FileInfo.h

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/*
 * Copyright 2017 MapD Technologies, 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 FILEINFO_H
#define FILEINFO_H

#include <fcntl.h>
#include <unistd.h>
#include <cstdio>
#include <cstring>
#include <mutex>
#include <set>
#include <vector>
#include "../../Shared/types.h"
#include "Page.h"
#include "Shared/Logger.h"

namespace File_Namespace {

struct Page;

#define DELETE_CONTINGENT (-1)

class FileMgr;
struct FileInfo {
  FileMgr* fileMgr;
  int fileId;       
  FILE* f;          
  size_t pageSize;  
  size_t numPages;  
  // std::vector<Page*> pages;          /// Page pointers for each page (including
  // free pages)
  std::set<size_t> freePages;  
  std::mutex freePagesMutex_;
  std::mutex readWriteMutex_;

  FileInfo(FileMgr* fileMgr,
           const int fileId,
           FILE* f,
           const size_t pageSize,
           const size_t numPages,
           const bool init = false);

  ~FileInfo();

  // for each apge
  void initNewFile();

  void freePageDeferred(int pageId);
  void freePage(int pageId);
  int getFreePage();
  size_t write(const size_t offset, const size_t size, int8_t* buf);
  size_t read(const size_t offset, const size_t size, int8_t* buf);

  void openExistingFile(std::vector<HeaderInfo>& headerVec, const int fileMgrEpoch);
  void print(bool pagesummary);

  inline size_t size() { return pageSize * numPages; }

  inline int syncToDisk() {
    if (fflush(f) != 0) {
      LOG(FATAL) << "Error trying to flush changes to disk, the error was: "
                 << std::strerror(errno);
    }
#ifdef __APPLE__
    return fcntl(fileno(f), 51);
#else
    return fsync(fileno(f));
#endif
  }

  inline size_t available() { return freePages.size() * pageSize; }

  inline size_t numFreePages() {
    std::lock_guard<std::mutex> lock(freePagesMutex_);
    return freePages.size();
  }

  inline size_t used() { return size() - available(); }
};
}  // namespace File_Namespace

#endif  // kkkkk