Add basic benchmarks (#102)

### Motivation

Fixes #28 to ensure we have a baseline before tagging the 1.0.

### Modifications

Added benchmarks and actually made a few small tweaks to reduce
allocations.

### Result

Baseline for benchmarks, any perf changes will be deliberate.

### Test Plan

Verified all locally.

Author: czechboy0

.github/workflows/main.yml

@@ -122,3 +122,12 @@ jobs:
     with:
       name: "Example packages"
       matrix_string: '${{ needs.construct-example-packages-matrix.outputs.example-packages-matrix }}'
+
+  benchmarks:
+    name: Benchmarks
+    uses: apple/swift-nio/.github/workflows/benchmarks.yml@main
+    with:
+      benchmark_package_path: "Benchmarks"
+      linux_5_10_enabled: false
+      linux_6_0_enabled: false
+      linux_6_1_enabled: false

.github/workflows/pull_request.yml

@@ -129,3 +129,12 @@ jobs:
     with:
       name: "Example packages"
       matrix_string: '${{ needs.construct-example-packages-matrix.outputs.example-packages-matrix }}'
+
+  benchmarks:
+    name: Benchmarks
+    uses: apple/swift-nio/.github/workflows/benchmarks.yml@main
+    with:
+      benchmark_package_path: "Benchmarks"
+      linux_5_10_enabled: false
+      linux_6_0_enabled: false
+      linux_6_1_enabled: false

Benchmarks/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

Benchmarks/Package.swift

@@ -0,0 +1,27 @@
+// swift-tools-version: 6.2
+
+import PackageDescription
+
+let package = Package(
+    name: "Benchmarks",
+    platforms: [
+        .macOS(.v15)
+    ],
+    dependencies: [
+        .package(path: "../"),
+        .package(url: "https://github.com/ordo-one/package-benchmark.git", from: "1.29.6"),
+    ],
+    targets: [
+        .executableTarget(
+            name: "Benchmarks",
+            dependencies: [
+                .product(name: "Benchmark", package: "package-benchmark"),
+                .product(name: "Configuration", package: "swift-configuration"),
+            ],
+            path: "Sources",
+            plugins: [
+                .plugin(name: "BenchmarkPlugin", package: "package-benchmark")
+            ]
+        )
+    ]
+)

Benchmarks/Sources/Benchmarks.swift

@@ -0,0 +1,105 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftConfiguration open source project
+//
+// Copyright (c) 2025 Apple Inc. and the SwiftConfiguration project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftConfiguration project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Benchmark
+import Configuration
+import Foundation
+
+let benchmarks: @Sendable () -> Void = {
+    let defaultMetrics: [BenchmarkMetric] = [
+        .mallocCountTotal
+        // .contextSwitches,
+        // .wallClock,
+    ]
+
+    Benchmark(
+        "ConfigReader_InMemoryProvider_notFound_string",
+        configuration: Benchmark.Configuration(
+            metrics: defaultMetrics,
+            scalingFactor: .kilo
+        )
+    ) { benchmark in
+        let emptyReader = ConfigReader(provider: InMemoryProvider(values: [:]))
+        for _ in benchmark.scaledIterations {
+            blackHole(emptyReader.string(forKey: "foo"))
+        }
+    }
+
+    Benchmark(
+        "ConfigReader_InMemoryProvider_found_string",
+        configuration: Benchmark.Configuration(
+            metrics: defaultMetrics,
+            scalingFactor: .kilo
+        )
+    ) { benchmark in
+        let emptyReader = ConfigReader(provider: InMemoryProvider(values: ["foo": "bar"]))
+        for _ in benchmark.scaledIterations {
+            blackHole(emptyReader.string(forKey: "foo"))
+        }
+    }
+
+    Benchmark(
+        "ConfigReader_InMemoryProvider_found_int",
+        configuration: Benchmark.Configuration(
+            metrics: defaultMetrics,
+            scalingFactor: .kilo
+        )
+    ) { benchmark in
+        let emptyReader = ConfigReader(provider: InMemoryProvider(values: ["foo": 24]))
+        for _ in benchmark.scaledIterations {
+            blackHole(emptyReader.int(forKey: "foo"))
+        }
+    }
+
+    Benchmark(
+        "ConfigReader_InMemoryProvider_found_fetchInt",
+        configuration: Benchmark.Configuration(
+            metrics: defaultMetrics,
+            scalingFactor: .kilo
+        )
+    ) { (benchmark) async throws -> Void in
+        let emptyReader = ConfigReader(provider: InMemoryProvider(values: ["foo": 24]))
+        for _ in benchmark.scaledIterations {
+            blackHole(try await emptyReader.fetchInt(forKey: "foo"))
+        }
+    }
+
+    Benchmark(
+        "EnvironmentVariablesProvider_notFound_string",
+        configuration: Benchmark.Configuration(
+            metrics: defaultMetrics,
+            scalingFactor: .kilo
+        )
+    ) { (benchmark) throws -> Void in
+        let provider = EnvironmentVariablesProvider(environmentVariables: [:])
+        let key: AbsoluteConfigKey = "foo"
+        for _ in benchmark.scaledIterations {
+            blackHole(try provider.value(forKey: key, type: .string))
+        }
+    }
+
+    Benchmark(
+        "EnvironmentVariablesProvider_found_string",
+        configuration: Benchmark.Configuration(
+            metrics: defaultMetrics,
+            scalingFactor: .kilo
+        )
+    ) { (benchmark) throws -> Void in
+        let provider = EnvironmentVariablesProvider(environmentVariables: ["foo": "bar"])
+        let key: AbsoluteConfigKey = "foo"
+        for _ in benchmark.scaledIterations {
+            blackHole(try provider.value(forKey: key, type: .string))
+        }
+    }
+}

Benchmarks/Thresholds/Benchmarks.ConfigReader_InMemoryProvider_found_fetchInt.p90.json

@@ -0,0 +1,3 @@
+{
+  "mallocCountTotal" : 3009
+}

Benchmarks/Thresholds/Benchmarks.ConfigReader_InMemoryProvider_found_int.p90.json

@@ -0,0 +1,3 @@
+{
+  "mallocCountTotal" : 3008
+}

Benchmarks/Thresholds/Benchmarks.ConfigReader_InMemoryProvider_found_string.p90.json

@@ -0,0 +1,3 @@
+{
+  "mallocCountTotal" : 3008
+}

Benchmarks/Thresholds/Benchmarks.ConfigReader_InMemoryProvider_notFound_string.p90.json

@@ -0,0 +1,3 @@
+{
+  "mallocCountTotal" : 3005
+}

Benchmarks/Thresholds/Benchmarks.EnvironmentVariablesProvider_found_string.p90.json

@@ -0,0 +1,3 @@
+{
+  "mallocCountTotal" : 3005
+}