A FIFO queuing system leveraging Swift's async/await structured concurrency

AsyncConcurrentQueue

A FIFO queuing system leveraging Swift’s async/await structured concurrency. Also includes FutureTask which allows you to arbitrairily delay/start a task.

Usage

import AsyncConcurrentQueue

// AsyncConcurrentQueue
Task {
        // initialize a new queue
      let queue = AsyncConcurrentQueue()
        
        // set how many tasks may run concurrently
      await queue.setMaximumConcurrentTasks(5)
        
        // feed it a bunch of tasks to perform.
      for i in 1...20 {
                let task = await queue.queueTask {
                        print("starting \(i)")
                        try await Task.sleep(for: .seconds(Double.random(in: 0.5...2)))
                        print("finishing \(i)")
                        return i
                }

                Task {
                        let value = try await task.value
                        print("Got \(value) from \(i)")
                }
        }
}

// FutureTask
Task {
        // create future task. Note that it does not run right away.
      let futureTask = FutureTask {
                print("Waited until called")
        }

        // create normal task for comparison. Note that it runs almost immediately.
      Task {
                print("Ran immediately")
        }

        // create a separate future task. It doesn't run right away, but also has a cancellation handler.
      let canceller = FutureTask(
                operation: {
                        print("Will never run")
                },
                onCancellation: {
                        print("Cancelled before activation")
                })

        // wait half a second
      try await Task.sleep(for: .seconds(0.5))
        // cancel the `canceller` task. The cancellation handler will run.
      canceller.cancel()

        // wait another couple seconds
      try await Task.sleep(for: .seconds(2))
        
        // activate the `futureTask`, allowing it to proceed now.
      futureTask.activate()
}

GitHub

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