Add support for synchronizingTimer

Author: rabelenda-abstracta

docs/guide/request-generation/index.md

@@ -6,8 +6,7 @@
 <!-- @include: csv-dataset.md -->
 <!-- @include: counter.md -->
 <!-- @include: jsr223-pre-processor.md -->
-<!-- @include: timers.md -->
-<!-- @include: throughput-timer.md -->
+<!-- @include: timers/index.md -->
 <!-- @include: percent-controller.md -->
 <!-- @include: weighted-switch-controller.md -->
 <!-- @include: parallel-controller.md -->

docs/guide/request-generation/timers.md …generation/timers/constant-and-random.mddocs/guide/request-generation/timers.md renamed to docs/guide/request-generation/timers/constant-and-random.md docs/guide/request-generation/timers.md renamed to docs/guide/request-generation/timers/constant-and-random.md

@@ -1,4 +1,4 @@
-### Emulate user delays between requests
+#### Emulate user delays between requests
 
 Sometimes, is necessary to replicate users' behavior on the test plan adding pauses between requests is one of the most used practices. For example, simulate the time it will take to complete a purchase form. JMeter (and the DSL) provide Constant & Uniform Random timers for this purpose. Here is an example that adds a delay of 3 seconds and another between 4 and 10 seconds:
 

docs/guide/request-generation/timers/index.md

@@ -0,0 +1,5 @@
+### Timers
+
+<!-- @include: constant-and-random.md -->
+<!-- @include: throughput-timer.md -->
+<!-- @include: synchronizing-timer.md -->

docs/guide/request-generation/timers/not-synchronized-samples.png

@@ -0,0 +1,24 @@
+#### Requests synchronization
+
+Usually, samples generated by different threads in a test plan thread group start deviating from each other according to the different durations each of them may experience.
+
+Here is a diagram depicting this behavior, extracted from [this nice example](https://github.com/abstracta/jmeter-java-dsl/discussions/204) provided by one of JMeter DSL users:
+
+![not synchronized samples in 2 threads and 3 iterations](./not-synchronized-samples.png)
+
+In most cases this is ok. But, if you want to generate batches of simultaneous requests to a system under test, this variability will prevent you from getting the expected behavior.
+
+So, to synchronize requests, by holding some of them until all are in sync, like in this diagram:
+
+![synchronized samples in 2 threads and 3 iterations](./synchronized-samples.png)
+
+You can use `synchronizingTimer` like in the following example:
+
+```java
+testPlan(
+    threadGroup(2, 3,
+      httpSample("https://mysite"),
+      synchronizingTimer()
+    )
+)
+```

docs/guide/request-generation/timers/synchronized-samples.png

@@ -1,4 +1,4 @@
-### Control throughput
+#### Control throughput
 
 To achieve a specific constant throughput for specific samplers or section of a test plan, you can use `throughputTimer`, which uses JMeter `ConstantThroughputTimer`.
 

docs/guide/request-generation/timers/synchronizing-timer.md

@@ -42,6 +42,7 @@
 import us.abstracta.jmeter.javadsl.core.threadgroups.DslTeardownThreadGroup;
 import us.abstracta.jmeter.javadsl.core.threadgroups.RpsThreadGroup;
 import us.abstracta.jmeter.javadsl.core.timers.DslConstantTimer;
+import us.abstracta.jmeter.javadsl.core.timers.DslSynchronizingTimer;
 import us.abstracta.jmeter.javadsl.core.timers.DslThroughputTimer;
 import us.abstracta.jmeter.javadsl.core.timers.DslUniformRandomTimer;
 import us.abstracta.jmeter.javadsl.core.util.PropertyScriptBuilder.PropertyScript;
@@ -1609,6 +1610,20 @@ public static DslThroughputTimer throughputTimer(double throughputPerMinute) {
     return new DslThroughputTimer(throughputPerMinute);
   }
 
+  /**
+   * Builds a Synchronizing Timer that allows synchronizing samples to be sent all at once.
+   * <p>
+   * This timer is useful when you need to send requests in simultaneous batches, as a way to asure
+   * the system under test gets the requests all at the same time.
+   *
+   * @return the timer for usage in a test plan.
+   * @see DslSynchronizingTimer
+   * @since 1.17
+   */
+  public static DslSynchronizingTimer synchronizingTimer() {
+    return new DslSynchronizingTimer();
+  }
+
   /**
    * Builds a CSV Data Set which allows loading from a CSV file variables to be used in test plan.
    * <p>

…e/request-generation/throughput-timer.md …st-generation/timers/throughput-timer.mddocs/guide/request-generation/throughput-timer.md renamed to docs/guide/request-generation/timers/throughput-timer.md docs/guide/request-generation/throughput-timer.md renamed to docs/guide/request-generation/timers/throughput-timer.md

@@ -0,0 +1,42 @@
+package us.abstracta.jmeter.javadsl.core.timers;
+
+import java.lang.reflect.Method;
+import java.util.List;
+import org.apache.jmeter.testbeans.gui.TestBeanGUI;
+import org.apache.jmeter.testelement.TestElement;
+import org.apache.jmeter.timers.SyncTimer;
+import us.abstracta.jmeter.javadsl.codegeneration.MethodCall;
+import us.abstracta.jmeter.javadsl.codegeneration.MethodCallContext;
+import us.abstracta.jmeter.javadsl.codegeneration.SingleTestElementCallBuilder;
+
+/**
+ * Uses JMeter Synchronizing Timer to allow sending a batch of requests simultaneously to a system
+ * under test.
+ *
+ * @since 1.17
+ */
+public class DslSynchronizingTimer extends BaseTimer {
+
+  public DslSynchronizingTimer() {
+    super("Synchronizing Timer", TestBeanGUI.class);
+  }
+
+  @Override
+  protected TestElement buildTestElement() {
+    return new SyncTimer();
+  }
+
+  public static class CodeBuilder extends SingleTestElementCallBuilder<SyncTimer> {
+
+    public CodeBuilder(List<Method> builderMethods) {
+      super(SyncTimer.class, builderMethods);
+    }
+
+    @Override
+    protected MethodCall buildMethodCall(SyncTimer testElement, MethodCallContext context) {
+      return buildMethodCall();
+    }
+
+  }
+
+}

jmeter-java-dsl/src/main/java/us/abstracta/jmeter/javadsl/JmeterDsl.java

@@ -0,0 +1,53 @@
+package us.abstracta.jmeter.javadsl.core.timers;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static us.abstracta.jmeter.javadsl.JmeterDsl.*;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import us.abstracta.jmeter.javadsl.codegeneration.MethodCallBuilderTest;
+import us.abstracta.jmeter.javadsl.core.DslTestPlan;
+
+public class DslSynchronizingTimerTest {
+
+  @Test
+  public void shouldSynchronizeRequestsWhenTestPlanWithSynchronizingTimer() throws Exception {
+    List<Instant> reqTimes = new ArrayList<>();
+    testPlan(
+        threadGroup(2, 1,
+            jsr223Sampler(s -> {
+              if (Thread.currentThread().getName().endsWith("2")) {
+                Thread.sleep(3000);
+              }
+            }),
+            jsr223Sampler(s -> {
+              synchronized (reqTimes) {
+                reqTimes.add(Instant.now());
+              }
+            }).children(
+                synchronizingTimer()
+            )
+        )
+    ).run();
+    assertThat(Duration.between(reqTimes.get(0), reqTimes.get(1))).isLessThan(Duration.ofMillis(500));
+  }
+
+  @Nested
+  public class CodeBuilderTest extends MethodCallBuilderTest {
+
+    public DslTestPlan testPlanWithSynchronizingTimer() {
+      return testPlan(
+          threadGroup(2, 3,
+              synchronizingTimer(),
+              httpSampler("http://localhost")
+          )
+      );
+    }
+
+  }
+
+}