* [PATCH 3/3] init: implement locking
2019-10-03 7:21 7% [PATCH 0/3] init: add manpage and locking Eric Wong
@ 2019-10-03 7:21 6% ` Eric Wong
0 siblings, 0 replies; 2+ results
From: Eric Wong @ 2019-10-03 7:21 UTC (permalink / raw)
To: meta
First, we use flock(2) to wait on parallel public-inbox-init(1)
invocations while we make multiple changes using git-config(1).
This flock allows -init processes to wait on each other if using
reasonable POSIX filesystems.
Then, we also need a git-config(1)-compatible lock to prevent
user-invoked git-config(1) processes from clobbering our
changes while we're holding the flock.
---
script/public-inbox-init | 24 ++++++++++++++++++++++++
t/init.t | 12 ++++++++++++
2 files changed, 36 insertions(+)
diff --git a/script/public-inbox-init b/script/public-inbox-init
index 39f2a067..8fd2f9dc 100755
--- a/script/public-inbox-init
+++ b/script/public-inbox-init
@@ -12,8 +12,10 @@ PublicInbox::Admin::require_or_die('-base');
require PublicInbox::Config;
require PublicInbox::InboxWritable;
use File::Temp qw/tempfile/;
+use PublicInbox::Lock;
use File::Basename qw/dirname/;
use File::Path qw/mkpath/;
+use Fcntl qw(:DEFAULT);
use Cwd qw/abs_path/;
sub x { system(@_) and die join(' ', @_). " failed: $?\n" }
@@ -38,7 +40,29 @@ my %seen;
my $pi_config = PublicInbox::Config->default_file;
my $dir = dirname($pi_config);
mkpath($dir); # will croak on fatal errors
+
+# first, we grab a flock to prevent simultaneous public-inbox-init
+# processes from trampling over each other, or exiting with 255 on
+# O_EXCL failure below. This gets unlocked automatically on exit:
+my $lock_obj = { lock_path => "$pi_config.flock" };
+PublicInbox::Lock::lock_acquire($lock_obj);
+
+# git-config will operate on this (and rename on success):
my ($fh, $pi_config_tmp) = tempfile('pi-init-XXXXXXXX', DIR => $dir);
+
+# Now, we grab another lock to use git-config(1) locking, so it won't
+# wait on the lock, unlike some of our internal flock()-based locks.
+# This is to prevent direct git-config(1) usage from clobbering our
+# changes.
+my $lockfile = "$pi_config.lock";
+my $lockfh;
+sysopen($lockfh, $lockfile, O_RDWR|O_CREAT|O_EXCL) or do {
+ $lockfh = undef;
+ warn "could not open config file: $lockfile: $!\n";
+ exit(255);
+};
+END { unlink($lockfile) if $lockfh };
+
my $perm;
if (-e $pi_config) {
open(my $oh, '<', $pi_config) or die "unable to read $pi_config: $!\n";
diff --git a/t/init.t b/t/init.t
index 667b09fe..0cd6f31f 100644
--- a/t/init.t
+++ b/t/init.t
@@ -10,6 +10,8 @@ my $tmpdir = tempdir('pi-init-XXXXXX', TMPDIR => 1, CLEANUP => 1);
use constant pi_init => 'blib/script/public-inbox-init';
use PublicInbox::Import;
use File::Basename;
+use PublicInbox::Spawn qw(spawn);
+use Cwd qw(getcwd);
open my $null, '>>', '/dev/null';
my $rdr = { 2 => fileno($null) };
sub quiet_fail {
@@ -47,6 +49,16 @@ sub quiet_fail {
@cmd = (pi_init, 'clist', '-V2', "$tmpdir/clist",
qw(http://example.com/clist clist@example.com));
quiet_fail(\@cmd, 'attempting to init V2 from V1 fails');
+
+ open my $lock, '+>', "$cfgfile.lock" or die;
+ @cmd = (getcwd(). '/'. pi_init, 'lock', "$tmpdir/lock",
+ qw(http://example.com/lock lock@example.com));
+ ok(-e "$cfgfile.lock", 'lock exists');
+ my $pid = spawn(\@cmd, undef, $rdr);
+ is(waitpid($pid, 0), $pid, 'lock init failed');
+ is($? >> 8, 255, 'got expected exit code on lock failure');
+ ok(unlink("$cfgfile.lock"),
+ '-init did not unlink lock on failure');
}
SKIP: {
--
EW
^ permalink raw reply related [relevance 6%]
* [PATCH 0/3] init: add manpage and locking
@ 2019-10-03 7:21 7% Eric Wong
2019-10-03 7:21 6% ` [PATCH 3/3] init: implement locking Eric Wong
0 siblings, 1 reply; 2+ results
From: Eric Wong @ 2019-10-03 7:21 UTC (permalink / raw)
To: meta
And this reminds me, --skip-articles needs to be added for
--skip-epoch to make sense, too..
Eric Wong (3):
init: favor --skip-epoch instead of --skip
doc: add manpage for public-inbox-init(1)
init: implement locking
Documentation/include.mk | 1 +
Documentation/public-inbox-init.pod | 86 +++++++++++++++++++++++++++++
MANIFEST | 1 +
script/public-inbox-init | 39 ++++++++++---
t/init.t | 18 +++++-
5 files changed, 135 insertions(+), 10 deletions(-)
create mode 100644 Documentation/public-inbox-init.pod
--
EW
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2019-10-03 7:21 7% [PATCH 0/3] init: add manpage and locking Eric Wong
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