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AK: Remove history from DuplexMemoryStream.

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That feature was really only useful for Compress::DeflateDecompressor
but that is now using CircularDuplexBuffer instead.
This commit is contained in:
asynts 2020-09-01 11:30:41 +02:00 • committed by Andreas Kling
parent 9ce4475907
commit f9516a99bf
2 changed files with 5 additions and 70 deletions
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33
AK/Stream.h
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@ -326,13 +326,9 @@ private:
// All data written to this stream can be read from it. Reading and writing is done
// using different offsets, meaning that it is not necessary to seek to the start
// before reading; this behaviour differs from BufferStream.
//
// The stream keeps a history of 64KiB which means that seeking backwards is well
// defined. Data past that point will be discarded.
class DuplexMemoryStream final : public DuplexStream {
public:
static constexpr size_t chunk_size = 4 * 1024;
static constexpr size_t history_size = 64 * 1024;
bool eof() const override { return m_write_offset == m_read_offset; }
@ -411,22 +407,6 @@ public:
return nread;
}
size_t read(Bytes bytes, size_t offset)
{
const auto backup = this->roffset();
bool do_discard_chunks = false;
exchange(m_do_discard_chunks, do_discard_chunks);
rseek(offset);
const auto count = read(bytes);
rseek(backup);
exchange(m_do_discard_chunks, do_discard_chunks);
return count;
}
bool read_or_error(Bytes bytes) override
{
if (m_write_offset - m_read_offset < bytes.size()) {
@ -461,22 +441,12 @@ public:
size_t roffset() const { return m_read_offset; }
size_t woffset() const { return m_write_offset; }
void rseek(size_t offset)
{
ASSERT(offset >= m_base_offset);
ASSERT(offset <= m_write_offset);
m_read_offset = offset;
}
size_t remaining() const { return m_write_offset - m_read_offset; }
private:
void try_discard_chunks()
{
if (!m_do_discard_chunks)
return;
while (m_read_offset - m_base_offset >= history_size + chunk_size) {
while (m_read_offset - m_base_offset >= chunk_size) {
m_chunks.take_first();
m_base_offset += chunk_size;
}
@ -486,7 +456,6 @@ private:
size_t m_write_offset { 0 };
size_t m_read_offset { 0 };
size_t m_base_offset { 0 };
bool m_do_discard_chunks { false };
};
}