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Refactor 4.0

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This commit is contained in:
Pavel Kruglov 2021-02-21 17:03:24 +03:00
parent 9bd9ea9fbc
commit dd5185c779
14 changed files with 639 additions and 498 deletions
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285
src/Client/ConnectionEstablisher.cpp
View File

@ -16,153 +16,24 @@ namespace ErrorCodes
extern const int ATTEMPT_TO_READ_AFTER_EOF;
extern const int NETWORK_ERROR;
extern const int SOCKET_TIMEOUT;
extern const int LOGICAL_ERROR;
}
ConnectionEstablisher::ConnectionEstablisher(
IConnectionPool * pool_,
const ConnectionTimeouts * timeouts_,
const Settings * settings_,
const QualifiedTableName * table_to_check_)
: pool(pool_), timeouts(timeouts_), settings(settings_), table_to_check(table_to_check_),
stage(Stage::INITIAL), log(&Poco::Logger::get("ConnectionEstablisher"))
Poco::Logger * log_,
const QualifiedTableName * table_to_check_) : pool(pool_), timeouts(timeouts_), settings(settings_), log(log_), table_to_check(table_to_check_)
{
#if defined(OS_LINUX)
epoll.add(receive_timeout.getDescriptor());
#endif
}
void ConnectionEstablisher::Routine::ReadCallback::operator()(int fd, const Poco::Timespan & timeout, const std::string &)
{
#if defined(OS_LINUX)
if (connection_establisher.socket_fd != fd)
{
if (connection_establisher.socket_fd != -1)
connection_establisher.epoll.remove(connection_establisher.socket_fd);
connection_establisher.epoll.add(fd);
connection_establisher.socket_fd = fd;
}
connection_establisher.receive_timeout.setRelative(timeout);
fiber = std::move(fiber).resume();
connection_establisher.receive_timeout.reset();
#else
(void) fd;
(void) timeout;
#endif
}
Fiber ConnectionEstablisher::Routine::operator()(Fiber && sink)
void ConnectionEstablisher::run(ConnectionEstablisher::TryResult & result, std::string & fail_message)
{
is_finished = false;
SCOPE_EXIT(is_finished = true);
try
{
connection_establisher.establishConnection(ReadCallback{connection_establisher, sink});
}
catch (const boost::context::detail::forced_unwind &)
{
/// This exception is thrown by fiber implementation in case if fiber is being deleted but hasn't exited
/// It should not be caught or it will segfault.
/// Other exceptions must be caught
throw;
}
catch (...)
{
connection_establisher.exception = std::current_exception();
}
return std::move(sink);
}
void ConnectionEstablisher::resume()
{
if (!fiber_created)
{
reset();
fiber = boost::context::fiber(std::allocator_arg_t(), fiber_stack, Routine{*this});
fiber_created = true;
resumeFiber();
return;
}
#if defined(OS_LINUX)
bool is_socket_ready = false;
bool is_receive_timeout_alarmed = false;
epoll_event events[2];
events[0].data.fd = events[1].data.fd = -1;
size_t ready_count = epoll.getManyReady(2, events, true);
for (size_t i = 0; i != ready_count; ++i)
{
if (events[i].data.fd == socket_fd)
is_socket_ready = true;
if (events[i].data.fd == receive_timeout.getDescriptor())
is_receive_timeout_alarmed = true;
}
if (is_receive_timeout_alarmed && !is_socket_ready)
processReceiveTimeout();
#endif
resumeFiber();
}
void ConnectionEstablisher::cancel()
{
destroyFiber();
reset();
}
void ConnectionEstablisher::processReceiveTimeout()
{
#if defined(OS_LINUX)
destroyFiber();
stage = Stage::FAILED;
fail_message = "Code: 209, e.displayText() = DB::NetException: Timeout exceeded while reading from socket (" + result.entry->getDescription() + ")";
epoll.remove(socket_fd);
resetResult();
#endif
}
void ConnectionEstablisher::resetResult()
{
if (!result.entry.isNull())
{
result.entry->disconnect();
result.reset();
}
}
void ConnectionEstablisher::reset()
{
stage = Stage::INITIAL;
resetResult();
fail_message.clear();
socket_fd = -1;
}
void ConnectionEstablisher::resumeFiber()
{
fiber = std::move(fiber).resume();
if (exception)
std::rethrow_exception(std::move(exception));
if (stage == Stage::FAILED)
destroyFiber();
}
void ConnectionEstablisher::destroyFiber()
{
Fiber to_destroy = std::move(fiber);
fiber_created = false;
}
void ConnectionEstablisher::establishConnection(AsyncCallback async_callback)
{
try
{
stage = Stage::IN_PROCESS;
result.entry = pool->get(*timeouts, settings, /* force_connected = */ false);
AsyncCallbackSetter async_setter(&*result.entry, std::move(async_callback));
@ -175,7 +46,6 @@ void ConnectionEstablisher::establishConnection(AsyncCallback async_callback)
result.entry->forceConnected(*timeouts);
result.is_usable = true;
result.is_up_to_date = true;
stage = Stage::FINISHED;
return;
}
@ -192,8 +62,6 @@ void ConnectionEstablisher::establishConnection(AsyncCallback async_callback)
fail_message = fmt::format(message_pattern, backQuote(table_to_check->database), backQuote(table_to_check->table), result.entry->getDescription());
LOG_WARNING(log, fail_message);
ProfileEvents::increment(ProfileEvents::DistributedConnectionMissingTable);
stage = Stage::FINISHED;
return;
}
@ -203,7 +71,6 @@ void ConnectionEstablisher::establishConnection(AsyncCallback async_callback)
if (!max_allowed_delay)
{
result.is_up_to_date = true;
stage = Stage::FINISHED;
return;
}
@ -219,7 +86,6 @@ void ConnectionEstablisher::establishConnection(AsyncCallback async_callback)
LOG_TRACE(log, "Server {} has unacceptable replica delay for table {}.{}: {}", result.entry->getDescription(), table_to_check->database, table_to_check->table, delay);
ProfileEvents::increment(ProfileEvents::DistributedConnectionStaleReplica);
}
stage = Stage::FINISHED;
}
catch (const Exception & e)
{
@ -228,9 +94,144 @@ void ConnectionEstablisher::establishConnection(AsyncCallback async_callback)
throw;
fail_message = getCurrentExceptionMessage(/* with_stacktrace = */ false);
resetResult();
stage = Stage::FAILED;
if (!result.entry.isNull())
{
result.entry->disconnect();
result.reset();
}
}
}
ConnectionEstablisherAsync::ConnectionEstablisherAsync(
IConnectionPool * pool_,
const ConnectionTimeouts * timeouts_,
const Settings * settings_,
Poco::Logger * log_,
const QualifiedTableName * table_to_check_)
: connection_establisher(pool_, timeouts_, settings_, log_, table_to_check_)
{
epoll.add(receive_timeout.getDescriptor());
}
void ConnectionEstablisherAsync::Routine::ReadCallback::operator()(int fd, const Poco::Timespan & timeout, const std::string &)
{
if (connection_establisher_async.socket_fd != fd)
{
if (connection_establisher_async.socket_fd != -1)
connection_establisher_async.epoll.remove(connection_establisher_async.socket_fd);
connection_establisher_async.epoll.add(fd);
connection_establisher_async.socket_fd = fd;
}
connection_establisher_async.receive_timeout.setRelative(timeout);
fiber = std::move(fiber).resume();
connection_establisher_async.receive_timeout.reset();
}
Fiber ConnectionEstablisherAsync::Routine::operator()(Fiber && sink)
{
try
{
connection_establisher_async.connection_establisher.setAsyncCallback(ReadCallback{connection_establisher_async, sink});
connection_establisher_async.connection_establisher.run(connection_establisher_async.result, connection_establisher_async.fail_message);
}
catch (const boost::context::detail::forced_unwind &)
{
/// This exception is thrown by fiber implementation in case if fiber is being deleted but hasn't exited
/// It should not be caught or it will segfault.
/// Other exceptions must be caught
throw;
}
catch (...)
{
connection_establisher_async.exception = std::current_exception();
}
return std::move(sink);
}
std::variant<int, ConnectionEstablisher::TryResult> ConnectionEstablisherAsync::resume()
{
if (!fiber_created)
{
reset();
fiber = boost::context::fiber(std::allocator_arg_t(), fiber_stack, Routine{*this});
fiber_created = true;
} else if (!checkReceiveTimeout())
return result;
fiber = std::move(fiber).resume();
if (exception)
std::rethrow_exception(std::move(exception));
if (connection_establisher.isFinished())
{
destroyFiber();
return result;
}
return epoll.getFileDescriptor();
}
bool ConnectionEstablisherAsync::checkReceiveTimeout()
{
bool is_socket_ready = false;
bool is_receive_timeout_alarmed = false;
epoll_event events[2];
events[0].data.fd = events[1].data.fd = -1;
size_t ready_count = epoll.getManyReady(2, events, false);
for (size_t i = 0; i != ready_count; ++i)
{
if (events[i].data.fd == socket_fd)
is_socket_ready = true;
if (events[i].data.fd == receive_timeout.getDescriptor())
is_receive_timeout_alarmed = true;
}
if (is_receive_timeout_alarmed && !is_socket_ready)
{
destroyFiber();
/// In not async case this exception would be thrown and caught in ConnectionEstablisher::run,
/// but in async case we process timeout outside and cannot throw exception. So, we just save fail message.
fail_message = "Timeout exceeded while reading from socket (" + result.entry->getDescription() + ")";
epoll.remove(socket_fd);
resetResult();
return false;
}
return true;
}
void ConnectionEstablisherAsync::cancel()
{
destroyFiber();
reset();
}
void ConnectionEstablisherAsync::reset()
{
resetResult();
fail_message.clear();
socket_fd = -1;
}
void ConnectionEstablisherAsync::resetResult()
{
if (!result.entry.isNull())
{
result.entry->disconnect();
result.reset();
}
}
void ConnectionEstablisherAsync::destroyFiber()
{
Fiber to_destroy = std::move(fiber);
fiber_created = false;
}
}

131
src/Client/ConnectionEstablisher.h
View File

@ -1,5 +1,7 @@
#pragma once
#include <variant>
#include <Common/Epoll.h>
#include <Common/Fiber.h>
#include <Common/FiberStack.h>
@ -10,12 +12,8 @@
namespace DB
{
/// Class for nonblocking establishing connection to the replica.
/// It runs establishing connection process in fiber and sets special
/// read callback which is called when reading from socket blocks.
/// When read callback is called, socket and receive timeout are added in epoll
/// and execution returns to the main program.
/// So, you can poll this epoll file descriptor to determine when to resume.
/// Class for establishing connection to the replica. It supports setting up
/// an async callback that will be called when reading from socket blocks.
class ConnectionEstablisher
{
public:
@ -24,60 +22,74 @@ public:
ConnectionEstablisher(IConnectionPool * pool_,
const ConnectionTimeouts * timeouts_,
const Settings * settings_,
Poco::Logger * log,
const QualifiedTableName * table_to_check = nullptr);
/// Establish connection with replica, call async_callbeck when
/// reading from socket blocks.
void establishConnection(AsyncCallback async_callback = {});
/// Establish connection and save it in result, write possible exception message in fail_message.
void run(TryResult & result, std::string & fail_message);
/// In the first call create fiber with establishConnection function,
/// in the next - check timeout and resume fiber.
void resume();
/// Set async callback that will be called when reading from socket blocks.
void setAsyncCallback(AsyncCallback async_callback_) { async_callback = std::move(async_callback_); }
bool isFinished() const { return is_finished; }
private:
IConnectionPool * pool;
const ConnectionTimeouts * timeouts;
const Settings * settings;
Poco::Logger * log;
const QualifiedTableName * table_to_check;
bool is_finished;
AsyncCallback async_callback = {};
};
#if defined(OS_LINUX)
/// Class for nonblocking establishing connection to the replica.
/// It runs establishing connection process in fiber and sets special
/// read callback which is called when reading from socket blocks.
/// When read callback is called, socket and receive timeout are added in epoll
/// and execution returns to the main program.
/// So, you can poll this epoll file descriptor to determine when to resume.
class ConnectionEstablisherAsync
{
public:
using TryResult = PoolWithFailoverBase<IConnectionPool>::TryResult;
ConnectionEstablisherAsync(IConnectionPool * pool_,
const ConnectionTimeouts * timeouts_,
const Settings * settings_,
Poco::Logger * log_,
const QualifiedTableName * table_to_check = nullptr);
/// Resume establishing connection. If the process was not finished,
/// return file descriptor (you can add it in epoll and poll it,
/// when this fd become ready, call resume again),
/// if the process was failed or finished, return it's result,
std::variant<int, TryResult> resume();
/// Cancel establishing connections. Fiber will be destroyed,
/// class will be set in initial stage.
void cancel();
bool isInProcess() const { return stage == Stage::IN_PROCESS; }
bool isFinished() const { return stage == Stage::FINISHED; }
bool isFailed() const { return stage == Stage::FAILED; }
int getFileDescriptor() const
{
int fd = -1;
#if defined(OS_LINUX)
fd = epoll.getFileDescriptor();
#endif
return fd;
}
TryResult getResult() const { return result; }
const std::string & getFailMessage() const { return fail_message; }
TryResult getResult() { return result; }
Connection * getConnection() { return &*result.entry; }
private:
void processReceiveTimeout();
enum class Stage
{
INITIAL,
IN_PROCESS,
FINISHED,
FAILED,
};
/// When epoll file descriptor is ready, check if it's an expired timeout.
/// Return false if receive timeout expired and socket is not ready, return true otherwise.
bool checkReceiveTimeout();
struct Routine
{
ConnectionEstablisher & connection_establisher;
ConnectionEstablisherAsync & connection_establisher_async;
struct ReadCallback
{
ConnectionEstablisher & connection_establisher;
ConnectionEstablisherAsync & connection_establisher_async;
Fiber & fiber;
void operator()(int fd, const Poco::Timespan & timeout, const std::string &);
@ -86,31 +98,34 @@ private:
Fiber operator()(Fiber && sink);
};
void resetResult();
void reset();
void resetResult();
void destroyFiber();
void resumeFiber();
IConnectionPool * pool;
const ConnectionTimeouts * timeouts;
std::string fail_message;
const Settings * settings;
const QualifiedTableName * table_to_check;
ConnectionEstablisher connection_establisher;
TryResult result;
Stage stage;
Poco::Logger * log;
std::string fail_message;
Fiber fiber;
FiberStack fiber_stack;
std::exception_ptr exception;
int socket_fd = -1;
bool fiber_created = false;
#if defined(OS_LINUX)
/// We use timer descriptor for checking socket receive timeout.
TimerDescriptor receive_timeout;
/// In read callback we add socket file descriptor and timer descriptor with receive timeout
/// in epoll, so we can return epoll file descriptor outside for polling.
Epoll epoll;
#endif
int socket_fd = -1;
std::string socket_description;
/// If and exception occurred in fiber resume, we save it and rethrow.
std::exception_ptr exception;
bool fiber_created = false;
};
#endif
}

8
src/Client/ConnectionPoolWithFailover.cpp
View File

@ -247,10 +247,10 @@ ConnectionPoolWithFailover::tryGetEntry(
const Settings * settings,
const QualifiedTableName * table_to_check)
{
ConnectionEstablisher connection_establisher(&pool, &timeouts, settings, table_to_check);
connection_establisher.establishConnection();
fail_message = connection_establisher.getFailMessage();
return connection_establisher.getResult();
ConnectionEstablisher connection_establisher(&pool, &timeouts, settings, log, table_to_check);
TryResult result;
connection_establisher.run(result, fail_message);
return result;
}
std::vector<ConnectionPoolWithFailover::Base::ShuffledPool> ConnectionPoolWithFailover::getShuffledPools(const Settings * settings)

2
src/Client/ConnectionPoolWithFailover.h
View File

@ -99,7 +99,7 @@ private:
/// Try to get a connection from the pool and check that it is good.
/// If table_to_check is not null and the check is enabled in settings, check that replication delay
/// for this table is not too large.
static TryResult tryGetEntry(
TryResult tryGetEntry(
IConnectionPool & pool,
const ConnectionTimeouts & timeouts,
std::string & fail_message,

183
src/Client/HedgedConnections.cpp
View File

@ -39,8 +39,8 @@ HedgedConnections::HedgedConnections(
ReplicaState & replica = offset_states[i].replicas.back();
replica.connection->setThrottler(throttler_);
epoll.add(replica.packet_receiver.getFileDescriptor());
fd_to_replica_location[replica.packet_receiver.getFileDescriptor()] = ReplicaLocation{i, 0};
epoll.add(replica.packet_receiver->getFileDescriptor());
fd_to_replica_location[replica.packet_receiver->getFileDescriptor()] = ReplicaLocation{i, 0};
epoll.add(replica.change_replica_timeout.getDescriptor());
timeout_fd_to_replica_location[replica.change_replica_timeout.getDescriptor()] = ReplicaLocation{i, 0};
@ -143,6 +143,16 @@ void HedgedConnections::sendQuery(
break;
}
if (!disable_two_level_aggregation)
{
/// Tell hedged_connections_factory to skip replicas that doesn't support two-level aggregation.
hedged_connections_factory.setSkipPredicate(
[timeouts](Connection * connection)
{
return connection->getServerRevision(timeouts) < DBMS_MIN_REVISION_WITH_CURRENT_AGGREGATION_VARIANT_SELECTION_METHOD;
});
}
auto send_query = [this, timeouts, query, query_id, stage, client_info, with_pending_data](ReplicaState & replica)
{
Settings modified_settings = settings;
@ -157,7 +167,7 @@ void HedgedConnections::sendQuery(
if (offset_states.size() > 1)
{
modified_settings.parallel_replicas_count = offset_states.size();
modified_settings.parallel_replica_offset = fd_to_replica_location[replica.packet_receiver.getFileDescriptor()].offset;
modified_settings.parallel_replica_offset = fd_to_replica_location[replica.packet_receiver->getFileDescriptor()].offset;
}
replica.connection->sendQuery(timeouts, query, query_id, stage, &modified_settings, &client_info, with_pending_data);
@ -183,11 +193,8 @@ void HedgedConnections::disconnect()
if (hedged_connections_factory.hasEventsInProcess())
{
if (next_replica_in_process)
{
if (hedged_connections_factory.numberOfProcessingReplicas() > 0)
epoll.remove(hedged_connections_factory.getFileDescriptor());
next_replica_in_process = false;
}
hedged_connections_factory.stopChoosingReplicas();
}
@ -291,33 +298,23 @@ HedgedConnections::ReplicaLocation HedgedConnections::getReadyReplicaLocation(As
int event_fd;
while (true)
{
/// Check connections for pending data in buffer.
ReplicaLocation location;
if (checkPendingData(location))
{
ReplicaState & replica_state = offset_states[location.offset].replicas[location.index];
replica_state.packet_receiver.resume();
if (replica_state.packet_receiver.isPacketReady())
return location;
continue;
}
/// Get ready file descriptor from epoll and process it.
event_fd = getReadyFileDescriptor(async_callback);
if (event_fd == hedged_connections_factory.getFileDescriptor())
tryGetNewReplica(false);
checkNewReplica();
else if (fd_to_replica_location.contains(event_fd))
{
location = fd_to_replica_location[event_fd];
ReplicaLocation location = fd_to_replica_location[event_fd];
ReplicaState & replica_state = offset_states[location.offset].replicas[location.index];
replica_state.packet_receiver.resume();
auto res = replica_state.packet_receiver->resume();
if (replica_state.packet_receiver.isPacketReady())
if (std::holds_alternative<Packet>(res))
{
last_received_packet = std::move(std::get<Packet>(res));
return location;
if (replica_state.packet_receiver.isReceiveTimeoutExpired())
}
else if (std::holds_alternative<Poco::Timespan>(res))
{
finishProcessReplica(replica_state, true);
@ -328,11 +325,11 @@ HedgedConnections::ReplicaLocation HedgedConnections::getReadyReplicaLocation(As
}
else if (timeout_fd_to_replica_location.contains(event_fd))
{
location = timeout_fd_to_replica_location[event_fd];
ReplicaLocation location = timeout_fd_to_replica_location[event_fd];
offset_states[location.offset].replicas[location.index].change_replica_timeout.reset();
offset_states[location.offset].next_replica_in_process = true;
offsets_queue.push(location.offset);
tryGetNewReplica(true);
startNewReplica();
}
else
throw Exception("Unknown event from epoll", ErrorCodes::LOGICAL_ERROR);
@ -343,28 +340,20 @@ int HedgedConnections::getReadyFileDescriptor(AsyncCallback async_callback)
{
epoll_event event;
event.data.fd = -1;
epoll.getManyReady(1, &event, true, std::move(async_callback));
return event.data.fd;
}
bool HedgedConnections::checkPendingData(ReplicaLocation & location_out)
{
for (auto & [fd, location] : fd_to_replica_location)
size_t events_count = 0;
while (events_count == 0)
{
if (offset_states[location.offset].replicas[location.index].connection->hasReadPendingData())
{
location_out = location;
return true;
}
events_count = epoll.getManyReady(1, &event, false);
if (!events_count && async_callback)
async_callback(epoll.getFileDescriptor(), 0, epoll.getDescription());
}
return false;
return event.data.fd;
}
Packet HedgedConnections::receivePacketFromReplica(const ReplicaLocation & replica_location)
{
ReplicaState & replica = offset_states[replica_location.offset].replicas[replica_location.index];
Packet packet = replica.packet_receiver.getPacket();
Packet packet = std::move(last_received_packet);
switch (packet.type)
{
case Protocol::Server::Data:
@ -413,78 +402,84 @@ void HedgedConnections::processReceivedFirstDataPacket(const ReplicaLocation & r
/// If we received data from replicas with all offsets, we need to stop choosing new replicas.
if (hedged_connections_factory.hasEventsInProcess() && offsets_with_received_first_data_packet == offset_states.size())
{
if (next_replica_in_process)
{
if (hedged_connections_factory.numberOfProcessingReplicas() > 0)
epoll.remove(hedged_connections_factory.getFileDescriptor());
next_replica_in_process = false;
}
hedged_connections_factory.stopChoosingReplicas();
}
}
void HedgedConnections::tryGetNewReplica(bool start_new_connection)
void HedgedConnections::startNewReplica()
{
Connection * connection = nullptr;
HedgedConnectionsFactory::State state = hedged_connections_factory.getNextConnection(start_new_connection, false, connection);
HedgedConnectionsFactory::State state = hedged_connections_factory.startNewConnection(connection);
/// Skip replicas that doesn't support two-level aggregation if we didn't disable it in sendQuery.
while (state == HedgedConnectionsFactory::State::READY && !disable_two_level_aggregation
&& connection->getServerRevision(hedged_connections_factory.getConnectionTimeouts())
< DBMS_MIN_REVISION_WITH_CURRENT_AGGREGATION_VARIANT_SELECTION_METHOD)
state = hedged_connections_factory.getNextConnection(true, false, connection);
if (state == HedgedConnectionsFactory::State::READY)
{
size_t offset = offsets_queue.front();
offsets_queue.pop();
offset_states[offset].replicas.emplace_back(connection);
++offset_states[offset].active_connection_count;
offset_states[offset].next_replica_in_process = false;
++active_connection_count;
ReplicaState & replica = offset_states[offset].replicas.back();
epoll.add(replica.packet_receiver.getFileDescriptor());
fd_to_replica_location[replica.packet_receiver.getFileDescriptor()] = ReplicaLocation{offset, offset_states[offset].replicas.size() - 1};
epoll.add(replica.change_replica_timeout.getDescriptor());
timeout_fd_to_replica_location[replica.change_replica_timeout.getDescriptor()] = ReplicaLocation{offset, offset_states[offset].replicas.size() - 1};
pipeline_for_new_replicas.run(replica);
}
else if (state == HedgedConnectionsFactory::State::NOT_READY && !next_replica_in_process)
{
/// Check if we need to add hedged_connections_factory file descriptor to epoll.
if (state == HedgedConnectionsFactory::State::NOT_READY && hedged_connections_factory.numberOfProcessingReplicas() == 1)
epoll.add(hedged_connections_factory.getFileDescriptor());
next_replica_in_process = true;
}
/// Check if we cannot get new replica and there is no active replica with needed offsets.
else if (state == HedgedConnectionsFactory::State::CANNOT_CHOOSE)
{
while (!offsets_queue.empty())
{
if (offset_states[offsets_queue.front()].active_connection_count == 0)
throw Exception("Cannot find enough connections to replicas", ErrorCodes::ALL_CONNECTION_TRIES_FAILED);
offset_states[offsets_queue.front()].next_replica_in_process = false;
offsets_queue.pop();
}
}
processNewReplicaState(state, connection);
}
void HedgedConnections::checkNewReplica()
{
Connection * connection = nullptr;
HedgedConnectionsFactory::State state = hedged_connections_factory.waitForReadyConnections(/*blocking = */false, connection);
processNewReplicaState(state, connection);
/// Check if we don't need to listen hedged_connections_factory file descriptor in epoll anymore.
if (next_replica_in_process && (state == HedgedConnectionsFactory::State::CANNOT_CHOOSE || offsets_queue.empty()))
{
if (hedged_connections_factory.numberOfProcessingReplicas() == 0)
epoll.remove(hedged_connections_factory.getFileDescriptor());
next_replica_in_process = false;
}
void HedgedConnections::processNewReplicaState(HedgedConnectionsFactory::State state, Connection * connection)
{
switch (state)
{
case HedgedConnectionsFactory::State::READY:
{
size_t offset = offsets_queue.front();
offsets_queue.pop();
offset_states[offset].replicas.emplace_back(connection);
++offset_states[offset].active_connection_count;
offset_states[offset].next_replica_in_process = false;
++active_connection_count;
ReplicaState & replica = offset_states[offset].replicas.back();
epoll.add(replica.packet_receiver->getFileDescriptor());
fd_to_replica_location[replica.packet_receiver->getFileDescriptor()] = ReplicaLocation{offset, offset_states[offset].replicas.size() - 1};
epoll.add(replica.change_replica_timeout.getDescriptor());
timeout_fd_to_replica_location[replica.change_replica_timeout.getDescriptor()] = ReplicaLocation{offset, offset_states[offset].replicas.size() - 1};
pipeline_for_new_replicas.run(replica);
break;
}
case HedgedConnectionsFactory::State::CANNOT_CHOOSE:
{
while (!offsets_queue.empty())
{
/// Check if there is no active replica with needed offsets.
if (offset_states[offsets_queue.front()].active_connection_count == 0)
throw Exception("Cannot find enough connections to replicas", ErrorCodes::ALL_CONNECTION_TRIES_FAILED);
offset_states[offsets_queue.front()].next_replica_in_process = false;
offsets_queue.pop();
}
break;
}
case HedgedConnectionsFactory::State::NOT_READY:
break;
}
}
void HedgedConnections::finishProcessReplica(ReplicaState & replica, bool disconnect)
{
replica.packet_receiver.cancel();
replica.packet_receiver->cancel();
replica.change_replica_timeout.reset();
epoll.remove(replica.packet_receiver.getFileDescriptor());
--offset_states[fd_to_replica_location[replica.packet_receiver.getFileDescriptor()].offset].active_connection_count;
fd_to_replica_location.erase(replica.packet_receiver.getFileDescriptor());
epoll.remove(replica.packet_receiver->getFileDescriptor());
--offset_states[fd_to_replica_location[replica.packet_receiver->getFileDescriptor()].offset].active_connection_count;
fd_to_replica_location.erase(replica.packet_receiver->getFileDescriptor());
epoll.remove(replica.change_replica_timeout.getDescriptor());
timeout_fd_to_replica_location.erase(replica.change_replica_timeout.getDescriptor());

17
src/Client/HedgedConnections.h
View File

@ -21,14 +21,15 @@ namespace DB
class HedgedConnections : public IConnections
{
public:
using PacketReceiverPtr = std::unique_ptr<PacketReceiver>;
struct ReplicaState
{
ReplicaState(Connection * connection_) : connection(connection_), packet_receiver(connection_)
explicit ReplicaState(Connection * connection_) : connection(connection_), packet_receiver(std::make_unique<PacketReceiver>(connection_))
{
}
Connection * connection = nullptr;
PacketReceiver packet_receiver;
PacketReceiverPtr packet_receiver;
TimerDescriptor change_replica_timeout;
};
@ -119,14 +120,16 @@ private:
void processReceivedFirstDataPacket(const ReplicaLocation & replica_location);
void tryGetNewReplica(bool start_new_connection);
void startNewReplica();
void checkNewReplica();
void processNewReplicaState(HedgedConnectionsFactory::State state, Connection * connection);
void finishProcessReplica(ReplicaState & replica, bool disconnect);
int getReadyFileDescriptor(AsyncCallback async_callback = {});
bool checkPendingData(ReplicaLocation & location_out);
HedgedConnectionsFactory hedged_connections_factory;
/// All replicas in offset_states[offset] is responsible for process query
@ -159,9 +162,7 @@ private:
/// If we didn't disabled it, we need to skip this replica.
bool disable_two_level_aggregation = false;
/// This flag means we need to get connection with new replica, but no replica is ready.
/// When it's true, hedged_connections_factory.getFileDescriptor() is in epoll.
bool next_replica_in_process = false;
Packet last_received_packet;
Epoll epoll;
const Settings & settings;

323
src/Client/HedgedConnectionsFactory.cpp
View File

@ -22,15 +22,12 @@ HedgedConnectionsFactory::HedgedConnectionsFactory(
{
shuffled_pools = pool->getShuffledPools(settings);
for (size_t i = 0; i != shuffled_pools.size(); ++i)
replicas.emplace_back(ConnectionEstablisher(shuffled_pools[i].pool, &timeouts, settings, table_to_check.get()));
replicas.emplace_back(ConnectionEstablisherAsync(shuffled_pools[i].pool, &timeouts, settings, log, table_to_check.get()));
max_tries
= (settings ? size_t{settings->connections_with_failover_max_tries} : size_t{DBMS_CONNECTION_POOL_WITH_FAILOVER_DEFAULT_MAX_TRIES});
fallback_to_stale_replicas = settings && settings->fallback_to_stale_replicas_for_distributed_queries;
entries_count = 0;
usable_count = 0;
failed_pools_count = 0;
}
HedgedConnectionsFactory::~HedgedConnectionsFactory()
@ -62,18 +59,22 @@ std::vector<Connection *> HedgedConnectionsFactory::getManyConnections(PoolMode
/// Try to start establishing connections with max_entries replicas.
for (size_t i = 0; i != max_entries; ++i)
{
int index = startEstablishingNewConnection(connection);
if (index == -1)
break;
if (replicas[index].is_ready)
++requested_connections_count;
State state = startNewConnectionImpl(connection);
if (state == State::READY)
connections.push_back(connection);
if (state == State::CANNOT_CHOOSE)
break;
}
/// Process connections until we get enough READY connections
/// (work asynchronously with all connections we started).
/// TODO: when we get GET_ALL mode we can start reading packets from ready
/// TODO: connection as soon as we got it, not even waiting for the others.
while (connections.size() < max_entries)
{
auto state = getNextConnection(false, true, connection);
/// Set blocking = true to avoid busy-waiting here.
auto state = waitForReadyConnections(/*blocking = */true, connection);
if (state == State::READY)
connections.push_back(connection);
else if (state == State::CANNOT_CHOOSE)
@ -82,29 +83,38 @@ std::vector<Connection *> HedgedConnectionsFactory::getManyConnections(PoolMode
break;
/// Determine the reason of not enough replicas.
if (!fallback_to_stale_replicas && usable_count >= min_entries)
throw DB::Exception(
if (!fallback_to_stale_replicas && up_to_date_count < min_entries)
throw Exception(
"Could not find enough connections to up-to-date replicas. Got: " + std::to_string(connections.size())
+ ", needed: " + std::to_string(min_entries),
DB::ErrorCodes::ALL_REPLICAS_ARE_STALE);
if (usable_count < min_entries)
throw NetException(
"All connection tries failed. Log: \n\n" + fail_messages + "\n",
DB::ErrorCodes::ALL_CONNECTION_TRIES_FAILED);
throw DB::NetException(
"All connection tries failed. Log: \n\n" + fail_messages + "\n",
DB::ErrorCodes::ALL_CONNECTION_TRIES_FAILED);
throw Exception("Unknown reason of not enough replicas.", ErrorCodes::LOGICAL_ERROR);
}
}
return connections;
}
HedgedConnectionsFactory::State HedgedConnectionsFactory::getNextConnection(bool start_new_connection, bool blocking, Connection *& connection_out)
HedgedConnectionsFactory::State HedgedConnectionsFactory::startNewConnection(Connection *& connection_out)
{
if (start_new_connection)
{
int index = startEstablishingNewConnection(connection_out);
if (index != -1 && replicas[index].is_ready)
return State::READY;
}
LOG_DEBUG(log, "startNewConnection");
++requested_connections_count;
State state = startNewConnectionImpl(connection_out);
/// If we cannot start new connection but there are connections in epoll, return NOT_READY.
if (state == State::CANNOT_CHOOSE && !epoll.empty())
state = State::NOT_READY;
return state;
}
HedgedConnectionsFactory::State HedgedConnectionsFactory::waitForReadyConnections(bool blocking, Connection *& connection_out)
{
LOG_DEBUG(log, "waitForReadyConnections");
State state = processEpollEvents(blocking, connection_out);
if (state != State::CANNOT_CHOOSE)
@ -120,24 +130,6 @@ HedgedConnectionsFactory::State HedgedConnectionsFactory::getNextConnection(bool
return setBestUsableReplica(connection_out);
}
void HedgedConnectionsFactory::stopChoosingReplicas()
{
for (auto & [fd, index] : fd_to_replica_index)
{
epoll.remove(fd);
replicas[index].connection_establisher.cancel();
}
for (auto & [fd, index] : timeout_fd_to_replica_index)
{
replicas[index].change_replica_timeout.reset();
epoll.remove(fd);
}
fd_to_replica_index.clear();
timeout_fd_to_replica_index.clear();
}
int HedgedConnectionsFactory::getNextIndex()
{
/// Check if there is no free replica.
@ -158,8 +150,7 @@ int HedgedConnectionsFactory::getNextIndex()
next_index = (next_index + 1) % shuffled_pools.size();
/// Check if we can try this replica.
if (!replicas[next_index].connection_establisher.isInProcess()
&& !replicas[next_index].connection_establisher.isFinished()
if (replicas[next_index].connection_establisher.getResult().entry.isNull()
&& (max_tries == 0 || shuffled_pools[next_index].error_count < max_tries))
finish = true;
@ -172,100 +163,34 @@ int HedgedConnectionsFactory::getNextIndex()
return next_index;
}
int HedgedConnectionsFactory::startEstablishingNewConnection(Connection *& connection_out)
HedgedConnectionsFactory::State HedgedConnectionsFactory::startNewConnectionImpl(Connection *& connection_out)
{
LOG_DEBUG(log, "startNewConnectionImpl");
int index;
State state;
do
{
index = getNextIndex();
if (index == -1)
return -1;
return State::CANNOT_CHOOSE;
ReplicaStatus & replica = replicas[index];
++replicas_in_process_count;
replica.connection_establisher.resume();
processConnectionEstablisherStage(index);
if (replica.connection_establisher.isInProcess())
{
epoll.add(replica.connection_establisher.getFileDescriptor());
fd_to_replica_index[replica.connection_establisher.getFileDescriptor()] = index;
/// Add timeout for changing replica.
replica.change_replica_timeout.setRelative(timeouts.hedged_connection_timeout);
epoll.add(replica.change_replica_timeout.getDescriptor());
timeout_fd_to_replica_index[replica.change_replica_timeout.getDescriptor()] = index;
}
state = resumeConnectionEstablisher(index, connection_out);
}
while (!replicas[index].connection_establisher.isInProcess() && !replicas[index].is_ready);
while (state == State::CANNOT_CHOOSE);
if (replicas[index].is_ready)
connection_out = replicas[index].connection_establisher.getConnection();
return index;
}
void HedgedConnectionsFactory::processConnectionEstablisherStage(int index, bool remove_from_epoll)
{
ReplicaStatus & replica = replicas[index];
if (replica.connection_establisher.isFinished())
{
--replicas_in_process_count;
++entries_count;
if (remove_from_epoll)
removeReplicaFromEpoll(index);
if (replica.connection_establisher.getResult().is_usable)
{
++usable_count;
if (replica.connection_establisher.getResult().is_up_to_date)
replica.is_ready = true;
return;
}
/// If replica is not usable, we need to save fail message.
if (!replica.connection_establisher.getFailMessage().empty())
fail_messages += replica.connection_establisher.getFailMessage() + "\n";
}
else if (replica.connection_establisher.isFailed())
processFailedConnection(index, remove_from_epoll);
}
void HedgedConnectionsFactory::processFailedConnection(int index, bool remove_from_epoll)
{
ConnectionEstablisher & connection_establisher = replicas[index].connection_establisher;
if (remove_from_epoll)
removeReplicaFromEpoll(index);
if (!connection_establisher.getFailMessage().empty())
fail_messages += connection_establisher.getFailMessage() + "\n";
ShuffledPool & shuffled_pool = shuffled_pools[index];
LOG_WARNING(
log, "Connection failed at try №{}, reason: {}", (shuffled_pool.error_count + 1), connection_establisher.getFailMessage());
ProfileEvents::increment(ProfileEvents::DistributedConnectionFailTry);
shuffled_pool.error_count = std::min(pool->getMaxErrorCup(), shuffled_pool.error_count + 1);
if (shuffled_pool.error_count >= max_tries)
{
++failed_pools_count;
ProfileEvents::increment(ProfileEvents::DistributedConnectionFailAtAll);
}
--replicas_in_process_count;
return state;
}
HedgedConnectionsFactory::State HedgedConnectionsFactory::processEpollEvents(bool blocking, Connection *& connection_out)
{
LOG_DEBUG(log, "processEpollEvents");
int event_fd;
while (!epoll.empty())
{
LOG_DEBUG(log, "loop");
event_fd = getReadyFileDescriptor(blocking);
if (event_fd == -1)
@ -274,24 +199,29 @@ HedgedConnectionsFactory::State HedgedConnectionsFactory::processEpollEvents(boo
if (fd_to_replica_index.contains(event_fd))
{
int index = fd_to_replica_index[event_fd];
processConnectionEstablisherEvent(index, connection_out);
if (replicas[index].is_ready)
return State::READY;
if (replicas[index].connection_establisher.isInProcess())
State state = resumeConnectionEstablisher(index, connection_out);
if (state == State::NOT_READY)
continue;
/// Connection establishing not in process now, remove all
/// information about it from epoll.
removeReplicaFromEpoll(index, event_fd);
if (state == State::READY)
return state;
}
else if (timeout_fd_to_replica_index.contains(event_fd))
{
LOG_DEBUG(log, "change_replica_timeout");
replicas[timeout_fd_to_replica_index[event_fd]].change_replica_timeout.reset();
}
else
throw Exception("Unknown event from epoll", ErrorCodes::LOGICAL_ERROR);
/// We reach this point only if we need to start new connection
/// (Special timeout expired or one of the previous connections failed).
int index = startEstablishingNewConnection(connection_out);
/// Return only if replica is ready.
if (index != -1 && replicas[index].is_ready)
if (startNewConnectionImpl(connection_out) == State::READY)
return State::READY;
}
@ -306,35 +236,138 @@ int HedgedConnectionsFactory::getReadyFileDescriptor(bool blocking)
return event.data.fd;
}
void HedgedConnectionsFactory::removeReplicaFromEpoll(int index)
HedgedConnectionsFactory::State HedgedConnectionsFactory::resumeConnectionEstablisher(int index, Connection *& connection_out)
{
ReplicaStatus & replica = replicas[index];
epoll.remove(replica.connection_establisher.getFileDescriptor());
fd_to_replica_index.erase(replica.connection_establisher.getFileDescriptor());
LOG_DEBUG(log, "resumeConnectionEstablisher");
replica.change_replica_timeout.reset();
epoll.remove(replica.change_replica_timeout.getDescriptor());
timeout_fd_to_replica_index.erase(replica.change_replica_timeout.getDescriptor());
auto res = replicas[index].connection_establisher.resume();
if (std::holds_alternative<TryResult>(res))
return processFinishedConnection(index, std::get<TryResult>(res), connection_out);
int fd = std::get<int>(res);
if (!fd_to_replica_index.contains(fd))
addNewReplicaToEpoll(index, fd);
return State::NOT_READY;
}
void HedgedConnectionsFactory::processConnectionEstablisherEvent(int index, Connection *& connection_out)
HedgedConnectionsFactory::State HedgedConnectionsFactory::processFinishedConnection(int index, TryResult result, Connection *& connection_out)
{
replicas[index].connection_establisher.resume();
processConnectionEstablisherStage(index, true);
if (replicas[index].is_ready)
connection_out = replicas[index].connection_establisher.getConnection();
LOG_DEBUG(log, "processFinishedConnection");
const std::string & fail_message = replicas[index].connection_establisher.getFailMessage();
if (!fail_message.empty())
fail_messages += fail_message + "\n";
if (!result.entry.isNull())
{
++entries_count;
if (result.is_usable)
{
++usable_count;
if (result.is_up_to_date)
{
++up_to_date_count;
if (!skip_predicate || !skip_predicate(&*result.entry))
{
replicas[index].is_ready = true;
++ready_replicas_count;
connection_out = &*result.entry;
return State::READY;
}
}
}
}
else
{
ShuffledPool & shuffled_pool = shuffled_pools[index];
LOG_WARNING(
log, "Connection failed at try №{}, reason: {}", (shuffled_pool.error_count + 1), fail_message);
ProfileEvents::increment(ProfileEvents::DistributedConnectionFailTry);
shuffled_pool.error_count = std::min(pool->getMaxErrorCup(), shuffled_pool.error_count + 1);
if (shuffled_pool.error_count >= max_tries)
{
++failed_pools_count;
ProfileEvents::increment(ProfileEvents::DistributedConnectionFailAtAll);
}
}
return State::CANNOT_CHOOSE;
}
void HedgedConnectionsFactory::stopChoosingReplicas()
{
LOG_DEBUG(log, "stopChoosingReplicas");
for (auto & [fd, index] : fd_to_replica_index)
{
--replicas_in_process_count;
epoll.remove(fd);
replicas[index].connection_establisher.cancel();
}
for (auto & [timeout_fd, index] : timeout_fd_to_replica_index)
{
replicas[index].change_replica_timeout.reset();
epoll.remove(timeout_fd);
}
fd_to_replica_index.clear();
timeout_fd_to_replica_index.clear();
}
void HedgedConnectionsFactory::addNewReplicaToEpoll(int index, int fd)
{
LOG_DEBUG(log, "addNewReplicaToEpoll");
++replicas_in_process_count;
epoll.add(fd);
fd_to_replica_index[fd] = index;
/// Add timeout for changing replica.
replicas[index].change_replica_timeout.setRelative(timeouts.hedged_connection_timeout);
epoll.add(replicas[index].change_replica_timeout.getDescriptor());
timeout_fd_to_replica_index[replicas[index].change_replica_timeout.getDescriptor()] = index;
}
void HedgedConnectionsFactory::removeReplicaFromEpoll(int index, int fd)
{
LOG_DEBUG(log, "removeReplicaFromEpoll");
--replicas_in_process_count;
epoll.remove(fd);
fd_to_replica_index.erase(fd);
replicas[index].change_replica_timeout.reset();
epoll.remove(replicas[index].change_replica_timeout.getDescriptor());
timeout_fd_to_replica_index.erase(replicas[index].change_replica_timeout.getDescriptor());
}
int HedgedConnectionsFactory::numberOfProcessingReplicas() const
{
if (epoll.empty())
return 0;
return requested_connections_count - ready_replicas_count;
}
HedgedConnectionsFactory::State HedgedConnectionsFactory::setBestUsableReplica(Connection *& connection_out)
{
LOG_DEBUG(log, "setBestUsableReplica");
std::vector<int> indexes;
for (size_t i = 0; i != replicas.size(); ++i)
{
/// Don't add unusable, failed replicas and replicas that are ready or in process.
if (!replicas[i].connection_establisher.getResult().entry.isNull()
&& replicas[i].connection_establisher.getResult().is_usable
&& !replicas[i].connection_establisher.isInProcess()
&& !replicas[i].is_ready)
TryResult result = replicas[i].connection_establisher.getResult();
if (!result.entry.isNull()
&& result.is_usable
&& !replicas[i].is_ready
&& (!skip_predicate || !skip_predicate(&*result.entry)))
indexes.push_back(i);
}
@ -350,9 +383,9 @@ HedgedConnectionsFactory::State HedgedConnectionsFactory::setBestUsableReplica(C
return replicas[lhs].connection_establisher.getResult().staleness < replicas[rhs].connection_establisher.getResult().staleness;
});
++ready_replicas_count;
replicas[indexes[0]].is_ready = true;
connection_out = replicas[indexes[0]].connection_establisher.getConnection();
TryResult result = replicas[indexes[0]].connection_establisher.getResult();
connection_out = &*result.entry;
return State::READY;
}

43
src/Client/HedgedConnectionsFactory.h
View File

@ -25,6 +25,7 @@ class HedgedConnectionsFactory
{
public:
using ShuffledPool = ConnectionPoolWithFailover::Base::ShuffledPool;
using TryResult = PoolWithFailoverBase<IConnectionPool>::TryResult;
enum class State
{
@ -35,11 +36,11 @@ public:
struct ReplicaStatus
{
ReplicaStatus(ConnectionEstablisher connection_stablisher_) : connection_establisher(std::move(connection_stablisher_))
explicit ReplicaStatus(ConnectionEstablisherAsync connection_stablisher_) : connection_establisher(std::move(connection_stablisher_))
{
}
ConnectionEstablisher connection_establisher;
ConnectionEstablisherAsync connection_establisher;
TimerDescriptor change_replica_timeout;
bool is_ready = false;
};
@ -57,10 +58,9 @@ public:
/// if there is no events in epoll and blocking is false, return NOT_READY.
/// Returned state might be READY, NOT_READY and CANNOT_CHOOSE.
/// If state is READY, replica connection will be written in connection_out.
State getNextConnection(bool start_new_connection, bool blocking, Connection *& connection_out);
State waitForReadyConnections(bool blocking, Connection *& connection_out);
/// Check if we can try to produce new READY replica.
// bool canGetNewConnection() const { return ready_replicas_count + failed_pools_count < shuffled_pools.size(); }
State startNewConnection(Connection *& connection_out);
/// Stop working with all replicas that are not READY.
void stopChoosingReplicas();
@ -71,14 +71,16 @@ public:
const ConnectionTimeouts & getConnectionTimeouts() const { return timeouts; }
int numberOfProcessingReplicas() const;
void setSkipPredicate(std::function<bool(Connection *)> pred) { skip_predicate = std::move(pred); }
~HedgedConnectionsFactory();
private:
/// Try to start establishing connection to the new replica. Return
/// the index of the new replica or -1 if cannot start new connection.
int startEstablishingNewConnection(Connection *& connection_out);
void processConnectionEstablisherStage(int replica_index, bool remove_from_epoll = false);
State startNewConnectionImpl(Connection *& connection_out);
/// Find an index of the next free replica to start connection.
/// Return -1 if there is no free replica.
@ -86,11 +88,15 @@ private:
int getReadyFileDescriptor(bool blocking);
void processFailedConnection(int replica_index, bool remove_from_epoll);
void processFailedConnection(int index, const std::string & fail_message);
void processConnectionEstablisherEvent(int replica_index, Connection *& connection_out);
State resumeConnectionEstablisher(int index, Connection *& connection_out);
void removeReplicaFromEpoll(int index);
State processFinishedConnection(int index, TryResult result, Connection *& connection_out);
void removeReplicaFromEpoll(int index, int fd);
void addNewReplicaToEpoll(int index, int fd);
/// Return NOT_READY state if there is no ready events, READY if replica is ready
/// and CANNOT_CHOOSE if there is no more events in epoll.
@ -111,10 +117,7 @@ private:
/// Map timeout for changing replica to replica index.
std::unordered_map<int, int> timeout_fd_to_replica_index;
/// Indexes of replicas, that are in process of connection.
size_t replicas_in_process_count = 0;
/// Indexes of ready replicas.
size_t ready_replicas_count = 0;
std::function<bool(Connection *)> skip_predicate;
std::shared_ptr<QualifiedTableName> table_to_check;
int last_used_index = -1;
@ -122,10 +125,14 @@ private:
Epoll epoll;
Poco::Logger * log;
std::string fail_messages;
size_t entries_count;
size_t usable_count;
size_t failed_pools_count;
size_t max_tries;
size_t entries_count = 0;
size_t usable_count = 0;
size_t up_to_date_count = 0;
size_t failed_pools_count= 0;
size_t replicas_in_process_count = 0;
size_t requested_connections_count = 0;
size_t ready_replicas_count = 0;
};
}

119
src/Client/PacketReceiver.h
View File

@ -2,41 +2,86 @@
#if defined(OS_LINUX)
#include <variant>
#include <Client/IConnections.h>
#include <Common/FiberStack.h>
#include <Common/Fiber.h>
#include <Common/Epoll.h>
#include <Common/TimerDescriptor.h>
namespace DB
{
namespace ErrorCodes
{
extern const int CANNOT_OPEN_FILE;
extern const int CANNOT_READ_FROM_SOCKET;
}
/// Class for nonblocking packet receiving. It runs connection->receivePacket
/// in fiber and sets special read callback which is called when
/// reading from socket blocks. When read callback is called,
/// socket and receive timeout are added in epoll and execution returns to the main program.
/// So, you can poll this epoll file descriptor to determine when to resume
/// packet receiving (beside polling epoll descriptor, you also need to check connection->hasPendingData(),
/// because small packet can be read in buffer with the previous one, so new packet will be ready in buffer,
/// but there is no data socket to poll).
/// packet receiving.
class PacketReceiver
{
public:
PacketReceiver(Connection * connection_) : connection(connection_)
explicit PacketReceiver(Connection * connection_) : connection(connection_)
{
epoll.add(receive_timeout.getDescriptor());
epoll.add(connection->getSocket()->impl()->sockfd());
if (-1 == pipe2(pipe_fd, O_NONBLOCK))
throwFromErrno("Cannot create pipe", ErrorCodes::CANNOT_OPEN_FILE);
epoll.add(pipe_fd[0]);
fiber = boost::context::fiber(std::allocator_arg_t(), fiber_stack, Routine{*this});
}
~PacketReceiver()
{
close(pipe_fd[0]);
close(pipe_fd[1]);
}
/// Resume packet receiving.
void resume()
std::variant<int, Packet, Poco::Timespan> resume()
{
/// If there is no pending data, check receive timeout.
if (!connection->hasReadPendingData() && !checkReceiveTimeout())
return;
{
/// Receive timeout expired.
return Poco::Timespan();
}
/// Resume fiber.
fiber = std::move(fiber).resume();
if (exception)
std::rethrow_exception(std::move(exception));
if (is_read_in_process)
return epoll.getFileDescriptor();
/// Write something in pipe when buffer has pending data, because
/// in this case socket won't be ready in epoll but we need to tell
/// outside that there is more data in buffer.
if (connection->hasReadPendingData())
{
uint64_t buf = 0;
while (-1 == write(pipe_fd[1], &buf, sizeof(buf)))
{
if (errno == EAGAIN)
break;
if (errno != EINTR)
throwFromErrno("Cannot write to pipe", ErrorCodes::CANNOT_READ_FROM_SOCKET);
}
}
/// Receiving packet was finished.
return std::move(packet);
}
void cancel()
@ -45,20 +90,16 @@ public:
connection = nullptr;
}
Packet getPacket() { return std::move(packet); }
int getFileDescriptor() const { return epoll.getFileDescriptor(); }
bool isPacketReady() const { return !is_read_in_process; }
bool isReceiveTimeoutExpired() const { return is_receive_timeout_expired; }
private:
/// When epoll file descriptor is ready, check if it's an expired timeout
/// When epoll file descriptor is ready, check if it's an expired timeout.
/// Return false if receive timeout expired and socket is not ready, return true otherwise.
bool checkReceiveTimeout()
{
bool is_socket_ready = false;
is_receive_timeout_expired = false;
bool is_pipe_ready = false;
bool is_receive_timeout_expired = false;
epoll_event events[2];
events[0].data.fd = events[1].data.fd = -1;
@ -68,10 +109,19 @@ private:
{
if (events[i].data.fd == connection->getSocket()->impl()->sockfd())
is_socket_ready = true;
if (events[i].data.fd == pipe_fd[0])
is_pipe_ready = true;
if (events[i].data.fd == receive_timeout.getDescriptor())
is_receive_timeout_expired = true;
}
if (is_pipe_ready)
{
LOG_DEBUG(&Poco::Logger::get("PacketReceiver"), "pipe");
drainPipe();
return true;
}
if (is_receive_timeout_expired && !is_socket_ready)
{
receive_timeout.reset();
@ -81,6 +131,23 @@ private:
return true;
}
void drainPipe()
{
uint64_t buf;
while (true)
{
ssize_t res = read(pipe_fd[0], &buf, sizeof(buf));
if (res < 0)
{
if (errno == EAGAIN)
break;
if (errno != EINTR)
throwFromErrno("Cannot drain pipe_fd", ErrorCodes::CANNOT_READ_FROM_SOCKET);
}
}
}
struct Routine
{
PacketReceiver & receiver;
@ -131,14 +198,28 @@ private:
};
Connection * connection;
TimerDescriptor receive_timeout;
Epoll epoll;
Packet packet;
Fiber fiber;
FiberStack fiber_stack;
Packet packet;
bool is_read_in_process = false;
bool is_receive_timeout_expired = false;
/// We use timer descriptor for checking socket receive timeout.
TimerDescriptor receive_timeout;
/// In read callback we add socket file descriptor and timer descriptor with receive timeout
/// in epoll, so we can return epoll file descriptor outside for polling.
Epoll epoll;
/// Pipe is used when there is pending data in buffer
/// after receiving packet socket won't be ready in epoll in this case),
/// so we add pipe_fd in epoll and write something in it to tell
/// outside that we are ready to receive new packet.
int pipe_fd[2];
/// If and exception occurred in fiber resume, we save it and rethrow.
std::exception_ptr exception;
bool is_read_in_process = false;
};
}

7
src/Common/Epoll.cpp
View File

@ -57,22 +57,19 @@ void Epoll::remove(int fd)
throwFromErrno("Cannot remove descriptor from epoll", DB::ErrorCodes::EPOLL_ERROR);
}
size_t Epoll::getManyReady(int max_events, epoll_event * events_out, bool blocking, AsyncCallback async_callback) const
size_t Epoll::getManyReady(int max_events, epoll_event * events_out, bool blocking) const
{
if (events_count == 0)
throw Exception("There is no events in epoll", ErrorCodes::LOGICAL_ERROR);
int ready_size;
int timeout = blocking && !async_callback ? -1 : 0;
int timeout = blocking ? -1 : 0;
do
{
ready_size = epoll_wait(epoll_fd, events_out, max_events, timeout);
if (ready_size == -1 && errno != EINTR)
throwFromErrno("Error in epoll_wait", DB::ErrorCodes::EPOLL_ERROR);
if (ready_size == 0 && blocking && async_callback)
async_callback(epoll_fd, 0, "epoll");
}
while (ready_size <= 0 && (ready_size != 0 || blocking));

9
src/Common/Epoll.h
View File

@ -31,10 +31,8 @@ public:
/// Get events from epoll. Events are written in events_out, this function returns an amount of ready events.
/// If blocking is false and there are no ready events,
/// return empty vector, otherwise wait for ready events. If blocking is true,
/// async_callback is given and there is no ready events, async_callback is called
/// with epoll file descriptor.
size_t getManyReady(int max_events, epoll_event * events_out, bool blocking, AsyncCallback async_callback = {}) const;
/// return empty vector, otherwise wait for ready events.
size_t getManyReady(int max_events, epoll_event * events_out, bool blocking) const;
int getFileDescriptor() const { return epoll_fd; }
@ -42,11 +40,14 @@ public:
bool empty() const { return events_count == 0; }
const std::string & getDescription() const { return fd_description; }
~Epoll();
private:
int epoll_fd;
std::atomic<int> events_count;
const std::string fd_description = "epoll";
};
}

6
src/IO/ReadBufferFromPocoSocket.cpp
View File

@ -4,6 +4,7 @@
#include <Common/Exception.h>
#include <Common/NetException.h>
#include <Common/Stopwatch.h>
#include <common/logger_useful.h>
namespace ProfileEvents
@ -34,11 +35,16 @@ bool ReadBufferFromPocoSocket::nextImpl()
/// Add more details to exceptions.
try
{
if (!async_callback)
LOG_DEBUG(&Poco::Logger::get("ReadBufferFromPocoSocket"), "Don't have async callback");
bytes_read = socket.impl()->receiveBytes(internal_buffer.begin(), internal_buffer.size(), flags);
/// If async_callback is specified, and read is blocking, run async_callback and try again later.
/// It is expected that file descriptor may be polled externally.
/// Note that receive timeout is not checked here. External code should check it while polling.
LOG_DEBUG(&Poco::Logger::get("ReadBufferFromPocoSocket"), "Don't have async callback");
while (bytes_read < 0 && async_callback && errno == EAGAIN)
{
async_callback(socket.impl()->sockfd(), socket.getReceiveTimeout(), socket_description);

3
src/Interpreters/tests/CMakeLists.txt
View File

@ -40,6 +40,9 @@ add_executable (in_join_subqueries_preprocessor in_join_subqueries_preprocessor.
target_link_libraries (in_join_subqueries_preprocessor PRIVATE clickhouse_aggregate_functions dbms clickhouse_parsers)
add_check(in_join_subqueries_preprocessor)
add_executable (context context.cpp)
target_link_libraries (context PRIVATE dbms)
if (OS_LINUX)
add_executable (internal_iotop internal_iotop.cpp)
target_link_libraries (internal_iotop PRIVATE dbms)

1
tests/integration/test_distributed_respect_user_timeouts/test.py
View File

@ -78,6 +78,7 @@ def _check_exception(exception, expected_tries=3):
expected_lines = (
'Code: 209, ' + EXCEPTION_NETWORK + EXCEPTION_TIMEOUT,
'Code: 209, ' + EXCEPTION_NETWORK + EXCEPTION_CONNECT,
EXCEPTION_TIMEOUT,
)
assert any(line.startswith(expected) for expected in expected_lines), \