From d9f8f170ce537c139df934b535fd2e803113a7b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gon=C3=A7alo=20Rica=20Pais=20da=20Silva?=
 <goncalo.rica@elastic.co>
Date: Thu, 12 Dec 2024 16:28:19 +0100
Subject: [PATCH] [ObsUX][Synthtrace] Replace `multistream` use with own util
 method (#203988)

## Summary

A whole dependency was being pulled in for doing something that could
easily be done just using Node.js own utils and be made into a simple
method. As such, `multistream` has been removed since there is no other
place in the codebase that is using it.

## How to test

* Load Kibana local dev environment using synthtrace data/scenarios. No
scenario should fail to load normally, and all tests using synthtrace
data should pass as expected.

Closes #203860
---
 package.json                                  |  2 --
 .../src/lib/utils/stream_utils.ts             | 24 ++++++++++++++++---
 yarn.lock                                     | 15 ------------
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/package.json b/package.json
index ca7c719092f4b..48cafc692db56 100644
--- a/package.json
+++ b/package.json
@@ -1621,7 +1621,6 @@
     "@types/minimist": "^1.2.5",
     "@types/mock-fs": "^4.13.1",
     "@types/moment-duration-format": "^2.2.3",
-    "@types/multistream": "^4.1.0",
     "@types/mustache": "^0.8.31",
     "@types/nock": "^10.0.3",
     "@types/node": "20.10.5",
@@ -1798,7 +1797,6 @@
     "mock-fs": "^5.1.2",
     "ms-chromium-edge-driver": "^0.5.1",
     "msw": "^2.4.12",
-    "multistream": "^4.1.0",
     "mutation-observer": "^1.0.3",
     "native-hdr-histogram": "^1.0.0",
     "nock": "12.0.3",
diff --git a/packages/kbn-apm-synthtrace/src/lib/utils/stream_utils.ts b/packages/kbn-apm-synthtrace/src/lib/utils/stream_utils.ts
index 9e52e9fc2b0ad..77aba18974b38 100644
--- a/packages/kbn-apm-synthtrace/src/lib/utils/stream_utils.ts
+++ b/packages/kbn-apm-synthtrace/src/lib/utils/stream_utils.ts
@@ -8,11 +8,29 @@
  */
 
 import { eachSeries } from 'async';
-import MultiStream from 'multistream';
-import { Duplex, Readable, Transform } from 'stream';
+import { Duplex, Readable, Transform, PassThrough } from 'stream';
+
+/**
+ * Pipe one or many streams sequentially into the destination stream. Once all
+ * source streams have been exhausted, the destination stream is ended.
+ * @param sources A collection of streams to read from
+ * @param destination The stream to pipe data to
+ */
+async function combineStreams(sources: Readable[], destination: PassThrough) {
+  for (const stream of sources) {
+    await new Promise((resolve, reject) => {
+      stream.on('end', resolve);
+      stream.on('error', reject);
+      stream.pipe(destination, { end: false });
+    });
+  }
+  destination.emit('end');
+}
 
 export function sequential(...streams: Readable[]) {
-  return new MultiStream(streams, { objectMode: true });
+  const output = new PassThrough({ objectMode: true });
+  combineStreams(streams, output).catch((err) => output.destroy(err));
+  return output;
 }
 
 export function fork(...streams: Transform[]): Duplex {
diff --git a/yarn.lock b/yarn.lock
index c8054baf36e9c..9acbb5a9da964 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -11937,13 +11937,6 @@
   dependencies:
     moment ">=2.14.0"
 
-"@types/multistream@^4.1.0":
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/@types/multistream/-/multistream-4.1.0.tgz#517770a32e5715fdda87904a6da7d179142feba4"
-  integrity sha512-KiMkWve/Uu0qwCtNO6ZflMLjglkXsAdLdIwb31o5YQBbevdH2DF7inqebCli+F9am8McvEqCE4GXNOUZe8jOAg==
-  dependencies:
-    "@types/node" "*"
-
 "@types/mustache@^0.8.31":
   version "0.8.31"
   resolved "https://registry.yarnpkg.com/@types/mustache/-/mustache-0.8.31.tgz#7c86cbf74f7733f9e3bdc28817623927eb386616"
@@ -24796,14 +24789,6 @@ multipipe@^1.0.2:
     duplexer2 "^0.1.2"
     object-assign "^4.1.0"
 
-multistream@^4.1.0:
-  version "4.1.0"
-  resolved "https://registry.yarnpkg.com/multistream/-/multistream-4.1.0.tgz#7bf00dfd119556fbc153cff3de4c6d477909f5a8"
-  integrity sha512-J1XDiAmmNpRCBfIWJv+n0ymC4ABcf/Pl+5YvC5B/D2f/2+8PtHvCNxMPKiQcZyi922Hq69J2YOpb1pTywfifyw==
-  dependencies:
-    once "^1.4.0"
-    readable-stream "^3.6.0"
-
 murmurhash-js@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/murmurhash-js/-/murmurhash-js-1.0.0.tgz#b06278e21fc6c37fa5313732b0412bcb6ae15f51"