tlbmc/hft/core/manager.h

#ifndef THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HFT_CORE_MANAGER_H_
#define THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HFT_CORE_MANAGER_H_

#include <bit>
#include <cstdint>
#include <memory>

#include "absl/functional/any_invocable.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "payload.pb.h"
#include "subscription_params.pb.h"

namespace milotic_hft {

// The largest sensor sampling interval (ms) accepted; the largest power-of-two
// int32 (~12 days).
inline constexpr int32_t kMaxSensorSamplingIntervalMs = 1 << 30;

// Whether `sampling_interval_ms` is a valid sensor sampling interval: a power
// of two in [1, kMaxSensorSamplingIntervalMs]. Sensor subscriptions must
// request a power-of-two interval (AddSubscription rejects others) so that the
// lowest requested period divides every other, resampling reduces to
// power-of-two decimation, and a coarser subscriber's samples are a strict
// subset of a finer one's.
inline bool IsValidSensorSamplingIntervalMs(int32_t sampling_interval_ms) {
  return sampling_interval_ms >= 1 &&
         sampling_interval_ms <= kMaxSensorSamplingIntervalMs &&
         std::has_single_bit(static_cast<uint32_t>(sampling_interval_ms));
}

class SubscriptionManager {
 public:
  // Opaque subscription handle. The subscription is kept alive as long as
  // any strong reference to this handle exists; callers unwind the
  // subscription by calling Unsubscribe or by dropping the last reference.
  class Subscription {
   public:
    virtual ~Subscription() = default;
  };

  virtual ~SubscriptionManager() = default;

  // Adds a new subscription to the manager. The returned handle is the
  // subscription's lifetime anchor: the subscription persists until
  // Unsubscribe is called on it (or the handle is destroyed).
  // `on_data_callback` will be called when new data is available to be
  // exported to the subscriber.
  virtual absl::StatusOr<std::shared_ptr<Subscription>> AddSubscription(
      const SubscriptionParams& params,
      absl::AnyInvocable<void(Payload&&)> on_data_callback) = 0;
  virtual absl::Status Unsubscribe(
      const std::shared_ptr<Subscription>& subscription) = 0;
};

}  // namespace milotic_hft

#endif  // THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HFT_CORE_MANAGER_H_