[PATCH 24/27] v2writable: allow disabling parallelization

["Eric Wong (Contractor, The Linux Foundation)" <e@80x24.org>]

While parallel processes improves import speed for initial
imports; they are probably not necessary for daily mail imports
via WatchMaildir and certainly not for public-inbox-init.  Save
some memory for daily use and even helps improve readability of
some subroutines by showing which methods they call remotely.
---
 lib/PublicInbox/SearchIdx.pm         | 56 ++++++++++++++++++++++++++------
 lib/PublicInbox/SearchIdxPart.pm     | 62 ++++++++++++++++++-----------------
 lib/PublicInbox/SearchIdxSkeleton.pm | 63 +++++++++++++++++-------------------
 lib/PublicInbox/V2Writable.pm        |  3 +-
 lib/PublicInbox/WatchMaildir.pm      |  4 ++-
 script/public-inbox-init             |  3 +-
 t/v2writable.t                       |  6 ++--
 7 files changed, 118 insertions(+), 79 deletions(-)

diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm
index 0b9fb4b..3d80b00 100644
--- a/lib/PublicInbox/SearchIdx.pm
+++ b/lib/PublicInbox/SearchIdx.pm
@@ -523,6 +523,7 @@ sub link_and_save {
 	$doc->add_boolean_term('Q' . $_) foreach @$mids;
 
 	my $vivified = 0;
+	$self->{skel} and die "Should not have read-only skel here\n";;
 	foreach my $mid (@$mids) {
 		$self->each_smsg_by_mid($mid, sub {
 			my ($cur) = @_;
@@ -887,24 +888,59 @@ sub DESTROY {
 # remote_* subs are only used by SearchIdxPart and SearchIdxSkeleton
 sub remote_commit {
 	my ($self) = @_;
-	print { $self->{w} } "commit\n" or die "failed to write commit: $!";
+	if (my $w = $self->{w}) {
+		print $w "commit\n" or die "failed to write commit: $!";
+	} else {
+		$self->commit_txn_lazy;
+		if (my $skel = $self->{skeleton}) {
+			$skel->commit_txn_lazy;
+		}
+	}
 }
 
 sub remote_close {
 	my ($self) = @_;
-	my $pid = delete $self->{pid} or die "no process to wait on\n";
-	my $w = delete $self->{w} or die "no pipe to write to\n";
-	print $w "close\n" or die "failed to write to pid:$pid: $!\n";
-	close $w or die "failed to close pipe for pid:$pid: $!\n";
-	waitpid($pid, 0) == $pid or die "remote process did not finish";
-	$? == 0 or die ref($self)." pid:$pid exited with: $?";
+	if (my $w = delete $self->{w}) {
+		my $pid = delete $self->{pid} or die "no process to wait on\n";
+		print $w "close\n" or die "failed to write to pid:$pid: $!\n";
+		close $w or die "failed to close pipe for pid:$pid: $!\n";
+		waitpid($pid, 0) == $pid or die "remote process did not finish";
+		$? == 0 or die ref($self)." pid:$pid exited with: $?";
+	} else {
+		die "transaction in progress $self\n" if $self->{txn};
+		$self->_xdb_release if $self->{xdb};
+	}
 }
 
-# triggers remove_by_oid in partition or skeleton
 sub remote_remove {
 	my ($self, $oid, $mid) = @_;
-	print { $self->{w} } "D $oid $mid\n" or
-			die "failed to write remove $!";
+	if (my $w = $self->{w}) {
+		# triggers remove_by_oid in partition or skeleton
+		print $w "D $oid $mid\n" or die "failed to write remove $!";
+	} else {
+		$self->begin_txn_lazy;
+		$self->remove_by_oid($oid, $mid);
+	}
+}
+
+sub begin_txn_lazy {
+	my ($self) = @_;
+	return if $self->{txn};
+	my $xdb = $self->{xdb} || $self->_xdb_acquire;
+	$xdb->begin_transaction;
+	$self->{txn} = 1;
+}
+
+sub commit_txn_lazy {
+	my ($self) = @_;
+	delete $self->{txn} or return;
+	$self->{xdb}->commit_transaction;
+}
+
+sub worker_done {
+	my ($self) = @_;
+	die "$$ $0 xdb not released\n" if $self->{xdb};
+	die "$$ $0 still in transaction\n" if $self->{txn};
 }
 
 1;
diff --git a/lib/PublicInbox/SearchIdxPart.pm b/lib/PublicInbox/SearchIdxPart.pm
index d8c8c8b..82f5c1b 100644
--- a/lib/PublicInbox/SearchIdxPart.pm
+++ b/lib/PublicInbox/SearchIdxPart.pm
@@ -9,6 +9,15 @@ sub new {
 	my ($class, $v2writable, $part, $skel) = @_;
 	my $self = $class->SUPER::new($v2writable->{-inbox}, 1, $part);
 	$self->{skeleton} = $skel;
+	# create the DB:
+	$self->_xdb_acquire;
+	$self->_xdb_release;
+	$self->spawn_worker($v2writable, $part) if $v2writable->{parallel};
+	$self;
+}
+
+sub spawn_worker {
+	my ($self, $v2writable, $part) = @_;
 	my ($r, $w);
 	pipe($r, $w) or die "pipe failed: $!\n";
 	binmode $r, ':raw';
@@ -32,44 +41,30 @@ sub new {
 	$self->{pid} = $pid;
 	$self->{w} = $w;
 	close $r;
-	$self;
 }
 
 sub partition_worker_loop ($$$) {
 	my ($self, $r, $part) = @_;
 	$0 = "pi-v2-partition[$part]";
-	my $xdb = $self->_xdb_acquire;
-	$xdb->begin_transaction;
-	my $txn = 1;
+	$self->begin_txn_lazy;
 	while (my $line = $r->getline) {
 		if ($line eq "commit\n") {
-			$xdb->commit_transaction if $txn;
-			$txn = undef;
+			$self->commit_txn_lazy;
 			$self->{skeleton}->remote_commit;
 		} elsif ($line eq "close\n") {
 			$self->_xdb_release;
-			$xdb = $txn = undef;
 		} elsif ($line eq "barrier\n") {
-			$xdb->commit_transaction if $txn;
-			$txn = undef;
+			$self->commit_txn_lazy;
 			print { $self->{skeleton}->{w} } "barrier $part\n" or
 					die "write failed to skeleton: $!\n";
 		} elsif ($line =~ /\AD ([a-f0-9]{40,}) (.+)\n\z/s) {
 			my ($oid, $mid) = ($1, $2);
-			$xdb ||= $self->_xdb_acquire;
-			if (!$txn) {
-				$xdb->begin_transaction;
-				$txn = 1;
-			}
+			$self->begin_txn_lazy;
 			$self->remove_by_oid($oid, $mid);
 		} else {
 			chomp $line;
 			my ($len, $artnum, $oid, $mid0) = split(/ /, $line);
-			$xdb ||= $self->_xdb_acquire;
-			if (!$txn) {
-				$xdb->begin_transaction;
-				$txn = 1;
-			}
+			$self->begin_txn_lazy;
 			my $n = read($r, my $msg, $len) or die "read: $!\n";
 			$n == $len or die "short read: $n != $len\n";
 			my $mime = PublicInbox::MIME->new(\$msg);
@@ -77,17 +72,21 @@ sub partition_worker_loop ($$$) {
 			$self->add_message($mime, $n, $artnum, $oid, $mid0);
 		}
 	}
-	warn "$$ still in transaction\n" if $txn;
-	warn "$$ xdb active\n" if $xdb;
+	$self->worker_done;
 }
 
 # called by V2Writable
 sub index_raw {
-	my ($self, $len, $msgref, $artnum, $object_id, $mid0) = @_;
-	my $w = $self->{w};
-	print $w "$len $artnum $object_id $mid0\n", $$msgref or die
-		"failed to write partition $!\n";
-	$w->flush or die "failed to flush: $!\n";
+	my ($self, $bytes, $msgref, $artnum, $oid, $mid0, $mime) = @_;
+	if (my $w = $self->{w}) {
+		print $w "$bytes $artnum $oid $mid0\n", $$msgref or die
+			"failed to write partition $!\n";
+		$w->flush or die "failed to flush: $!\n";
+	} else {
+		$$msgref = undef;
+		$self->begin_txn_lazy;
+		$self->add_message($mime, $bytes, $artnum, $oid, $mid0);
+	}
 }
 
 sub atfork_child {
@@ -96,9 +95,14 @@ sub atfork_child {
 
 # called by V2Writable:
 sub remote_barrier {
-	my $w = $_[0]->{w};
-	print $w "barrier\n" or die "failed to print: $!";
-	$w->flush or die "failed to flush: $!";
+	my ($self) = @_;
+	if (my $w = $self->{w}) {
+		print $w "barrier\n" or die "failed to print: $!";
+		$w->flush or die "failed to flush: $!";
+	} else {
+		$self->commit_txn_lazy;
+		$self->{skeleton}->remote_commit;
+	}
 }
 
 1;
diff --git a/lib/PublicInbox/SearchIdxSkeleton.pm b/lib/PublicInbox/SearchIdxSkeleton.pm
index 54a59ab..ba43969 100644
--- a/lib/PublicInbox/SearchIdxSkeleton.pm
+++ b/lib/PublicInbox/SearchIdxSkeleton.pm
@@ -12,7 +12,12 @@ sub new {
 	# create the DB:
 	$self->_xdb_acquire;
 	$self->_xdb_release;
+	$self->spawn_worker($v2writable) if $v2writable->{parallel};
+	$self
+}
 
+sub spawn_worker {
+	my ($self, $v2writable) = @_;
 	my ($r, $w);
 	pipe($r, $w) or die "pipe failed: $!\n";
 	my ($barrier_wait, $barrier_note);
@@ -39,24 +44,19 @@ sub new {
 
 	# lock on only exists in parent, not in worker
 	$self->{lock_path} = $self->xdir . '/pi-v2-skeleton.lock';
-	$self;
 }
 
 sub skeleton_worker_loop {
 	my ($self, $r, $barrier_note) = @_;
 	$barrier_note->autoflush(1);
 	$0 = 'pi-v2-skeleton';
-	my $xdb = $self->_xdb_acquire;
-	$xdb->begin_transaction;
-	my $txn = 1;
+	$self->begin_txn_lazy;
 	my $barrier = undef;
 	while (my $line = $r->getline) {
 		if ($line eq "commit\n") {
-			$xdb->commit_transaction if $txn;
-			$txn = undef;
+			$self->commit_txn_lazy;
 		} elsif ($line eq "close\n") {
 			$self->_xdb_release;
-			$xdb = $txn = undef;
 		} elsif ($line =~ /\Abarrier_init (\d+)\n\z/) {
 			my $n = $1 - 1;
 			die "barrier in-progress\n" if defined $barrier;
@@ -67,18 +67,13 @@ sub skeleton_worker_loop {
 			delete $barrier->{$1} or die "unknown barrier: $part\n";
 			if ((scalar keys %$barrier) == 0) {
 				$barrier = undef;
-				$xdb->commit_transaction if $txn;
-				$txn = undef;
+				$self->commit_txn_lazy;
 				print $barrier_note "barrier_done\n" or die
 					"print failed to barrier note: $!";
 			}
 		} elsif ($line =~ /\AD ([a-f0-9]{40,}) (.*)\n\z/s) {
 			my ($oid, $mid) = ($1, $2);
-			$xdb ||= $self->_xdb_acquire;
-			if (!$txn) {
-				$xdb->begin_transaction;
-				$txn = 1;
-			}
+			$self->begin_txn_lazy;
 			$self->remove_by_oid($oid, $mid);
 		} else {
 			my $len = int($line);
@@ -86,35 +81,34 @@ sub skeleton_worker_loop {
 			$n == $len or die "short read: $n != $len\n";
 			$msg = thaw($msg); # should raise on error
 			defined $msg or die "failed to thaw buffer\n";
-			$xdb ||= $self->_xdb_acquire;
-			if (!$txn) {
-				$xdb->begin_transaction;
-				$txn = 1;
-			}
+			$self->begin_txn_lazy;
 			eval { index_skeleton_real($self, $msg) };
 			warn "failed to index message <$msg->[-1]>: $@\n" if $@;
 		}
 	}
-	die "xdb not released\n" if $xdb;
-	die "in transaction\n" if $txn;
+	$self->worker_done;
 }
 
 # called by a partition worker
 sub index_skeleton {
 	my ($self, $values) = @_;
-	my $w = $self->{w};
-	my $err;
-	my $str = freeze($values);
-	$str = length($str) . "\n" . $str;
+	if (my $w = $self->{w}) {
+		my $err;
+		my $str = freeze($values);
+		$str = length($str) . "\n" . $str;
 
-	# multiple processes write to the same pipe, so use flock
-	# We can't avoid this lock for <=PIPE_BUF writes, either,
-	# because those atomic writes can break up >PIPE_BUF ones
-	$self->lock_acquire;
-	print $w $str or $err = $!;
-	$self->lock_release;
+		# multiple processes write to the same pipe, so use flock
+		# We can't avoid this lock for <=PIPE_BUF writes, either,
+		# because those atomic writes can break up >PIPE_BUF ones
+		$self->lock_acquire;
+		print $w $str or $err = $!;
+		$self->lock_release;
 
-	die "print failed: $err\n" if $err;
+		die "print failed: $err\n" if $err;
+	} else {
+		$self->begin_txn_lazy;
+		index_skeleton_real($self, $values);
+	}
 }
 
 sub remote_remove {
@@ -148,7 +142,7 @@ sub index_skeleton_real ($$) {
 # write to the subprocess
 sub barrier_init {
 	my ($self, $nparts) = @_;
-	my $w = $self->{w};
+	my $w = $self->{w} or return;
 	my $err;
 	$self->lock_acquire;
 	print $w "barrier_init $nparts\n" or $err = "failed to write: $!\n";
@@ -158,7 +152,8 @@ sub barrier_init {
 
 sub barrier_wait {
 	my ($self) = @_;
-	my $l = $self->{barrier_wait}->getline;
+	my $bw = $self->{barrier_wait} or return;
+	my $l = $bw->getline;
 	$l eq "barrier_done\n" or die "bad response from barrier_wait: $l\n";
 }
 
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index 261f9d9..8e1363e 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -56,6 +56,7 @@ sub new {
 		xap_rw => undef, # PublicInbox::V2SearchIdx
 		xap_ro => undef,
 		partitions => $nparts,
+		parallel => 1,
 		transact_bytes => 0,
 		lock_path => "$dir/inbox.lock",
 		# limit each repo to 1GB or so
@@ -93,7 +94,7 @@ sub add {
 	my $nparts = $self->{partitions};
 	my $part = $num % $nparts;
 	my $idx = $self->idx_part($part);
-	$idx->index_raw($len, $msgref, $num, $oid, $mid0);
+	$idx->index_raw($len, $msgref, $num, $oid, $mid0, $mime);
 	my $n = $self->{transact_bytes} += $len;
 	if ($n > (PublicInbox::SearchIdx::BATCH_BYTES * $nparts)) {
 		$self->checkpoint;
diff --git a/lib/PublicInbox/WatchMaildir.pm b/lib/PublicInbox/WatchMaildir.pm
index 2808b72..e28e602 100644
--- a/lib/PublicInbox/WatchMaildir.pm
+++ b/lib/PublicInbox/WatchMaildir.pm
@@ -259,7 +259,9 @@ sub _importer_for {
 		if ($v == 2) {
 			eval { require PublicInbox::V2Writable };
 			die "v2 not supported: $@\n" if $@;
-			PublicInbox::V2Writable->new($inbox);
+			my $v2w = PublicInbox::V2Writable->new($inbox);
+			$v2w->{parallel} = 0;
+			$v2w;
 		} elsif ($v == 1) {
 			my $git = $inbox->git;
 			my $name = $inbox->{name};
diff --git a/script/public-inbox-init b/script/public-inbox-init
index f7a60fb..fdad136 100755
--- a/script/public-inbox-init
+++ b/script/public-inbox-init
@@ -83,8 +83,9 @@ if ($version >= 2) {
 	};
 	$ibx = PublicInbox::Inbox->new($ibx);
 	my $v2w = PublicInbox::V2Writable->new($ibx, 1);
+	$v2w->{parallel} = 0;
+	$v2w->idx_init;
 	$v2w->git_init(0);
-	$v2w->idx_init(0);
 	$v2w->done;
 } elsif ($version == 1) {
 	x(qw(git init -q --bare), $mainrepo);
diff --git a/t/v2writable.t b/t/v2writable.t
index 771e8c1..2088f3f 100644
--- a/t/v2writable.t
+++ b/t/v2writable.t
@@ -108,10 +108,10 @@ if ('ensure git configs are correct') {
 	ok($im->add($mime), 'message with multiple Message-ID');
 	$im->done;
 	my @found;
-	$ibx->search->reopen;
-	$ibx->search->each_smsg_by_mid('abcde@1', sub { push @found, @_; 1 });
+	my $srch = $ibx->search;
+	$srch->reopen->each_smsg_by_mid('abcde@1', sub { push @found, @_; 1 });
 	is(scalar(@found), 1, 'message found by first MID');
-	$ibx->search->each_smsg_by_mid('abcde@2', sub { push @found, @_; 1 });
+	$srch->reopen->each_smsg_by_mid('abcde@2', sub { push @found, @_; 1 });
 	is(scalar(@found), 2, 'message found by second MID');
 	is($found[0]->{doc_id}, $found[1]->{doc_id}, 'same document');
 	ok($found[1]->{doc_id} > 0, 'doc_id is positive');
-- 
EW