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JobClient: resolve endpoint only once

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The JobClient now resolves the server IP once (lazily, when needed) instead
on each connect attempt, reducing the amount of DNS requests sent out.

Change-Id: I9804048d3252da333cb3addbe94a01fdf3c707c8
This commit is contained in:
Horst Schirmeier
2018-07-31 12:31:07 +02:00
parent ad0640cedd
commit 00882f98ad
1 changed files with 29 additions and 18 deletions
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47
src/core/efw/JobClient.cc
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@ -3,6 +3,7 @@
#include <string>
#include <thread>
#include <boost/optional.hpp>
#include <boost/array.hpp>
#include <boost/asio.hpp>
@ -16,6 +17,7 @@ namespace fail {
struct JobClient::impl {
io_service ios;
ip::tcp::socket socket;
boost::optional<ip::tcp::endpoint> endpoint;
impl() : socket(ios) {}
};
@ -46,32 +48,41 @@ bool JobClient::connectToServer()
return false;
}
boost::asio::ip::tcp::resolver resolver(m_d->ios);
boost::asio::ip::tcp::resolver::query query(
m_server, std::to_string(m_server_port));
// random engine for backoff.
std::mt19937_64 engine(time(NULL));
for (int tries = CLIENT_RETRY_COUNT + 1; tries > 0; --tries) {
for (ip::tcp::resolver::iterator end,
addrs = resolver.resolve(query);
addrs != end; ++addrs) {
// server listens on IPv4 endpoint only, skip IPv6 endpoints
if (!addrs->endpoint().address().is_v4()) {
// resolve endpoint lazily
if (!m_d->endpoint) {
boost::asio::ip::tcp::resolver resolver(m_d->ios);
boost::asio::ip::tcp::resolver::query query(
m_server, std::to_string(m_server_port));
for (ip::tcp::resolver::iterator end,
addrs = resolver.resolve(query);
addrs != end; ++addrs) {
// server listens on IPv4 endpoint only, skip IPv6 endpoints
if (addrs->endpoint().address().is_v4()) {
m_d->endpoint = addrs->endpoint();
break;
}
}
if (!m_d->endpoint) {
cerr << "[Client] Failed to resolve " << m_server << endl;
continue;
}
boost::system::error_code error;
m_d->socket.connect(addrs->endpoint(), error);
if (!error) {
cout << "[Client] Connection established!"
<< endl;
return true;
}
perror("[Client@connect()]");
m_d->socket.close();
}
boost::system::error_code error;
m_d->socket.connect(*m_d->endpoint, error);
if (!error) {
cout << "[Client] Connection established!" << endl;
return true;
}
perror("[Client@connect()]");
m_d->socket.close();
std::uniform_real_distribution<> distribution(
CLIENT_RAND_BACKOFF_TSTART, CLIENT_RAND_BACKOFF_TEND);
const auto delay = std::chrono::duration<double>(distribution(engine));