user/dev discussion of public-inbox itself
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From: Eric Wong <e@yhbt.net>
To: meta@public-inbox.org
Subject: [9/8 PATCH] v2writable: git_hash_raw: avoid $TMPDIR write
Date: Fri, 17 Jul 2020 07:25:07 +0000	[thread overview]
Message-ID: <20200717072507.GA22251@dcvr> (raw)
In-Reply-To: <20200717063155.3734-1-e@yhbt.net>

We can rely on FD_CLOEXEC being set by default (since Perl 5.6+)
on pipes to avoid FS/page-cache traffic, here.  We also know
"git hash-object" won't output anything until it's consumed all
of its standard input; so there's no danger of a deadlock even
in the the unlikely case git uses a hash that can't fit into
PIPE_BUF :P
---
 lib/PublicInbox/V2Writable.pm | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index dffe90d8c..0582dd5e3 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -482,14 +482,12 @@ sub purge {
 sub git_hash_raw ($$) {
 	my ($self, $raw) = @_;
 	# grab the expected OID we have to reindex:
-	open my $tmp_fh, '+>', undef or die "failed to open tmp: $!";
-	$tmp_fh->autoflush(1);
-	print $tmp_fh $$raw or die "print \$tmp_fh: $!";
-	sysseek($tmp_fh, 0, 0) or die "seek failed: $!";
-
+	pipe(my($in, $w)) or die "pipe: $!";
 	my $git_dir = $self->{-inbox}->git->{git_dir};
 	my $cmd = ['git', "--git-dir=$git_dir", qw(hash-object --stdin)];
-	my $r = popen_rd($cmd, undef, { 0 => $tmp_fh });
+	my $r = popen_rd($cmd, undef, { 0 => $in });
+	print $w $$raw or die "print \$w: $!";
+	close $w or die "close \$w: $!";
 	local $/ = "\n";
 	chomp(my $oid = <$r>);
 	close $r or die "git hash-object failed: $?";

      parent reply	other threads:[~2020-07-17  7:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-17  6:31 [PATCH 0/8] indexing cleanup and code reduction Eric Wong
2020-07-17  6:31 ` [PATCH 1/8] v2: use v5.10.1, parent.pm, drop warnings Eric Wong
2020-07-17  6:31 ` [PATCH 2/8] drop binmode usage Eric Wong
2020-07-17  6:31 ` [PATCH 3/8] import: use common capitalization for filtering headers Eric Wong
2020-07-17  6:31 ` [PATCH 4/8] with_umask: pass args to callback Eric Wong
2020-07-17  6:31 ` [PATCH 5/8] overidx: each_by_mid: pass self and args to callbacks Eric Wong
2020-07-17  6:31 ` [PATCH 6/8] overidx: favor non-OO sub dispatch for internal subs Eric Wong
2020-07-17  6:31 ` [PATCH 7/8] searchidx: use v5.10.1, parent.pm, drop warnings Eric Wong
2020-07-17  6:31 ` [PATCH 8/8] search: simplify unindexing Eric Wong
2020-07-17  7:25 ` Eric Wong [this message]

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user/dev discussion of public-inbox itself

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