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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery
#include "mongo/platform/basic.h"
#include "mongo/s/async_requests_sender.h"
#include <fmt/format.h>
#include <memory>
#include "mongo/client/remote_command_targeter.h"
#include "mongo/executor/remote_command_request.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/grid.h"
#include "mongo/s/hedge_options_util.h"
#include "mongo/transport/baton.h"
#include "mongo/transport/transport_layer.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"
using namespace fmt::literals;
namespace mongo {
namespace {
// Maximum number of retries for network and replication notMaster errors (per host).
const int kMaxNumFailedHostRetryAttempts = 3;
} // namespace
AsyncRequestsSender::AsyncRequestsSender(OperationContext* opCtx,
std::shared_ptr<executor::TaskExecutor> executor,
StringData dbName,
const std::vector<AsyncRequestsSender::Request>& requests,
const ReadPreferenceSetting& readPreference,
Shard::RetryPolicy retryPolicy)
: _opCtx(opCtx),
_db(dbName.toString()),
_readPreference(readPreference),
_retryPolicy(retryPolicy),
_subExecutor(std::move(executor)),
_subBaton(opCtx->getBaton()->makeSubBaton()) {
_remotesLeft = requests.size();
// Initialize command metadata to handle the read preference.
_metadataObj = readPreference.toContainingBSON();
_remotes.reserve(requests.size());
for (const auto& request : requests) {
// Kick off requests immediately.
_remotes.emplace_back(this, request.shardId, request.cmdObj).executeRequest();
}
}
AsyncRequestsSender::Response AsyncRequestsSender::next() noexcept {
invariant(!done());
_remotesLeft--;
// If we've been interrupted, the response queue should be filled with interrupted answers, go
// ahead and return one of those
if (!_interruptStatus.isOK()) {
return _responseQueue.pop(_opCtx);
}
// Try to pop a value from the queue
try {
return _responseQueue.pop(_opCtx);
} catch (const DBException& ex) {
// If we're interrupted, save that value and overwrite all outstanding requests (that we're
// not going to wait to collect)
_interruptStatus = ex.toStatus();
}
// Make failed responses for all outstanding remotes with the interruption status and push them
// onto the response queue
for (auto& remote : _remotes) {
if (!remote) {
_responseQueue.push(std::move(remote).makeFailedResponse(_interruptStatus));
}
}
// Stop servicing callbacks
_subBaton.shutdown();
// shutdown the scoped task executor
_subExecutor->shutdown();
return _responseQueue.pop(_opCtx);
}
void AsyncRequestsSender::stopRetrying() noexcept {
_stopRetrying = true;
}
bool AsyncRequestsSender::done() noexcept {
return !_remotesLeft;
}
AsyncRequestsSender::Request::Request(ShardId shardId, BSONObj cmdObj)
: shardId(shardId), cmdObj(cmdObj) {}
AsyncRequestsSender::RemoteData::RemoteData(AsyncRequestsSender* ars,
ShardId shardId,
BSONObj cmdObj)
: _ars(ars), _shardId(std::move(shardId)), _cmdObj(std::move(cmdObj)) {}
std::shared_ptr<Shard> AsyncRequestsSender::RemoteData::getShard() {
// TODO: Pass down an OperationContext* to use here.
return Grid::get(getGlobalServiceContext())->shardRegistry()->getShardNoReload(_shardId);
}
void AsyncRequestsSender::RemoteData::executeRequest() {
scheduleRequest()
.thenRunOn(*_ars->_subBaton)
.getAsync([this](StatusWith<RemoteCommandOnAnyCallbackArgs> rcr) {
_done = true;
if (rcr.isOK()) {
_ars->_responseQueue.push(
{std::move(_shardId), rcr.getValue().response, std::move(_shardHostAndPort)});
} else {
_ars->_responseQueue.push(
{std::move(_shardId), rcr.getStatus(), std::move(_shardHostAndPort)});
}
});
}
auto AsyncRequestsSender::RemoteData::scheduleRequest()
-> SemiFuture<RemoteCommandOnAnyCallbackArgs> {
return resolveShardIdToHostAndPorts(_ars->_readPreference)
.thenRunOn(*_ars->_subBaton)
.then([this](auto&& hostAndPorts) {
_shardHostAndPort.emplace(hostAndPorts.front());
return scheduleRemoteCommand(std::move(hostAndPorts));
})
.then([this](auto&& rcr) { return handleResponse(std::move(rcr)); })
.semi();
}
SemiFuture<std::vector<HostAndPort>> AsyncRequestsSender::RemoteData::resolveShardIdToHostAndPorts(
const ReadPreferenceSetting& readPref) {
const auto shard = getShard();
if (!shard) {
return Status(ErrorCodes::ShardNotFound,
str::stream() << "Could not find shard " << _shardId);
}
return shard->getTargeter()->findHostsWithMaxWait(readPref, Seconds(20));
}
auto AsyncRequestsSender::RemoteData::scheduleRemoteCommand(std::vector<HostAndPort>&& hostAndPorts)
-> SemiFuture<RemoteCommandOnAnyCallbackArgs> {
auto hedgeOptions = extractHedgeOptions(_ars->_opCtx, _cmdObj);
executor::RemoteCommandRequestOnAny request(std::move(hostAndPorts),
_ars->_db,
_cmdObj,
_ars->_metadataObj,
_ars->_opCtx,
hedgeOptions);
// We have to make a promise future pair because the TaskExecutor doesn't currently support a
// future returning variant of scheduleRemoteCommand
auto [p, f] = makePromiseFuture<RemoteCommandOnAnyCallbackArgs>();
// Failures to schedule skip the retry loop
uassertStatusOK(_ars->_subExecutor->scheduleRemoteCommandOnAny(
request,
// We have to make a shared_ptr<Promise> here because scheduleRemoteCommand requires
// copyable callbacks
[p = std::make_shared<Promise<RemoteCommandOnAnyCallbackArgs>>(std::move(p))](
const RemoteCommandOnAnyCallbackArgs& cbData) { p->emplaceValue(cbData); },
*_ars->_subBaton));
return std::move(f).semi();
}
auto AsyncRequestsSender::RemoteData::handleResponse(RemoteCommandOnAnyCallbackArgs&& rcr)
-> SemiFuture<RemoteCommandOnAnyCallbackArgs> {
if (rcr.response.target) {
_shardHostAndPort = rcr.response.target;
}
auto status = rcr.response.status;
if (status.isOK()) {
status = getStatusFromCommandResult(rcr.response.data);
}
if (status.isOK()) {
status = getWriteConcernStatusFromCommandResult(rcr.response.data);
}
// If we're okay (RemoteCommandResponse, command result and write concern)-wise we're done.
// Otherwise check for retryability
if (status.isOK()) {
return std::move(rcr);
}
// There was an error with either the response or the command.
auto shard = getShard();
if (!shard) {
uasserted(ErrorCodes::ShardNotFound, str::stream() << "Could not find shard " << _shardId);
} else {
std::vector<HostAndPort> failedTargets;
if (rcr.response.target) {
failedTargets = {*rcr.response.target};
} else {
failedTargets = rcr.request.target;
}
shard->updateReplSetMonitor(failedTargets.front(), status);
if (!_ars->_stopRetrying && shard->isRetriableError(status.code(), _ars->_retryPolicy) &&
_retryCount < kMaxNumFailedHostRetryAttempts) {
LOG(1) << "Command to remote " << _shardId
<< (failedTargets.empty()
? " "
: (failedTargets.size() > 1 ? " for hosts " : " at host "))
<< "{}"_format(fmt::join(failedTargets, ", "))
<< "failed with retriable error and will be retried "
<< causedBy(redact(status));
++_retryCount;
_shardHostAndPort.reset();
// retry through recursion
return scheduleRequest();
}
}
// Status' in the response.status field that aren't retried get converted to top level errors
uassertStatusOK(rcr.response.status);
// We're not okay (on the remote), but still not going to retry
return std::move(rcr);
};
} // namespace mongo
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