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Diffstat (limited to 'src/mongo/util/concurrency/semaphore_ticketholder.h')
-rw-r--r-- | src/mongo/util/concurrency/semaphore_ticketholder.h | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/src/mongo/util/concurrency/semaphore_ticketholder.h b/src/mongo/util/concurrency/semaphore_ticketholder.h new file mode 100644 index 00000000000..56606c3da2e --- /dev/null +++ b/src/mongo/util/concurrency/semaphore_ticketholder.h @@ -0,0 +1,100 @@ +/** + * Copyright (C) 2022-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. + */ +#pragma once + +#if defined(__linux__) +#include <semaphore.h> +#endif + +#include <queue> + +#include "mongo/db/operation_context.h" +#include "mongo/db/service_context.h" +#include "mongo/platform/mutex.h" +#include "mongo/stdx/condition_variable.h" +#include "mongo/util/concurrency/admission_context.h" +#include "mongo/util/concurrency/mutex.h" +#include "mongo/util/concurrency/ticket_queues.h" +#include "mongo/util/concurrency/ticketholder.h" +#include "mongo/util/hierarchical_acquisition.h" +#include "mongo/util/time_support.h" + +namespace mongo { + +class SemaphoreTicketHolder final : public TicketHolderWithQueueingStats { +public: + explicit SemaphoreTicketHolder(int numTickets, ServiceContext* serviceContext); + ~SemaphoreTicketHolder() override final; + + int available() const override final; + + int queued() const override final { + auto removed = _semaphoreStats.totalRemovedQueue.loadRelaxed(); + auto added = _semaphoreStats.totalAddedQueue.loadRelaxed(); + return std::max(static_cast<int>(added - removed), 0); + }; + + bool recordImmediateTicketStatistics() noexcept override final { + // Historically, operations that now acquire 'immediate' tickets bypassed the ticketing + // mechanism completely. Preserve legacy behavior where 'immediate' ticketing is not tracked + // in the statistics. + return false; + } + +private: + boost::optional<Ticket> _waitForTicketUntilImpl(OperationContext* opCtx, + AdmissionContext* admCtx, + Date_t until, + WaitMode waitMode) override final; + + boost::optional<Ticket> _tryAcquireImpl(AdmissionContext* admCtx) override final; + void _releaseToTicketPoolImpl(AdmissionContext* admCtx) noexcept override final; + + void _appendImplStats(BSONObjBuilder& b) const override final; + + void _resize(int newSize, int oldSize) noexcept override final; + + QueueStats& _getQueueStatsToUse(const AdmissionContext* admCtx) noexcept override final { + return _semaphoreStats; + } +#if defined(__linux__) + mutable sem_t _sem; + +#else + bool _tryAcquire(); + + int _numTickets; + Mutex _mutex = + MONGO_MAKE_LATCH(HierarchicalAcquisitionLevel(0), "SemaphoreTicketHolder::_mutex"); + stdx::condition_variable _newTicket; +#endif + QueueStats _semaphoreStats; +}; + +} // namespace mongo |