Hi Colm,
Done.
https://issues.apache.org/jira/browse/SANTUARIO-337
-Eric.
On 7/31/12 3:24 AM, Colm O hEigeartaigh wrote:
Hi Eric,
I agree that there is a potential issue here, although as you point
out it's unlikely to occur in practise. Could you open a JIRA?
Thanks,
Colm.
On Wed, Jul 25, 2012 at 10:38 PM, Eric Johnson <e...@tibco.com
<mailto:e...@tibco.com>> wrote:
I've been looking over the Santuario Java code and I noticed what
appears to be a bug.
Specifically this code (with details not needed elided) from
ResourceResolver.getInstance():
for (ResourceResolver resolver : resolverList) {
ResourceResolver resolverTmp = resolver;
if (!resolver.resolverSpi.engineIsThreadSafe()) {
// generate a new instances of resolverSpi ...
}
// ...
resolverTmp.resolverSpi.secureValidation =
secureValidation;
if ((resolverTmp != null) &&
resolverTmp.canResolve(uri, baseURI)) {
// Check to see whether the Resolver is allowed
// check for certain types ....
return resolverTmp;
}
}
In case you didn't see it, the trouble is the juxtaposition of
"resolverSpi.engineIsThreadSafe()" followed by code that sets
"secureValidation" on the very same instance of the spi, whether
or not it is thread safe.
Meaning, if two threads resolve at the same time, and one thread
is attempting secure resolution while the other is not, all the
"thread safe" resolvers risk a race condition where they will now
be in an uncertain state. Of course, it turns out that all the
built-in resolvers declare themselves thread-safe, so this
magnifies the problem.
In practice, this is not likely ever to occur, because any given
application will likely share the same notion of "secureValidation".
Am I mis-reading this code?
Three observations
#1 - the secureValidation flag needs only be set for the resolver
that is actually chosen
#2 - the secureValidation flag should instead be passed as a
parameter ResourceResolverSpi.engineResolve() method, not stored
as data in the SPI instance.
#3 - if there were ever a resolver to show up that isn't thread
safe, and it also has properties, the logic above which creates a
new instance of the SPI would obliterate the properties of the
spi. It turns out only the HTTP resolver uses these properties for
anything, so this may not be problematic in the real world.
-Eric.
--
Colm O hEigeartaigh
Talend Community Coder
http://coders.talend.com
