feat(minor): Add Benchmark tags

Sometimes it is convenient to run the same benchmark multiple times under slightly different scenarios.
For example, benchmarking `func foo(_ n: Int)` for various parameterizations of `n`.
This adds support for specifying tags for a benchmark but makes no functional changes beyond the name/identifier of a benchmark now including a parameter list when one was provided.

This unlocks the potential for the benchmark exporters (such as the Influx exporter) to leverage these tags (by emitting appropriate tags/fields in the case of Influx) in their output.

Sources/Benchmark/Benchmark.swift

@@ -69,8 +69,28 @@ public final class Benchmark: Codable, Hashable {
     #endif
     public static var benchmarks: [Benchmark] = [] // Bookkeeping of all registered benchmarks
 
+    /// The default name used for display purposes of the benchmark when no parameters exist.
+    private var baseName: String
+
     /// The name used for display purposes of the benchmark (also used for matching when comparing to baselines)
-    public var name: String
+    public var name: String {
+        get {
+            if configuration.tags.isEmpty {
+                return baseName
+            } else {
+                return baseName
+                    + " ("
+                    + configuration.tags
+                        .sorted(by: { $0.key < $1.key })
+                        .map({ "\($0.key): \($0.value)" })
+                        .joined(separator: ", ")
+                    + ")"
+            }
+        }
+        set {
+            baseName = newValue
+        }
+    }
 
     /// The reason for a benchmark failure, not set if successful
     public var failureReason: String?
@@ -119,6 +139,7 @@ public final class Benchmark: Codable, Hashable {
 
     /// Hook for setting defaults for a whole benchmark suite
     public static var defaultConfiguration: Configuration = .init(metrics: BenchmarkMetric.default,
+                                                                  tags: [:],
                                                                   timeUnits: .automatic,
                                                                   warmupIterations: 1,
                                                                   scalingFactor: .one,
@@ -131,7 +152,7 @@ public final class Benchmark: Codable, Hashable {
     var measurementCompleted = false // Keep track so we skip multiple 'end of measurement'
 
     enum CodingKeys: String, CodingKey {
-        case name
+        case baseName = "name"
         case target
         case executablePath
         case configuration
@@ -168,7 +189,7 @@ public final class Benchmark: Codable, Hashable {
             return nil
         }
         target = ""
-        self.name = name
+        self.baseName = name
         self.configuration = configuration
         self.closure = closure
         self.setup = setup
@@ -193,7 +214,7 @@ public final class Benchmark: Codable, Hashable {
             return nil
         }
         target = ""
-        self.name = name
+        self.baseName = name
         self.configuration = configuration
         asyncClosure = closure
         self.setup = setup
@@ -362,6 +383,8 @@ public extension Benchmark {
     struct Configuration: Codable {
         /// Defines the metrics that should be measured for the benchmark
         public var metrics: [BenchmarkMetric]
+        /// Specifies the parameters used to define the benchmark.
+        public var tags: [String: String]
         /// Override the automatic detection of timeunits for metrics related to time to a specific
         /// one (auto should work for most use cases)
         public var timeUnits: BenchmarkTimeUnits
@@ -386,6 +409,7 @@ public extension Benchmark {
         public var teardown: BenchmarkTeardownHook?
 
         public init(metrics: [BenchmarkMetric] = defaultConfiguration.metrics,
+                    tags: [String: String] = defaultConfiguration.tags,
                     timeUnits: BenchmarkTimeUnits = defaultConfiguration.timeUnits,
                     warmupIterations: Int = defaultConfiguration.warmupIterations,
                     scalingFactor: BenchmarkScalingFactor = defaultConfiguration.scalingFactor,
@@ -397,6 +421,7 @@ public extension Benchmark {
                     setup: BenchmarkSetupHook? = nil,
                     teardown: BenchmarkTeardownHook? = nil) {
             self.metrics = metrics
+            self.tags = tags
             self.timeUnits = timeUnits
             self.warmupIterations = warmupIterations
             self.scalingFactor = scalingFactor
@@ -411,6 +436,7 @@ public extension Benchmark {
         // swiftlint:disable nesting
         enum CodingKeys: String, CodingKey {
             case metrics
+            case tags
             case timeUnits
             case warmupIterations
             case scalingFactor

Sources/Benchmark/BenchmarkExecutor.swift

@@ -444,6 +444,7 @@ struct BenchmarkExecutor { // swiftlint:disable:this type_body_length
                                                      scalingFactor: benchmark.configuration.scalingFactor,
                                                      warmupIterations: benchmark.configuration.warmupIterations,
                                                      thresholds: benchmark.configuration.thresholds?[metric],
+                                                     tags: benchmark.configuration.tags,
                                                      statistics: value)
                         results.append(result)
                     }
@@ -457,6 +458,7 @@ struct BenchmarkExecutor { // swiftlint:disable:this type_body_length
                                                      scalingFactor: benchmark.configuration.scalingFactor,
                                                      warmupIterations: benchmark.configuration.warmupIterations,
                                                      thresholds: benchmark.configuration.thresholds?[metric],
+                                                     tags: benchmark.configuration.tags,
                                                      statistics: value)
                         results.append(result)
                     }

Sources/Benchmark/BenchmarkResult.swift

@@ -161,12 +161,14 @@ public struct BenchmarkResult: Codable, Comparable, Equatable {
                 scalingFactor: BenchmarkScalingFactor,
                 warmupIterations: Int,
                 thresholds: BenchmarkThresholds? = nil,
+                tags: [String: String] = [:],
                 statistics: Statistics) {
         self.metric = metric
         self.timeUnits = timeUnits == .automatic ? BenchmarkTimeUnits(statistics.units()) : timeUnits
         self.scalingFactor = scalingFactor
         self.warmupIterations = warmupIterations
         self.thresholds = thresholds
+        self.tags = tags
         self.statistics = statistics
     }
 
@@ -175,6 +177,7 @@ public struct BenchmarkResult: Codable, Comparable, Equatable {
     public var scalingFactor: BenchmarkScalingFactor
     public var warmupIterations: Int
     public var thresholds: BenchmarkThresholds?
+    public var tags: [String: String]
     public var statistics: Statistics
 
     public var scaledTimeUnits: BenchmarkTimeUnits {

Tests/BenchmarkTests/BenchmarkTests.swift

@@ -73,4 +73,17 @@ final class BenchmarkTests: XCTestCase {
         XCTAssertNotNil(benchmark)
         benchmark?.run()
     }
+
+    func testBenchmarkParameterizedDescription() throws {
+        let benchmark = Benchmark("testBenchmarkParameterizedDescription benchmark",
+                                  configuration: .init(
+                                    tags: [
+                                        "foo": "bar",
+                                        "bin": String(42),
+                                        "pi": String(3.14)
+                                    ]
+                                  )) { _ in }
+        XCTAssertNotNil(benchmark)
+        XCTAssertEqual(benchmark?.name, "testBenchmarkParameterizedDescription benchmark (bin: 42, foo: bar, pi: 3.14)")
+    }
 }