From 6aed7e5429cab61514fe2eb3cacad3d11462cd5f Mon Sep 17 00:00:00 2001
From: Pascal Rigaux <pixel@mandriva.com>
Date: Thu, 23 Nov 2006 10:49:51 +0000
Subject: - move lock functions to a full blown module - handle get_exclusive
 and release_exclusive on existing lock,   *but* don't use it for now! (not
 useful) - remove urpmi_db locking from add_medium and update_media - move
 rpm_db locking into _read_cachedir_pubkey - update_media: restrict rpm_db
 exclusive locking to parse_pubkeys - urpmi: move locking rpm_db near its use
 - handle lock directly in urpmi.addmedia, urpmi.update, urpme, urpmf - log
 locking/unlocking

---
 urpm/lock.pm | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 urpm/lock.pm

(limited to 'urpm/lock.pm')

diff --git a/urpm/lock.pm b/urpm/lock.pm
new file mode 100644
index 00000000..e59e3faa
--- /dev/null
+++ b/urpm/lock.pm
@@ -0,0 +1,89 @@
+package urpm::lock;
+
+# $Id$
+
+use urpm::msg;
+
+
+#- avoid putting a require on Fcntl ':flock' (which is perl and not perl-base).
+my ($LOCK_SH, $LOCK_EX, $LOCK_NB, $LOCK_UN) = (1, 2, 4, 8);
+
+
+################################################################################
+#- class functions
+
+#- lock policy concerning chroot :
+#  - lock rpm db in chroot
+#  - lock urpmi db in /
+sub rpm_db {
+    my ($urpm, $b_exclusive) = @_;
+    urpm::lock->new($urpm, "$urpm->{root}/$urpm->{statedir}/.RPMLOCK", 'rpm', $b_exclusive);
+}
+sub urpmi_db {
+    my ($urpm, $b_exclusive, $b_nofatal) = @_;
+    urpm::lock->new($urpm, "$urpm->{statedir}/.LOCK", 'urpmi', $b_exclusive, $b_nofatal);
+}
+
+
+################################################################################
+#- methods
+
+sub new {
+    my ($_class, $urpm, $file, $db_name, $b_exclusive, $b_nofatal) = @_;
+    
+    my $fh;
+    #- we don't care what the mode is. ">" allow creating the file, but can't be done as user
+    open($fh, '>', $file) or open($fh, '<', $file) or return;
+
+    my $lock = bless { 
+	fh => $fh, db_name => $db_name, 
+	fatal => $b_nofatal ? $urpm->{error} : sub { $urpm->{fatal}(7, $_[0]) }, 
+	log => $urpm->{log},
+    };
+    _lock($lock, $b_exclusive);
+    $lock;
+}
+
+sub _flock_failed {
+    my ($lock) = @_;
+    $lock->{fatal}(N("%s database locked", $lock->{db_name}));
+}
+
+sub _lock {
+    my ($lock, $b_exclusive) = @_;
+    $b_exclusive ||= '';
+    if ($lock->{log}) {
+	my $action = $lock->{exclusive} && !$b_exclusive ? 'releasing exclusive' : $b_exclusive ? 'getting exclusive' : 'getting';
+	$lock->{log}("$action lock on $lock->{db_name}");
+    }
+    my $mode = $b_exclusive ? $LOCK_EX : $LOCK_SH;
+    flock $lock->{fh}, $mode|$LOCK_NB or _flock_failed($lock);
+    $lock->{locked} = 1;
+    $lock->{exclusive} = $b_exclusive;
+}
+
+sub get_exclusive {
+    my ($lock) = @_;
+    _lock($lock, 'exclusive');
+}
+sub release_exclusive {
+    my ($lock) = @_;
+    _lock($lock);
+}
+
+sub unlock {
+    my ($lock) = @_;
+    $lock->{fh} or warn "lock $lock->{db_name} already release\n", return;
+
+    if ($lock->{locked}) {
+	$lock->{log} and $lock->{log}("unlocking $lock->{db_name} database");
+	flock $lock->{fh}, $LOCK_UN;
+    }
+    close $lock->{fh};
+    delete $lock->{fh};
+}
+
+sub DESTROY { 
+    my ($lock) = @_;
+    unlock($lock) if $lock->{fh};
+}
-- 
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