Various Swift code improvements (#58)

aperture/Recorder.swift

@@ -29,7 +29,7 @@ final class Recorder: NSObject {
   /// TODO: When targeting macOS 10.13, make the `videoCodec` option the type `AVVideoCodecType`
   init(
     destination: URL,
-    fps: Int,
+    framesPerSecond: Int,
     cropRect: CGRect?,
     showCursor: Bool,
     highlightClicks: Bool,
@@ -42,8 +42,7 @@ final class Recorder: NSObject {
 
     let input = AVCaptureScreenInput(displayID: screenId)
 
-    /// TODO: Use `CMTime(seconds:)` here instead
-    input.minFrameDuration = CMTime(value: 1, timescale: Int32(fps))
+    input.minFrameDuration = CMTime(videoFramesPerSecond: framesPerSecond)
 
     if let cropRect = cropRect {
       input.cropRect = cropRect

aperture/main.swift

@@ -1,18 +1,9 @@
 import Foundation
 import AVFoundation
 
-var recorder: Recorder!
-let arguments = CommandLine.arguments.dropFirst()
-
-func quit(_: Int32) {
-  recorder.stop()
-  // Do not call `exit()` here as the video is not always done
-  // saving at this point and will be corrupted randomly
-}
-
 struct Options: Decodable {
   let destination: URL
-  let fps: Int
+  let framesPerSecond: Int
   let cropRect: CGRect?
   let showCursor: Bool
   let highlightClicks: Bool
@@ -22,12 +13,11 @@ struct Options: Decodable {
 }
 
 func record() throws {
-  let json = arguments.first!.data(using: .utf8)!
-  let options = try JSONDecoder().decode(Options.self, from: json)
+  let options: Options = try CLI.arguments.first!.jsonDecoded()
 
-  recorder = try Recorder(
+  let recorder = try Recorder(
     destination: options.destination,
-    fps: options.fps,
+    framesPerSecond: options.framesPerSecond,
     cropRect: options.cropRect,
     showCursor: options.showCursor,
     highlightClicks: options.highlightClicks,
@@ -45,22 +35,23 @@ func record() throws {
   }
 
   recorder.onError = {
-    printErr($0)
+    print($0, to: .standardError)
     exit(1)
   }
 
-  signal(SIGHUP, quit)
-  signal(SIGINT, quit)
-  signal(SIGTERM, quit)
-  signal(SIGQUIT, quit)
+  CLI.onExit = {
+    recorder.stop()
+    // Do not call `exit()` here as the video is not always done
+    // saving at this point and will be corrupted randomly
+  }
 
   recorder.start()
-  setbuf(__stdoutp, nil)
 
+  setbuf(__stdoutp, nil)
   RunLoop.main.run()
 }
 
-func usage() {
+func showUsage() {
   print(
     """
     Usage:
@@ -71,21 +62,17 @@ func usage() {
   )
 }
 
-if arguments.first == "list-screens" {
-  printErr(try toJson(DeviceList.screen()))
+switch CLI.arguments.first {
+case "list-screens":
+  print(try toJson(DeviceList.screen()), to: .standardError)
   exit(0)
-}
-
-if arguments.first == "list-audio-devices" {
+case "list-audio-devices":
   // Uses stderr because of unrelated stuff being outputted on stdout
-  printErr(try toJson(DeviceList.audio()))
+  print(try toJson(DeviceList.audio()), to: .standardError)
   exit(0)
-}
-
-if arguments.first != nil {
+case .none:
+  showUsage()
+  exit(1)
+default:
   try record()
-  exit(0)
 }
-
-usage()
-exit(1)

aperture/util.swift

@@ -1,16 +1,236 @@
 import AppKit
 import AVFoundation
 
-private final class StandardErrorOutputStream: TextOutputStream {
-  func write(_ string: String) {
-    FileHandle.standardError.write(string.data(using: .utf8)!)
+
+// MARK: - SignalHandler
+struct SignalHandler {
+  struct Signal: Hashable {
+    static let hangup = Signal(rawValue: SIGHUP)
+    static let interrupt = Signal(rawValue: SIGINT)
+    static let quit = Signal(rawValue: SIGQUIT)
+    static let abort = Signal(rawValue: SIGABRT)
+    static let kill = Signal(rawValue: SIGKILL)
+    static let alarm = Signal(rawValue: SIGALRM)
+    static let termination = Signal(rawValue: SIGTERM)
+    static let userDefined1 = Signal(rawValue: SIGUSR1)
+    static let userDefined2 = Signal(rawValue: SIGUSR2)
+
+    /// Signals that cause the process to exit
+    static let exitSignals = [
+      hangup,
+      interrupt,
+      quit,
+      abort,
+      alarm,
+      termination
+    ]
+
+    let rawValue: Int32
+    init(rawValue: Int32) {
+      self.rawValue = rawValue
+    }
+  }
+
+  typealias CSignalHandler = @convention(c) (Int32) -> Void
+  typealias SignalHandler = (Signal) -> Void
+
+  private static var handlers = [Signal: [SignalHandler]]()
+
+  private static var cHandler: CSignalHandler = { rawSignal in
+    let signal = Signal(rawValue: rawSignal)
+
+    guard let signalHandlers = handlers[signal] else {
+      return
+    }
+
+    for handler in signalHandlers {
+      handler(signal)
+    }
+  }
+
+  /// Handle some signals
+  static func handle(signals: [Signal], handler: @escaping SignalHandler) {
+    for signal in signals {
+      // Since Swift has no way of running code on "struct creation", we need to initialize here…
+      if handlers[signal] == nil {
+        handlers[signal] = []
+      }
+      handlers[signal]?.append(handler)
+
+      var signalAction = sigaction(
+        __sigaction_u: unsafeBitCast(cHandler, to: __sigaction_u.self),
+        sa_mask: 0,
+        sa_flags: 0
+      )
+
+      _ = withUnsafePointer(to: &signalAction) { pointer in
+        sigaction(signal.rawValue, pointer, nil)
+      }
+    }
+  }
+
+  /// Raise a signal
+  static func raise(signal: Signal) {
+    _ = Darwin.raise(signal.rawValue)
+  }
+
+  /// Ignore a signal
+  static func ignore(signal: Signal) {
+    _ = Darwin.signal(signal.rawValue, SIG_IGN)
+  }
+
+  /// Restore default signal handling
+  static func restore(signal: Signal) {
+    _ = Darwin.signal(signal.rawValue, SIG_DFL)
   }
 }
 
-private var stderr = StandardErrorOutputStream()
+extension Array where Element == SignalHandler.Signal {
+  static let exitSignals = SignalHandler.Signal.exitSignals
+}
+// MARK: -
 
-func printErr(_ item: Any) {
-  print(item, to: &stderr)
+
+// MARK: - CLI utils
+extension FileHandle: TextOutputStream {
+  public func write(_ string: String) {
+    write(string.data(using: .utf8)!)
+  }
+}
+
+struct CLI {
+  static var standardInput = FileHandle.standardOutput
+  static var standardOutput = FileHandle.standardOutput
+  static var standardError = FileHandle.standardError
+
+  static let arguments = Array(CommandLine.arguments.dropFirst(1))
+}
+
+extension CLI {
+  private static let once = Once()
+
+  /// Called when the process exits, either normally or forced (through signals)
+  /// When this is set, it's up to you to exit the process
+  static var onExit: (() -> Void)? {
+    didSet {
+      guard let exitHandler = onExit else {
+        return
+      }
+
+      let handler = {
+        once.run(exitHandler)
+      }
+
+      atexit_b {
+        handler()
+      }
+
+      SignalHandler.handle(signals: .exitSignals) { _ in
+        handler()
+      }
+    }
+  }
+
+  /// Called when the process is being forced (through signals) to exit
+  /// When this is set, it's up to you to exit the process
+  static var onForcedExit: ((SignalHandler.Signal) -> Void)? {
+    didSet {
+      guard let exitHandler = onForcedExit else {
+        return
+      }
+
+      SignalHandler.handle(signals: .exitSignals, handler: exitHandler)
+    }
+  }
+}
+
+enum PrintOutputTarget {
+  case standardOutput
+  case standardError
+}
+
+/// Make `print()` accept an array of items
+/// Since Swift doesn't support spreading...
+private func print<Target>(
+  _ items: [Any],
+  separator: String = " ",
+  terminator: String = "\n",
+  to output: inout Target
+) where Target: TextOutputStream {
+  let item = items.map { "\($0)" }.joined(separator: separator)
+  Swift.print(item, terminator: terminator, to: &output)
+}
+
+func print(
+  _ items: Any...,
+  separator: String = " ",
+  terminator: String = "\n",
+  to output: PrintOutputTarget = .standardOutput
+) {
+  switch output {
+  case .standardOutput:
+    print(items, separator: separator, terminator: terminator)
+  case .standardError:
+    print(items, separator: separator, terminator: terminator, to: &CLI.standardError)
+  }
+}
+// MARK: -
+
+
+// MARK: - Misc
+func synchronized<T>(lock: AnyObject, closure: () throws -> T) rethrows -> T {
+	objc_sync_enter(lock)
+	defer {
+		objc_sync_exit(lock)
+	}
+
+	return try closure()
+}
+
+final class Once {
+  private var hasRun = false
+
+  /**
+  Executes the given closure only once (thread-safe)
+
+  ```
+  final class Foo {
+    private let once = Once()
+
+    func bar() {
+      once.run {
+        print("Called only once")
+      }
+    }
+  }
+
+  let foo = Foo()
+  foo.bar()
+  foo.bar()
+  ```
+  */
+  func run(_ closure: () -> Void) {
+    synchronized(lock: self) {
+      guard !hasRun else {
+        return
+      }
+
+      hasRun = true
+      closure()
+    }
+  }
+}
+
+extension Data {
+  func jsonDecoded<T: Decodable>() throws -> T {
+    return try JSONDecoder().decode(T.self, from: self)
+  }
+}
+
+extension String {
+  func jsonDecoded<T: Decodable>() throws -> T {
+    return try data(using: .utf8)!.jsonDecoded()
+  }
 }
 
 func toJson<T>(_ data: T) throws -> String {
@@ -18,9 +238,17 @@ func toJson<T>(_ data: T) throws -> String {
   return String(data: json, encoding: .utf8)!
 }
 
+extension CMTimeScale {
+  static var video: CMTimeScale = 600 // This is what Apple recommends
+}
+
 extension CMTime {
-  static var zero: CMTime = kCMTimeZero
-  static var invalid: CMTime = kCMTimeInvalid
+  static let zero = kCMTimeZero
+  static let invalid = kCMTimeInvalid
+
+  init(videoFramesPerSecond: Int) {
+    self.init(seconds: 1 / Double(videoFramesPerSecond), preferredTimescale: .video)
+  }
 }
 
 extension CGDirectDisplayID {
@@ -77,3 +305,4 @@ extension NSScreen {
     return name
   }
 }
+// MARK: -