src/core/lib/transport/bdp_estimator.c

/*
 *
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 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#include "src/core/lib/transport/bdp_estimator.h"

#include <stdlib.h>

#include <grpc/support/log.h>
#include <grpc/support/useful.h>

void grpc_bdp_estimator_init(grpc_bdp_estimator *estimator) {
  estimator->num_samples = 0;
  estimator->first_sample_idx = 0;
  estimator->ping_state = GRPC_BDP_PING_UNSCHEDULED;
}

bool grpc_bdp_estimator_get_estimate(grpc_bdp_estimator *estimator,
                                     int64_t *estimate) {
  if (estimator->num_samples < GRPC_BDP_MIN_SAMPLES_FOR_ESTIMATE) {
    return false;
  }

  *estimate = -1;
  for (uint8_t i = 0; i < estimator->num_samples; i++) {
    *estimate = GPR_MAX(
        *estimate,
        estimator
            ->samples[(estimator->first_sample_idx + i) % GRPC_BDP_SAMPLES]);
  }
  return true;
}

static int64_t *sampling(grpc_bdp_estimator *estimator) {
  return &estimator
              ->samples[(estimator->first_sample_idx + estimator->num_samples) %
                        GRPC_BDP_SAMPLES];
}

bool grpc_bdp_estimator_add_incoming_bytes(grpc_bdp_estimator *estimator,
                                           int64_t num_bytes) {
  switch (estimator->ping_state) {
    case GRPC_BDP_PING_UNSCHEDULED:
      return true;
    case GRPC_BDP_PING_SCHEDULED:
      return false;
    case GRPC_BDP_PING_STARTED:
      *sampling(estimator) += num_bytes;
      return false;
  }
  GPR_UNREACHABLE_CODE(return false);
}

void grpc_bdp_estimator_schedule_ping(grpc_bdp_estimator *estimator) {
  GPR_ASSERT(estimator->ping_state == GRPC_BDP_PING_UNSCHEDULED);
  estimator->ping_state = GRPC_BDP_PING_SCHEDULED;
}

void grpc_bdp_estimator_start_ping(grpc_bdp_estimator *estimator) {
  GPR_ASSERT(estimator->ping_state == GRPC_BDP_PING_SCHEDULED);
  estimator->ping_state = GRPC_BDP_PING_STARTED;
  if (estimator->num_samples == GRPC_BDP_SAMPLES) {
    estimator->first_sample_idx++;
    estimator->num_samples--;
  }
  *sampling(estimator) = 0;
}

void grpc_bdp_estimator_complete_ping(grpc_bdp_estimator *estimator) {
  GPR_ASSERT(estimator->ping_state == GRPC_BDP_PING_STARTED);
  estimator->num_samples++;
  estimator->ping_state = GRPC_BDP_PING_UNSCHEDULED;
}