version_manager.h

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#ifndef GRAPHSCOPE_DATABASE_VERSION_MANAGER_H_
#define GRAPHSCOPE_DATABASE_VERSION_MANAGER_H_
 
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
 
#include <array>
#include <atomic>
#include <bitset>
#include <thread>
 
#include "glog/logging.h"
#include "grape/utils/bitset.h"
#include "grape/utils/concurrent_queue.h"
 
namespace gs {
 
class VersionManager {
 public:
  VersionManager();
  ~VersionManager();
 
  void init_ts(uint32_t ts, int thread_num);
 
  void clear();
 
  uint32_t acquire_read_timestamp();
 
  void release_read_timestamp();
 
  uint32_t acquire_insert_timestamp();
  void release_insert_timestamp(uint32_t ts);
 
  uint32_t acquire_update_timestamp();
  void release_update_timestamp(uint32_t ts);
  bool revert_update_timestamp(uint32_t ts);
 
 private:
  std::atomic<uint32_t> write_ts_{1};
  std::atomic<uint32_t> read_ts_{0};
 
  std::atomic<int> pending_reqs_{0};
  std::atomic<int> pending_update_reqs_{0};
 
  grape::Bitset buf_;
  grape::SpinLock lock_;
 
  int thread_num_;
};
 
}  // namespace gs
 
#endif  // GRAPHSCOPE_DATABASE_VERSION_MANAGER_H_