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/**
* Copyright (C) 2018-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 "mongo/db/exec/requires_collection_stage.h"
#include "mongo/db/exec/write_stage_common.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/session/logical_session_id.h"
#include "mongo/db/shard_role.h"
#include "mongo/db/storage/remove_saver.h"
namespace mongo {
class CanonicalQuery;
class OpDebug;
class OperationContext;
class PlanExecutor;
struct DeleteStageParams {
using DocumentCounter = std::function<size_t(const BSONObj&)>;
DeleteStageParams()
: isMulti(false),
fromMigrate(false),
isExplain(false),
returnDeleted(false),
canonicalQuery(nullptr),
opDebug(nullptr) {}
// Should we delete all documents returned from the child (a "multi delete"), or at most one
// (a "single delete")?
bool isMulti;
// Is this delete part of a migrate operation that is essentially like a no-op
// when the cluster is observed by an external client.
bool fromMigrate;
// Are we explaining a delete command rather than actually executing it?
bool isExplain;
// Should we return the document we just deleted?
bool returnDeleted;
// The stmtId for this particular delete.
StmtId stmtId = kUninitializedStmtId;
// The parsed query predicate for this delete. Not owned here.
CanonicalQuery* canonicalQuery;
// The user-requested sort specification. Currently used just for findAndModify.
BSONObj sort;
// Optional. When not null, delete metrics are recorded here.
OpDebug* opDebug;
// Optional. When not null, send document about to be deleted to removeSaver.
// RemoveSaver is called before actual deletes are executed.
// Note: the differentiating factor between this and returnDeleted is that the caller will get
// the deleted document after it was already deleted. That means that if the caller would have
// to use the removeSaver at that point, they miss the document if the process dies before it
// reaches the removeSaver. However, this is still best effort since the RemoveSaver
// operates on a different persistence system from the the database storage engine.
std::unique_ptr<RemoveSaver> removeSaver;
// Determines how the delete stats should be incremented. Will be incremented by 1 if the
// function is empty.
DocumentCounter numStatsForDoc;
};
/**
* This stage delete documents by RecordId that are returned from its child. If the deleted
* document was requested to be returned, then ADVANCED is returned after deleting a document.
* Otherwise, NEED_TIME is returned after deleting a document.
*
* Callers of work() must be holding a write lock (and, for replicated deletes, callers must have
* had the replication coordinator approve the write).
*/
class DeleteStage : public RequiresMutableCollectionStage {
DeleteStage(const DeleteStage&) = delete;
DeleteStage& operator=(const DeleteStage&) = delete;
public:
static constexpr StringData kStageType = "DELETE"_sd;
DeleteStage(ExpressionContext* expCtx,
std::unique_ptr<DeleteStageParams> params,
WorkingSet* ws,
const ScopedCollectionAcquisition& collection,
PlanStage* child);
DeleteStage(const char* stageType,
ExpressionContext* expCtx,
std::unique_ptr<DeleteStageParams> params,
WorkingSet* ws,
const ScopedCollectionAcquisition& collection,
PlanStage* child);
bool isEOF();
StageState doWork(WorkingSetID* out);
StageType stageType() const {
return STAGE_DELETE;
}
std::unique_ptr<mongo::PlanStageStats> getStats();
const SpecificStats* getSpecificStats() const;
protected:
void doSaveStateRequiresCollection() final {
_preWriteFilter.saveState();
}
void doRestoreStateRequiresCollection() final;
std::unique_ptr<DeleteStageParams> _params;
// Not owned by us.
WorkingSet* _ws;
// Stats
DeleteStats _specificStats;
/**
* This member is used to check whether the write should be performed, and if so, any other
* behavior that should be done as part of the write (e.g. skipping it because it affects an
* orphan document). A yield cannot happen between the check and the write, so the checks are
* embedded in the stage.
*
* It's refreshed after yielding and reacquiring the locks.
*/
write_stage_common::PreWriteFilter _preWriteFilter;
private:
/**
* Stores 'idToRetry' in '_idRetrying' so the delete can be retried during the next call to
* work(). Sets 'out' to WorkingSet::INVALID_ID.
*/
void prepareToRetryWSM(WorkingSetID idToRetry, WorkingSetID* out);
// If not WorkingSet::INVALID_ID, we use this rather than asking our child what to do next.
WorkingSetID _idRetrying;
// If not WorkingSet::INVALID_ID, we return this member to our caller.
WorkingSetID _idReturning;
};
} // namespace mongo
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