From 3f6f508cccdb8fe5282d765a199154e496da8cee Mon Sep 17 00:00:00 2001
From: Roman Golyshev <roman.golyshev@jetbrains.com>
Date: Tue, 25 Feb 2025 17:09:47 +0100
Subject: [PATCH] KTIJ-33008 [coroutines] Use `StringBuilder` instead of string
 concatenation to render `CoroutineContext`

Since there might be a lot of elements in the `CoroutineContext`,
joining them with string concatenation in a cycle basically
means O(N^2) performance

GitOrigin-RevId: fe5652f0ff9b0abb43320fc7dd4d18f3118f2f38
---
 .../base/src/com/intellij/diagnostic/coroutineDumper.kt  | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/platform/util/base/src/com/intellij/diagnostic/coroutineDumper.kt b/platform/util/base/src/com/intellij/diagnostic/coroutineDumper.kt
index fa0fb17f8ea5..7a39dfa200f6 100644
--- a/platform/util/base/src/com/intellij/diagnostic/coroutineDumper.kt
+++ b/platform/util/base/src/com/intellij/diagnostic/coroutineDumper.kt
@@ -336,9 +336,12 @@ private fun traceToDump(info: DebugCoroutineInfo, stripTrace: Boolean): List<Sta
 }
 
 private fun CoroutineContext.joinElementsToString(): String =
-  this.fold("") { acc, element ->
-    if (acc.isEmpty()) element.toString() else "$acc, $element"
-  }
+  this.fold(StringBuilder()) { acc, element ->
+    if (acc.isNotEmpty()) {
+      acc.append(", ")
+    }
+    acc.append(element.toString())
+  }.toString()
 
 private fun <T, R> MutableSet<T>.withElement(elem: T, body: (added: Boolean) -> R): R {
   val added = add(elem)