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libuv/test/test-loop-handles.c  view on Meta::CPAN

/*
 * Purpose of this test is to check semantics of starting and stopping
 * prepare, check and idle watchers.
 *
 * - A watcher must be able to safely stop or close itself;
 * - Once a watcher is stopped or closed its callback should never be called.
 * - If a watcher is closed, it is implicitly stopped and its close_cb should
 *   be called exactly once.
 * - A watcher can safely start and stop other watchers of the same type.
 * - Prepare and check watchers are called once per event loop iterations.
 * - All active idle watchers are queued when the event loop has no more work
 *   to do. This is done repeatedly until all idle watchers are inactive.
 * - If a watcher starts another watcher of the same type its callback is not
 *   immediately queued. For check and prepare watchers, that means that if
 *   a watcher makes another of the same type active, it'll not be called until
 *   the next event loop iteration. For idle. watchers this means that the
 *   newly activated idle watcher might not be queued immediately.
 * - Prepare, check, idle watchers keep the event loop alive even when they're
 *   not active.
 *
 * This is what the test globally does:
 *
 * - prepare_1 is always active and counts event loop iterations. It also
 *   creates and starts prepare_2 every other iteration. Finally it verifies
 *   that no idle watchers are active before polling.
 * - prepare_2 is started by prepare_1 every other iteration. It immediately
 *   stops itself. It verifies that a watcher is not queued immediately
 *   if created by another watcher of the same type.
 * - There's a check watcher that stops the event loop after a certain number
 *   of iterations. It starts a varying number of idle_1 watchers.
 * - Idle_1 watchers stop themselves after being called a few times. All idle_1
 *   watchers try to start the idle_2 watcher if it is not already started or
 *   awaiting its close callback.
 * - The idle_2 watcher always exists but immediately closes itself after
 *   being started by a check_1 watcher. It verifies that a watcher is
 *   implicitly stopped when closed, and that a watcher can close itself
 *   safely.
 * - There is a repeating timer. It does not keep the event loop alive
 *   (ev_unref) but makes sure that the loop keeps polling the system for
 *   events.