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/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Atomic.h>
#include <AK/RefCounted.h>
#include <Kernel/SpinLock.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/VMObject.h>
namespace Kernel {
class FutexQueue : public Thread::BlockCondition
, public RefCounted<FutexQueue>
, public VMObjectDeletedHandler {
public:
FutexQueue(FlatPtr user_address_or_offset, VMObject* vmobject = nullptr);
virtual ~FutexQueue();
u32 wake_n_requeue(u32, const Function<FutexQueue*()>&, u32, bool&, bool&);
u32 wake_n(u32, const Optional<u32>&, bool&);
u32 wake_all(bool&);
template<class... Args>
Thread::BlockResult wait_on(const Thread::BlockTimeout& timeout, Args&&... args)
{
return Thread::current()->block<Thread::FutexBlocker>(timeout, *this, forward<Args>(args)...);
}
virtual void vmobject_deleted(VMObject&) override;
bool queue_imminent_wait();
void did_remove();
bool try_remove();
bool is_empty_and_no_imminent_waits()
{
ScopedSpinLock lock(m_lock);
return is_empty_and_no_imminent_waits_locked();
}
bool is_empty_and_no_imminent_waits_locked();
protected:
virtual bool should_add_blocker(Thread::Blocker& b, void* data) override;
private:
// For private futexes we just use the user space address.
// But for global futexes we use the offset into the VMObject
const FlatPtr m_user_address_or_offset;
WeakPtr<VMObject> m_vmobject;
const bool m_is_global;
size_t m_imminent_waits { 1 }; // We only create this object if we're going to be waiting, so start out with 1
bool m_was_removed { false };
};
}
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