Synchronization Primitives — Series 3

import asyncio

async def worker():
    try:
        await asyncio.sleep(1)
    except asyncio.CancelledError as e:
        print("cancelled with args:", e.args)
        raise

async def main():
    task = asyncio.create_task(worker())
    await asyncio.sleep(0.01)
    task.cancel("shutting down")
    try:
        await task
    except asyncio.CancelledError:
        print("main sees cancellation")

asyncio.run(main())

import asyncio

results = []

async def runner(barrier, n):
    results.append(f"{n} waiting")
    await barrier.wait()
    results.append(f"{n} passed")

async def main():
    barrier = asyncio.Barrier(3)
    await asyncio.gather(runner(barrier, 1), runner(barrier, 2), runner(barrier, 3))
    waiting_count = sum(1 for r in results if "waiting" in r)
    passed_count = sum(1 for r in results if "passed" in r)
    first_passed_index = next(i for i, r in enumerate(results) if "passed" in r)
    print(waiting_count, passed_count)
    print(all("waiting" in results[i] for i in range(first_passed_index)))

asyncio.run(main())

import asyncio

async def main():
    loop = asyncio.get_running_loop()
    deadline = loop.time() + 0.05
    try:
        async with asyncio.timeout_at(deadline):
            await asyncio.sleep(1)
    except TimeoutError:
        print("TimeoutError")

asyncio.run(main())