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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/platform/basic.h"
#include "mongo/db/s/metadata_manager.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/simple_bsonobj_comparator.h"
#include "mongo/bson/util/builder.h"
#include "mongo/db/query/internal_plans.h"
#include "mongo/db/range_arithmetic.h"
#include "mongo/db/s/migration_util.h"
#include "mongo/db/s/range_deletion_util.h"
#include "mongo/db/s/sharding_runtime_d_params_gen.h"
#include "mongo/logv2/log.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/time_support.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kSharding
namespace mongo {
namespace {
using TaskExecutor = executor::TaskExecutor;
using CallbackArgs = TaskExecutor::CallbackArgs;
/**
* Returns whether the given metadata object has a chunk owned by this shard that overlaps the
* input range.
*/
bool metadataOverlapsRange(const CollectionMetadata& metadata, const ChunkRange& range) {
auto chunkRangeToCompareToMetadata =
migrationutil::extendOrTruncateBoundsForMetadata(metadata, range);
return metadata.rangeOverlapsChunk(chunkRangeToCompareToMetadata);
}
bool metadataOverlapsRange(const boost::optional<CollectionMetadata>& metadata,
const ChunkRange& range) {
if (!metadata) {
return false;
}
return metadataOverlapsRange(metadata.value(), range);
}
} // namespace
class RangePreserver : public ScopedCollectionDescription::Impl {
public:
// Must be called locked with the MetadataManager's _managerLock
RangePreserver(WithLock,
std::shared_ptr<MetadataManager> metadataManager,
std::shared_ptr<MetadataManager::CollectionMetadataTracker> metadataTracker)
: _metadataManager(std::move(metadataManager)),
_metadataTracker(std::move(metadataTracker)) {
++_metadataTracker->usageCounter;
}
~RangePreserver() {
stdx::lock_guard<Latch> managerLock(_metadataManager->_managerLock);
invariant(_metadataTracker->usageCounter != 0);
if (--_metadataTracker->usageCounter == 0) {
// MetadataManager doesn't care which usageCounter went to zero. It just retires all
// that are older than the oldest metadata still in use by queries (some start out at
// zero, some go to zero but can't be expired yet).
//
// Note that new instances of ScopedCollectionDescription may get attached to
// _metadata.back(), so its usage count can increase from zero, unlike other reference
// counts.
_metadataManager->_retireExpiredMetadata(managerLock);
}
}
// This will only ever refer to the active metadata, so CollectionMetadata should never be
// boost::none
const CollectionMetadata& get() {
invariant(_metadataTracker->metadata);
return _metadataTracker->metadata.value();
}
private:
std::shared_ptr<MetadataManager> _metadataManager;
std::shared_ptr<MetadataManager::CollectionMetadataTracker> _metadataTracker;
};
MetadataManager::MetadataManager(ServiceContext* serviceContext,
NamespaceString nss,
std::shared_ptr<TaskExecutor> executor,
CollectionMetadata initialMetadata)
: _serviceContext(serviceContext),
_nss(std::move(nss)),
_collectionUuid(initialMetadata.getChunkManager()->getUUID()),
_executor(std::move(executor)) {
_metadata.emplace_back(std::make_shared<CollectionMetadataTracker>(std::move(initialMetadata)));
}
std::shared_ptr<ScopedCollectionDescription::Impl> MetadataManager::getActiveMetadata(
const boost::optional<LogicalTime>& atClusterTime) {
stdx::lock_guard<Latch> lg(_managerLock);
auto activeMetadataTracker = _metadata.back();
const auto& activeMetadata = activeMetadataTracker->metadata;
// We don't keep routing history for unsharded collections, so if the collection is unsharded
// just return the active metadata
if (!atClusterTime || !activeMetadata->isSharded()) {
return std::make_shared<RangePreserver>(
lg, shared_from_this(), std::move(activeMetadataTracker));
}
class MetadataAtTimestamp : public ScopedCollectionDescription::Impl {
public:
MetadataAtTimestamp(CollectionMetadata metadata) : _metadata(std::move(metadata)) {}
const CollectionMetadata& get() override {
return _metadata;
}
private:
CollectionMetadata _metadata;
};
return std::make_shared<MetadataAtTimestamp>(CollectionMetadata(
ChunkManager::makeAtTime(*activeMetadata->getChunkManager(), atClusterTime->asTimestamp()),
activeMetadata->shardId()));
}
size_t MetadataManager::numberOfMetadataSnapshots() const {
stdx::lock_guard<Latch> lg(_managerLock);
invariant(!_metadata.empty());
return _metadata.size() - 1;
}
int MetadataManager::numberOfEmptyMetadataSnapshots() const {
stdx::lock_guard<Latch> lg(_managerLock);
int emptyMetadataSnapshots = 0;
for (const auto& collMetadataTracker : _metadata) {
if (!collMetadataTracker->metadata)
emptyMetadataSnapshots++;
}
return emptyMetadataSnapshots;
}
void MetadataManager::setFilteringMetadata(CollectionMetadata remoteMetadata) {
stdx::lock_guard<Latch> lg(_managerLock);
invariant(!_metadata.empty());
// The active metadata should always be available (not boost::none)
invariant(_metadata.back()->metadata);
const auto& activeMetadata = _metadata.back()->metadata.value();
const auto remoteCollVersion = remoteMetadata.getCollVersion();
const auto activeCollVersion = activeMetadata.getCollVersion();
// Do nothing if the remote version is older than or equal to the current active one
if (remoteCollVersion.isOlderOrEqualThan(activeCollVersion)) {
LOGV2_DEBUG(21984,
1,
"Ignoring incoming metadata update {activeMetadata} for {namespace} because "
"the active (current) metadata {remoteMetadata} has the same or a newer "
"collection version",
"Ignoring incoming metadata update for this namespace because the active "
"(current) metadata has the same or a newer collection version",
"namespace"_attr = _nss.ns(),
"activeMetadata"_attr = activeMetadata.toStringBasic(),
"remoteMetadata"_attr = remoteMetadata.toStringBasic());
return;
}
LOGV2(21985,
"Updating metadata {activeMetadata} for {namespace} because the remote metadata "
"{remoteMetadata} has a newer collection version",
"Updating metadata for this namespace because the remote metadata has a newer "
"collection version",
"namespace"_attr = _nss.ns(),
"activeMetadata"_attr = activeMetadata.toStringBasic(),
"remoteMetadata"_attr = remoteMetadata.toStringBasic());
_setActiveMetadata(lg, std::move(remoteMetadata));
}
void MetadataManager::_setActiveMetadata(WithLock wl, CollectionMetadata newMetadata) {
_metadata.emplace_back(std::make_shared<CollectionMetadataTracker>(std::move(newMetadata)));
_retireExpiredMetadata(wl);
}
void MetadataManager::_retireExpiredMetadata(WithLock) {
// Remove entries with a usage count of 0 from the front of _metadata, which may schedule
// orphans for deletion. We cannot remove an entry from the middle of _metadata because a
// previous entry (whose usageCount is not 0) could have a query that is actually still
// accessing those documents.
while (_metadata.size() > 1 && !_metadata.front()->usageCounter) {
_metadata.pop_front();
}
// To avoid memory build up of ChunkManager objects, we can clear the CollectionMetadata object
// in an entry when its usageCount is 0 as long as it is not the last item in _metadata (which
// is the active metadata). If _metadata is empty, decrementing iter will be out of bounds, so
// we must check that the size is > 1 as well.
if (_metadata.size() > 1) {
auto iter = _metadata.begin();
while (iter != (--_metadata.end())) {
if ((*iter)->usageCounter == 0) {
(*iter)->metadata = boost::none;
}
++iter;
}
}
}
void MetadataManager::append(BSONObjBuilder* builder) const {
stdx::lock_guard<Latch> lg(_managerLock);
BSONArrayBuilder arr(builder->subarrayStart("rangesToClean"));
for (auto const& [range, _] : _rangesScheduledForDeletion) {
BSONObjBuilder obj;
range.append(&obj);
arr.append(obj.done());
}
invariant(!_metadata.empty());
BSONArrayBuilder amrArr(builder->subarrayStart("activeMetadataRanges"));
for (const auto& entry : _metadata.back()->metadata->getChunks()) {
BSONObjBuilder obj;
ChunkRange r = ChunkRange(entry.first, entry.second);
r.append(&obj);
amrArr.append(obj.done());
}
amrArr.done();
}
SharedSemiFuture<void> MetadataManager::cleanUpRange(ChunkRange const& range,
const UUID& migrationId,
bool shouldDelayBeforeDeletion) {
stdx::lock_guard<Latch> lg(_managerLock);
invariant(!_metadata.empty());
auto* const activeMetadata = _metadata.back().get();
auto* const overlapMetadata = _findNewestOverlappingMetadata(lg, range);
if (overlapMetadata == activeMetadata) {
return Status{ErrorCodes::RangeOverlapConflict,
str::stream() << "Requested deletion range overlaps a live shard chunk"};
}
auto delayForActiveQueriesOnSecondariesToComplete =
shouldDelayBeforeDeletion ? Seconds(orphanCleanupDelaySecs.load()) : Seconds(0);
if (overlapMetadata) {
LOGV2_OPTIONS(21989,
{logv2::LogComponent::kShardingMigration},
"Deletion of {namespace} range {range} will be scheduled after all possibly "
"dependent queries finish",
"Deletion of the collection's specified range will be scheduled after all "
"possibly dependent queries finish",
"namespace"_attr = _nss.ns(),
"range"_attr = redact(range.toString()));
++overlapMetadata->numContingentRangeDeletionTasks;
// Schedule the range for deletion once the overlapping metadata object is destroyed
// (meaning no more queries can be using the range) and obtain a future which will be
// signaled when deletion is complete.
return _submitRangeForDeletion(lg,
overlapMetadata->onDestructionPromise.getFuture().semi(),
range,
migrationId,
delayForActiveQueriesOnSecondariesToComplete);
} else {
// No running queries can depend on this range, so queue it for deletion immediately.
LOGV2_OPTIONS(21990,
{logv2::LogComponent::kShardingMigration},
"Scheduling deletion of {namespace} range {range}",
"Scheduling deletion of the collection's specified range",
"namespace"_attr = _nss.ns(),
"range"_attr = redact(range.toString()));
return _submitRangeForDeletion(lg,
SemiFuture<void>::makeReady(),
range,
migrationId,
delayForActiveQueriesOnSecondariesToComplete);
}
}
size_t MetadataManager::numberOfRangesToCleanStillInUse() const {
stdx::lock_guard<Latch> lg(_managerLock);
size_t count = 0;
for (auto& tracker : _metadata) {
count += tracker->numContingentRangeDeletionTasks;
}
return count;
}
size_t MetadataManager::numberOfRangesToClean() const {
auto rangesToCleanInUse = numberOfRangesToCleanStillInUse();
stdx::lock_guard<Latch> lg(_managerLock);
return _rangesScheduledForDeletion.size() - rangesToCleanInUse;
}
size_t MetadataManager::numberOfRangesScheduledForDeletion() const {
stdx::lock_guard<Latch> lg(_managerLock);
return _rangesScheduledForDeletion.size();
}
boost::optional<SharedSemiFuture<void>> MetadataManager::trackOrphanedDataCleanup(
ChunkRange const& range) const {
stdx::lock_guard<Latch> lg(_managerLock);
for (const auto& [orphanRange, deletionComplete] : _rangesScheduledForDeletion) {
if (orphanRange.overlapWith(range)) {
return deletionComplete;
}
}
return boost::none;
}
auto MetadataManager::_findNewestOverlappingMetadata(WithLock, ChunkRange const& range)
-> CollectionMetadataTracker* {
invariant(!_metadata.empty());
auto it = _metadata.rbegin();
if (metadataOverlapsRange((*it)->metadata, range)) {
return (*it).get();
}
++it;
for (; it != _metadata.rend(); ++it) {
auto& tracker = *it;
if (tracker->usageCounter && metadataOverlapsRange(tracker->metadata, range)) {
return tracker.get();
}
}
return nullptr;
}
bool MetadataManager::_overlapsInUseChunk(WithLock lk, ChunkRange const& range) {
auto* cm = _findNewestOverlappingMetadata(lk, range);
return (cm != nullptr);
}
SharedSemiFuture<void> MetadataManager::_submitRangeForDeletion(
const WithLock&,
SemiFuture<void> waitForActiveQueriesToComplete,
const ChunkRange& range,
const UUID& migrationId,
Seconds delayForActiveQueriesOnSecondariesToComplete) {
auto cleanupComplete =
removeDocumentsInRange(_executor,
std::move(waitForActiveQueriesToComplete),
_nss,
_metadata.back()->metadata->getChunkManager()->getUUID(),
_metadata.back()->metadata->getKeyPattern().getOwned(),
range,
migrationId,
delayForActiveQueriesOnSecondariesToComplete);
_rangesScheduledForDeletion.emplace_front(range, cleanupComplete);
// Attach a continuation so that once the range has been deleted, we will remove the deletion
// from the _rangesScheduledForDeletion. std::list iterators are never invalidated, which
// allows us to save the iterator pointing to the newly added element for use later when
// deleting it.
cleanupComplete.thenRunOn(_executor).getAsync(
[self = shared_from_this(), it = _rangesScheduledForDeletion.begin()](Status s) {
stdx::lock_guard<Latch> lg(self->_managerLock);
self->_rangesScheduledForDeletion.erase(it);
});
return cleanupComplete;
}
} // namespace mongo
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