lock.hh

#ifndef __VEREIGN_KVSTORE_LOCK_HH
#define __VEREIGN_KVSTORE_LOCK_HH

#include <vereign/kvstore/storage.hh>
#include <chrono>

namespace vereign::kvstore {

/**
 * Lock guard used for lock/unlock Storage within a scope.
 *
 * When the Lock is constructed it locks the Storage, and when it is destroyed it unlock it.
 */
class Lock {
public:
  /**
   * Creates a Lock and locks the Storage.
   *
   * @param storage The storage to lock.
   * @throws LockError when the lock is held by another process.
   */
  explicit Lock(Storage& storage);

  /**
   * Creates a Lock and locks the Storage.
   *
   * If the lock is not possible it retries `retry_count` and sleeps between retries `sleep_interval`.
   *
   * @param storage The storage to lock.
   * @param retry_count How many times to retry if the lock is held by another process.
   * @param sleep_interval How many time to sleep between retries.
   *
   * @throws LockError If the lock could not be held after `retry_count` retries.
   */
  Lock(Storage& storage, int retry_count, std::chrono::milliseconds sleep_interval);

  /**
   * Unlocks the storage.
   */
  ~Lock() noexcept;

  // copying is disabled.
  Lock(const Lock&) = delete;
  auto operator=(const Lock&) -> Lock&  = delete;

private:
  Storage& storage_;
};


} // namespace vereign::kvstore

#endif // __VEREIGN_KVSTORE_LOCK_HH