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3f3f45580a
Each of these strings would previously rely on StringView's char const* constructor overload, which would call __builtin_strlen on the string. Since we now have operator ""sv, we can replace these with much simpler versions. This opens the door to being able to remove StringView(char const*). No functional changes.
78 lines
2.2 KiB
C++
78 lines
2.2 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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#pragma once
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#include <AK/Types.h>
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#include <Kernel/KBuffer.h>
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#include <Kernel/Locking/Mutex.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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static ErrorOr<NonnullOwnPtr<DoubleBuffer>> try_create(StringView name, size_t capacity = 65536);
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ErrorOr<size_t> write(UserOrKernelBuffer const&, size_t);
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ErrorOr<size_t> write(u8 const* 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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ErrorOr<size_t> read(UserOrKernelBuffer&, size_t);
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ErrorOr<size_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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ErrorOr<size_t> peek(UserOrKernelBuffer&, size_t);
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ErrorOr<size_t> peek(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 peek(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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size_t immediately_readable() const
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{
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return (m_read_buffer->size - m_read_buffer_index) + m_write_buffer->size;
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}
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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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explicit DoubleBuffer(size_t capacity, NonnullOwnPtr<KBuffer> storage);
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void flip();
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void compute_lockfree_metadata();
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ErrorOr<size_t> read_impl(UserOrKernelBuffer&, size_t, MutexLocker&, bool advance_buffer_index);
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struct InnerBuffer {
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u8* data { nullptr };
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size_t size { 0 };
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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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NonnullOwnPtr<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 Mutex m_lock { "DoubleBuffer"sv };
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};
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}
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