mirror of https://gitee.com/bigwinds/arangodb
120 lines
3.6 KiB
C++
120 lines
3.6 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2017 ArangoDB GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Max Neunhoeffer
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////////////////////////////////////////////////////////////////////////////////
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#include <thread>
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#include "RestServer/AqlFeature.h"
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#include "Aql/QueryRegistry.h"
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#include "Cluster/TraverserEngineRegistry.h"
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#include "FeaturePhases/V8FeaturePhase.h"
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#include "Logger/LogMacros.h"
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#include "Logger/Logger.h"
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#include "Logger/LoggerStream.h"
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#include "RestServer/QueryRegistryFeature.h"
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#include "RestServer/TraverserEngineRegistryFeature.h"
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using namespace arangodb::application_features;
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namespace {
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// number of leases currently handed out
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// the highest bit of the value has a special meaning
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// and must be masked out.
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// if it is set, then a new lease can be acquired.
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// if not set, then no new lease can be acquired.
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std::atomic<uint64_t> leases{0};
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static constexpr uint64_t readyBit = 0x8000000000000000ULL;
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} // namespace
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namespace arangodb {
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AqlFeature::AqlFeature(application_features::ApplicationServer& server)
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: ApplicationFeature(server, "Aql") {
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setOptional(false);
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startsAfter<V8FeaturePhase>();
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startsAfter<QueryRegistryFeature>();
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startsAfter<TraverserEngineRegistryFeature>();
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}
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AqlFeature::~AqlFeature() {
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// always clean up here
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::leases.fetch_and(~::readyBit);
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}
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bool AqlFeature::lease() noexcept {
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uint64_t previous = ::leases.fetch_add(1);
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if ((previous & ::readyBit) == 0) {
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// oops, no lease can be acquired yet.
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// revert the increase and return false
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::leases.fetch_sub(1);
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return false;
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}
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return true;
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}
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void AqlFeature::unlease() noexcept { ::leases.fetch_sub(1); }
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void AqlFeature::start() {
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::leases.fetch_or(::readyBit);
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LOG_TOPIC("cf921", DEBUG, Logger::QUERIES) << "AQL feature started";
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}
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void AqlFeature::stop() {
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::leases.fetch_and(~::readyBit);
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LOG_TOPIC("8ed81", DEBUG, Logger::QUERIES) << "AQL feature stopped";
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// Wait until all AQL queries are done
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auto queryRegistry = QueryRegistryFeature::registry();
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auto traverserEngineRegistry = TraverserEngineRegistryFeature::registry();
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TRI_ASSERT(queryRegistry != nullptr);
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TRI_ASSERT(traverserEngineRegistry != nullptr);
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while (true) {
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try {
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queryRegistry->destroyAll();
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traverserEngineRegistry->destroyAll();
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} catch (...) {
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// ignore errors here. if it fails, we'll try again in next round
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}
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uint64_t m = ::leases.load();
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TRI_ASSERT((m & ::readyBit) == 0);
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size_t n = queryRegistry->numberRegisteredQueries();
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size_t o = traverserEngineRegistry->numberRegisteredEngines();
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if (n == 0 && m == 0 && o == 0) {
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break;
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}
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LOG_TOPIC("63d54", DEBUG, Logger::QUERIES)
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<< "AQLFeature shutdown, waiting for " << o
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<< " registered traverser engines to terminate and for " << n
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<< " registered queries to terminate and for " << m
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<< " feature leases to be released";
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std::this_thread::sleep_for(std::chrono::milliseconds(250));
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}
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}
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} // namespace arangodb
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