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/*
*
* Copyright 2016 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include <grpc/support/port_platform.h>
#include "src/core/lib/transport/bdp_estimator.h"
#include <inttypes.h>
#include <stdlib.h>
#include "src/core/lib/gpr/useful.h"
grpc_core::TraceFlag grpc_bdp_estimator_trace(false, "bdp_estimator");
namespace grpc_core {
BdpEstimator::BdpEstimator(const char* name)
: ping_state_(PingState::UNSCHEDULED),
accumulator_(0),
estimate_(65536),
ping_start_time_(gpr_time_0(GPR_CLOCK_MONOTONIC)),
inter_ping_delay_(100.0), // start at 100ms
stable_estimate_count_(0),
bw_est_(0),
name_(name) {}
grpc_millis BdpEstimator::CompletePing() {
gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
gpr_timespec dt_ts = gpr_time_sub(now, ping_start_time_);
double dt = static_cast<double>(dt_ts.tv_sec) +
1e-9 * static_cast<double>(dt_ts.tv_nsec);
double bw = dt > 0 ? (static_cast<double>(accumulator_) / dt) : 0;
int start_inter_ping_delay = inter_ping_delay_;
if (grpc_bdp_estimator_trace.enabled()) {
gpr_log(GPR_INFO,
"bdp[%s]:complete acc=%" PRId64 " est=%" PRId64
" dt=%lf bw=%lfMbs bw_est=%lfMbs",
name_, accumulator_, estimate_, dt, bw / 125000.0,
bw_est_ / 125000.0);
}
GPR_ASSERT(ping_state_ == PingState::STARTED);
if (accumulator_ > 2 * estimate_ / 3 && bw > bw_est_) {
estimate_ = GPR_MAX(accumulator_, estimate_ * 2);
bw_est_ = bw;
if (grpc_bdp_estimator_trace.enabled()) {
gpr_log(GPR_INFO, "bdp[%s]: estimate increased to %" PRId64, name_,
estimate_);
}
inter_ping_delay_ /= 2; // if the ping estimate changes,
// exponentially get faster at probing
} else if (inter_ping_delay_ < 10000) {
stable_estimate_count_++;
if (stable_estimate_count_ >= 2) {
inter_ping_delay_ +=
100 + static_cast<int>(rand() * 100.0 /
RAND_MAX); // if the ping estimate is steady,
// slowly ramp down the probe time
}
}
if (start_inter_ping_delay != inter_ping_delay_) {
stable_estimate_count_ = 0;
if (grpc_bdp_estimator_trace.enabled()) {
gpr_log(GPR_INFO, "bdp[%s]:update_inter_time to %dms", name_,
inter_ping_delay_);
}
}
ping_state_ = PingState::UNSCHEDULED;
accumulator_ = 0;
return grpc_core::ExecCtx::Get()->Now() + inter_ping_delay_;
}
} // namespace grpc_core
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