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Diffstat (limited to 'src/mongo/db/prefetch.cpp')
| -rw-r--r-- | src/mongo/db/prefetch.cpp | 274 |
1 files changed, 0 insertions, 274 deletions
diff --git a/src/mongo/db/prefetch.cpp b/src/mongo/db/prefetch.cpp deleted file mode 100644 index a55993037bc..00000000000 --- a/src/mongo/db/prefetch.cpp +++ /dev/null @@ -1,274 +0,0 @@ -/** - * Copyright (C) 2008-2014 MongoDB Inc. - * - * This program is free software: you can redistribute it and/or modify - * it under the terms of the GNU Affero General Public License, version 3, - * as published by the Free Software Foundation. - * - * 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 - * GNU Affero General Public License for more details. - * - * You should have received a copy of the GNU Affero General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. - * - * 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 GNU Affero General 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::kReplication - -#include "mongo/platform/basic.h" - -#include "mongo/db/prefetch.h" - -#include "mongo/db/catalog/collection.h" -#include "mongo/db/catalog/database.h" -#include "mongo/db/catalog/index_catalog.h" -#include "mongo/db/commands/server_status_metric.h" -#include "mongo/db/concurrency/d_concurrency.h" -#include "mongo/db/dbhelpers.h" -#include "mongo/db/index/index_access_method.h" -#include "mongo/db/jsobj.h" -#include "mongo/db/repl/oplog_entry.h" -#include "mongo/db/repl/repl_settings.h" -#include "mongo/db/repl/replication_coordinator.h" -#include "mongo/db/server_parameters.h" -#include "mongo/db/stats/timer_stats.h" -#include "mongo/db/storage/mmap_v1/mmap.h" -#include "mongo/util/log.h" - -namespace mongo { - -using std::endl; -using std::string; - -namespace repl { -namespace { -// todo / idea: the prefetcher, when it fetches _id, on an upsert, will see if the record exists. if -// it does not, at write time, we can just do an insert, which will be faster. - -// The count (of batches) and time spent fetching pages before application -// -- meaning depends on the prefetch behavior: all, _id index, none, etc.) -TimerStats prefetchIndexStats; -ServerStatusMetricField<TimerStats> displayPrefetchIndexPages("repl.preload.indexes", - &prefetchIndexStats); -TimerStats prefetchDocStats; -ServerStatusMetricField<TimerStats> displayPrefetchDocPages("repl.preload.docs", &prefetchDocStats); - -// page in pages needed for all index lookups on a given object -void prefetchIndexPages(OperationContext* opCtx, - Collection* collection, - const ReplSettings::IndexPrefetchConfig& prefetchConfig, - const BSONObj& obj) { - // do we want prefetchConfig to be (1) as-is, (2) for update ops only, or (3) configured per op - // type? One might want PREFETCH_NONE for updates, but it's more rare that it is a bad idea for - // inserts. #3 (per op), a big issue would be "too many knobs". - switch (prefetchConfig) { - case ReplSettings::IndexPrefetchConfig::PREFETCH_NONE: - return; - case ReplSettings::IndexPrefetchConfig::PREFETCH_ID_ONLY: { - TimerHolder timer(&prefetchIndexStats); - // on the update op case, the call to prefetchRecordPages will touch the _id index. - // thus perhaps this option isn't very useful? - try { - IndexDescriptor* desc = collection->getIndexCatalog()->findIdIndex(opCtx); - if (!desc) - return; - IndexAccessMethod* iam = collection->getIndexCatalog()->getIndex(desc); - invariant(iam); - iam->touch(opCtx, obj).transitional_ignore(); - } catch (const DBException& e) { - LOG(2) << "ignoring exception in prefetchIndexPages(): " << redact(e); - } - break; - } - case ReplSettings::IndexPrefetchConfig::PREFETCH_ALL: { - // indexCount includes all indexes, including ones - // in the process of being built - IndexCatalog::IndexIterator ii = - collection->getIndexCatalog()->getIndexIterator(opCtx, true); - while (ii.more()) { - TimerHolder timer(&prefetchIndexStats); - // This will page in all index pages for the given object. - try { - IndexDescriptor* desc = ii.next(); - IndexAccessMethod* iam = collection->getIndexCatalog()->getIndex(desc); - verify(iam); - iam->touch(opCtx, obj).transitional_ignore(); - } catch (const DBException& e) { - LOG(2) << "ignoring exception in prefetchIndexPages(): " << redact(e); - } - } - break; - } - default: - fassertFailed(16427); - } -} - -// page in the data pages for a record associated with an object -void prefetchRecordPages(OperationContext* opCtx, - Database* db, - const char* ns, - const BSONObj& obj) { - BSONElement _id; - if (obj.getObjectID(_id)) { - TimerHolder timer(&prefetchDocStats); - BSONObjBuilder builder; - builder.append(_id); - BSONObj result; - try { - if (Helpers::findById(opCtx, db, ns, builder.done(), result)) { - // do we want to use Record::touch() here? it's pretty similar. - // volatile - avoid compiler optimizations for touching a mmap page - volatile char _dummy_char = '\0'; // NOLINT - - // Touch the first word on every page in order to fault it into memory - for (int i = 0; i < result.objsize(); i += getMinOSPageSizeBytes()) { - _dummy_char += *(result.objdata() + i); - } - // hit the last page, in case we missed it above - _dummy_char += *(result.objdata() + result.objsize() - 1); - } - } catch (const DBException& e) { - LOG(2) << "ignoring exception in prefetchRecordPages(): " << redact(e); - } - } -} -} // namespace - -// prefetch for an oplog operation -void prefetchPagesForReplicatedOp(OperationContext* opCtx, - Database* db, - const OplogEntry& oplogEntry) { - invariant(db); - const ReplSettings::IndexPrefetchConfig prefetchConfig = - ReplicationCoordinator::get(opCtx)->getIndexPrefetchConfig(); - - // Prefetch ignores non-CRUD operations. - if (!oplogEntry.isCrudOpType()) { - return; - } - - // This will have to change for engines other than MMAP V1, because they might not have - // means for directly prefetching pages from the collection. For this purpose, acquire S - // lock on the database, instead of optimizing with IS. - const auto& nss = oplogEntry.getNamespace(); - Lock::CollectionLock collLock(opCtx->lockState(), nss.ns(), MODE_S); - - Collection* collection = db->getCollection(opCtx, nss); - if (!collection) { - return; - } - - auto opType = oplogEntry.getOpType(); - LOG(4) << "index prefetch for op " << OpType_serializer(opType); - - // should we prefetch index pages on updates? if the update is in-place and doesn't change - // indexed values, it is actually slower - a lot slower if there are a dozen indexes or - // lots of multikeys. possible variations (not all mutually exclusive): - // 1) current behavior: full prefetch - // 2) don't do it for updates - // 3) don't do multikey indexes for updates - // 4) don't prefetchIndexPages on some heuristic; e.g., if it's an $inc. - // 5) if not prefetching index pages (#2), we should do it if we are upsertings and it - // will be an insert. to do that we could do the prefetchRecordPage first and if DNE - // then we do #1. - // - // note that on deletes 'obj' does not have all the keys we would want to prefetch on. - // a way to achieve that would be to prefetch the record first, and then afterwards do - // this part. - // - auto obj = oplogEntry.getOperationToApply(); - invariant(!obj.isEmpty()); - prefetchIndexPages(opCtx, collection, prefetchConfig, obj); - - // do not prefetch the data for inserts; it doesn't exist yet - // - // we should consider doing the record prefetch for the delete op case as we hit the record - // when we delete. note if done we only want to touch the first page. - // - // update: do record prefetch. - if ((opType == OpTypeEnum::kUpdate) && - // do not prefetch the data for capped collections because - // they typically do not have an _id index for findById() to use. - !collection->isCapped()) { - prefetchRecordPages(opCtx, db, nss.ns().c_str(), obj); - } -} - -class ReplIndexPrefetch : public ServerParameter { -public: - ReplIndexPrefetch() : ServerParameter(ServerParameterSet::getGlobal(), "replIndexPrefetch") {} - - virtual ~ReplIndexPrefetch() {} - - const char* _value() { - if (ReplicationCoordinator::get(getGlobalServiceContext())->getReplicationMode() != - ReplicationCoordinator::modeReplSet) { - return "uninitialized"; - } - ReplSettings::IndexPrefetchConfig ip = - ReplicationCoordinator::get(getGlobalServiceContext())->getIndexPrefetchConfig(); - switch (ip) { - case ReplSettings::IndexPrefetchConfig::PREFETCH_NONE: - return "none"; - case ReplSettings::IndexPrefetchConfig::PREFETCH_ID_ONLY: - return "_id_only"; - case ReplSettings::IndexPrefetchConfig::PREFETCH_ALL: - return "all"; - default: - return "invalid"; - } - } - - virtual void append(OperationContext* opCtx, BSONObjBuilder& b, const string& name) { - b.append(name, _value()); - } - - virtual Status set(const BSONElement& newValueElement) { - if (ReplicationCoordinator::get(getGlobalServiceContext())->getReplicationMode() != - ReplicationCoordinator::modeReplSet) { - return Status(ErrorCodes::BadValue, "replication is not enabled"); - } - - std::string prefetch = newValueElement.valuestrsafe(); - return setFromString(prefetch); - } - - virtual Status setFromString(const string& prefetch) { - log() << "changing replication index prefetch behavior to " << prefetch; - - ReplSettings::IndexPrefetchConfig prefetchConfig; - - if (prefetch == "none") - prefetchConfig = ReplSettings::IndexPrefetchConfig::PREFETCH_NONE; - else if (prefetch == "_id_only") - prefetchConfig = ReplSettings::IndexPrefetchConfig::PREFETCH_ID_ONLY; - else if (prefetch == "all") - prefetchConfig = ReplSettings::IndexPrefetchConfig::PREFETCH_ALL; - else { - return Status(ErrorCodes::BadValue, - str::stream() << "unrecognized indexPrefetch setting: " << prefetch); - } - - ReplicationCoordinator::get(getGlobalServiceContext()) - ->setIndexPrefetchConfig(prefetchConfig); - return Status::OK(); - } - -} replIndexPrefetch; - -} // namespace repl -} // namespace mongo |