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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "async_resolver.h"
#include "socket_spec.h"
#include <vespa/vespalib/util/size_literals.h>
#include <vespa/vespalib/util/threadstackexecutor.h>
#include <vespa/log/log.h>
LOG_SETUP(".vespalib.net.async_resolver");
namespace vespalib {
VESPA_THREAD_STACK_TAG(async_resolver_executor_thread);
//-----------------------------------------------------------------------------
AsyncResolver::time_point
AsyncResolver::SteadyClock::now()
{
return std::chrono::steady_clock::now();
}
//-----------------------------------------------------------------------------
vespalib::string
AsyncResolver::SimpleHostResolver::ip_address(const vespalib::string &host_name)
{
return SocketAddress::select_remote(80, host_name.c_str()).ip_address();
}
//-----------------------------------------------------------------------------
AsyncResolver::Params::Params()
: clock(std::make_shared<SteadyClock>()),
resolver(std::make_shared<SimpleHostResolver>()),
max_cache_size(10000),
max_result_age(60.0),
max_resolve_time(1.0),
num_threads(4)
{
}
//-----------------------------------------------------------------------------
vespalib::string
AsyncResolver::LoggingHostResolver::ip_address(const vespalib::string &host_name)
{
auto before = _clock->now();
vespalib::string ip_address = _resolver->ip_address(host_name);
seconds resolve_time = (_clock->now() - before);
if (resolve_time >= _max_resolve_time) {
LOG(warning, "slow resolve time: '%s' -> '%s' (%g s)",
host_name.c_str(), ip_address.c_str(), resolve_time.count());
}
if (ip_address.empty()) {
LOG(warning, "could not resolve host name: '%s'", host_name.c_str());
}
return ip_address;
}
//-----------------------------------------------------------------------------
bool
AsyncResolver::CachingHostResolver::should_evict_oldest_entry(const std::lock_guard<std::mutex> &, time_point now)
{
if (_queue.empty()) {
return false;
}
if (_queue.size() > _max_cache_size) {
return true;
}
return (_queue.front()->second.end_time <= now);
}
bool
AsyncResolver::CachingHostResolver::lookup(const vespalib::string &host_name, vespalib::string &ip_address)
{
auto now = _clock->now();
std::lock_guard<std::mutex> guard(_lock);
while (should_evict_oldest_entry(guard, now)) {
_map.erase(_queue.front());
_queue.pop();
}
assert(_map.size() == _queue.size());
auto pos = _map.find(host_name);
if (pos != _map.end()) {
ip_address = pos->second.ip_address;
return true;
}
return false;
}
void
AsyncResolver::CachingHostResolver::store(const vespalib::string &host_name, const vespalib::string &ip_address)
{
auto end_time = _clock->now() + std::chrono::duration_cast<time_point::duration>(_max_result_age);
std::lock_guard<std::mutex> guard(_lock);
auto res = _map.emplace(host_name, Entry(ip_address, end_time));
if (res.second) {
_queue.push(res.first);
}
assert(_map.size() == _queue.size());
}
AsyncResolver::CachingHostResolver::CachingHostResolver(Clock::SP clock, HostResolver::SP resolver, size_t max_cache_size, seconds max_result_age) noexcept
: _clock(std::move(clock)),
_resolver(std::move(resolver)),
_max_cache_size(max_cache_size),
_max_result_age(max_result_age),
_lock(),
_map(),
_queue()
{
}
vespalib::string
AsyncResolver::CachingHostResolver::ip_address(const vespalib::string &host_name)
{
vespalib::string ip_address;
if (lookup(host_name, ip_address)) {
return ip_address;
}
ip_address = _resolver->ip_address(host_name);
if (ip_address != host_name) {
store(host_name, ip_address);
}
return ip_address;
}
//-----------------------------------------------------------------------------
void
AsyncResolver::ResolveTask::run()
{
if (ResultHandler::SP handler = weak_handler.lock()) {
SocketSpec socket_spec(spec);
if (!socket_spec.valid()) {
LOG(warning, "invalid socket spec: '%s'", spec.c_str());
}
if (!socket_spec.host().empty()) {
socket_spec = socket_spec.replace_host(resolver.ip_address(socket_spec.host()));
}
handler->handle_result(socket_spec.client_address());
}
}
//-----------------------------------------------------------------------------
std::mutex AsyncResolver::_shared_lock;
AsyncResolver::SP AsyncResolver::_shared_resolver(nullptr);
AsyncResolver::AsyncResolver(HostResolver::SP resolver, size_t num_threads)
: _resolver(std::move(resolver)),
_executor(std::make_unique<ThreadStackExecutor>(num_threads, async_resolver_executor_thread))
{
}
AsyncResolver::~AsyncResolver() = default;
void
AsyncResolver::wait_for_pending_resolves() {
_executor->sync();
}
void
AsyncResolver::resolve_async(const vespalib::string &spec, ResultHandler::WP result_handler)
{
auto task = std::make_unique<ResolveTask>(spec, *_resolver, std::move(result_handler));
auto rejected = _executor->execute(std::move(task));
assert(!rejected);
}
AsyncResolver::SP
AsyncResolver::create(Params params)
{
auto logger = std::make_shared<LoggingHostResolver>(params.clock, std::move(params.resolver), params.max_resolve_time);
auto cacher = std::make_shared<CachingHostResolver>(std::move(params.clock), std::move(logger), params.max_cache_size, params.max_result_age);
return SP(new AsyncResolver(std::move(cacher), params.num_threads));
}
AsyncResolver::SP
AsyncResolver::get_shared()
{
std::lock_guard<std::mutex> guard(_shared_lock);
if (!_shared_resolver) {
_shared_resolver = create(Params());
}
return _shared_resolver;
}
//-----------------------------------------------------------------------------
} // namespace vespalib
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