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#pragma once
#include <Processors/Formats/IInputFormat.h>
#include <Processors/ISimpleTransform.h>
#include <IO/EmptyReadBuffer.h>
namespace DB
{
using SimpleTransformPtr = std::shared_ptr<ISimpleTransform>;
/// Receives format and allows to execute
/// it multiple times for streaming processing of data.
class StreamingFormatExecutor
{
public:
/// Callback is called, when exception is thrown in `execute` method.
/// It provides currently accumulated columns to make a rollback, for example,
/// and exception to rethrow it or add context to it.
/// Should return number of new rows, which are added in callback
/// to result columns in comparison to previous call of `execute`.
using ErrorCallback = std::function<size_t(const MutableColumns &, Exception &)>;
StreamingFormatExecutor(
const Block & header_,
InputFormatPtr format_,
ErrorCallback on_error_ = [](const MutableColumns &, Exception & e) -> size_t { throw std::move(e); },
SimpleTransformPtr adding_defaults_transform_ = nullptr);
/// Returns numbers of new read rows.
size_t execute();
/// Execute with provided read buffer.
size_t execute(ReadBuffer & buffer);
/// Releases currently accumulated columns.
MutableColumns getResultColumns();
private:
const Block header;
const InputFormatPtr format;
const ErrorCallback on_error;
const SimpleTransformPtr adding_defaults_transform;
InputPort port;
MutableColumns result_columns;
};
}
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