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LimitReadBuffer fix [#CLICKHOUSE-2].

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Evgeniy Gatov 2017-08-14 06:38:32 +03:00 committed by alexey-milovidov
parent eca1b39dee
commit 2e6eb504dc
1 changed files with 43 additions and 17 deletions
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40
dbms/src/IO/LimitReadBuffer.h
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@ -8,26 +8,52 @@ namespace DB
/** Lets read from another ReadBuffer no more than the specified number of bytes.
*/
class LimitReadBuffer : public ReadBuffer
{
private:
class LimitReadBuffer : public ReadBuffer
{
private:
ReadBuffer & in;
size_t limit;
bool nextImpl() override
{
if (count() >= limit || !in.next())
/// Let underlying buffer calculate read bytes in `next()` call.
in.position() = position();
if (bytes >= limit || !in.next())
{
return false;
}
position() = in.position();
working_buffer = in.buffer();
if (limit - count() < working_buffer.size())
{
working_buffer.resize(limit - count());
}
return true;
}
public:
LimitReadBuffer(ReadBuffer & in_, size_t limit_) : ReadBuffer(nullptr, 0), in(in_), limit(limit_) {}
};
public:
LimitReadBuffer(ReadBuffer & in_, size_t limit_) : ReadBuffer(in_.position(), 0), in(in_), limit(limit_)
{
working_buffer = in.buffer();
size_t bytes_in_buffer = working_buffer.end() - position();
working_buffer = Buffer(position(), working_buffer.end());
if (limit < bytes_in_buffer)
working_buffer.resize(limit);
}
virtual ~LimitReadBuffer() override
{
/// Update underlying buffer's position in case when limit wasn't reached.
if (working_buffer.size() != 0)
in.position() = position();
}
};
}