[pve-devel] [PATCH v3 pve-zsync 1/2] Refactor locking
Thomas Lamprecht
t.lamprecht at proxmox.com
Tue Oct 8 11:00:24 CEST 2019
On 10/7/19 11:16 AM, Fabian Ebner wrote:
> This introduces a new locked() mechanism allowing to enclose locked
> sections in a cleaner way. There's only two types of locks namely one
> for state and cron (they are always read together and almost always
> written together) and one for sync.
>
> Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
> ---
>
> Changes from v2:
> * Split into two patches
>
> Changes from v1:
> * Refactored locking as Thomas and Fabian suggested
>
> pve-zsync | 239 +++++++++++++++++++++++++++---------------------------
> 1 file changed, 119 insertions(+), 120 deletions(-)
>
so below a "git show -w" to ignore indentation changes, makes it easier
to see what you change - as IMO not all changes are related to the lock
refactoring only - which should be just a cleanup but no semantic code
changes. I'll reply to this with the places I'm unsure (makes it easier
to see for others, if done in quotes, IMO)
----8<----
commit 68ecaed42b6778c3f21729468ce6e1a71ad81a7f
Author: Fabian Ebner <f.ebner at proxmox.com>
Date: Mon Oct 7 11:16:10 2019 +0200
Refactor locking
This introduces a new locked() mechanism allowing to enclose locked
sections in a cleaner way. There's only two types of locks namely one
for state and cron (they are always read together and almost always
written together) and one for sync.
Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
diff --git a/pve-zsync b/pve-zsync
index 425ffa2..f7bf5bd 100755
--- a/pve-zsync
+++ b/pve-zsync
@@ -18,7 +18,6 @@ my $PATH = "/usr/sbin";
my $PVE_DIR = "/etc/pve/local";
my $QEMU_CONF = "${PVE_DIR}/qemu-server";
my $LXC_CONF = "${PVE_DIR}/lxc";
-my $LOCKFILE = "$CONFIG_PATH/${PROGNAME}.lock";
my $PROG_PATH = "$PATH/${PROGNAME}";
my $INTERVAL = 15;
my $DEBUG;
@@ -110,14 +109,20 @@ sub cut_target_width {
return "$head/" . $path . "/$tail";
}
-sub lock {
- my ($fh) = @_;
- flock($fh, LOCK_EX) || die "Can't lock config - $!\n";
-}
-
-sub unlock {
- my ($fh) = @_;
- flock($fh, LOCK_UN) || die "Can't unlock config- $!\n";
+sub locked {
+ my ($lock_fn, $code) = @_;
+
+ my $lock_fh = IO::File->new("> $lock_fn");
+
+ flock($lock_fh, LOCK_EX) || die "Couldn't acquire lock - $!\n";
+ my $res = eval { $code->() };
+ my $err = $@;
+
+ flock($lock_fh, LOCK_UN) || warn "Error unlocking - $!\n";
+ die "$err" if $err;
+
+ close($lock_fh);
+ return $res;
}
sub get_status {
@@ -338,13 +343,11 @@ sub update_state {
my $text;
my $in_fh;
- eval {
-
+ if (-e $STATE) {
$in_fh = IO::File->new("< $STATE");
die "Could not open file $STATE: $!\n" if !$in_fh;
- lock($in_fh);
$text = <$in_fh>;
- };
+ }
my $out_fh = IO::File->new("> $STATE.new");
die "Could not open file ${STATE}.new: $!\n" if !$out_fh;
@@ -376,9 +379,7 @@ sub update_state {
close($out_fh);
rename "$STATE.new", $STATE;
- eval {
close($in_fh);
- };
return $states;
}
@@ -395,7 +396,6 @@ sub update_cron {
my $fh = IO::File->new("< $CRONJOBS");
die "Could not open file $CRONJOBS: $!\n" if !$fh;
- lock($fh);
my @test = <$fh>;
@@ -502,6 +502,7 @@ sub vm_exists {
sub init {
my ($param) = @_;
+ locked("$CONFIG_PATH/cron_and_state.lock", sub {
my $cfg = read_cron();
my $job = param_to_job($param);
@@ -539,6 +540,7 @@ sub init {
update_cron($job);
update_state($job);
+ }); #cron and state lock
eval {
sync($param) if !$param->{skip};
@@ -568,55 +570,52 @@ sub get_job {
sub destroy_job {
my ($param) = @_;
+ locked("$CONFIG_PATH/cron_and_state.lock", sub {
my $job = get_job($param);
$job->{state} = "del";
-
update_cron($job);
update_state($job);
+ });
}
sub sync {
my ($param) = @_;
- my $lock_fh = IO::File->new("> $LOCKFILE");
- die "Can't open Lock File: $LOCKFILE $!\n" if !$lock_fh;
- lock($lock_fh);
-
my $date = get_date();
my $job;
- eval {
- $job = get_job($param);
- };
+ my $dest;
+ my $source;
+ my $vm_type;
+
+ locked("$CONFIG_PATH/sync.lock", sub {
+ locked("$CONFIG_PATH/cron_and_state.lock", sub {
+ eval { $job = get_job($param); };
if ($job && defined($job->{state}) && $job->{state} eq "syncing") {
die "Job --source $param->{source} --name $param->{name} is syncing at the moment";
}
- my $dest = parse_target($param->{dest});
- my $source = parse_target($param->{source});
+ $dest = parse_target($param->{dest});
+ $source = parse_target($param->{source});
+
+ $vm_type = vm_exists($source, $param->{source_user});
+ $source->{vm_type} = $vm_type;
+
+ if ($job) {
+ $job->{state} = "syncing";
+ $job->{vm_type} = $vm_type if !$job->{vm_type};
+ update_state($job);
+ }
+ }); #cron and state lock
my $sync_path = sub {
my ($source, $dest, $job, $param, $date) = @_;
-
($source->{old_snap}, $source->{last_snap}) = snapshot_get($source, $dest, $param->{maxsnap}, $param->{name}, $param->{source_user});
-
snapshot_add($source, $dest, $param->{name}, $date, $param->{source_user}, $param->{dest_user});
-
send_image($source, $dest, $param);
-
snapshot_destroy($source, $dest, $param->{method}, $source->{old_snap}, $param->{source_user}, $param->{dest_user}) if ($source->{destroy} && $source->{old_snap});
-
};
- my $vm_type = vm_exists($source, $param->{source_user});
- $source->{vm_type} = $vm_type;
-
- if ($job) {
- $job->{state} = "syncing";
- $job->{vm_type} = $vm_type if !$job->{vm_type};
- update_state($job);
- }
-
eval{
if ($source->{vmid}) {
die "VM $source->{vmid} doesn't exist\n" if !$vm_type;
@@ -642,9 +641,7 @@ sub sync {
if (my $err = $@) {
if ($job) {
$job->{state} = "error";
- update_state($job);
- unlock($lock_fh);
- close($lock_fh);
+ locked("$CONFIG_PATH/cron_and_state.lock", sub { update_state($job); });
print "Job --source $param->{source} --name $param->{name} got an ERROR!!!\nERROR Message:\n";
}
die "$err\n";
@@ -653,11 +650,9 @@ sub sync {
if ($job) {
$job->{state} = "ok";
$job->{lsync} = $date;
- update_state($job);
+ locked("$CONFIG_PATH/cron_and_state.lock", sub { update_state($job); });
}
-
- unlock($lock_fh);
- close($lock_fh);
+ }); #sync lock
}
sub snapshot_get{
@@ -1031,19 +1026,23 @@ sub status {
sub enable_job {
my ($param) = @_;
+ locked("$CONFIG_PATH/cron_and_state.lock", sub {
my $job = get_job($param);
$job->{state} = "ok";
update_state($job);
update_cron($job);
+ });
}
sub disable_job {
my ($param) = @_;
+ locked("$CONFIG_PATH/cron_and_state.lock", sub {
my $job = get_job($param);
$job->{state} = "stopped";
update_state($job);
update_cron($job);
+ });
}
my $cmd_help = {
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