internal_boot_counter.h

#ifndef PRODUCTION_BORG_MGMT_NODE_PROXY_SAFEPOWER_SAFEPOWER_AGENT_INTERNAL_BOOT_COUNTER_H_
#define PRODUCTION_BORG_MGMT_NODE_PROXY_SAFEPOWER_SAFEPOWER_AGENT_INTERNAL_BOOT_COUNTER_H_

#include <optional>
#include <string>

#include "absl/base/thread_annotations.h"
#include "absl/status/status.h"
#include "absl/synchronization/mutex.h"

namespace safepower_agent {

class InternalBootCounter {
 public:
  explicit InternalBootCounter(
      std::string boot_id_path = "/proc/sys/kernel/random/boot_id");

  // Reads the boot ID from the configured path.
  // Checks if it matches the persisted boot ID.
  // If not, increments the persisted boot counter and updates the persisted
  // boot ID. Updates the cached boot counter.
  absl::Status CheckAndIncrement() ABSL_LOCKS_EXCLUDED(mutex_);

  // Returns the cached boot counter if available.
  std::optional<int> value() const ABSL_LOCKS_EXCLUDED(mutex_);

 private:
  const std::string boot_id_path_;
  mutable absl::Mutex mutex_;
  std::optional<int> boot_counter_ ABSL_GUARDED_BY(mutex_);
};

}  // namespace safepower_agent

#endif  // PRODUCTION_BORG_MGMT_NODE_PROXY_SAFEPOWER_SAFEPOWER_AGENT_INTERNAL_BOOT_COUNTER_H_