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#include "halting_stream.h"
#include <yt/yt/core/actions/bind.h>
#include <yt/yt/core/concurrency/async_stream.h>
namespace NYT::NDetail {
using namespace NConcurrency;
////////////////////////////////////////////////////////////////////////////////
class THaltingAsyncStream
: public IAsyncInputStream
{
public:
THaltingAsyncStream(
IAsyncInputStreamPtr underlying,
i64 bytesBeforeHalt)
: Underlying_(std::move(underlying))
, BytesBeforeHalt_(bytesBeforeHalt)
{ }
private:
void OnRead(TPromise<size_t> promise, const TErrorOr<size_t>& result)
{
if (result.IsOK()) {
BytesRead_ += result.Value();
}
promise.TrySet(result);
}
TFuture<size_t> Read(const TSharedMutableRef& buffer) override
{
if (BytesRead_ >= BytesBeforeHalt_) {
HaltPromise_ = NewPromise<size_t>();
return HaltPromise_.ToFuture();
}
auto limit = std::min(buffer.Size(), static_cast<size_t>(BytesBeforeHalt_ - BytesRead_));
auto promise = NewPromise<size_t>();
auto future = promise.ToFuture();
Underlying_->Read(buffer.Slice(0, limit)).Subscribe(
BIND(&THaltingAsyncStream::OnRead, MakeStrong(this), std::move(promise)));
return future;
}
private:
IAsyncInputStreamPtr Underlying_;
const i64 BytesBeforeHalt_;
i64 BytesRead_ = 0;
TPromise<size_t> HaltPromise_;
};
////////////////////////////////////////////////////////////////////////////////
IAsyncInputStreamPtr CreateHaltingAsyncStream(
IAsyncInputStreamPtr underlying,
i64 bytesBeforeHalt)
{
return New<THaltingAsyncStream>(std::move(underlying), bytesBeforeHalt);
}
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT::NDetail
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