Saxon

SourceForge user: mhkay

The saxon:evaluate() extension function causes a static

context for the XPath expression to be established when

the containing stylesheet (or query) is compiled. This

static context is then modified, by declaring the

variables $p1..$p9, when the XPath expression is

compiled, that is, when the saxon:evaluate()

instruction is executed.

This has two adverse consequences:

(a) saxon:evaluate is not thread-safe: undefined errors

may occur if it is used in a compiled stylesheet or

query that is executed in multiple threads concurrently

(b) performance gradually degrades when a compiled

stylesheet or query containing calls to saxon:evaluate

is serially reused.

The problem applies to 8.3 and 8.2, and possibly

earlier releases.

A patch is provided. This is in two parts.

(a) replace the module net.sf.saxon.functions.Evaluate

with the new version attached.

(b) add the following method to module

net.sf.saxon.trans.IndependentContext

/**

 * Create a copy of this IndependentContext. All

aspects of the context are copied

 * except for declared variables.

 */


public IndependentContext copy() {

    IndependentContext ic = new

IndependentContext(config);

    ic.namespaces = new HashMap(namespaces);

    ic.collations = new HashMap(collations);

    ic.variables = new HashMap();

    ic.defaultCollationName = defaultCollationName;

    ic.baseURI = baseURI;

    ic.locationMap = locationMap;

    ic.functionLibrary = functionLibrary;

    ic.defaultFunctionNamespace =

defaultFunctionNamespace;

    ic.schemaImporter = schemaImporter;

    ic.externalResolver = externalResolver;

    return ic;

}