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Add internal locking to DoubleBuffer.
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parent
e42f090ed3
commit
52c004eb53
Notes:
sideshowbarker
2024-07-19 16:02:01 +09:00
Author: https://github.com/awesomekling
Commit: 52c004eb53
2 changed files with 16 additions and 2 deletions
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@ -1,8 +1,12 @@
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#include "DoubleBuffer.h"
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#include "DoubleBuffer.h"
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inline void DoubleBuffer::compute_emptiness()
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{
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m_empty = m_read_buffer_index >= m_read_buffer->size() && m_write_buffer->is_empty();
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}
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void DoubleBuffer::flip()
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void DoubleBuffer::flip()
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{
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{
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InterruptDisabler disabler;
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ASSERT(m_read_buffer_index == m_read_buffer->size());
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ASSERT(m_read_buffer_index == m_read_buffer->size());
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swap(m_read_buffer, m_write_buffer);
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swap(m_read_buffer, m_write_buffer);
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if (m_write_buffer->capacity() < 32)
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if (m_write_buffer->capacity() < 32)
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@ -10,16 +14,20 @@ void DoubleBuffer::flip()
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else
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else
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m_write_buffer->clear();
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m_write_buffer->clear();
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m_read_buffer_index = 0;
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m_read_buffer_index = 0;
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compute_emptiness();
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}
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}
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ssize_t DoubleBuffer::write(const byte* data, size_t size)
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ssize_t DoubleBuffer::write(const byte* data, size_t size)
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{
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{
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LOCKER(m_lock);
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m_write_buffer->append(data, size);
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m_write_buffer->append(data, size);
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compute_emptiness();
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return size;
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return size;
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}
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}
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ssize_t DoubleBuffer::read(byte* data, size_t size)
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ssize_t DoubleBuffer::read(byte* data, size_t size)
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{
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{
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LOCKER(m_lock);
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if (m_read_buffer_index >= m_read_buffer->size() && !m_write_buffer->is_empty())
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if (m_read_buffer_index >= m_read_buffer->size() && !m_write_buffer->is_empty())
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flip();
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flip();
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if (m_read_buffer_index >= m_read_buffer->size())
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if (m_read_buffer_index >= m_read_buffer->size())
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@ -27,5 +35,6 @@ ssize_t DoubleBuffer::read(byte* data, size_t size)
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ssize_t nread = min(m_read_buffer->size() - m_read_buffer_index, size);
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ssize_t nread = min(m_read_buffer->size() - m_read_buffer_index, size);
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memcpy(data, m_read_buffer->data() + m_read_buffer_index, nread);
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memcpy(data, m_read_buffer->data() + m_read_buffer_index, nread);
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m_read_buffer_index += nread;
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m_read_buffer_index += nread;
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compute_emptiness();
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return nread;
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return nread;
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}
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}
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@ -2,6 +2,7 @@
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#include <AK/Types.h>
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#include <AK/Types.h>
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#include <AK/Vector.h>
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#include <AK/Vector.h>
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#include <AK/Lock.h>
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class DoubleBuffer {
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class DoubleBuffer {
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public:
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public:
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@ -14,16 +15,20 @@ public:
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ssize_t write(const byte*, size_t);
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ssize_t write(const byte*, size_t);
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ssize_t read(byte*, size_t);
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ssize_t read(byte*, size_t);
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bool is_empty() const { return m_read_buffer_index >= m_read_buffer->size() && m_write_buffer->is_empty(); }
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bool is_empty() const { return m_empty; }
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// FIXME: Isn't this racy? What if we get interrupted between getting the buffer pointer and dereferencing it?
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size_t bytes_in_write_buffer() const { return m_write_buffer->size(); }
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size_t bytes_in_write_buffer() const { return m_write_buffer->size(); }
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private:
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private:
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void flip();
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void flip();
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void compute_emptiness();
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Vector<byte>* m_write_buffer { nullptr };
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Vector<byte>* m_write_buffer { nullptr };
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Vector<byte>* m_read_buffer { nullptr };
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Vector<byte>* m_read_buffer { nullptr };
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Vector<byte> m_buffer1;
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Vector<byte> m_buffer1;
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Vector<byte> m_buffer2;
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Vector<byte> m_buffer2;
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size_t m_read_buffer_index { 0 };
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size_t m_read_buffer_index { 0 };
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bool m_empty { true };
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SpinLock m_lock;
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};
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};
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