add batching demo

Author: lhoward

Examples/BatchingDemo/BatchingDemo.swift

@@ -0,0 +1,98 @@
+//
+// Copyright (c) 2025 PADL Software Pty Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the License);
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an 'AS IS' BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation // for String(format:)
+@testable import IORing
+import struct SystemPackage.Errno
+import struct SystemPackage.FileDescriptor
+
+let operationCount = 100
+
+@main
+struct BatchingDemo {
+  static func main() async {
+    print("IORing Batching Performance Demo")
+    print("================================")
+
+    await testBatchingPerformance()
+  }
+
+  static func testBatchingPerformance() async {
+    do {
+      // Test 1: No batching (batch size 1)
+      print("\nTest 1: No Batching (batch size 1)")
+      let noBatchRing = try IORing(batchSize: 1, batchTimeout: .microseconds(1))
+      let noBatchTime = await measureOperations(ring: noBatchRing, count: operationCount)
+      print("Time: \(String(format: "%.3f", noBatchTime)) seconds")
+
+      // Test 2: Small batches (batch size 4)
+      print("\nTest 2: Small Batching (batch size 4)")
+      let smallBatchRing = try IORing(batchSize: 4, batchTimeout: .microseconds(100))
+      let smallBatchTime = await measureOperations(ring: smallBatchRing, count: operationCount)
+      print("Time: \(String(format: "%.3f", smallBatchTime)) seconds")
+
+      // Test 3: Large batches (batch size 16)
+      print("\nTest 3: Large Batching (batch size 16)")
+      let largeBatchRing = try IORing(batchSize: 16, batchTimeout: .microseconds(200))
+      let largeBatchTime = await measureOperations(ring: largeBatchRing, count: operationCount)
+      print("Time: \(String(format: "%.3f", largeBatchTime)) seconds")
+
+      // Analysis
+      print("\nPerformance Analysis:")
+      print("--------------------")
+      let smallBatchImprovement = ((noBatchTime - smallBatchTime) / noBatchTime) * 100
+      let largeBatchImprovement = ((noBatchTime - largeBatchTime) / noBatchTime) * 100
+
+      if smallBatchImprovement > 0 {
+        print(
+          "Small batching improved performance by \(String(format: "%.1f", smallBatchImprovement))%"
+        )
+      }
+      if largeBatchImprovement > 0 {
+        print(
+          "Large batching improved performance by \(String(format: "%.1f", largeBatchImprovement))%"
+        )
+      }
+
+    } catch {
+      print("Error: \(error)")
+    }
+  }
+
+  static func measureOperations(ring: IORing, count: Int) async -> Double {
+    let startTime = ContinuousClock.now
+
+    await withTaskGroup(of: Void.self) { group in
+      for i in 0..<count {
+        group.addTask {
+          do {
+            let data = "Test operation \(i)\n".data(using: .utf8) ?? Data()
+            // Write to /dev/null to avoid actual I/O overhead
+            let devNull = try FileDescriptor.open("/dev/null", .writeOnly)
+            defer { try? devNull.close() }
+            _ = try await ring.write([UInt8](data), to: devNull)
+          } catch {
+            // Ignore errors for performance testing
+          }
+        }
+      }
+    }
+
+    let endTime = ContinuousClock.now
+    let duration = endTime - startTime
+    return Double(duration.components.seconds) + Double(duration.components.attoseconds) / 1e18
+  }
+}

Package.swift

@@ -146,6 +146,11 @@ let package = Package(
       dependencies: ["IORing", "IORingUtils"],
       path: "Examples/IORingDeviceSpy"
     ),
+    .executableTarget(
+      name: "BatchingDemo",
+      dependencies: ["IORing", "IORingUtils"],
+      path: "Examples/BatchingDemo"
+    ),
   ],
   cLanguageStandard: .c18,
   cxxLanguageStandard: .cxx20