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https://github.com/SerenityOS/serenity
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![Ben Wiederhake](/assets/img/avatar_default.png)
This may seem like a no-op change, however it shrinks down the Kernel by a bit: .text -432 .unmap_after_init -60 .data -480 .debug_info -673 .debug_aranges 8 .debug_ranges -232 .debug_line -558 .debug_str -308 .debug_frame -40 With '= default', the compiler can do more inlining, hence the savings. I intentionally omitted some opportunities for '= default', because they would increase the Kernel size.
167 lines
4.8 KiB
C++
167 lines
4.8 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/Assertions.h>
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#include <AK/Atomic.h>
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#include <AK/HashMap.h>
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#include <AK/Types.h>
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#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/Forward.h>
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#include <Kernel/LockMode.h>
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#include <Kernel/WaitQueue.h>
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namespace Kernel {
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class Lock {
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AK_MAKE_NONCOPYABLE(Lock);
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AK_MAKE_NONMOVABLE(Lock);
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public:
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using Mode = LockMode;
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Lock(const char* name = nullptr)
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: m_name(name)
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{
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}
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~Lock() = default;
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void lock(Mode = Mode::Exclusive);
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#if LOCK_DEBUG
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void lock(const char* file, int line, Mode mode = Mode::Exclusive);
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void restore_lock(const char* file, int line, Mode, u32);
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#endif
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void unlock();
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[[nodiscard]] Mode force_unlock_if_locked(u32&);
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void restore_lock(Mode, u32);
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[[nodiscard]] bool is_locked() const { return m_mode != Mode::Unlocked; }
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void clear_waiters();
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[[nodiscard]] const char* name() const { return m_name; }
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static const char* mode_to_string(Mode mode)
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{
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switch (mode) {
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case Mode::Unlocked:
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return "unlocked";
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case Mode::Exclusive:
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return "exclusive";
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case Mode::Shared:
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return "shared";
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default:
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return "invalid";
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}
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}
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private:
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Atomic<bool> m_lock { false };
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const char* m_name { nullptr };
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WaitQueue m_queue;
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Atomic<Mode, AK::MemoryOrder::memory_order_relaxed> m_mode { Mode::Unlocked };
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// When locked exclusively, only the thread already holding the lock can
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// lock it again. When locked in shared mode, any thread can do that.
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u32 m_times_locked { 0 };
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// One of the threads that hold this lock, or nullptr. When locked in shared
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// mode, this is stored on best effort basis: nullptr value does *not* mean
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// the lock is unlocked, it just means we don't know which threads hold it.
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// When locked exclusively, this is always the one thread that holds the
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// lock.
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RefPtr<Thread> m_holder;
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HashMap<Thread*, u32> m_shared_holders;
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};
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class Locker {
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public:
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#if LOCK_DEBUG
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ALWAYS_INLINE explicit Locker(const char* file, int line, Lock& l, Lock::Mode mode = Lock::Mode::Exclusive)
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: m_lock(l)
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{
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m_lock.lock(file, line, mode);
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}
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#endif
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ALWAYS_INLINE explicit Locker(Lock& l, Lock::Mode mode = Lock::Mode::Exclusive)
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: m_lock(l)
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{
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m_lock.lock(mode);
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}
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ALWAYS_INLINE ~Locker()
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{
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if (m_locked)
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unlock();
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}
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ALWAYS_INLINE void unlock()
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{
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VERIFY(m_locked);
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m_locked = false;
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m_lock.unlock();
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}
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ALWAYS_INLINE void lock(Lock::Mode mode = Lock::Mode::Exclusive)
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{
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VERIFY(!m_locked);
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m_locked = true;
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m_lock.lock(mode);
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}
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private:
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Lock& m_lock;
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bool m_locked { true };
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};
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#if LOCK_DEBUG
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# define LOCKER(...) Locker locker(__FILE__, __LINE__, __VA_ARGS__)
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# define RESTORE_LOCK(lock, ...) (lock).restore_lock(__FILE__, __LINE__, __VA_ARGS__)
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#else
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# define LOCKER(...) Locker locker(__VA_ARGS__)
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# define RESTORE_LOCK(lock, ...) (lock).restore_lock(__VA_ARGS__)
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#endif
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template<typename T>
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class Lockable {
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public:
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Lockable() = default;
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Lockable(T&& resource)
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: m_resource(move(resource))
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{
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}
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[[nodiscard]] Lock& lock() { return m_lock; }
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[[nodiscard]] T& resource() { return m_resource; }
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[[nodiscard]] T lock_and_copy()
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{
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LOCKER(m_lock);
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return m_resource;
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}
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private:
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T m_resource;
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Lock m_lock;
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};
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}
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