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arangodb/arangod/Aql/SharedQueryState.cpp

106 lines
3.0 KiB
C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2018 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////
#include "SharedQueryState.h"
#include "Scheduler/Scheduler.h"
#include "Scheduler/SchedulerFeature.h"
#include "Logger/LogMacros.h"
using namespace arangodb;
using namespace arangodb::aql;
void SharedQueryState::invalidate() {
std::lock_guard<std::mutex> guard(_mutex);
_numWakeups += 1;
_wakeupCb = nullptr;
_valid = false;
// guard.unlock();
_cv.notify_all();
}
/// this has to stay for a backwards-compatible AQL HTTP API (hasMore).
void SharedQueryState::waitForAsyncWakeup() {
std::unique_lock<std::mutex> guard(_mutex);
TRI_ASSERT(!_wakeupCb);
_cv.wait(guard, [&] { return _numWakeups > 0; });
TRI_ASSERT(_numWakeups > 0);
_numWakeups--;
}
/// @brief setter for the continue handler:
/// We can either have a handler or a callback
void SharedQueryState::setWakeupHandler(std::function<bool()> const& cb) {
std::lock_guard<std::mutex> guard(_mutex);
_wakeupCb = cb;
}
void SharedQueryState::resetWakeupHandler() {
std::lock_guard<std::mutex> guard(_mutex);
_wakeupCb = nullptr;
}
/// execute the _continueCallback. must hold _mutex,
bool SharedQueryState::executeWakeupCallback() {
TRI_ASSERT(_valid);
TRI_ASSERT(_wakeupCb);
auto scheduler = SchedulerFeature::SCHEDULER;
if (ADB_UNLIKELY(scheduler == nullptr)) {
// We are shutting down
return false;
}
TRI_ASSERT(_numWakeups > 0);
if (_queuedWakeup) {
return false;
}
_queuedWakeup = true;
return scheduler->queue(RequestLane::CLIENT_AQL,
[self = shared_from_this(),
cb = _wakeupCb] () mutable {
while(true) {
bool cntn = false;
try {
cntn = cb();
} catch (std::exception const& ex) {
LOG_TOPIC("e988a", WARN, Logger::QUERIES)
<< "Exception when continuing rest handler: " << ex.what();
} catch (...) {
LOG_TOPIC("e988b", WARN, Logger::QUERIES)
<< "Exception when continuing rest handler";
}
std::lock_guard<std::mutex> guard(self->_mutex);
TRI_ASSERT(self->_numWakeups > 0);
if (cntn) {
cntn = (--(self->_numWakeups) > 0);
}
if (!cntn) {
self->_queuedWakeup = false;
break;
}
}
});
}