grpc/src/core/lib/support/backoff.h

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#ifndef GRPC_CORE_LIB_SUPPORT_BACKOFF_H
#define GRPC_CORE_LIB_SUPPORT_BACKOFF_H

#include <grpc/support/time.h>

typedef struct {
  /// const: multiplier between retry attempts
  double multiplier;
  /// const: amount to randomize backoffs
  double jitter;
  /// const: minimum time between retries in milliseconds
  int64_t min_timeout_millis;
  /// const: maximum time between retries in milliseconds
  int64_t max_timeout_millis;

  /// random number generator
  uint32_t rng_state;

  /// current retry timeout in milliseconds
  int64_t current_timeout_millis;
} gpr_backoff;

/// Initialize backoff machinery - does not need to be destroyed
void gpr_backoff_init(gpr_backoff *backoff, double multiplier, double jitter,
                      int64_t min_timeout_millis, int64_t max_timeout_millis);

/// Begin retry loop: returns a timespec for the NEXT retry
gpr_timespec gpr_backoff_begin(gpr_backoff *backoff, gpr_timespec now);
/// Step a retry loop: returns a timespec for the NEXT retry
gpr_timespec gpr_backoff_step(gpr_backoff *backoff, gpr_timespec now);
/// Reset the backoff, so the next gpr_backoff_step will be a gpr_backoff_begin
/// instead
void gpr_backoff_reset(gpr_backoff *backoff);

#endif /* GRPC_CORE_LIB_SUPPORT_BACKOFF_H */