xapcmd: increase scope of lock

The old lock scope was only sufficient for protecting against
concurrent modifications from the common -mda, -watch, or -learn
writers.

It was not sufficient for protecting against parallel -compact
or -xcpdb invocations from eager admins.  Most of the time this
only leads to confusing and misleading warning messages, but
parallel xcpdb --reshard could lead to errors.

diff --git a/lib/PublicInbox/Xapcmd.pm b/lib/PublicInbox/Xapcmd.pm
index 19c6ff077d21911f003888edd2cc74a0b99f16e5..2864b0d4ec9ce5d10e0a745ed28479a63445d176 100644 (file)
--- a/lib/PublicInbox/Xapcmd.pm
+++ b/lib/PublicInbox/Xapcmd.pm
@@ -122,7 +122,8 @@ sub same_fs_or_die ($$) {
 }
 
 sub process_queue {
-       my ($queue, $cb, $max, $opt) = @_;
+       my ($queue, $cb, $opt) = @_;
+       my $max = $opt->{jobs} || scalar(@$queue);
        if ($max <= 1) {
                while (defined(my $args = shift @$queue)) {
                        $cb->($args, $opt);
@@ -152,36 +153,18 @@ sub setup_signals () {
        $SIG{HUP} = $SIG{PIPE} = $SIG{TERM} = sub { exit(1) };
 }
 
-sub run {
-       my ($ibx, $task, $opt) = @_; # task = 'cpdb' or 'compact'
-       my $cb = \&${\"PublicInbox::Xapcmd::$task"};
-       PublicInbox::Admin::progress_prepare($opt ||= {});
-       my $dir = $ibx->{inboxdir} or die "no inboxdir in inbox\n";
-       runnable_or_die($XAPIAN_COMPACT) if $opt->{compact};
-       my $reindex; # v1:{ from => $x40 }, v2:{ from => [ $x40, $x40, .. ] } }
-       my $from; # per-epoch ranges
-
-       if (!$opt->{-coarse_lock}) {
-               $reindex = $opt->{reindex} = {};
-               $from = $reindex->{from} = [];
-               require PublicInbox::SearchIdx;
-               PublicInbox::SearchIdx::load_xapian_writable();
-       }
+sub prepare_run {
+       my ($ibx, $opt) = @_;
+       my $tmp = {}; # old shard dir => File::Temp->newdir object or undef
+       my @queue; # ([old//src,newdir]) - list of args for cpdb() or compact()
 
-       $ibx->umask_prepare;
        my $old = $ibx->search->xdir(1);
        -d $old or die "$old does not exist\n";
-
-       my $tmp = {};
-       my @q;
        my $reshard = $opt->{reshard};
        if (defined $reshard && $reshard <= 0) {
                die "--reshard must be a positive number\n";
        }
 
-       local %SIG = %SIG;
-       setup_signals();
-
        # we want temporary directories to be as deep as possible,
        # so v2 shards can keep "xap$SCHEMA_VERSION" on a separate FS.
        if ($ibx->version == 1) {
@@ -194,7 +177,7 @@ sub run {
                my $v = PublicInbox::Search::SCHEMA_VERSION();
                my $wip = File::Temp->newdir("xapian$v-XXXXXXXX", DIR => $dir);
                $tmp->{$old} = $wip;
-               push @q, [ $old, $wip ];
+               push @queue, [ $old, $wip ];
        } else {
                opendir my $dh, $old or die "Failed to opendir $old: $!\n";
                my @old_shards;
@@ -223,7 +206,7 @@ sub run {
                        my $wip = File::Temp->newdir($tmpl, DIR => $old);
                        same_fs_or_die($old, $wip->dirname);
                        my $cur = "$old/$dn";
-                       push @q, [ $src // $cur , $wip ];
+                       push @queue, [ $src // $cur , $wip ];
                        $tmp->{$cur} = $wip;
                }
                # mark old shards to be unlinked
@@ -231,10 +214,32 @@ sub run {
                        $tmp->{$_} ||= undef for @$src;
                }
        }
-       my $max = $opt->{jobs} || scalar(@q);
+       ($tmp, \@queue);
+}
+
+sub run {
+       my ($ibx, $task, $opt) = @_; # task = 'cpdb' or 'compact'
+       my $cb = \&${\"PublicInbox::Xapcmd::$task"};
+       PublicInbox::Admin::progress_prepare($opt ||= {});
+       defined(my $dir = $ibx->{inboxdir}) or die "no inboxdir defined\n";
+       -d $dir or die "inboxdir=$dir does not exist\n";
+       runnable_or_die($XAPIAN_COMPACT) if $opt->{compact};
+       my $reindex; # v1:{ from => $x40 }, v2:{ from => [ $x40, $x40, .. ] } }
+
+       if (!$opt->{-coarse_lock}) {
+               $reindex = $opt->{reindex} = {};
+               $reindex->{from} = []; # per-epoch ranges
+               require PublicInbox::SearchIdx;
+               PublicInbox::SearchIdx::load_xapian_writable();
+       }
+
+       local %SIG = %SIG;
+       setup_signals();
+       $ibx->umask_prepare;
        $ibx->with_umask(sub {
                my $im = $ibx->importer(0);
                $im->lock_acquire;
+               my ($tmp, $queue) = prepare_run($ibx, $opt);
 
                # fine-grained locking if we prepare for reindex
                if (!$opt->{-coarse_lock}) {
@@ -243,7 +248,7 @@ sub run {
                }
 
                $ibx->cleanup;
-               process_queue(\@q, $cb, $max, $opt);
+               process_queue($queue, $cb, $opt);
                $im->lock_acquire if !$opt->{-coarse_lock};
                commit_changes($ibx, $im, $tmp, $opt);
        });