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/**
* Copyright (C) 2020-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 <vector>
#include "mongo/db/cancelable_operation_context.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/pipeline/pipeline.h"
#include "mongo/db/repl/oplog_entry.h"
#include "mongo/db/s/resharding/donor_oplog_id_gen.h"
#include "mongo/executor/task_executor.h"
#include "mongo/util/future.h"
namespace mongo {
class OperationContext;
namespace resharding {
class OnInsertAwaitable {
public:
virtual ~OnInsertAwaitable() = default;
/**
* Returns a future that becomes ready when the {_id: lastSeen} document is no longer the last
* inserted document in the oplog buffer collection.
*/
virtual Future<void> awaitInsert(const ReshardingDonorOplogId& lastSeen) = 0;
};
} // namespace resharding
class ReshardingDonorOplogIteratorInterface {
public:
virtual ~ReshardingDonorOplogIteratorInterface() = default;
/**
* Returns the next batch of oplog entries to apply.
*
* - An empty vector is returned when there are no more oplog entries left to apply.
* - A non-immediately ready future is returned when the iterator has been exhausted, but the
* final oplog entry hasn't been returned yet.
*/
virtual ExecutorFuture<std::vector<repl::OplogEntry>> getNextBatch(
std::shared_ptr<executor::TaskExecutor> executor,
CancellationToken cancelToken,
CancelableOperationContextFactory factory) = 0;
};
/**
* Iterator for fetching batches of oplog entries from the oplog buffer collection for a particular
* donor shard.
*
* Instances of this class are not thread-safe.
*/
class ReshardingDonorOplogIterator : public ReshardingDonorOplogIteratorInterface {
public:
ReshardingDonorOplogIterator(NamespaceString oplogBufferNss,
ReshardingDonorOplogId resumeToken,
resharding::OnInsertAwaitable* insertNotifier);
/**
* Returns a pipeline for iterating the buffered copy of the donor's oplog.
*
* The documents returned by the pipeline have the oplog entries linked together with their
* preImage/postImage entries.
*/
std::unique_ptr<Pipeline, PipelineDeleter> makePipeline(
OperationContext* opCtx, std::shared_ptr<MongoProcessInterface> mongoProcessInterface);
ExecutorFuture<std::vector<repl::OplogEntry>> getNextBatch(
std::shared_ptr<executor::TaskExecutor> executor,
CancellationToken cancelToken,
CancelableOperationContextFactory factory) override;
static constexpr auto kActualOpFieldName = "actualOp"_sd;
static constexpr auto kPreImageOpFieldName = "preImageOp"_sd;
static constexpr auto kPostImageOpFieldName = "postImageOp"_sd;
private:
template <typename Callable>
auto _withTemporaryOperationContext(Callable&& callable);
std::vector<repl::OplogEntry> _fillBatch(Pipeline& pipeline);
const NamespaceString _oplogBufferNss;
ReshardingDonorOplogId _resumeToken;
// _insertNotifier is used to asynchronously wait for a document to be inserted into the oplog
// buffer collection by the ReshardingOplogFetcher after _pipeline is exhausted and the final
// oplog entry hasn't been reached yet.
resharding::OnInsertAwaitable* const _insertNotifier;
std::unique_ptr<Pipeline, PipelineDeleter> _pipeline;
bool _hasSeenFinalOplogEntry{false};
};
} // namespace mongo
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