From 06c16b1a26394cad90f5342e50ef92c2c512f4a1 Mon Sep 17 00:00:00 2001
From: Rick Newton-Rogers <rnro@apple.com>
Date: Thu, 17 Oct 2024 13:03:52 +0100
Subject: [PATCH] Add future wait benchmark to catch memory leaks (#2931)

### Motivation:

In the past we introduced a memory leak around the creation of and
waiting on futures - we should protect against leaks in this fundamental
operation.

### Modifications:

Add a new benchmark which would have failed with the previous bug

### Result:

Regression protection for this type of memory leak.
---
 .../NIOCoreBenchmarks/Benchmarks.swift        | 29 +++++++++++++++++++
 .../NIOCoreBenchmarks.WaitOnPromise.p90.json  |  4 +++
 .../NIOCoreBenchmarks.WaitOnPromise.p90.json  |  4 +++
 .../NIOCoreBenchmarks.WaitOnPromise.p90.json  |  4 +++
 4 files changed, 41 insertions(+)
 create mode 100644 Benchmarks/Thresholds/5.10/NIOCoreBenchmarks.WaitOnPromise.p90.json
 create mode 100644 Benchmarks/Thresholds/5.8/NIOCoreBenchmarks.WaitOnPromise.p90.json
 create mode 100644 Benchmarks/Thresholds/5.9/NIOCoreBenchmarks.WaitOnPromise.p90.json

diff --git a/Benchmarks/Benchmarks/NIOCoreBenchmarks/Benchmarks.swift b/Benchmarks/Benchmarks/NIOCoreBenchmarks/Benchmarks.swift
index cea2e10af5..c821b872dd 100644
--- a/Benchmarks/Benchmarks/NIOCoreBenchmarks/Benchmarks.swift
+++ b/Benchmarks/Benchmarks/NIOCoreBenchmarks/Benchmarks.swift
@@ -21,6 +21,11 @@ let benchmarks = {
         .mallocCountTotal
     ]
 
+    let leakMetrics: [BenchmarkMetric] = [
+        .mallocCountTotal,
+        .memoryLeaked,
+    ]
+
     Benchmark(
         "NIOAsyncChannel.init",
         configuration: .init(
@@ -46,4 +51,28 @@ let benchmarks = {
             blackHole(asyncChanel)
         }
     }
+
+    Benchmark(
+        "WaitOnPromise",
+        configuration: .init(
+            metrics: leakMetrics,
+            scalingFactor: .kilo,
+            maxDuration: .seconds(10_000_000),
+            maxIterations: 10_000  // need 10k to get a signal
+        )
+    ) { benchmark in
+        // Elide the cost of the 'EmbeddedEventLoop'.
+        let el = EmbeddedEventLoop()
+
+        benchmark.startMeasurement()
+        defer {
+            benchmark.stopMeasurement()
+        }
+
+        for _ in 0..<benchmark.scaledIterations.count {
+            let p = el.makePromise(of: Int.self)
+            p.succeed(0)
+            do { _ = try! p.futureResult.wait() }
+        }
+    }
 }
diff --git a/Benchmarks/Thresholds/5.10/NIOCoreBenchmarks.WaitOnPromise.p90.json b/Benchmarks/Thresholds/5.10/NIOCoreBenchmarks.WaitOnPromise.p90.json
new file mode 100644
index 0000000000..eb79e76371
--- /dev/null
+++ b/Benchmarks/Thresholds/5.10/NIOCoreBenchmarks.WaitOnPromise.p90.json
@@ -0,0 +1,4 @@
+{
+  "mallocCountTotal" : 6000,
+  "memoryLeaked" : 0
+}
diff --git a/Benchmarks/Thresholds/5.8/NIOCoreBenchmarks.WaitOnPromise.p90.json b/Benchmarks/Thresholds/5.8/NIOCoreBenchmarks.WaitOnPromise.p90.json
new file mode 100644
index 0000000000..eb79e76371
--- /dev/null
+++ b/Benchmarks/Thresholds/5.8/NIOCoreBenchmarks.WaitOnPromise.p90.json
@@ -0,0 +1,4 @@
+{
+  "mallocCountTotal" : 6000,
+  "memoryLeaked" : 0
+}
diff --git a/Benchmarks/Thresholds/5.9/NIOCoreBenchmarks.WaitOnPromise.p90.json b/Benchmarks/Thresholds/5.9/NIOCoreBenchmarks.WaitOnPromise.p90.json
new file mode 100644
index 0000000000..eb79e76371
--- /dev/null
+++ b/Benchmarks/Thresholds/5.9/NIOCoreBenchmarks.WaitOnPromise.p90.json
@@ -0,0 +1,4 @@
+{
+  "mallocCountTotal" : 6000,
+  "memoryLeaked" : 0
+}