From b2c2feab6bed2aeb3e83e444b02fc0b04d854f25 Mon Sep 17 00:00:00 2001
From: Paul Brauner <141240651+paulbrauner-da@users.noreply.github.com>
Date: Tue, 13 Aug 2024 09:23:50 +0200
Subject: [PATCH] add flag and instructions for attaching a java debugger to
 the canton fixture (#19763)

* add flag and instructions for attaching a java debugger to the canton fixture

* revert leftover debugging code
---
 .../daml/integrationtest/CantonConfig.scala   |  1 +
 .../daml/integrationtest/CantonFixture.scala  |  9 +++++++++
 .../daml/integrationtest/CantonRunner.scala   | 19 +++++++++++--------
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonConfig.scala b/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonConfig.scala
index d56b82321f0f..e9a476ff77fe 100644
--- a/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonConfig.scala
+++ b/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonConfig.scala
@@ -58,6 +58,7 @@ final case class CantonConfig(
     bootstrapScript: Option[String] = None,
     targetScope: Option[String] = None,
     disableUpgradeValidation: Boolean = false,
+    enableRemoteJavaDebugging: Boolean = false,
 ) {
 
   lazy val tlsConfig =
diff --git a/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonFixture.scala b/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonFixture.scala
index e4f5afa4c43f..8592d3ad825a 100644
--- a/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonFixture.scala
+++ b/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonFixture.scala
@@ -88,6 +88,14 @@ trait CantonFixtureWithResource[A]
   // temporary files after a test is done running
   protected val cantonFixtureDebugModeRemoveTmpFilesRegardless = false
 
+  // When true, the canton process is started with the necessary flags to enable remote debugging and is suspended until
+  // a debugger is attached. In order to use this feature, launch the test making use of the fixture from IntelliJ
+  // *in debug mode* and look for "Listening for transport dt_socket at address: 5005" in the console output. IntelliJ
+  // should display a clickable chip labelled "Attach debugger" next to this line. Clicking on this chip will attach the
+  // debugger to the canton process and resume execution. Breakpoints in the canton code under canton/* will then be
+  // taken into account by IntelliJ.
+  protected val remoteJavaDebugging: Boolean = false
+
   final protected val logger = org.slf4j.LoggerFactory.getLogger(getClass)
 
   if (cantonFixtureDebugModeIsDebug) {
@@ -127,6 +135,7 @@ trait CantonFixtureWithResource[A]
     bootstrapScript = bootstrapScript,
     targetScope = targetScope,
     disableUpgradeValidation = disableUpgradeValidation,
+    enableRemoteJavaDebugging = remoteJavaDebugging,
   )
 
   protected def info(msg: String): Unit =
diff --git a/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonRunner.scala b/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonRunner.scala
index 83c4d7434fb1..f1455361089f 100644
--- a/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonRunner.scala
+++ b/sdk/test-common/canton/it-lib/src/main/scala/com/daml/integrationtest/CantonRunner.scala
@@ -192,14 +192,17 @@ object CantonRunner {
     )
     var outputBuffer = ""
     val cmd = java ::
-      "-jar" ::
-      config.jarPath.toString ::
-      "daemon" ::
-      "-c" ::
-      files.configFile.toString ::
-      "--bootstrap" ::
-      files.bootstrapFile.toString ::
-      debugOptions
+      (if (config.enableRemoteJavaDebugging)
+         List("-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005")
+       else List.empty) ++
+      ("-jar" ::
+        config.jarPath.toString ::
+        "daemon" ::
+        "-c" ::
+        files.configFile.toString ::
+        "--bootstrap" ::
+        files.bootstrapFile.toString ::
+        debugOptions)
     info(cmd.mkString("\\\n    "))
     for {
       proc <- Future(