annotate tests/test-debugindexdot.t @ 16414:e8d37b78acfb

parsers: use base-16 trie for faster node->rev mapping

This greatly speeds up node->rev lookups, with results that are
often user-perceptible: for instance, "hg --time log" of the node
associated with rev 1000 on a linux-2.6 repo improves from 0.3
seconds to 0.03.  I have not found any instances of slowdowns.

The new perfnodelookup command in contrib/perf.py demonstrates the
speedup more dramatically, since it performs no I/O.  For a single
lookup, the new code is about 40x faster.

These changes also prepare the ground for the possibility of further
improving the performance of prefix-based node lookups.

Just exercize debugindexdot
Create a short file history including a merge.
  $ hg init t
  $ cd t
  $ echo a > a
  $ hg ci -qAm t1 -d '0 0'
  $ echo a >> a
  $ hg ci -m t2 -d '1 0'
  $ hg up -qC 0
  $ echo b >> a
  $ hg ci -m t3 -d '2 0'
  created new head
  $ HGMERGE=true hg merge -q
  $ hg ci -m merge -d '3 0'

  $ hg debugindexdot .hg/store/data/a.i
  digraph G {
  	-1 -> 0
  	0 -> 1
  	0 -> 2
  	2 -> 3
  	1 -> 3
  }