index+xcpdb: improve SIG{INT,TERM,HUP,PIPE} behavior

-index now invokes ->DESTROY like xcpdb does, which is necessary
to cleanup $INBOX_DIR/msgmap-XXXXXXX files.  We'll also exit
with the expected values for various signals by adding 128
as described in <https://www.tldp.org/LDP/abs/html/exitcodes.html>

-xcpdb now terminates worker processes and xapian-compact(1)
invocations when prematurely killed, too.

2 files changed, 44 insertions, 13 deletions

diff --git a/lib/PublicInbox/Admin.pm b/lib/PublicInbox/Admin.pm
index e42b01e0..af2b3da9 100644
--- a/lib/PublicInbox/Admin.pm
+++ b/lib/PublicInbox/Admin.pm
@@ -5,14 +5,28 @@
 # Unstable internal API
 package PublicInbox::Admin;
 use strict;
-use warnings;
-use Cwd 'abs_path';
-use base qw(Exporter);
-our @EXPORT_OK = qw(resolve_repo_dir);
+use parent qw(Exporter);
+use Cwd qw(abs_path);
+use POSIX ();
+our @EXPORT_OK = qw(resolve_repo_dir setup_signals);
 use PublicInbox::Config;
 use PublicInbox::Inbox;
 use PublicInbox::Spawn qw(popen_rd);
 
+sub setup_signals {
+        my ($cb, $arg) = @_; # optional
+
+        # we call exit() here instead of _exit() so DESTROY methods
+        # get called (e.g. File::Temp::Dir and PublicInbox::Msgmap)
+        $SIG{INT} = $SIG{HUP} = $SIG{PIPE} = $SIG{TERM} = sub {
+                my ($sig) = @_;
+                # https://www.tldp.org/LDP/abs/html/exitcodes.html
+                eval { $cb->($sig, $arg) } if $cb;
+                $sig = 'SIG'.$sig;
+                exit(128 + POSIX->$sig);
+        };
+}
+
 sub resolve_repo_dir {
         my ($cd, $ver) = @_;
         my $prefix = defined $cd ? $cd : './';
@@ -185,9 +199,16 @@ invalid indexlevel=$indexlevel (must be `basic', `medium', or `full')
         die missing_mod_msg($err) ." required for indexlevel=$indexlevel\n";
 }
 
+sub index_terminate {
+        my (undef, $ibx) = @_; # $_[0] = signal name
+        $ibx->git->cleanup;
+}
+
 sub index_inbox {
         my ($ibx, $im, $opt) = @_;
         my $jobs = delete $opt->{jobs} if $opt;
+        local %SIG = %SIG;
+        setup_signals(\&index_terminate, $ibx);
         if (ref($ibx) && $ibx->version == 2) {
                 eval { require PublicInbox::V2Writable };
                 die "v2 requirements not met: $@\n" if $@;
diff --git a/lib/PublicInbox/Xapcmd.pm b/lib/PublicInbox/Xapcmd.pm
index 714f6859..348621ce 100644
--- a/lib/PublicInbox/Xapcmd.pm
+++ b/lib/PublicInbox/Xapcmd.pm
@@ -2,8 +2,8 @@
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 package PublicInbox::Xapcmd;
 use strict;
-use warnings;
 use PublicInbox::Spawn qw(which popen_rd nodatacow_dir);
+use PublicInbox::Admin qw(setup_signals);
 use PublicInbox::Over;
 use PublicInbox::SearchIdx;
 use File::Temp 0.19 (); # ->newdir
@@ -126,6 +126,11 @@ sub same_fs_or_die ($$) {
         die "$x and $y reside on different filesystems\n";
 }
 
+sub kill_pids {
+        my ($sig, $pids) = @_;
+        kill($sig, keys %$pids); # pids may be empty
+}
+
 sub process_queue {
         my ($queue, $cb, $opt) = @_;
         my $max = $opt->{jobs} // scalar(@$queue);
@@ -138,6 +143,8 @@ sub process_queue {
 
         # run in parallel:
         my %pids;
+        local %SIG = %SIG;
+        setup_signals(\&kill_pids, \%pids);
         while (@$queue) {
                 while (scalar(keys(%pids)) < $max && scalar(@$queue)) {
                         my $args = shift @$queue;
@@ -156,12 +163,6 @@ sub process_queue {
         }
 }
 
-sub setup_signals () {
-        # http://www.tldp.org/LDP/abs/html/exitcodes.html
-        $SIG{INT} = sub { exit(130) };
-        $SIG{HUP} = $SIG{PIPE} = $SIG{TERM} = sub { exit(1) };
-}
-
 sub prepare_run {
         my ($ibx, $opt) = @_;
         my $tmp = {}; # old shard dir => File::Temp->newdir object or undef
@@ -294,6 +295,11 @@ sub progress_pfx ($) {
         ($p[-1] =~ /\A([0-9]+)/) ? "$p[-2]/$1" : $p[-1];
 }
 
+sub kill_compact { # setup_signals callback
+        my ($sig, $pidref) = @_;
+        kill($sig, $$pidref) if defined($$pidref);
+}
+
 # xapian-compact wrapper
 sub compact ($$) {
         my ($args, $opt) = @_;
@@ -319,14 +325,18 @@ sub compact ($$) {
         }
         $pr->("$pfx `".join(' ', @$cmd)."'\n") if $pr;
         push @$cmd, $src, $dst;
-        my $rd = popen_rd($cmd, undef, $rdr);
+        my ($rd, $pid);
+        local %SIG = %SIG;
+        setup_signals(\&kill_compact, \$pid);
+        ($rd, $pid) = popen_rd($cmd, undef, $rdr);
         while (<$rd>) {
                 if ($pr) {
                         s/\r/\r$pfx /g;
                         $pr->("$pfx $_");
                 }
         }
-        close $rd or die join(' ', @$cmd)." failed: $?n";
+        waitpid($pid, 0);
+        die "@$cmd failed: \$?=$?\n" if $?;
 }
 
 sub cpdb_loop ($$$;$$) {