Livt.Collections

tests/queue/QueueClearConcurrencyTest.lvt

namespace Livt.Collections.Tests

using Livt.Collections

/**
 * Checks clear against a concurrent enqueue without assuming arrival order.
 */
@Test
component QueueClearConcurrencyTest
{
	// Shared fixture instances, signals, and observation state.
	queue: Livt.Collections.Queue<byte, 3>
	start: bool
	cleared: bool
	produced: bool

	/**
	 * Uses one shared queue for both independently dispatched operations.
	 */
	new()
	{
		this.queue = new Livt.Collections.Queue<byte, 3>()
	}

	/**
	 * Waits until the test has inserted an old value, then clears concurrently.
	 */
	process Clearer()
	{
		while (!start) {
			state {
			}
		}

		this.queue.Clear()
		cleared = true

		state Done {
			goto Done
		}
	}

	/**
	 * Submits a distinguishable value while clear is pending.
	 */
	process Producer()
	{
		while (!start) {
			state {
			}
		}

		assert this.queue.TryEnqueue(0x5A) == true
		produced = true

		state Done {
			goto Done
		}
	}

	/**
	 * Clear must remove the old value, and neither request may complete twice.
	 */
	@Test
	fn TestClearAndEnqueue()
	{
		assert this.queue.TryEnqueue(0x11) == true
		start = true
		Simulation.Wait(500)
		assert cleared == true
		assert produced == true
		var count = this.queue.GetCount()
		assert count == 0 || count == 1
		var value: byte
		var accepted = this.queue.TryDequeue(value)

		if (count == 1) {
			assert accepted == true
			assert value == 0x5A
		} else {
			assert accepted == false
			assert value == 0x00
		}

		assert this.queue.TryDequeue(value) == false
		assert value == 0x00
		assert this.queue.GetCount() == 0
	}
}