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emulab
emulab-devel
Commits
de0c1000
Commit
de0c1000
authored
Aug 27, 2012
by
Leigh B Stoller
Browse files
Add lan table locking to assist with avoiding race conditions when
operating on shared lans.
parent
c2f63e4f
Changes
1
Hide whitespace changes
Inline
Side-by-side
db/Lan.pm.in
View file @
de0c1000
...
...
@@ -231,6 +231,7 @@ sub vidx($) { return field($_[0], 'vidx'); }
sub
ready
($)
{
return
field
($
_
[
0
],
'ready'
);
}
sub
link
($)
{
return
field
($
_
[
0
],
'link'
);
}
sub
type
($)
{
return
field
($
_
[
0
],
'type'
);
}
sub
locked
($)
{
return
field
($
_
[
0
],
'locked'
);
}
#
#
Lookup
an
internal
vlan
(
in
the
vlan
-
holding
experiment
).
...
...
@@ -1260,6 +1261,68 @@ sub LookupSharedVLanByToken($$)
return
$
query_result
->
fetchrow_hashref
();
}
#
#
Try
to
lock
this
lan
.
Optional
timeout
in
seconds
.
#
sub
Lock
($;$)
{
my
($
self
,
$
timeout
)
=
@
_
;
my
$
lockmsg
=
0
;
#
Must
be
a
real
reference
.
return
-
1
if
(
! ref($self));
my
$
lanid
=
$
self
->
lanid
();
if
(
!defined($timeout)) {
$
timeout
=
0
;
}
elsif
($
timeout
==
0
)
{
$
timeout
=
999999
;
}
while
($
timeout
>=
0
)
{
my
$
query_result
=
DBQueryWarn
(
"update lans set locked=now() "
.
"where lanid='$lanid' and locked is null"
);
return
-
1
if
(
!$query_result);
return
0
if
($
query_result
->
numrows
);
$
timeout
-=
2
;
if
(
!$lockmsg && $timeout >= 0) {
print
"$self is locked by another; "
.
"will keep trying for another $timeout seconds
\n
"
;
$
lockmsg
++;
}
sleep
(
2
);
}
return
-
1
;
}
sub
Unlock
($)
{
my
($
self
)
=
@
_
;
#
Must
be
a
real
reference
.
return
-
1
if
(
! ref($self));
my
$
lanid
=
$
self
->
lanid
();
my
$
query_result
=
DBQueryWarn
(
"update lans set locked=NULL where lanid='$lanid'"
);
if
(
! $query_result ||
$
query_result
->
numrows
==
0
)
{
return
-
1
;
}
return
0
;
}
############################################################################
#
#
Lan
::
Member
is
just
a
set
of
attributes
in
the
DB
associated
with
an
...
...
@@ -3509,6 +3572,19 @@ sub GetLinkedTo($$;$)
return
@
tmp
;
}
sub
Lock
($;$)
{
my
($
self
,
$
timeout
)
=
@
_
;
return
$
self
->
GetLan
()->
Lock
($
timeout
);
}
sub
Unlock
($)
{
my
($
self
)
=
@
_
;
return
$
self
->
GetLan
()->
Unlock
();
}
############################################################################
#
#
Another
convenience
package
,
for
tunnels
.
...
...
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