Method optimize

src/org/apache/pig/newplan/optimizer/PlanOptimizer.java:95–132

Run the optimizer. This method attempts to match each of the Rules against the plan. If a Rule matches, it then calls the check method of the associated Transformer to give the it a chance to check whether it really wants to do the optimization. If that returns true as well, then Transformer.tran

()

     * @throws FrontendException
     */
    public void optimize() throws FrontendException {

        for (Set<Rule> rs : ruleSets) {
            boolean sawMatch = false;
            int numIterations = 0;
            do {
                sawMatch = false;
                for (Rule rule : rs) {
                    List<OperatorPlan> matches = rule.match(plan);
                    if (matches != null) {
                        Transformer transformer = rule.getNewTransformer();
                        for (OperatorPlan m : matches) {
                            try {
                                if (transformer.check(m)) {
                                    sawMatch = true;
                                    transformer.transform(m);
                                    OperatorPlan change = transformer.reportChanges();
                                    if (change == null) {
                                        sawMatch = false;
                                    } else if (!rule.isSkipListener()) {
                                        for(PlanTransformListener l: listeners) {
                                            l.transformed(plan, change);
                                        }
                                    }
                                }
                            } catch (Exception e) {
                                StringBuffer message = new StringBuffer("Error processing rule " + rule.name);
                                if (!rule.isMandatory()) {
                                    message.append(". Try -t " + rule.name);
                                }
                                throw new FrontendException(message.toString(), 2000, e);
                            }
                        }
                    }
                }
            } while(sawMatch && ++numIterations < maxIter);
        }
    }
}