[GitHub] [jmeter] vlsi opened a new issue, #5968: Optimize getPropertyOrNull(PropertyDescriptor) access with index-based storage

["vlsi (via GitHub)" <gi...@apache.org>]

vlsi opened a new issue, #5968:
URL: https://github.com/apache/jmeter/issues/5968

   ### Use case
   
   JMeter often queries properties at runtime. For instance, `ResultCollector` `isSuccessOnlyLogging` and `isErrorLogging` call `getProperty(String)` which is cotly.
   
   
   ### Possible solution
   
   If test element schemas are specified with inheritance, then we could copy properties to an array where elements are `JMeterProperty` in their declaration order.
   Then access `getPropertyOrNull(PropertyDescriptor)` could be optimized with indices.
   
   For instance:
   
   ```kotlin
   public open class TestElementSchema protected constructor() : DefaultTestElementSchema() {
       public companion object INSTANCE : TestElementSchema()
   
       public val name: StringPropertyDescriptor<TestElementSchema> =
           string("TestElement.name")
       public val comments: StringPropertyDescriptor<TestElementSchema> =
           string("TestElement.comments")
   ...
   ```
   
   ```kotlin
   public open class ResultCollectorSchema: TestElementSchema() {
       public companion object INSTANCE: ResultCollectorSchema()
   
       public val successOnly: BooleanPropertyDescriptor<ResultCollectorSchema> =
           boolean("ResultCollector.success_only_logging")
   
       public val errorOnly: BooleanPropertyDescriptor<ResultCollectorSchema> =
           boolean("ResultCollector.error_logging")
   ```
   
   It would result in the following indices:
   
   ```
   0 name
   1 comments
   2 successOnly
   3 errorOnly
   ```
   
   Then, if we need to query `successOnly` at runtime, we can check if the element declares `ResultCollectorSchema` (or its subtype), and then we can access element `2` from properties array.
   
   Here's a sketch:
   
   ```java
   public class ResultCollector extends ... {
       public boolean isSuccessOnlyLogging() {
           return get(getSchema().getSuccessOnly());
           // return getPropertyAsBoolean(SUCCESS_ONLY_LOGGING,false);
       }
   
       public boolean isErrorLogging() {
           return get(getSchema().getErrorOnly());
           // return getPropertyAsBoolean(ERROR_LOGGING);
       }
   ```
   
   ```java
   public abstract class AbstractTestElement ... {
       private final transient JMeterProperty[] fastProps = new JMeterProperty[getSchema().getProperties().size()];
   
       // Optimized property access
       public JMeterProperty getPropertyOrNull(PropertyDescriptor<?, ?> key) {
           int index = key.getIndex();
           JMeterProperty[] fastProps = this.fastProps;
           if (index >= 0 && index < fastProps.length) {
               if (key.getSchema().isInstance(getSchema())) {
                   return fastProps[index];
               }
           }
           return getPropertyOrNull(key.getName());
       }
   
       // Every property store would store the property to fastProps array
       private void storeFastProperty(JMeterProperty prop) {
           PropertyDescriptor<?, ?> descr = getSchema().getProperties().get(prop.getName());
           if (descr != null) {
               int propIndex = descr.getIndex();
               if (propIndex >= 0 && propIndex < fastProps.length) {
                   fastProps[propIndex] = prop;
               }
           }
       }
   ```
   
   I assume we have only a few "property store" calls at the runtime, so it should be fine to perform extra work in `setProperty`, `remove(JMeterProperty)`.
   
   A draft benchmark (see `ResultCollectorBenchmark` in `core/src/jmh`) shows ~8ns for the current `isSampleWanted` and ~3ns with the optimized `getPropertyOrNull(PropertyDescriptor` case.
   
   It is not dramatic, however, it would be interesting to test it more.
   
   ### Possible workarounds
   
   _No response_
   
   ### JMeter Version
   
   5.5
   
   ### Java Version
   
   _No response_
   
   ### OS Version
   
   _No response_


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