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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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kCommand
#include "mongo/platform/basic.h"
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/db/pipeline/document_source_check_invalidate.h"
#include "mongo/util/log.h"
namespace mongo {
using DSCS = DocumentSourceChangeStream;
namespace {
// Returns true if the given 'operationType' should invalidate the change stream based on the
// namespace in 'pExpCtx'.
bool isInvalidatingCommand(const boost::intrusive_ptr<ExpressionContext>& pExpCtx,
StringData operationType) {
if (pExpCtx->isSingleNamespaceAggregation()) {
return operationType == DSCS::kDropCollectionOpType ||
operationType == DSCS::kRenameCollectionOpType ||
operationType == DSCS::kDropDatabaseOpType;
} else if (!pExpCtx->isClusterAggregation()) {
return operationType == DSCS::kDropDatabaseOpType;
} else {
return false;
}
};
} // namespace
DocumentSource::GetNextResult DocumentSourceCheckInvalidate::doGetNext() {
if (_queuedInvalidate) {
const auto res = DocumentSource::GetNextResult(std::move(_queuedInvalidate.get()));
_queuedInvalidate.reset();
return res;
}
auto nextInput = pSource->getNext();
if (!nextInput.isAdvanced())
return nextInput;
auto doc = nextInput.getDocument();
const auto& kOperationTypeField = DSCS::kOperationTypeField;
DSCS::checkValueType(doc[kOperationTypeField], kOperationTypeField, BSONType::String);
auto operationType = doc[kOperationTypeField].getString();
// If this command should invalidate the stream, generate an invalidate entry and queue it up
// to be returned after the notification of this command. The new entry will have a nearly
// identical resume token to the notification for the command, except with an extra flag
// indicating that the token is from an invalidate. This flag is necessary to disambiguate
// the two tokens, and thus preserve a total ordering on the stream.
if (isInvalidatingCommand(pExpCtx, operationType)) {
auto resumeTokenData = ResumeToken::parse(doc[DSCS::kIdField].getDocument()).getData();
resumeTokenData.fromInvalidate = ResumeTokenData::FromInvalidate::kFromInvalidate;
// If a client receives an invalidate and wants to start a new stream after the invalidate,
// they can use the 'startAfter' option. In this case, '_startAfterInvalidate' will be set
// to the resume token with which the client restarted the stream. We must be sure to avoid
// re-invalidating the new stream, and so we will swallow the first invalidate we see on
// each shard. The one exception is the invalidate which matches the 'startAfter' resume
// token. We must re-generate this invalidate, since DSEnsureResumeTokenPresent needs to see
// (and will take care of swallowing) the event which exactly matches the client's token.
if (_startAfterInvalidate && resumeTokenData != _startAfterInvalidate) {
_startAfterInvalidate.reset();
return nextInput;
}
auto resumeTokenDoc = ResumeToken(resumeTokenData).toDocument();
MutableDocument result(Document{{DSCS::kIdField, resumeTokenDoc},
{DSCS::kOperationTypeField, DSCS::kInvalidateOpType},
{DSCS::kClusterTimeField, doc[DSCS::kClusterTimeField]}});
result.copyMetaDataFrom(doc);
// We set the resume token as the document's sort key in both the sharded and non-sharded
// cases, since we will later rely upon it to generate a correct postBatchResumeToken. We
// must therefore update the sort key to match the new resume token that we generated above.
const bool isSingleElementKey = true;
result.metadata().setSortKey(Value{resumeTokenDoc}, isSingleElementKey);
_queuedInvalidate = result.freeze();
}
// Regardless of whether the first document we see is an invalidating command, we only skip the
// first invalidate for streams with the 'startAfter' option, so we should not skip any
// invalidates that come after the first one.
_startAfterInvalidate.reset();
return nextInput;
}
} // namespace mongo
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