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Until now, our kernel has reimplemented a number of AK classes to provide automatic internal locking: - RefPtr - NonnullRefPtr - WeakPtr - Weakable This patch renames the Kernel classes so that they can coexist with the original AK classes: - RefPtr => LockRefPtr - NonnullRefPtr => NonnullLockRefPtr - WeakPtr => LockWeakPtr - Weakable => LockWeakable The goal here is to eventually get rid of the Lock* classes in favor of using external locking.
233 lines
7.1 KiB
C++
233 lines
7.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Singleton.h>
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#include <AK/Time.h>
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#include <Kernel/Scheduler.h>
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#include <Kernel/Sections.h>
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#include <Kernel/Time/TimeManagement.h>
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#include <Kernel/TimerQueue.h>
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namespace Kernel {
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static Singleton<TimerQueue> s_the;
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static Spinlock g_timerqueue_lock { LockRank::None };
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Time Timer::remaining() const
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{
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return m_remaining;
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}
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Time Timer::now(bool is_firing) const
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{
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// NOTE: If is_firing is true then TimePrecision::Precise isn't really useful here.
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// We already have a quite precise time stamp because we just updated the time in the
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// interrupt handler. In those cases, just use coarse timestamps.
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auto clock_id = m_clock_id;
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if (is_firing) {
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switch (clock_id) {
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case CLOCK_MONOTONIC:
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clock_id = CLOCK_MONOTONIC_COARSE;
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break;
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case CLOCK_MONOTONIC_RAW:
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// TODO: use a special CLOCK_MONOTONIC_RAW_COARSE like mechanism here
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break;
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case CLOCK_REALTIME:
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clock_id = CLOCK_REALTIME_COARSE;
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break;
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default:
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break;
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}
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}
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return TimeManagement::the().current_time(clock_id);
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}
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TimerQueue& TimerQueue::the()
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{
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return *s_the;
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}
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UNMAP_AFTER_INIT TimerQueue::TimerQueue()
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{
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m_ticks_per_second = TimeManagement::the().ticks_per_second();
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}
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bool TimerQueue::add_timer_without_id(NonnullLockRefPtr<Timer> timer, clockid_t clock_id, Time const& deadline, Function<void()>&& callback)
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{
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if (deadline <= TimeManagement::the().current_time(clock_id))
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return false;
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// Because timer handlers can execute on any processor and there is
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// a race between executing a timer handler and cancel_timer() this
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// *must* be a LockRefPtr<Timer>. Otherwise, calling cancel_timer() could
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// inadvertently cancel another timer that has been created between
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// returning from the timer handler and a call to cancel_timer().
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timer->setup(clock_id, deadline, move(callback));
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SpinlockLocker lock(g_timerqueue_lock);
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timer->m_id = 0; // Don't generate a timer id
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add_timer_locked(move(timer));
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return true;
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}
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TimerId TimerQueue::add_timer(NonnullLockRefPtr<Timer>&& timer)
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{
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SpinlockLocker lock(g_timerqueue_lock);
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timer->m_id = ++m_timer_id_count;
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VERIFY(timer->m_id != 0); // wrapped
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auto id = timer->m_id;
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add_timer_locked(move(timer));
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return id;
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}
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void TimerQueue::add_timer_locked(NonnullLockRefPtr<Timer> timer)
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{
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Time timer_expiration = timer->m_expires;
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timer->clear_cancelled();
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timer->clear_callback_finished();
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timer->set_in_use();
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auto& queue = queue_for_timer(*timer);
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if (queue.list.is_empty()) {
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queue.list.append(timer.leak_ref());
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queue.next_timer_due = timer_expiration;
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} else {
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Timer* following_timer = nullptr;
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for (auto& t : queue.list) {
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if (t.m_expires > timer_expiration) {
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following_timer = &t;
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break;
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}
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}
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if (following_timer) {
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bool next_timer_needs_update = queue.list.first() == following_timer;
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queue.list.insert_before(*following_timer, timer.leak_ref());
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if (next_timer_needs_update)
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queue.next_timer_due = timer_expiration;
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} else {
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queue.list.append(timer.leak_ref());
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}
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}
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}
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bool TimerQueue::cancel_timer(Timer& timer, bool* was_in_use)
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{
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bool in_use = timer.is_in_use();
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if (was_in_use)
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*was_in_use = in_use;
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// If the timer isn't in use, the cancellation is a no-op.
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if (!in_use) {
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VERIFY(!timer.m_list_node.is_in_list());
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return false;
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}
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bool did_already_run = timer.set_cancelled();
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auto& timer_queue = queue_for_timer(timer);
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if (!did_already_run) {
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timer.clear_in_use();
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SpinlockLocker lock(g_timerqueue_lock);
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if (timer_queue.list.contains(timer)) {
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// The timer has not fired, remove it
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VERIFY(timer.ref_count() > 1);
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remove_timer_locked(timer_queue, timer);
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return true;
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}
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// The timer was queued to execute but hasn't had a chance
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// to run. In this case, it should still be in m_timers_executing
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// and we don't need to spin. It still holds a reference
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// that will be dropped when it does get a chance to run,
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// but since we called set_cancelled it will only drop its reference
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VERIFY(m_timers_executing.contains(timer));
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m_timers_executing.remove(timer);
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return true;
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}
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// At this point the deferred call is queued and is being executed
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// on another processor. We need to wait until it's complete!
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while (!timer.is_callback_finished())
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Processor::wait_check();
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return false;
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}
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void TimerQueue::remove_timer_locked(Queue& queue, Timer& timer)
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{
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bool was_next_timer = (queue.list.first() == &timer);
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queue.list.remove(timer);
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auto now = timer.now(false);
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if (timer.m_expires > now)
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timer.m_remaining = timer.m_expires - now;
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if (was_next_timer)
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update_next_timer_due(queue);
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// Whenever we remove a timer that was still queued (but hasn't been
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// fired) we added a reference to it. So, when removing it from the
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// queue we need to drop that reference.
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timer.unref();
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}
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void TimerQueue::fire()
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{
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SpinlockLocker lock(g_timerqueue_lock);
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auto fire_timers = [&](Queue& queue) {
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auto* timer = queue.list.first();
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VERIFY(timer);
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VERIFY(queue.next_timer_due == timer->m_expires);
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while (timer && timer->now(true) > timer->m_expires) {
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queue.list.remove(*timer);
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m_timers_executing.append(*timer);
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update_next_timer_due(queue);
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lock.unlock();
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// Defer executing the timer outside of the irq handler
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Processor::deferred_call_queue([this, timer]() {
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// Check if we were cancelled in between being triggered
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// by the timer irq handler and now. If so, just drop
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// our reference and don't execute the callback.
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if (!timer->set_cancelled()) {
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timer->m_callback();
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SpinlockLocker lock(g_timerqueue_lock);
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m_timers_executing.remove(*timer);
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}
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timer->clear_in_use();
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timer->set_callback_finished();
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// Drop the reference we added when queueing the timer
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timer->unref();
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});
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lock.lock();
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timer = queue.list.first();
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}
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};
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if (!m_timer_queue_monotonic.list.is_empty())
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fire_timers(m_timer_queue_monotonic);
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if (!m_timer_queue_realtime.list.is_empty())
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fire_timers(m_timer_queue_realtime);
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}
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void TimerQueue::update_next_timer_due(Queue& queue)
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{
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VERIFY(g_timerqueue_lock.is_locked());
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if (auto* next_timer = queue.list.first())
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queue.next_timer_due = next_timer->m_expires;
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else
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queue.next_timer_due = {};
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}
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}
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