Hello,
I am new to Rhino, and I want to make sure I understand how it works in
multithreaded environment. In particular, I have a java class that wraps a
JavaScript expression, and I hope it is thread safe. I would really appreciate
if someone with more experience can confirm it is thread safe, or point to
things to change in order to make it thread safe.
I am using Rhino version that comes with Weblogic 10.0.1 (I think I read
somewhere it is a modified 1.6R4).
Please note the following constraints which should help with thread safety:
- objects put into sharedScope during initialization are all with
thread safe methods;
- each JS script must by just a function, without any variables
declared aoutside of the function scope;
- parameters passed to a JS function are all thread safe.
Thanks,
Aleksandar Likic
package rule;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.Function;
import org.mozilla.javascript.NativeJavaObject;
import org.mozilla.javascript.Scriptable;
/**
* Rule that evaluates a JavaScript expression.
*
* @author Aleksandar Likic
*
*/
public class JavaScriptRule implements Rule {
public static final String RULE_REPOSITORY = "__r";
private Scriptable sharedScope;
private Function f;
private ExpressionCompiler compiler =
JavaScriptExpressionCompiler.getInstance();
private String ruleName = null;
private String expression = null;
public JavaScriptRule(RuleRepository ruleRepository, String
ruleName, String expression) {
try {
if (ruleName == null ||
ruleName.trim().length() == 0) {
throw new
IllegalArgumentException("Rule name must not be empty");
}
if (expression == null ||
expression.trim().length() == 0) {
throw new
IllegalArgumentException("Expression must not be empty");
}
this.ruleName = ruleName;
this.expression = expression;
this.expression =
compiler.compile(expression);
Context context = Context.enter();
if (sharedScope == null) {
sharedScope =
context.initStandardObjects(null);
sharedScope.put(RULE_REPOSITORY, sharedScope, ruleRepository);
sharedScope.put("out",
sharedScope, System.out);
}
f = context.compileFunction(sharedScope,
this.expression, ruleName, 1, null);
} finally {
Context.exit();
}
}
public Object invoke(Object[] args) throws RuleException {
Context context = Context.enter();
try {
Object result = f.call(context,
sharedScope, sharedScope, args);
if (result instanceof NativeJavaObject) {
result =
((NativeJavaObject)result).unwrap();
}
return result;
} catch (Throwable t) {
throw new RuleException("Error executing
rule: " + getName(), t);
} finally {
Context.exit();
}
}
public String getName() {
return ruleName;
}
public String getExpression() {
return expression;
}
}
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