
- - polish the plain-text output:
- + do the same formatting as in HTML, by showing files as a
- single unit and also sorting by size? (Probably the other way
- up, due to scrolling.)
- + configurable recursive output depth
-
- curses-ish equivalent of the web output
+ try using xterm 256-colour mode. Can (n)curses handle that? If
not, try doing it manually.
+ + I think my current best idea is to bypass ncurses and go
+ 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".
+ + 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
+ the index lookups, percentage calculation, vector arithmetic
+ and line sorting), and another part to generate the literal
+ HTML. Then the former can be reused to produce very similar
+ reports in coloured plain text.
- - cross-module:
- + 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!
-
- - more flexible running modes
- + decouple the disk scan from the index building code, so that
- the former can optionally output in the same format as --dump
- and the latter can optionally work from input on stdin (having
- also fixed the --dump format in the process so it's perfectly
- general). Then we could scan on one machine and transfer the
- results over the net to another machine where they'd be
- indexed; in particular, this way the indexing machine could be
- 64-bit even if the machine owning the filesystems was only 32.
- + in the other direction, ability to build a database _and_
- immediately run one of the ongoing interactive report modes
- (httpd, curses) in a single invocation would seem handy.
-
- - portability
- + between Unices:
- * 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?
- + 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
+ - http://msdn.microsoft.com/en-us/library/ms724290.aspx suggest
+ modern Windowses support atime-equivalents, so a Windows port is
+ 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,
- the path separator character (yuck). 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.
+ 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.
+ + 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, it might be the case that the space gain is no longer
+ worthwhile.