IJPL-156281 make coroutine dumper resilient to circular job dependencies

GitOrigin-RevId: 95d64a8fca56c22a2fd9c3d0a7efd29c39ff8126

platform/util/base/src/com/intellij/diagnostic/coroutineDumper.kt

@@ -159,22 +159,29 @@ private fun jobTrees(scope: CoroutineScope? = null): Sequence<JobTree> {
 
   return sequence {
     for (job in rootJobs) {
-      yieldAll(buildJobTrees(job, jobToStack))
+      yieldAll(buildJobTrees(job, jobToStack, hashSetOf()))
     }
   }
 }
 
 private fun buildJobTrees(
   job: Job,
-  jobToStack: Map<Job, DebugCoroutineInfo>
+  jobToStack: Map<Job, DebugCoroutineInfo>,
+  visited: MutableSet<Job>
 ): List<JobTree> {
+  return visited.withElement(job) { notSeenThisJob ->
+    if (notSeenThisJob) {
       val info = jobToStack[job]
       if (info === null && job is ScopeCoroutine<*>) {
         // don't yield ScopeCoroutine without info, such as `coroutineScope` or `withContext`
-    return job.children.flatMap { buildJobTrees(it, jobToStack) }.toList()
+        job.children.flatMap { buildJobTrees(it, jobToStack, visited) }.toList()
       }
       else {
-    return listOf(JobTree(job, info, job.children.flatMap { buildJobTrees(it, jobToStack) }.toList()))
+        listOf(JobTree(job, info, job.children.flatMap { buildJobTrees(it, jobToStack, visited) }.toList()))
+      }
+    } else {
+      listOf(JobTree(RecursiveJob(job), null, emptyList()))
+    }
   }
 }
 
@@ -309,3 +316,19 @@ private fun traceToDump(info: DebugCoroutineInfo, stripTrace: Boolean): List<Sta
   }
   return DebugProbesImpl.enhanceStackTraceWithThreadDump(info, trace)
 }
+
+private fun <T, R> MutableSet<T>.withElement(elem: T, body: (added: Boolean) -> R): R {
+  val added = add(elem)
+  try {
+    return body(added)
+  }
+  finally {
+    if (added) remove(elem)
+  }
+}
+
+private class RecursiveJob(private val originalJob: Job) : Job by originalJob {
+  override fun toString(): String {
+    return "CIRCULAR REFERENCE: $originalJob"
+  }
+}

platform/util/testSrc/com/intellij/diagnostic/CoroutineDumpTest.kt

@@ -0,0 +1,46 @@
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.diagnostic
+
+import com.intellij.platform.util.coroutines.childScope
+import kotlinx.coroutines.*
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.BeforeAll
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.Timeout
+import java.util.concurrent.TimeUnit
+
+class CoroutineDumpTest {
+  companion object {
+    @JvmStatic
+    @BeforeAll
+    fun enableDumps() {
+      enableCoroutineDump()
+    }
+  }
+
+  @OptIn(InternalCoroutinesApi::class)
+  @Suppress("SSBasedInspection", "DEPRECATION_ERROR")
+  @Test
+  @Timeout(value = 5, unit = TimeUnit.SECONDS)
+  fun testRecursiveJobsDump() {
+    val projectScope = CoroutineScope(CoroutineName("Project"))
+    val pluginScope = CoroutineScope(CoroutineName("Plugin"))
+    val activity = projectScope.childScope("Project Activity")
+    pluginScope.coroutineContext[Job]!!.attachChild(activity.coroutineContext[Job]!! as ChildJob)
+    // e.g. bug here
+    activity.coroutineContext[Job]!!.attachChild(pluginScope.coroutineContext[Job]!! as ChildJob)
+    assertEquals("""
+- JobImpl{Active}
+	- "Project Activity":supervisor:ChildScope{Active}
+		- JobImpl{Active}
+			- CIRCULAR REFERENCE: "Project Activity":supervisor:ChildScope{Active}
+""", dumpCoroutines(projectScope, true, true))
+    assertEquals("""
+- JobImpl{Active}
+	- "Project Activity":supervisor:ChildScope{Active}
+		- CIRCULAR REFERENCE: JobImpl{Active}
+""", dumpCoroutines(pluginScope, true, true))
+    projectScope.cancel()
+    pluginScope.cancel()
+  }
+}