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Wait exponentially longer when all hosts have been exhausted during reconnect

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Summary: related to T13746

Reviewers: ivica

Reviewed By: ivica

Subscribers: miljen, iljazovic

Differential Revision: https://repo.mireo.local/D27995
This commit is contained in:
Korina Šimičević
2024-02-19 13:25:20 +01:00
parent 38f2cb2496
commit 7cbd7725fc
2 changed files with 63 additions and 2 deletions
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29
include/async_mqtt5/impl/reconnect_op.hpp
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@ -6,15 +6,38 @@
#include <boost/asio/prepend.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/any_completion_handler.hpp>
#include <boost/asio/experimental/parallel_group.hpp>
#include <boost/random/linear_congruential.hpp>
#include <boost/random/uniform_smallint.hpp>
#include <async_mqtt5/types.hpp>
#include <async_mqtt5/detail/async_traits.hpp>
#include <async_mqtt5/impl/connect_op.hpp>
namespace async_mqtt5::detail {
class exponential_backoff {
int _curr_exp { 0 };
static constexpr int _base_mulptilier = 1000;
static constexpr int _max_exp = 4;
// sizeof(_generator) = 8
boost::random::rand48 _generator { uint32_t(std::time(0)) };
boost::random::uniform_smallint<> _distribution { -500, 500 };
public:
exponential_backoff() = default;
duration generate() {
int exponent = _curr_exp < _max_exp ? _curr_exp++ : _max_exp;
int base = 1 << exponent;
return std::chrono::milliseconds(
base * _base_mulptilier + _distribution(_generator) /* noise */
);
}
};
namespace asio = boost::asio;
template <typename Owner>
@ -31,6 +54,8 @@ class reconnect_op {
std::unique_ptr<std::string> _buffer_ptr;
exponential_backoff _generator;
using endpoint = asio::ip::tcp::endpoint;
using epoints = asio::ip::tcp::resolver::results_type;
@ -87,7 +112,7 @@ public:
}
void backoff_and_reconnect() {
_owner._connect_timer.expires_from_now(std::chrono::seconds(5));
_owner._connect_timer.expires_from_now(_generator.generate());
_owner._connect_timer.async_wait(
asio::prepend(std::move(*this), on_backoff {})
);

36
test/unit/reconnect_op.cpp Normal file
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@ -0,0 +1,36 @@
#include <boost/test/unit_test.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/steady_timer.hpp>
#include <async_mqtt5/impl/reconnect_op.hpp>
using namespace async_mqtt5;
BOOST_AUTO_TEST_SUITE(reconnect_op/*, *boost::unit_test::disabled()*/)
BOOST_AUTO_TEST_CASE(exponential_backoff) {
using namespace std::chrono_literals;
detail::exponential_backoff generator;
auto first_iter = generator.generate();
BOOST_TEST((first_iter >= 500ms && first_iter <= 1500ms));
auto second_iter = generator.generate();
BOOST_TEST((second_iter >= 1500ms && first_iter <= 2500ms));
auto third_iter = generator.generate();
BOOST_TEST((third_iter >= 3500ms && third_iter <= 4500ms));
auto fourth_iter = generator.generate();
BOOST_TEST((fourth_iter >= 7500ms && fourth_iter <= 8500ms));
auto fifth_iter = generator.generate();
BOOST_TEST((fifth_iter >= 15500ms && fourth_iter <= 16500ms));
auto sixth_iter = generator.generate();
BOOST_TEST((sixth_iter >= 15500ms && sixth_iter <= 16500ms));
}
BOOST_AUTO_TEST_SUITE_END();