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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.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/s/resharding/resharding_donor_recipient_common.h"
#include <fmt/format.h>
namespace mongo {
namespace resharding {
using DonorStateMachine = ReshardingDonorService::DonorStateMachine;
using RecipientStateMachine = ReshardingRecipientService::RecipientStateMachine;
namespace {
using namespace fmt::literals;
std::vector<DonorShardMirroringEntry> createDonorShardMirroringEntriesFromDonorShardIds(
const std::vector<ShardId>& shardIds) {
std::vector<DonorShardMirroringEntry> donorShards(shardIds.size());
for (size_t i = 0; i < shardIds.size(); ++i) {
donorShards[i] = {shardIds[i], false /* mirroring */};
}
return donorShards;
}
/*
* Creates a ReshardingStateMachine with the assumption that the state machine does not already
* exist.
*/
template <class Service, class StateMachine, class ReshardingDocument>
void createReshardingStateMachine(OperationContext* opCtx, const ReshardingDocument& doc) {
auto registry = repl::PrimaryOnlyServiceRegistry::get(opCtx->getServiceContext());
auto service = registry->lookupServiceByName(Service::kServiceName);
StateMachine::getOrCreate(opCtx, service, doc.toBSON());
}
/*
* Either constructs a new ReshardingDonorStateMachine with 'reshardingFields' or passes
* 'reshardingFields' to an already-existing ReshardingDonorStateMachine.
*/
void processReshardingFieldsForDonorCollection(OperationContext* opCtx,
const NamespaceString& nss,
const CollectionMetadata& metadata,
const ReshardingFields& reshardingFields) {
if (auto donorStateMachine = tryGetReshardingStateMachine<ReshardingDonorService,
DonorStateMachine,
ReshardingDonorDocument>(
opCtx, reshardingFields.getUuid())) {
donorStateMachine->get()->onReshardingFieldsChanges(reshardingFields);
return;
}
// If a resharding operation is BEFORE state kPreparingToDonate, then the config.collections
// entry won't have yet been created for the temporary resharding collection. The
// DonorStateMachine refreshes the temporary resharding collection immediately after being
// constructed. Accordingly, we avoid constructing the DonorStateMachine until the collection
// entry for the temporary resharding collection is known to exist.
//
// If a resharding operation is PAST state kPreparingToDonate, but does not currently have a
// donor document in-memory, this means that the document will be recovered by the
// ReshardingDonorService. Accordingly, at time-of-recovery, the latest instance of
// 'reshardingFields' will be read. Return no-op.
if (reshardingFields.getState() != CoordinatorStateEnum::kPreparingToDonate) {
return;
}
// This could be a shard not indicated as a donor that's trying to refresh the source
// collection. In this case, we don't want to create a donor machine.
if (!metadata.currentShardHasAnyChunks()) {
return;
}
auto donorDoc = constructDonorDocumentFromReshardingFields(nss, metadata, reshardingFields);
createReshardingStateMachine<ReshardingDonorService,
DonorStateMachine,
ReshardingDonorDocument>(opCtx, donorDoc);
}
/*
* Either constructs a new ReshardingRecipientStateMachine with 'reshardingFields' or passes
* 'reshardingFields' to an already-existing ReshardingRecipientStateMachine.
*/
void processReshardingFieldsForRecipientCollection(OperationContext* opCtx,
const CollectionMetadata& metadata,
const ReshardingFields& reshardingFields) {
if (auto recipientStateMachine = tryGetReshardingStateMachine<ReshardingRecipientService,
RecipientStateMachine,
ReshardingRecipientDocument>(
opCtx, reshardingFields.getUuid())) {
recipientStateMachine->get()->onReshardingFieldsChanges(reshardingFields);
return;
}
// If a resharding operation is past state kCloning but does not currently have a recipient
// document in-memory, this means that the document will be recovered by the
// ReshardingRecipientService, and at that time the latest instance of 'reshardingFields'
// will be read. Return no-op.
//
// The RecipientStateMachine creates the temporary resharding collection immediately after being
// constructed. If a resharding operation has yet to reach state kCloning, then some donor
// shards may not be prepared for the recipient to start cloning. We avoid constructing the
// RecipientStateMachine until all donor shards are known to be prepared for the recipient to
// start cloning.
if (reshardingFields.getState() != CoordinatorStateEnum::kCloning) {
return;
}
// This could be a shard not indicated as a recipient that's trying to refresh the temporary
// collection. In this case, we don't want to create a recipient machine.
if (!metadata.currentShardHasAnyChunks()) {
return;
}
auto recipientDoc =
constructRecipientDocumentFromReshardingFields(opCtx, metadata, reshardingFields);
createReshardingStateMachine<ReshardingRecipientService,
RecipientStateMachine,
ReshardingRecipientDocument>(opCtx, recipientDoc);
}
} // namespace
ReshardingDonorDocument constructDonorDocumentFromReshardingFields(
const NamespaceString& nss,
const CollectionMetadata& metadata,
const ReshardingFields& reshardingFields) {
auto donorDoc = ReshardingDonorDocument(DonorStateEnum::kPreparingToDonate);
auto commonMetadata =
CommonReshardingMetadata(reshardingFields.getUuid(),
nss,
getCollectionUUIDFromChunkManger(nss, *metadata.getChunkManager()),
reshardingFields.getDonorFields()->getReshardingKey().toBSON());
donorDoc.setCommonReshardingMetadata(std::move(commonMetadata));
return donorDoc;
}
ReshardingRecipientDocument constructRecipientDocumentFromReshardingFields(
OperationContext* opCtx,
const CollectionMetadata& metadata,
const ReshardingFields& reshardingFields) {
std::vector<DonorShardMirroringEntry> donorShards =
createDonorShardMirroringEntriesFromDonorShardIds(
reshardingFields.getRecipientFields()->getDonorShardIds());
auto recipientDoc = ReshardingRecipientDocument(RecipientStateEnum::kCreatingCollection,
std::move(donorShards));
auto commonMetadata =
CommonReshardingMetadata(reshardingFields.getUuid(),
reshardingFields.getRecipientFields()->getOriginalNamespace(),
reshardingFields.getRecipientFields()->getExistingUUID(),
metadata.getShardKeyPattern().toBSON());
recipientDoc.setCommonReshardingMetadata(std::move(commonMetadata));
emplaceFetchTimestampIfExists(recipientDoc,
reshardingFields.getRecipientFields()->getFetchTimestamp());
return recipientDoc;
}
void processReshardingFieldsForCollection(OperationContext* opCtx,
const NamespaceString& nss,
const CollectionMetadata& metadata,
const ReshardingFields& reshardingFields) {
auto coordinatorState = reshardingFields.getState();
if (coordinatorState != CoordinatorStateEnum::kError) {
if (coordinatorState < CoordinatorStateEnum::kDecisionPersisted) {
// Prior to the state CoordinatorStateEnum::kDecisionPersisted, only the source
// collection's config.collections entry should have donorFields, and only the
// temporary resharding collection's entry should have recipientFields.
uassert(
5274201,
fmt::format("reshardingFields must contain either donorFields or recipientFields "
"(and not both) when the "
"coordinator is in state {}. Got reshardingFields {}",
CoordinatorState_serializer(reshardingFields.getState()),
reshardingFields.toBSON().toString()),
reshardingFields.getDonorFields().is_initialized() ^
reshardingFields.getRecipientFields().is_initialized());
} else {
// At and after state CoordinatorStateEnum::kDecisionPersisted, the temporary
// resharding collection's config.collections entry has been removed, and so the
// source collection's entry should have both donorFields and recipientFields.
uassert(
5274202,
fmt::format("reshardingFields must contain both donorFields and recipientFields "
"when the coordinator's state is greater than or equal to "
"CoordinatorStateEnum::kDecisionPersisted. Got reshardingFields {}",
reshardingFields.toBSON().toString()),
reshardingFields.getDonorFields() && reshardingFields.getRecipientFields());
}
}
if (reshardingFields.getDonorFields()) {
processReshardingFieldsForDonorCollection(opCtx, nss, metadata, reshardingFields);
}
if (reshardingFields.getRecipientFields()) {
processReshardingFieldsForRecipientCollection(opCtx, metadata, reshardingFields);
}
}
} // namespace resharding
} // namespace mongo
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