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/**
* Copyright (C) 2021-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
#include <memory>
#include "mongo/db/client.h"
#include "mongo/db/service_context.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/util/cancellation.h"
#include "mongo/util/future.h"
#include "mongo/util/out_of_line_executor.h"
namespace mongo {
class OperationContext;
/**
* Wrapper class around an OperationContext that calls markKilled(ErrorCodes::Interrupted) when the
* supplied CancellationToken is canceled.
*
* This class is useful for having an OperationContext be interrupted when a CancellationToken is
* canceled. Note that OperationContext::getCancellationToken() is instead useful for having a
* CancellationToken be canceled when an OperationContext is interrupted. The combination of the two
* enables bridging between OperationContext interruption and CancellationToken cancellation
* arbitrarily.
*
* IMPORTANT: Executors are allowed to refuse work. markKilled(ErrorCodes::Interrupted) won't be
* called when the supplied CancellationToken is canceled if the task executor has already been shut
* down, for example. Use a task executor bound to the process lifetime if you must guarantee that
* the OperationContext is interrupted when the CancellationToken is canceled.
*/
class CancelableOperationContext {
public:
CancelableOperationContext(ServiceContext::UniqueOperationContext opCtx,
const CancellationToken& cancelToken,
ExecutorPtr executor);
CancelableOperationContext(const CancelableOperationContext&) = delete;
CancelableOperationContext& operator=(const CancelableOperationContext&) = delete;
CancelableOperationContext(CancelableOperationContext&&) = delete;
CancelableOperationContext& operator=(CancelableOperationContext&&) = delete;
~CancelableOperationContext();
OperationContext* get() const noexcept {
return _opCtx.get();
}
OperationContext* operator->() const noexcept {
return get();
}
OperationContext& operator*() const noexcept {
return *get();
}
private:
struct SharedBlock {
AtomicWord<bool> done{false};
};
const std::shared_ptr<SharedBlock> _sharedBlock;
const ServiceContext::UniqueOperationContext _opCtx;
const SemiFuture<void> _markKilledFinished;
};
/**
* A factory to create CancelableOperationContext objects that use the same CancelationToken and
* executor.
*/
class CancelableOperationContextFactory {
public:
CancelableOperationContextFactory(CancellationToken cancelToken, ExecutorPtr executor)
: _cancelToken{std::move(cancelToken)}, _executor{std::move(executor)} {}
CancelableOperationContext makeOperationContext(Client* client) const {
return CancelableOperationContext{client->makeOperationContext(), _cancelToken, _executor};
}
private:
const CancellationToken _cancelToken;
const ExecutorPtr _executor;
};
} // namespace mongo
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