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5d180d1f99
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED) Since all of these checks are done in release builds as well, let's rename them to VERIFY to prevent confusion, as everyone is used to assertions being compiled out in release. We can introduce a new ASSERT macro that is specifically for debug checks, but I'm doing this wholesale conversion first since we've accumulated thousands of these already, and it's not immediately obvious which ones are suitable for ASSERT.
86 lines
2.9 KiB
C++
86 lines
2.9 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/Types.h>
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#include <Kernel/KBuffer.h>
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#include <Kernel/Lock.h>
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#include <Kernel/Thread.h>
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#include <Kernel/UserOrKernelBuffer.h>
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namespace Kernel {
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class DoubleBuffer {
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public:
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explicit DoubleBuffer(size_t capacity = 65536);
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[[nodiscard]] ssize_t write(const UserOrKernelBuffer&, size_t);
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[[nodiscard]] ssize_t write(const u8* data, size_t size)
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{
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return write(UserOrKernelBuffer::for_kernel_buffer(const_cast<u8*>(data)), size);
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}
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[[nodiscard]] ssize_t read(UserOrKernelBuffer&, size_t);
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[[nodiscard]] ssize_t read(u8* data, size_t size)
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{
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auto buffer = UserOrKernelBuffer::for_kernel_buffer(data);
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return read(buffer, size);
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}
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bool is_empty() const { return m_empty; }
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size_t space_for_writing() const { return m_space_for_writing; }
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void set_unblock_callback(Function<void()> callback)
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{
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VERIFY(!m_unblock_callback);
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m_unblock_callback = move(callback);
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}
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private:
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void flip();
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void compute_lockfree_metadata();
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struct InnerBuffer {
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u8* data { nullptr };
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size_t size;
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};
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InnerBuffer* m_write_buffer { nullptr };
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InnerBuffer* m_read_buffer { nullptr };
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InnerBuffer m_buffer1;
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InnerBuffer m_buffer2;
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KBuffer m_storage;
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Function<void()> m_unblock_callback;
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size_t m_capacity { 0 };
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size_t m_read_buffer_index { 0 };
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size_t m_space_for_writing { 0 };
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bool m_empty { true };
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mutable Lock m_lock { "DoubleBuffer" };
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};
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}
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