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/*
* Copyright (c) 2020, The SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/Thread.h>
#include <Kernel/WaitQueue.h>
//#define WAITQUEUE_DEBUG
namespace Kernel {
bool WaitQueue::should_add_blocker(Thread::Blocker& b, void* data)
{
ASSERT(data != nullptr); // Thread that is requesting to be blocked
ASSERT(m_lock.is_locked());
ASSERT(b.blocker_type() == Thread::Blocker::Type::Queue);
if (m_wake_requested) {
m_wake_requested = false;
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": do not block thread " << *static_cast<Thread*>(data) << ", wake was pending";
#endif
return false;
}
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": should block thread " << *static_cast<Thread*>(data);
#endif
return true;
}
void WaitQueue::wake_one()
{
ScopedSpinLock lock(m_lock);
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": wake_one";
#endif
bool did_unblock_one = do_unblock([&](Thread::Blocker& b, void* data, bool& stop_iterating) {
ASSERT(data);
ASSERT(b.blocker_type() == Thread::Blocker::Type::Queue);
auto& blocker = static_cast<Thread::QueueBlocker&>(b);
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": wake_one unblocking " << *static_cast<Thread*>(data);
#endif
if (blocker.unblock()) {
stop_iterating = true;
return true;
}
return false;
});
m_wake_requested = !did_unblock_one;
}
void WaitQueue::wake_n(u32 wake_count)
{
if (wake_count == 0)
return; // should we assert instaed?
ScopedSpinLock lock(m_lock);
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": wake_n(" << wake_count << ")";
#endif
bool did_unblock_some = do_unblock([&](Thread::Blocker& b, void* data, bool& stop_iterating) {
ASSERT(data);
ASSERT(b.blocker_type() == Thread::Blocker::Type::Queue);
auto& blocker = static_cast<Thread::QueueBlocker&>(b);
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": wake_n unblocking " << *static_cast<Thread*>(data);
#endif
ASSERT(wake_count > 0);
if (blocker.unblock()) {
if (--wake_count == 0)
stop_iterating = true;
return true;
}
return false;
});
m_wake_requested = !did_unblock_some;
}
void WaitQueue::wake_all()
{
ScopedSpinLock lock(m_lock);
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": wake_all";
#endif
bool did_unblock_any = do_unblock([&](Thread::Blocker& b, void* data, bool&) {
ASSERT(data);
ASSERT(b.blocker_type() == Thread::Blocker::Type::Queue);
auto& blocker = static_cast<Thread::QueueBlocker&>(b);
#ifdef WAITQUEUE_DEBUG
dbg() << "WaitQueue @ " << this << ": wake_all unblocking " << *static_cast<Thread*>(data);
#endif
bool did_unblock = blocker.unblock();
ASSERT(did_unblock);
return true;
});
m_wake_requested = !did_unblock_any;
}
}
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