cindex: document pipelines created for prune

This ought to make things easier-to-understand for people
reading the code for the first time (or rereading it for the
first time in a few days :x)

diff --git a/lib/PublicInbox/CodeSearchIdx.pm b/lib/PublicInbox/CodeSearchIdx.pm
index a9a7d3134d2832579bd2d4c546d8dc7a8f6ad6e9..2700744dfa4cb4600d6af90cff4e5f2f07f65157 100644 (file)
--- a/lib/PublicInbox/CodeSearchIdx.pm
+++ b/lib/PublicInbox/CodeSearchIdx.pm
@@ -948,7 +948,8 @@ sub init_prune ($) {
        # Dealing with millions of commits here at once, so use faster tools.
        # xapian-delve is nearly an order-of-magnitude faster than Xapian Perl
        # bindings.  sed/awk are faster than Perl for simple stream ops, and
-       # sort+comm are more memory-efficient with gigantic lists
+       # sort+comm are more memory-efficient with gigantic lists.
+       # pipeline: delve | sed | sort >indexed_commits
        my @delve = (undef, qw(-A Q -1));
        my @sed = (undef, '-ne', 's/^Q//p');
        @COMM = (undef, qw(-2 -3 indexed_commits -));
@@ -988,6 +989,12 @@ sub dump_git_commits { # awaitpid cb
 sub run_prune { # OnDestroy when `git config extensions.objectFormat' are done
        my ($self) = @_;
        return if $DO_QUIT;
+       # setup the following pipeline: (
+       #       git --git-dir=hexlen40.git cat-file \
+       #               --batch-all-objects --batch-check &&
+       #       git --git-dir=hexlen64.git cat-file \
+       #               --batch-all-objects --batch-check
+       # ) | awk | sort | comm | cidx_read_comm()
        pipe(my ($awk_in, $batch_out)) or die "pipe: $!";
        pipe(my ($sort_in, $awk_out)) or die "pipe: $!";
        pipe(my ($comm_in, $sort_out)) or die "pipe: $!";