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#pragma once
#include <memory>
#include <atomic>
namespace DB
{
class Block;
class Chunk;
class QueryPipeline;
class PipelineExecutor;
class PullingOutputFormat;
struct ProfileInfo;
using PipelineExecutorPtr = std::shared_ptr<PipelineExecutor>;
/// Pulling executor for QueryPipeline. Always execute pipeline in single thread.
/// Typical usage is:
///
/// PullingPipelineExecutor executor(query_pipeline);
/// while (executor.pull(chunk))
/// ... process chunk ...
class PullingPipelineExecutor
{
public:
explicit PullingPipelineExecutor(QueryPipeline & pipeline_);
~PullingPipelineExecutor();
/// Get structure of returned block or chunk.
const Block & getHeader() const;
/// Methods return false if query is finished.
/// You can use any pull method.
bool pull(Chunk & chunk);
bool pull(Block & block);
/// Stop execution. It is not necessary, but helps to stop execution before executor is destroyed.
void cancel();
/// Get totals and extremes. Returns empty chunk if doesn't have any.
Chunk getTotals();
Chunk getExtremes();
/// Get totals and extremes. Returns empty chunk if doesn't have any.
Block getTotalsBlock();
Block getExtremesBlock();
/// Get query profile info.
ProfileInfo & getProfileInfo();
private:
std::atomic_bool has_data_flag = false;
QueryPipeline & pipeline;
std::shared_ptr<PullingOutputFormat> pulling_format;
PipelineExecutorPtr executor;
};
}
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