Java: how to set a transaction to the current Scope. (#3025)

Author: maciejwalkowiak

src/includes/performance/set-transaction-current-scope/java.mdx

@@ -0,0 +1,55 @@
+## Set Transaction to Current Scope
+
+To avoid passing `ITransaction` objects to method calls when creating child spans, you can bind the transaction to the current scope using `Sentry#configureScope` and `Scope#setTransaction` methods:
+
+```java {tabTitle:Java}
+import io.sentry.ISpan;
+import io.sentry.ITransaction;
+import io.sentry.Sentry;
+
+void executeTask() {
+  ITransaction transaction = Sentry.startTransaction("task");
+  Sentry.configureScope(scope -> scope.setTransaction(transaction));
+
+  executeSubTask();
+
+  transaction.finish();
+}
+
+private void executeSubTask() {
+  ISpan span = Sentry.getSpan();
+  if (span == null) {
+    span = Sentry.startTransaction("sub-task");
+  } else {
+    span = span.startChild();
+  }
+  // ...
+  span.finish();
+}
+```
+
+```kotlin {tabTitle:Kotlin}
+import io.sentry.ISpan
+import io.sentry.ITransaction
+import io.sentry.Sentry
+
+fun executeTask() {
+  val transaction = Sentry.startTransaction("task")
+  Sentry.configureScope(scope -> scope.setTransaction(transaction))
+
+  executeSubTask()
+
+  transaction.finish()
+}
+
+private fun executeSubTask() {
+  var span = Sentry.getSpan()
+  span = if (span == null) {
+    Sentry.startTransaction("sub-task")
+  } else {
+    span.startChild()
+  }
+  // ...
+  span.finish()
+}
+```

src/platforms/common/performance/custom-instrumentation.mdx

@@ -32,4 +32,6 @@ To instrument certain regions of your code, you can create transactions to captu
 
 <PlatformContent includePath="performance/connect-errors-spans" />
 
+<PlatformContent includePath="performance/set-transaction-current-scope" />
+
 </PlatformSection>