Add benchmark suite.

_read coroutine on CircularBufferLineList subscript: Replaced get with
_read + yield, so every _lines[index] access yields a borrowed reference
instead of retaining/releasing the BufferLine.  Reduces ARC overhead
on the hot path.

Direct array access in shiftElements: The loop now uses
array[getCyclicIndex(...)] instead of self[...], bypassing the subscript
entirely. Shifted elements are always populated, so the makeEmpty
check is unnecessary here.

Author: migueldeicaza

Benchmarks/SwiftTermBenchmarks/SwiftTermBenchmarks.swift

@@ -0,0 +1,41 @@
+#if os(macOS)
+import Benchmark
+import Dispatch
+import Foundation
+import SwiftTerm
+
+private enum SwiftTermBenchmarks {
+    static let queue: DispatchQueue = {
+        DispatchQueue(label: "Runner", qos: .userInteractive, attributes: .concurrent, autoreleaseFrequency: .inherit, target: nil)
+    }()
+}
+
+private func testFeed(benchmark: Benchmark, data: [UInt8], innerIterations: Int) {
+    let h = HeadlessTerminal(queue: SwiftTermBenchmarks.queue) { _ in }
+    let t = h.terminal!
+
+    t.feed(text: "\u{1b}[38;2;19;49;174;48;2;23;56;179mStringThis is a very long line\n\r")
+
+    benchmark.startMeasurement()
+    for _ in benchmark.scaledIterations {
+        for _ in 0..<innerIterations {
+            t.feed(byteArray: data)
+        }
+    }
+    benchmark.stopMeasurement()
+}
+
+let benchmarks: @Sendable () -> Void = {
+    Benchmark("testPerformance", configuration: .init(metrics: [.wallClock], maxDuration: .seconds(10))) { benchmark in
+        let data = [UInt8]("pointless repetition\n".utf8)
+        testFeed(benchmark: benchmark, data: data, innerIterations: 1_000)
+    }
+
+    Benchmark("testPerformance2", configuration: .init(metrics: [.wallClock], maxDuration: .seconds(10))) { benchmark in
+        let data = [UInt8]("pointless repetition\n".utf8)
+        testFeed(benchmark: benchmark, data: data, innerIterations: 1_000)
+    }
+}
+#else
+let benchmarks: @Sendable () -> Void = { }
+#endif

Package.swift

@@ -80,6 +80,17 @@ let targets: [Target] = [
         name: "SwiftTermTests",
         dependencies: ["SwiftTerm"],
         path: "Tests/SwiftTermTests"
+    ),
+    .executableTarget(
+        name: "SwiftTermBenchmarks",
+        dependencies: [
+            "SwiftTerm",
+            .product(name: "Benchmark", package: "package-benchmark")
+        ],
+        path: "Benchmarks/SwiftTermBenchmarks",
+        plugins: [
+            .plugin(name: "BenchmarkPlugin", package: "package-benchmark")
+        ]
     )
 ]
 #endif
@@ -96,6 +107,7 @@ let package = Package(
     dependencies: [
         .package(url: "https://github.com/apple/swift-argument-parser", from: "1.0.0"),
         .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.4.3"),
+        .package(url: "https://github.com/ordo-one/package-benchmark", .upToNextMajor(from: "1.29.11")),
 //        .package(url: "https://github.com/swiftlang/swift-subprocess", revision: "426790f3f24afa60b418450da0afaa20a8b3bdd4")
     ],
     targets: targets,

Sources/SwiftTerm/CircularList.swift

@@ -31,7 +31,7 @@ class CircularList<T> {
             _count = newValue
         }
     }
-    
+
     private var _count: Int
     var maxLength: Int {
         didSet {
@@ -54,23 +54,23 @@ class CircularList<T> {
     /// does not exist, or the index requested otherwise
     //
     var makeEmpty: ((_ idx: Int) -> T)? = nil
-    
+
     public init (maxLength: Int)
     {
         array = Array.init(repeating: nil, count: Int(maxLength))
         self.maxLength = maxLength
         self._count = 0
         self.startIndex = 0
     }
-    
+
     private func getCyclicIndex(_ index: Int) -> Int {
         return Int(startIndex + index) % (array.count)
     }
-    
+
     func debugGetCyclicIndex(_ index: Int) -> Int {
         getCyclicIndex(index)
     }
-    
+
     subscript (index: Int) -> T {
         get {
             let idx = getCyclicIndex(index)
@@ -87,7 +87,7 @@ class CircularList<T> {
             array [getCyclicIndex(index)] = newValue
       }
     }
-    
+
     func push (_ value: T)
     {
         array [getCyclicIndex(count)] = value
@@ -109,17 +109,17 @@ class CircularList<T> {
         }
         let index = getCyclicIndex(count)
         startIndex += 1
-        startIndex = startIndex % maxLength        
+        startIndex = startIndex % maxLength
         array [index] = makeEmpty! (-1)
     }
-    
+
     @discardableResult
     func pop () -> T {
         let v = array [getCyclicIndex(count-1)]!
         count = count - 1
         return v
     }
-    
+
     func splice (start: Int, deleteCount: Int, items: [T], change: (Int) -> Void)
     {
         if deleteCount > 0 {
@@ -147,7 +147,7 @@ class CircularList<T> {
             change(start + i)
             array [getCyclicIndex(start + i)] = items [i]
         }
-        
+
         // Adjust length as needed
         if Int(count) + ic > array.count {
             let countToTrim = count + items.count - array.count
@@ -157,21 +157,21 @@ class CircularList<T> {
             count = count + items.count
         }
      }
-    
+
     func trimStart (count: Int)
     {
         let c = count > self.count ? self.count : count
         startIndex = startIndex + c
         self.count -= count
     }
-    
+
     func shiftElements (start: Int, count: Int, offset: Int) -> Bool
     {
         func dumpState (_ msg: String) -> Bool {
             print ("Assertion at start=\(start) count=\(count) offset=\(offset): \(msg)")
             return false
         }
-        
+
         if count < 0 {
             return dumpState ("count < 0")
         }
@@ -208,7 +208,7 @@ class CircularList<T> {
         }
         return true
     }
-    
+
     var isFull: Bool {
         get {
             return count == maxLength
@@ -272,36 +272,33 @@ internal class CircularBufferLineList {
 
     /// Called when a line is pushed, with true if the line has images
     var onLinePushed: ((_ hasImages: Bool) -> Void)? = nil
-    
+
     public init (maxLength: Int)
     {
         array = Array.init(repeating: nil, count: Int(maxLength))
         self.maxLength = maxLength
         self._count = 0
         self.startIndex = 0
     }
-    
+
     /// The private version exists to allow the Swift optimizer to avoid calls to
     /// `swift_beginAccess`
     private func getCyclicIndex(_ index: Int) -> Int {
         return Int(startIndex &+ index) % (array.count)
     }
-    
+
     /// Public version of the same method
     func debugGetCyclicIndex(_ index: Int) -> Int {
         return getCyclicIndex(index)
     }
-    
+
     subscript (index: Int) -> BufferLine {
-        get {
+        _read {
             let idx = getCyclicIndex(index)
-            if let p = array [idx] {
-                return p
-            } else {
-                let new = makeEmpty! (idx)
-                array [idx] = new
-                return new
+            if array[idx] == nil {
+                array[idx] = makeEmpty!(idx)
             }
+            yield array[idx]!
         }
         set (newValue){
             array [getCyclicIndex(index)] = newValue
@@ -336,14 +333,14 @@ internal class CircularBufferLineList {
         onLineRecycled?(hadImages)
         //array [index] = makeEmpty! (-1)
     }
-    
+
     @discardableResult
     func pop () -> BufferLine {
         let v = array [getCyclicIndex(count-1)]!
         count = count - 1
         return v
     }
-    
+
     func splice (start: Int, deleteCount: Int, items: [BufferLine], change: (Int) -> Void)
     {
         if deleteCount > 0 {
@@ -371,7 +368,7 @@ internal class CircularBufferLineList {
             change(start + i)
             array [getCyclicIndex(start + i)] = items [i]
         }
-        
+
         // Adjust length as needed
         if Int(count) + ic > array.count {
             let countToTrim = count + items.count - array.count
@@ -381,21 +378,21 @@ internal class CircularBufferLineList {
             count = count + items.count
         }
      }
-    
+
     func trimStart (count: Int)
     {
         let c = count > self.count ? self.count : count
         startIndex = startIndex + c
         self.count -= count
     }
-    
+
     func shiftElements (start: Int, count: Int, offset: Int) -> Bool
     {
         func dumpState (_ msg: String) -> Bool {
             print ("Assertion at start=\(start) count=\(count) offset=\(offset): \(msg)")
             return false
         }
-        
+
         if count < 0 {
             return dumpState ("count < 0")
         }
@@ -408,13 +405,9 @@ internal class CircularBufferLineList {
         if start+offset <= 0 {
             return dumpState ("start+offset <= 0")
         }
-//        precondition (count > 0)
-//        precondition (start >= 0)
-//        precondition (start < self.count)
-//        precondition (start+offset > 0)
         if offset > 0 {
             for i in (0..<count).reversed() {
-                self [start + i + offset] = self [start + i]
+                array[getCyclicIndex(start + i + offset)] = array[getCyclicIndex(start + i)]
             }
             let expandListBy = start + count + offset - self.count
             if expandListBy > 0 {
@@ -427,16 +420,15 @@ internal class CircularBufferLineList {
             }
         } else {
             for i in 0..<count {
-                self [start + i + offset] = self [start + i]
+                array[getCyclicIndex(start + i + offset)] = array[getCyclicIndex(start + i)]
             }
         }
         return true
     }
-    
+
     var isFull: Bool {
         get {
             return count == maxLength
         }
     }
 }
-