multi_git: hoist out common epoch/alternates handling

IMHO, this greatly improves code sharing and organization
between v2, extindex, and lei/store.  Common git-related
logic for these is lightly-refactored and easier to reason
about.

The impetus for this big change was to ensure inboxes
created+managed by public-inbox-{clone,fetch} could have
alternates and configs setup properly without depending on
SQLite (via V2Writable).  This change does that while
making old code shorter and better factored.

1 files changed, 8 insertions, 9 deletions

diff --git a/lib/PublicInbox/Fetch.pm b/lib/PublicInbox/Fetch.pm
index 6a6daee6..9ea55e9d 100644
--- a/lib/PublicInbox/Fetch.pm
+++ b/lib/PublicInbox/Fetch.pm
@@ -6,12 +6,11 @@ use strict;
 use v5.10.1;
 use parent qw(PublicInbox::IPC);
 use URI ();
-use PublicInbox::Spawn qw(popen_rd);
+use PublicInbox::Spawn qw(popen_rd run_die);
 use PublicInbox::Admin;
 use PublicInbox::LEI;
 use PublicInbox::LeiCurl;
 use PublicInbox::LeiMirror;
-use IO::Uncompress::Gunzip qw(gunzip $GunzipError);
 use File::Temp ();
 
 sub new { bless {}, __PACKAGE__ }
@@ -87,15 +86,15 @@ sub do_fetch {
         my $ibx_ver;
         $lei->{curl} //= PublicInbox::LeiCurl->new($lei) or return;
         my $dir = PublicInbox::Admin::resolve_inboxdir($cd, \$ibx_ver);
-        my ($ibx_uri, @git_dir, @epochs);
+        my ($ibx_uri, @git_dir, @epochs, $mg, @new_epoch);
         if ($ibx_ver == 1) {
                 my $url = remote_url($lei, $dir) //
                         die "E: $dir missing remote.origin.url\n";
                 $ibx_uri = URI->new($url);
         } else { # v2:
-                opendir my $dh, "$dir/git" or die "opendir $dir/git: $!";
-                @epochs = sort { $b <=> $a } map { substr($_, 0, -4) + 0 }
-                                        grep(/\A[0-9]+\.git\z/, readdir($dh));
+                require PublicInbox::MultiGit;
+                $mg = PublicInbox::MultiGit->new($dir, 'all.git', 'git');
+                my @epochs = $mg->git_epochs;
                 my ($git_url, $epoch);
                 for my $nr (@epochs) { # try newest epoch, first
                         my $edir = "$dir/git/$nr.git";
@@ -121,9 +120,7 @@ EOM
         if ($code == 404) {
                 # any pre-manifest.js.gz instances running? Just fetch all
                 # existing ones and unconditionally try cloning the next
-                $v2_epochs = [ map {;
-                                "$dir/git/$_.git";
-                                } @epochs ];
+                $v2_epochs = [ map { "$dir/git/$_.git" } @epochs ];
                 push @$v2_epochs, "$dir/git/".($epochs[-1] + 1) if @epochs;
         } else {
                 $code == 200 or die "BUG unexpected code $code\n";
@@ -154,6 +151,7 @@ EOM
                         $cmd = [ @$torsocks,
                                 PublicInbox::LeiMirror::clone_cmd($lei, $opt),
                                 $$e_uri, $d];
+                        push @new_epoch, substr($epath, 5, -4) + 0;
                 }
                 my $cerr = PublicInbox::LeiMirror::run_reap($lei, $cmd, $opt);
                 # do not bail on clone failure if we didn't have a manifest
@@ -162,6 +160,7 @@ EOM
                         return;
                 }
         }
+        for my $i (@new_epoch) { $mg->epoch_cfg_set($i) }
         if ($ft) {
                 my $fn = $ft->filename;
                 rename($fn, $mf) or die "E: rename($fn, $mf): $!\n";