ClickHouse/src/Coordination/KeeperDispatcher.cpp
2022-04-19 08:08:35 +00:00

658 lines
24 KiB
C++

#include <Coordination/KeeperDispatcher.h>
#include <Common/setThreadName.h>
#include <Common/ZooKeeper/KeeperException.h>
#include <future>
#include <chrono>
#include <Poco/Path.h>
#include <Common/hex.h>
#include <filesystem>
#include <Common/checkStackSize.h>
namespace fs = std::filesystem;
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
extern const int TIMEOUT_EXCEEDED;
extern const int SYSTEM_ERROR;
}
KeeperDispatcher::KeeperDispatcher()
: responses_queue(std::numeric_limits<size_t>::max())
, configuration_and_settings(std::make_shared<KeeperConfigurationAndSettings>())
, log(&Poco::Logger::get("KeeperDispatcher"))
{
}
void KeeperDispatcher::requestThread()
{
setThreadName("KeeperReqT");
/// Result of requests batch from previous iteration
RaftAppendResult prev_result = nullptr;
/// Requests from previous iteration. We store them to be able
/// to send errors to the client.
KeeperStorage::RequestsForSessions prev_batch;
while (!shutdown_called)
{
KeeperStorage::RequestForSession request;
auto coordination_settings = configuration_and_settings->coordination_settings;
uint64_t max_wait = coordination_settings->operation_timeout_ms.totalMilliseconds();
uint64_t max_batch_size = coordination_settings->max_requests_batch_size;
/// The code below do a very simple thing: batch all write (quorum) requests into vector until
/// previous write batch is not finished or max_batch size achieved. The main complexity goes from
/// the ability to process read requests without quorum (from local state). So when we are collecting
/// requests into a batch we must check that the new request is not read request. Otherwise we have to
/// process all already accumulated write requests, wait them synchronously and only after that process
/// read request. So reads are some kind of "separator" for writes.
try
{
if (requests_queue->tryPop(request, max_wait))
{
if (shutdown_called)
break;
KeeperStorage::RequestsForSessions current_batch;
bool has_read_request = false;
/// If new request is not read request or we must to process it through quorum.
/// Otherwise we will process it locally.
if (coordination_settings->quorum_reads || !request.request->isReadRequest())
{
current_batch.emplace_back(request);
/// Waiting until previous append will be successful, or batch is big enough
/// has_result == false && get_result_code == OK means that our request still not processed.
/// Sometimes NuRaft set errorcode without setting result, so we check both here.
while (prev_result && (!prev_result->has_result() && prev_result->get_result_code() == nuraft::cmd_result_code::OK) && current_batch.size() <= max_batch_size)
{
/// Trying to get batch requests as fast as possible
if (requests_queue->tryPop(request, 1))
{
/// Don't append read request into batch, we have to process them separately
if (!coordination_settings->quorum_reads && request.request->isReadRequest())
{
has_read_request = true;
break;
}
else
{
current_batch.emplace_back(request);
}
}
if (shutdown_called)
break;
}
}
else
has_read_request = true;
if (shutdown_called)
break;
/// Forcefully process all previous pending requests
if (prev_result)
forceWaitAndProcessResult(prev_result, prev_batch);
/// Process collected write requests batch
if (!current_batch.empty())
{
auto result = server->putRequestBatch(current_batch);
if (result)
{
if (has_read_request) /// If we will execute read request next, than we have to process result now
forceWaitAndProcessResult(result, current_batch);
}
else
{
addErrorResponses(current_batch, Coordination::Error::ZCONNECTIONLOSS);
current_batch.clear();
}
prev_batch = std::move(current_batch);
prev_result = result;
}
/// Read request always goes after write batch (last request)
if (has_read_request)
{
if (server->isLeaderAlive())
server->putLocalReadRequest(request);
else
addErrorResponses({request}, Coordination::Error::ZCONNECTIONLOSS);
}
}
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
}
}
void KeeperDispatcher::responseThread()
{
setThreadName("KeeperRspT");
while (!shutdown_called)
{
KeeperStorage::ResponseForSession response_for_session;
uint64_t max_wait = configuration_and_settings->coordination_settings->operation_timeout_ms.totalMilliseconds();
if (responses_queue.tryPop(response_for_session, max_wait))
{
if (shutdown_called)
break;
try
{
setResponse(response_for_session.session_id, response_for_session.response);
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
}
}
}
void KeeperDispatcher::snapshotThread()
{
setThreadName("KeeperSnpT");
while (!shutdown_called)
{
CreateSnapshotTask task;
if (!snapshots_queue.pop(task))
break;
if (shutdown_called)
break;
try
{
task.create_snapshot(std::move(task.snapshot));
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
}
}
void KeeperDispatcher::setResponse(int64_t session_id, const Coordination::ZooKeeperResponsePtr & response)
{
std::lock_guard lock(session_to_response_callback_mutex);
/// Special new session response.
if (response->xid != Coordination::WATCH_XID && response->getOpNum() == Coordination::OpNum::SessionID)
{
const Coordination::ZooKeeperSessionIDResponse & session_id_resp = dynamic_cast<const Coordination::ZooKeeperSessionIDResponse &>(*response);
/// Nobody waits for this session id
if (session_id_resp.server_id != server->getServerID() || !new_session_id_response_callback.count(session_id_resp.internal_id))
return;
auto callback = new_session_id_response_callback[session_id_resp.internal_id];
callback(response);
new_session_id_response_callback.erase(session_id_resp.internal_id);
}
else /// Normal response, just write to client
{
auto session_response_callback = session_to_response_callback.find(session_id);
/// Session was disconnected, just skip this response
if (session_response_callback == session_to_response_callback.end())
{
LOG_TEST(log, "Cannot write response xid={}, op={}, session {} disconnected", response->xid, response->getOpNum(), session_id);
return;
}
session_response_callback->second(response);
/// Session closed, no more writes
if (response->xid != Coordination::WATCH_XID && response->getOpNum() == Coordination::OpNum::Close)
{
session_to_response_callback.erase(session_response_callback);
}
}
}
bool KeeperDispatcher::putRequest(const Coordination::ZooKeeperRequestPtr & request, int64_t session_id)
{
{
/// If session was already disconnected than we will ignore requests
std::lock_guard lock(session_to_response_callback_mutex);
if (session_to_response_callback.count(session_id) == 0)
return false;
}
KeeperStorage::RequestForSession request_info;
request_info.request = request;
using namespace std::chrono;
request_info.time = duration_cast<milliseconds>(system_clock::now().time_since_epoch()).count();
request_info.session_id = session_id;
std::lock_guard lock(push_request_mutex);
if (shutdown_called)
return false;
/// Put close requests without timeouts
if (request->getOpNum() == Coordination::OpNum::Close)
{
if (!requests_queue->push(std::move(request_info)))
throw Exception("Cannot push request to queue", ErrorCodes::SYSTEM_ERROR);
}
else if (!requests_queue->tryPush(std::move(request_info), configuration_and_settings->coordination_settings->operation_timeout_ms.totalMilliseconds()))
{
throw Exception("Cannot push request to queue within operation timeout", ErrorCodes::TIMEOUT_EXCEEDED);
}
return true;
}
void KeeperDispatcher::initialize(const Poco::Util::AbstractConfiguration & config, bool standalone_keeper, bool start_async)
{
LOG_DEBUG(log, "Initializing storage dispatcher");
configuration_and_settings = KeeperConfigurationAndSettings::loadFromConfig(config, standalone_keeper);
requests_queue = std::make_unique<RequestsQueue>(configuration_and_settings->coordination_settings->max_requests_batch_size);
request_thread = ThreadFromGlobalPool([this] { requestThread(); });
responses_thread = ThreadFromGlobalPool([this] { responseThread(); });
snapshot_thread = ThreadFromGlobalPool([this] { snapshotThread(); });
server = std::make_unique<KeeperServer>(configuration_and_settings, config, responses_queue, snapshots_queue);
try
{
LOG_DEBUG(log, "Waiting server to initialize");
server->startup(config, configuration_and_settings->enable_ipv6);
LOG_DEBUG(log, "Server initialized, waiting for quorum");
if (!start_async)
{
server->waitInit();
LOG_DEBUG(log, "Quorum initialized");
}
else
{
LOG_INFO(log, "Starting Keeper asynchronously, server will accept connections to Keeper when it will be ready");
}
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
throw;
}
/// Start it after keeper server start
session_cleaner_thread = ThreadFromGlobalPool([this] { sessionCleanerTask(); });
update_configuration_thread = ThreadFromGlobalPool([this] { updateConfigurationThread(); });
updateConfiguration(config);
LOG_DEBUG(log, "Dispatcher initialized");
}
void KeeperDispatcher::shutdown()
{
try
{
{
std::lock_guard lock(push_request_mutex);
if (shutdown_called)
return;
LOG_DEBUG(log, "Shutting down storage dispatcher");
shutdown_called = true;
if (session_cleaner_thread.joinable())
session_cleaner_thread.join();
if (requests_queue)
{
requests_queue->finish();
if (request_thread.joinable())
request_thread.join();
}
responses_queue.finish();
if (responses_thread.joinable())
responses_thread.join();
snapshots_queue.finish();
if (snapshot_thread.joinable())
snapshot_thread.join();
update_configuration_queue.finish();
if (update_configuration_thread.joinable())
update_configuration_thread.join();
}
if (server)
server->shutdown();
KeeperStorage::RequestForSession request_for_session;
/// Set session expired for all pending requests
while (requests_queue && requests_queue->tryPop(request_for_session))
{
auto response = request_for_session.request->makeResponse();
response->error = Coordination::Error::ZSESSIONEXPIRED;
setResponse(request_for_session.session_id, response);
}
/// Clear all registered sessions
std::lock_guard lock(session_to_response_callback_mutex);
session_to_response_callback.clear();
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
LOG_DEBUG(log, "Dispatcher shut down");
}
KeeperDispatcher::~KeeperDispatcher()
{
shutdown();
}
void KeeperDispatcher::registerSession(int64_t session_id, ZooKeeperResponseCallback callback)
{
std::lock_guard lock(session_to_response_callback_mutex);
if (!session_to_response_callback.try_emplace(session_id, callback).second)
throw Exception(DB::ErrorCodes::LOGICAL_ERROR, "Session with id {} already registered in dispatcher", session_id);
}
void KeeperDispatcher::sessionCleanerTask()
{
while (true)
{
if (shutdown_called)
return;
try
{
/// Only leader node must check dead sessions
if (server->checkInit() && isLeader())
{
auto dead_sessions = server->getDeadSessions();
for (int64_t dead_session : dead_sessions)
{
LOG_INFO(log, "Found dead session {}, will try to close it", dead_session);
/// Close session == send close request to raft server
Coordination::ZooKeeperRequestPtr request = Coordination::ZooKeeperRequestFactory::instance().get(Coordination::OpNum::Close);
request->xid = Coordination::CLOSE_XID;
KeeperStorage::RequestForSession request_info;
request_info.request = request;
using namespace std::chrono;
request_info.time = duration_cast<milliseconds>(system_clock::now().time_since_epoch()).count();
request_info.session_id = dead_session;
{
std::lock_guard lock(push_request_mutex);
if (!requests_queue->push(std::move(request_info)))
LOG_INFO(log, "Cannot push close request to queue while cleaning outdated sessions");
}
/// Remove session from registered sessions
finishSession(dead_session);
LOG_INFO(log, "Dead session close request pushed");
}
}
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
auto time_to_sleep = configuration_and_settings->coordination_settings->dead_session_check_period_ms.totalMilliseconds();
std::this_thread::sleep_for(std::chrono::milliseconds(time_to_sleep));
}
}
void KeeperDispatcher::finishSession(int64_t session_id)
{
std::lock_guard lock(session_to_response_callback_mutex);
auto session_it = session_to_response_callback.find(session_id);
if (session_it != session_to_response_callback.end())
session_to_response_callback.erase(session_it);
}
void KeeperDispatcher::addErrorResponses(const KeeperStorage::RequestsForSessions & requests_for_sessions, Coordination::Error error)
{
for (const auto & [session_id, time, request] : requests_for_sessions)
{
KeeperStorage::ResponsesForSessions responses;
auto response = request->makeResponse();
response->xid = request->xid;
response->zxid = 0;
response->error = error;
if (!responses_queue.push(DB::KeeperStorage::ResponseForSession{session_id, response}))
throw Exception(ErrorCodes::SYSTEM_ERROR,
"Could not push error response xid {} zxid {} error message {} to responses queue",
response->xid,
response->zxid,
errorMessage(error));
}
}
void KeeperDispatcher::forceWaitAndProcessResult(RaftAppendResult & result, KeeperStorage::RequestsForSessions & requests_for_sessions)
{
if (!result->has_result())
result->get();
/// If we get some errors, than send them to clients
if (!result->get_accepted() || result->get_result_code() == nuraft::cmd_result_code::TIMEOUT)
addErrorResponses(requests_for_sessions, Coordination::Error::ZOPERATIONTIMEOUT);
else if (result->get_result_code() != nuraft::cmd_result_code::OK)
addErrorResponses(requests_for_sessions, Coordination::Error::ZCONNECTIONLOSS);
result = nullptr;
requests_for_sessions.clear();
}
int64_t KeeperDispatcher::getSessionID(int64_t session_timeout_ms)
{
/// New session id allocation is a special request, because we cannot process it in normal
/// way: get request -> put to raft -> set response for registered callback.
KeeperStorage::RequestForSession request_info;
std::shared_ptr<Coordination::ZooKeeperSessionIDRequest> request = std::make_shared<Coordination::ZooKeeperSessionIDRequest>();
/// Internal session id. It's a temporary number which is unique for each client on this server
/// but can be same on different servers.
request->internal_id = internal_session_id_counter.fetch_add(1);
request->session_timeout_ms = session_timeout_ms;
request->server_id = server->getServerID();
request_info.request = request;
using namespace std::chrono;
request_info.time = duration_cast<milliseconds>(system_clock::now().time_since_epoch()).count();
request_info.session_id = -1;
auto promise = std::make_shared<std::promise<int64_t>>();
auto future = promise->get_future();
{
std::lock_guard lock(session_to_response_callback_mutex);
new_session_id_response_callback[request->internal_id] = [promise, internal_id = request->internal_id] (const Coordination::ZooKeeperResponsePtr & response)
{
if (response->getOpNum() != Coordination::OpNum::SessionID)
promise->set_exception(std::make_exception_ptr(Exception(ErrorCodes::LOGICAL_ERROR,
"Incorrect response of type {} instead of SessionID response", Coordination::toString(response->getOpNum()))));
auto session_id_response = dynamic_cast<const Coordination::ZooKeeperSessionIDResponse &>(*response);
if (session_id_response.internal_id != internal_id)
{
promise->set_exception(std::make_exception_ptr(Exception(ErrorCodes::LOGICAL_ERROR,
"Incorrect response with internal id {} instead of {}", session_id_response.internal_id, internal_id)));
}
if (response->error != Coordination::Error::ZOK)
promise->set_exception(std::make_exception_ptr(zkutil::KeeperException("SessionID request failed with error", response->error)));
promise->set_value(session_id_response.session_id);
};
}
/// Push new session request to queue
{
std::lock_guard lock(push_request_mutex);
if (!requests_queue->tryPush(std::move(request_info), session_timeout_ms))
throw Exception("Cannot push session id request to queue within session timeout", ErrorCodes::TIMEOUT_EXCEEDED);
}
if (future.wait_for(std::chrono::milliseconds(session_timeout_ms)) != std::future_status::ready)
throw Exception("Cannot receive session id within session timeout", ErrorCodes::TIMEOUT_EXCEEDED);
/// Forcefully wait for request execution because we cannot process any other
/// requests for this client until it get new session id.
return future.get();
}
void KeeperDispatcher::updateConfigurationThread()
{
while (true)
{
if (shutdown_called)
return;
try
{
if (!server->checkInit())
{
LOG_INFO(log, "Server still not initialized, will not apply configuration until initialization finished");
std::this_thread::sleep_for(std::chrono::milliseconds(5000));
continue;
}
ConfigUpdateAction action;
if (!update_configuration_queue.pop(action))
break;
/// We must wait this update from leader or apply it ourself (if we are leader)
bool done = false;
while (!done)
{
if (shutdown_called)
return;
if (isLeader())
{
server->applyConfigurationUpdate(action);
done = true;
}
else
{
done = server->waitConfigurationUpdate(action);
if (!done)
LOG_INFO(log, "Cannot wait for configuration update, maybe we become leader, or maybe update is invalid, will try to wait one more time");
}
}
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
}
}
void KeeperDispatcher::updateConfiguration(const Poco::Util::AbstractConfiguration & config)
{
auto diff = server->getConfigurationDiff(config);
if (diff.empty())
LOG_TRACE(log, "Configuration update triggered, but nothing changed for RAFT");
else if (diff.size() > 1)
LOG_WARNING(log, "Configuration changed for more than one server ({}) from cluster, it's strictly not recommended", diff.size());
else
LOG_DEBUG(log, "Configuration change size ({})", diff.size());
for (auto & change : diff)
{
bool push_result = update_configuration_queue.push(change);
if (!push_result)
throw Exception(ErrorCodes::SYSTEM_ERROR, "Cannot push configuration update to queue");
}
}
void KeeperDispatcher::updateKeeperStatLatency(uint64_t process_time_ms)
{
keeper_stats.updateLatency(process_time_ms);
}
static uint64_t getDirSize(const fs::path & dir)
{
checkStackSize();
if (!fs::exists(dir))
return 0;
fs::directory_iterator it(dir);
fs::directory_iterator end;
uint64_t size{0};
while (it != end)
{
if (it->is_regular_file())
size += fs::file_size(*it);
else
size += getDirSize(it->path());
++it;
}
return size;
}
uint64_t KeeperDispatcher::getLogDirSize() const
{
return getDirSize(configuration_and_settings->log_storage_path);
}
uint64_t KeeperDispatcher::getSnapDirSize() const
{
return getDirSize(configuration_and_settings->snapshot_storage_path);
}
Keeper4LWInfo KeeperDispatcher::getKeeper4LWInfo() const
{
Keeper4LWInfo result;
result.is_follower = server->isFollower();
result.is_standalone = !result.is_follower && server->getFollowerCount() == 0;
result.is_leader = isLeader();
result.is_observer = server->isObserver();
result.has_leader = hasLeader();
{
std::lock_guard lock(push_request_mutex);
result.outstanding_requests_count = requests_queue->size();
}
{
std::lock_guard lock(session_to_response_callback_mutex);
result.alive_connections_count = session_to_response_callback.size();
}
if (result.is_leader)
{
result.follower_count = server->getFollowerCount();
result.synced_follower_count = server->getSyncedFollowerCount();
}
result.total_nodes_count = server->getKeeperStateMachine()->getNodesCount();
result.last_zxid = server->getKeeperStateMachine()->getLastProcessedZxid();
return result;
}
}