base-sequence-scanner.h

Go to the documentation of this file.

// Copyright 2012 Cloudera Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


#ifndef IMPALA_EXEC_BASE_SEQUENCE_SCANNER_H
#define IMPALA_EXEC_BASE_SEQUENCE_SCANNER_H

#include <vector>
#include <memory>
#include <stdint.h>

#include "exec/hdfs-scanner.h"

namespace impala {

struct HdfsFileDesc;
class ScannerContext;

class BaseSequenceScanner : public HdfsScanner {
 public:
  static Status IssueInitialRanges(HdfsScanNode* scan_node,
                                   const std::vector<HdfsFileDesc*>& files);

  virtual Status Prepare(ScannerContext* context);
  virtual void Close();
  virtual Status ProcessSplit();

  virtual ~BaseSequenceScanner();

 protected:
  const static int SYNC_HASH_SIZE = 16;

  struct FileHeader {
    virtual ~FileHeader() {}

    uint8_t sync[SYNC_HASH_SIZE];

    bool is_compressed;

    std::string codec;

    THdfsCompression::type compression_type;

    int64_t header_size;
  };


  virtual FileHeader* AllocateFileHeader() = 0;

  virtual Status ReadFileHeader() = 0;

  virtual Status ProcessRange() = 0;

  virtual THdfsFileFormat::type file_format() const = 0;

  BaseSequenceScanner(HdfsScanNode*, RuntimeState*);

  Status ReadSync();

  Status SkipToSync(const uint8_t* sync, int sync_size);

  bool finished() { return finished_; }

  const static int HEADER_SIZE;

  const static int SYNC_MARKER;

  FileHeader* header_;

  bool only_parsing_header_;

 private:
  //
  //
  bool finished_;

  int64_t block_start_;

  int total_block_size_;

  int num_syncs_;

  int ReadPastSize(int64_t file_offset);

  int FindSyncBlock(const uint8_t* buffer, int buffer_len, const uint8_t* sync,
                    int sync_len);

  void CloseFileRanges(const char* file);

  RuntimeProfile::Counter* bytes_skipped_counter_;
};

}

#endif