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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.
*/
#include "mongo/s/query/document_source_update_on_add_shard.h"
#include <algorithm>
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/grid.h"
#include "mongo/s/query/async_results_merger_params_gen.h"
#include "mongo/s/query/establish_cursors.h"
namespace mongo {
namespace {
// Returns true if the change stream document has an 'operationType' of 'newShardDetected'.
bool needsUpdate(const Document& childResult) {
return childResult[DocumentSourceChangeStream::kOperationTypeField].getStringData() ==
DocumentSourceChangeStream::kNewShardDetectedOpType;
}
} // namespace
boost::intrusive_ptr<DocumentSourceUpdateOnAddShard> DocumentSourceUpdateOnAddShard::create(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
executor::TaskExecutor* executor,
const boost::intrusive_ptr<DocumentSourceMergeCursors>& mergeCursors,
std::vector<ShardId> shardsWithCursors,
BSONObj cmdToRunOnNewShards) {
return new DocumentSourceUpdateOnAddShard(
expCtx, executor, mergeCursors, std::move(shardsWithCursors), cmdToRunOnNewShards);
}
DocumentSourceUpdateOnAddShard::DocumentSourceUpdateOnAddShard(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
executor::TaskExecutor* executor,
const boost::intrusive_ptr<DocumentSourceMergeCursors>& mergeCursors,
std::vector<ShardId>&& shardsWithCursors,
BSONObj cmdToRunOnNewShards)
: DocumentSource(expCtx),
_executor(executor),
_mergeCursors(mergeCursors),
_shardsWithCursors(std::move(shardsWithCursors)),
_cmdToRunOnNewShards(cmdToRunOnNewShards.getOwned()) {}
DocumentSource::GetNextResult DocumentSourceUpdateOnAddShard::getNext() {
auto childResult = pSource->getNext();
while (childResult.isAdvanced() && needsUpdate(childResult.getDocument())) {
addNewShardCursors(childResult.getDocument());
childResult = pSource->getNext();
}
return childResult;
}
void DocumentSourceUpdateOnAddShard::addNewShardCursors(const Document& newShardDetectedObj) {
_mergeCursors->addNewShardCursors(establishShardCursorsOnNewShards(newShardDetectedObj));
}
std::vector<RemoteCursor> DocumentSourceUpdateOnAddShard::establishShardCursorsOnNewShards(
const Document& newShardDetectedObj) {
auto* opCtx = pExpCtx->opCtx;
// Reload the shard registry. We need to ensure a reload initiated after calling this method
// caused the reload, otherwise we aren't guaranteed to get all the new shards.
auto* shardRegistry = Grid::get(opCtx)->shardRegistry();
if (!shardRegistry->reload(opCtx)) {
// A 'false' return from shardRegistry.reload() means a reload was already in progress and
// it completed before reload() returned. So another reload(), regardless of return value,
// will ensure a reload started after the first call to reload().
shardRegistry->reload(opCtx);
}
std::vector<ShardId> shardIds, newShardIds;
shardRegistry->getAllShardIdsNoReload(&shardIds);
std::sort(_shardsWithCursors.begin(), _shardsWithCursors.end());
std::sort(shardIds.begin(), shardIds.end());
std::set_difference(shardIds.begin(),
shardIds.end(),
_shardsWithCursors.begin(),
_shardsWithCursors.end(),
std::back_inserter(newShardIds));
auto cmdObj = DocumentSourceChangeStream::replaceResumeTokenInCommand(
_cmdToRunOnNewShards,
newShardDetectedObj[DocumentSourceChangeStream::kIdField].getDocument());
std::vector<std::pair<ShardId, BSONObj>> requests;
for (const auto& shardId : newShardIds) {
requests.emplace_back(shardId, cmdObj);
_shardsWithCursors.push_back(shardId);
}
const bool allowPartialResults = false; // partial results are not allowed
return establishCursors(opCtx,
_executor,
pExpCtx->ns,
ReadPreferenceSetting::get(opCtx),
requests,
allowPartialResults);
}
} // namespace mongo
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