feat: Make it possible to build and run without jemalloc available

Package.swift

@@ -1,6 +1,11 @@
 // swift-tools-version: 5.7
 
 import PackageDescription
+import class Foundation.ProcessInfo
+
+// If the environment variable BENCHMARK_DISABLE_JEMALLOC is set, we'll build the package without Jemalloc support
+
+let disableJemalloc = ProcessInfo.processInfo.environment["BENCHMARK_DISABLE_JEMALLOC"]
 
 let package = Package(
     name: "Benchmark",
@@ -19,7 +24,6 @@ let package = Package(
         .package(url: "https://github.com/swift-extras/swift-extras-json", .upToNextMajor(from: "0.6.0")),
 //        .package(url: "https://github.com/SwiftPackageIndex/SPIManifest", from: "0.12.0"),
         .package(url: "https://github.com/ordo-one/TextTable", .upToNextMajor(from: "0.0.1")),
-        .package(url: "https://github.com/ordo-one/package-jemalloc", .upToNextMajor(from: "1.0.0")),
         .package(url: "https://github.com/ordo-one/package-datetime", .upToNextMajor(from: "0.0.0")),
         .package(url: "https://github.com/ordo-one/package-histogram", .upToNextMajor(from: "0.0.1")),
         .package(url: "https://github.com/ordo-one/Progress.swift", .upToNextMajor(from: "1.0.0")),
@@ -85,22 +89,6 @@ let package = Package(
             path: "Plugins/BenchmarkHelpGenerator"
         ),
 
-        // Benchmark package
-        .target(
-            name: "Benchmark",
-            dependencies: [
-                .product(name: "Histogram", package: "package-histogram"),
-                .product(name: "ArgumentParser", package: "swift-argument-parser"),
-                .product(name: "ExtrasJSON", package: "swift-extras-json"),
-                .product(name: "SystemPackage", package: "swift-system"),
-                .product(name: "jemalloc", package: "package-jemalloc"),
-                .product(name: "DateTime", package: "package-datetime"),
-                .product(name: "Progress", package: "Progress.swift"),
-                .byNameItem(name: "CDarwinOperatingSystemStats", condition: .when(platforms: [.macOS])),
-                .byNameItem(name: "CLinuxOperatingSystemStats", condition: .when(platforms: [.linux])),
-            ]
-        ),
-
         // Getting OS specific information
         .target(
             name: "CDarwinOperatingSystemStats",
@@ -154,3 +142,37 @@ let package = Package(
         ),
     ]
 )
+
+if let disableJemalloc, disableJemalloc != "false", disableJemalloc != "0" {
+    package.targets += [
+        .target(
+            name: "Benchmark",
+            dependencies: [
+                .product(name: "Histogram", package: "package-histogram"),
+                .product(name: "ArgumentParser", package: "swift-argument-parser"),
+                .product(name: "ExtrasJSON", package: "swift-extras-json"),
+                .product(name: "SystemPackage", package: "swift-system"),
+                .product(name: "DateTime", package: "package-datetime"),
+                .product(name: "Progress", package: "Progress.swift"),
+                .byNameItem(name: "CDarwinOperatingSystemStats", condition: .when(platforms: [.macOS])),
+                .byNameItem(name: "CLinuxOperatingSystemStats", condition: .when(platforms: [.linux])),
+            ]
+        )]
+} else {
+    package.dependencies += [.package(url: "https://github.com/ordo-one/package-jemalloc", .upToNextMajor(from: "1.0.0"))]
+    package.targets += [
+        .target(
+            name: "Benchmark",
+            dependencies: [
+                .product(name: "Histogram", package: "package-histogram"),
+                .product(name: "ArgumentParser", package: "swift-argument-parser"),
+                .product(name: "ExtrasJSON", package: "swift-extras-json"),
+                .product(name: "SystemPackage", package: "swift-system"),
+                .product(name: "jemalloc", package: "package-jemalloc"),
+                .product(name: "DateTime", package: "package-datetime"),
+                .product(name: "Progress", package: "Progress.swift"),
+                .byNameItem(name: "CDarwinOperatingSystemStats", condition: .when(platforms: [.macOS])),
+                .byNameItem(name: "CLinuxOperatingSystemStats", condition: .when(platforms: [.linux])),
+            ]
+        )]
+}

Sources/Benchmark/Documentation.docc/GettingStarted.md

@@ -16,11 +16,19 @@ After having done those, running your benchmarks are as simple as running `swift
 
 Benchmark requires Swift 5.7 support as it uses Regex and Duration types introduced with the `macOS 13` runtime, most versions of Linux will work as long as Swift 5.7+ is used. 
 
-Benchmark also depends and needs the [jemalloc](https://jemalloc.net) memory allocation library, which is used by the Benchmark infrastructure to capture memory allocation statistics, as `jemalloc` provides a rich programmatic API for extracting memory allocation statistics at runtime. 
+Benchmark also by default depends on and uses the [jemalloc](https://jemalloc.net) memory allocation library, which is used by the Benchmark infrastructure to capture memory allocation statistics.
 
-The Benchmark package requires you to install jemalloc on any machine used for benchmarking. 
+For platforms where `jemalloc` isn't available it's possible to build the Benchmark package without a `jemalloc` dependency by setting the environment variable BENCHMARK_DISABLE_JEMALLOC to any value except `false` or `0`.
 
-If you want to avoid adding the `jemalloc` dependency to your project, the recommended approach is to embed a separate Swift project in a subdirectory that uses your project, then the dependency on `jemalloc` is contained to that subproject only.
+E.g. to run the benchmark on the command line without memory allocation stats could look like:
+
+```bash
+BENCHMARK_DISABLE_JEMALLOC=true swift package benchmark
+```
+
+The Benchmark package requires you to install jemalloc on any machine used for benchmarking if you want malloc statistics. 
+
+If you want to avoid adding the `jemalloc` dependency to your main project while still getting malloc statistics when benchmarking, the recommended approach is to embed a separate Swift project in a subdirectory that uses your project, then the dependency on `jemalloc` is contained to that subproject only.
 
 #### Installing `jemalloc` on macOS
 

Sources/Benchmark/MallocStats/MallocStatsProducer+jemalloc.swift

@@ -9,6 +9,8 @@
 //
 
 import ExtrasJSON
+
+#if canImport(jemalloc)
 import jemalloc
 
 // We currently register a number of MIB:s that aren't in use that
@@ -165,3 +167,17 @@ class MallocStatsProducer {
         return carrier.data
     }
 }
+
+#else
+
+// stub if no jemalloc available
+class MallocStatsProducer {
+    func makeMallocStats() -> MallocStats {
+        return MallocStats(mallocCountTotal: 0,
+                           mallocCountSmall: 0,
+                           mallocCountLarge: 0,
+                           allocatedResidentMemory: 0)
+    }
+}
+
+#endif

Tests/BenchmarkTests/OperatingSystemAndMallocTests.swift

@@ -53,7 +53,7 @@ final class OperatingSystemAndMallocTests: XCTestCase {
         blackHole(operatingSystemStatsProducer.metricSupported(.writeBytesPhysical))
         blackHole(operatingSystemStatsProducer.metricSupported(.throughput))
     }
-
+#if canImport(jemalloc)
     func testMallocProducerLeaks() throws {
         let mallocStatsProducer = MallocStatsProducer()
         let startMallocStats = mallocStatsProducer.makeMallocStats()
@@ -68,4 +68,5 @@ final class OperatingSystemAndMallocTests: XCTestCase {
         XCTAssertGreaterThanOrEqual(stopMallocStats.allocatedResidentMemory - startMallocStats.allocatedResidentMemory,
                                     100 * 1_024)
     }
+#endif
 }