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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 "src/core/lib/backoff/backoff.h"
#include <algorithm>
#include <grpc/support/log.h>
#include <gtest/gtest.h>
#include "test/core/util/test_config.h"
namespace grpc {
namespace testing {
namespace {
using grpc_core::BackOff;
TEST(BackOffTest, ConstantBackOff) {
const grpc_millis initial_backoff = 200;
const double multiplier = 1.0;
const double jitter = 0.0;
const grpc_millis max_backoff = 1000;
grpc_core::ExecCtx exec_ctx;
BackOff::Options options;
options.set_initial_backoff(initial_backoff)
.set_multiplier(multiplier)
.set_jitter(jitter)
.set_max_backoff(max_backoff);
BackOff backoff(options);
grpc_millis next_attempt_start_time = backoff.NextAttemptTime();
EXPECT_EQ(next_attempt_start_time - grpc_core::ExecCtx::Get()->Now(),
initial_backoff);
for (int i = 0; i < 10000; i++) {
next_attempt_start_time = backoff.NextAttemptTime();
EXPECT_EQ(next_attempt_start_time - grpc_core::ExecCtx::Get()->Now(),
initial_backoff);
}
}
TEST(BackOffTest, MinConnect) {
const grpc_millis initial_backoff = 100;
const double multiplier = 1.0;
const double jitter = 0.0;
const grpc_millis max_backoff = 1000;
grpc_core::ExecCtx exec_ctx;
BackOff::Options options;
options.set_initial_backoff(initial_backoff)
.set_multiplier(multiplier)
.set_jitter(jitter)
.set_max_backoff(max_backoff);
BackOff backoff(options);
grpc_millis next = backoff.NextAttemptTime();
EXPECT_EQ(next - grpc_core::ExecCtx::Get()->Now(), initial_backoff);
}
TEST(BackOffTest, NoJitterBackOff) {
const grpc_millis initial_backoff = 2;
const double multiplier = 2.0;
const double jitter = 0.0;
const grpc_millis max_backoff = 513;
BackOff::Options options;
options.set_initial_backoff(initial_backoff)
.set_multiplier(multiplier)
.set_jitter(jitter)
.set_max_backoff(max_backoff);
BackOff backoff(options);
// x_1 = 2
// x_n = 2**i + x_{i-1} ( = 2**(n+1) - 2 )
grpc_core::ExecCtx exec_ctx;
grpc_core::ExecCtx::Get()->TestOnlySetNow(0);
grpc_millis next = backoff.NextAttemptTime();
EXPECT_EQ(next, 2);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 6);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 14);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 30);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 62);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 126);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 254);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 510);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 1022);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
// Hit the maximum timeout. From this point onwards, retries will increase
// only by max timeout.
EXPECT_EQ(next, 1535);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 2048);
grpc_core::ExecCtx::Get()->TestOnlySetNow(next);
next = backoff.NextAttemptTime();
EXPECT_EQ(next, 2561);
}
TEST(BackOffTest, JitterBackOff) {
const grpc_millis initial_backoff = 500;
grpc_millis current_backoff = initial_backoff;
const grpc_millis max_backoff = 1000;
const double multiplier = 1.0;
const double jitter = 0.1;
BackOff::Options options;
options.set_initial_backoff(initial_backoff)
.set_multiplier(multiplier)
.set_jitter(jitter)
.set_max_backoff(max_backoff);
BackOff backoff(options);
backoff.SetRandomSeed(0); // force consistent PRNG
grpc_core::ExecCtx exec_ctx;
grpc_millis next = backoff.NextAttemptTime();
EXPECT_EQ(next - grpc_core::ExecCtx::Get()->Now(), initial_backoff);
grpc_millis expected_next_lower_bound = static_cast<grpc_millis>(
static_cast<double>(current_backoff) * (1 - jitter));
grpc_millis expected_next_upper_bound = static_cast<grpc_millis>(
static_cast<double>(current_backoff) * (1 + jitter));
for (int i = 0; i < 10000; i++) {
next = backoff.NextAttemptTime();
// next-now must be within (jitter*100)% of the current backoff (which
// increases by * multiplier up to max_backoff).
const grpc_millis timeout_millis = next - grpc_core::ExecCtx::Get()->Now();
EXPECT_GE(timeout_millis, expected_next_lower_bound);
EXPECT_LE(timeout_millis, expected_next_upper_bound);
current_backoff =
std::min(static_cast<grpc_millis>(static_cast<double>(current_backoff) *
multiplier),
max_backoff);
expected_next_lower_bound = static_cast<grpc_millis>(
static_cast<double>(current_backoff) * (1 - jitter));
expected_next_upper_bound = static_cast<grpc_millis>(
static_cast<double>(current_backoff) * (1 + jitter));
}
}
} // namespace
} // namespace testing
} // namespace grpc
int main(int argc, char** argv) {
grpc::testing::TestEnvironment env(argc, argv);
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
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