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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 <boost/optional.hpp>
#include <map>
#include <set>
#include <string>
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/collection_catalog_helper.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/commands.h"
#include "mongo/db/commands/test_commands_enabled.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/db/logical_clock.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/query/internal_plans.h"
#include "mongo/db/repl/replication_coordinator.h"
#include "mongo/db/storage/storage_engine.h"
#include "mongo/db/transaction_participant.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/log.h"
#include "mongo/util/md5.hpp"
#include "mongo/util/net/socket_utils.h"
#include "mongo/util/timer.h"
namespace mongo {
namespace {
class DBHashCmd : public ErrmsgCommandDeprecated {
public:
DBHashCmd() : ErrmsgCommandDeprecated("dbHash", "dbhash") {}
virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
return false;
}
bool allowsAfterClusterTime(const BSONObj& cmd) const override {
return false;
}
bool canIgnorePrepareConflicts() const override {
return true;
}
ReadWriteType getReadWriteType() const override {
return ReadWriteType::kRead;
}
AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
return AllowedOnSecondary::kAlways;
}
virtual void addRequiredPrivileges(const std::string& dbname,
const BSONObj& cmdObj,
std::vector<Privilege>* out) const {
ActionSet actions;
actions.addAction(ActionType::dbHash);
out->push_back(Privilege(ResourcePattern::forDatabaseName(dbname), actions));
}
virtual bool errmsgRun(OperationContext* opCtx,
const std::string& dbname,
const BSONObj& cmdObj,
std::string& errmsg,
BSONObjBuilder& result) {
Timer timer;
std::set<std::string> desiredCollections;
if (cmdObj["collections"].type() == Array) {
BSONObjIterator i(cmdObj["collections"].Obj());
while (i.more()) {
BSONElement e = i.next();
if (e.type() != String) {
errmsg = "collections entries have to be strings";
return false;
}
desiredCollections.insert(e.String());
}
}
const std::string ns = parseNs(dbname, cmdObj);
uassert(ErrorCodes::InvalidNamespace,
str::stream() << "Invalid db name: " << ns,
NamespaceString::validDBName(ns, NamespaceString::DollarInDbNameBehavior::Allow));
if (auto elem = cmdObj["$_internalReadAtClusterTime"]) {
uassert(ErrorCodes::InvalidOptions,
"The '$_internalReadAtClusterTime' option is only supported when testing"
" commands are enabled",
getTestCommandsEnabled());
auto* replCoord = repl::ReplicationCoordinator::get(opCtx);
uassert(ErrorCodes::InvalidOptions,
"The '$_internalReadAtClusterTime' option is only supported when replication is"
" enabled",
replCoord->isReplEnabled());
auto* storageEngine = opCtx->getServiceContext()->getStorageEngine();
uassert(ErrorCodes::InvalidOptions,
"The '$_internalReadAtClusterTime' option is only supported by storage engines"
" that support document-level concurrency",
storageEngine->supportsDocLocking());
uassert(ErrorCodes::TypeMismatch,
"The '$_internalReadAtClusterTime' option must be a Timestamp",
elem.type() == BSONType::bsonTimestamp);
auto targetClusterTime = elem.timestamp();
uassert(ErrorCodes::InvalidOptions,
str::stream() << "$_internalReadAtClusterTime value must not be a null"
" timestamp.",
!targetClusterTime.isNull());
// We aren't holding the global lock in intent mode, so it is possible after comparing
// 'targetClusterTime' to 'lastAppliedOpTime' for the last applied opTime to go
// backwards or for the term to change due to replication rollback. This isn't an actual
// concern because the testing infrastructure won't use the $_internalReadAtClusterTime
// option in any test suite where rollback is expected to occur.
auto lastAppliedOpTime = replCoord->getMyLastAppliedOpTime();
uassert(ErrorCodes::InvalidOptions,
str::stream() << "$_internalReadAtClusterTime value must not be greater"
" than the last applied opTime. Requested clusterTime: "
<< targetClusterTime.toString()
<< "; last applied opTime: " << lastAppliedOpTime.toString(),
lastAppliedOpTime.getTimestamp() >= targetClusterTime);
// We aren't holding the global lock in intent mode, so it is possible for the global
// storage engine to have been destructed already as a result of the server shutting
// down. This isn't an actual concern because the testing infrastructure won't use the
// $_internalReadAtClusterTime option in any test suite where clean shutdown is expected
// to occur concurrently with tests running.
auto allDurableTime = storageEngine->getAllDurableTimestamp();
invariant(!allDurableTime.isNull());
uassert(ErrorCodes::InvalidOptions,
str::stream() << "$_internalReadAtClusterTime value must not be greater"
" than the all_durable timestamp. Requested clusterTime: "
<< targetClusterTime.toString()
<< "; all_durable timestamp: " << allDurableTime.toString(),
allDurableTime >= targetClusterTime);
// The $_internalReadAtClusterTime option causes any storage-layer cursors created
// during plan execution to read from a consistent snapshot of data at the supplied
// clusterTime, even across yields.
opCtx->recoveryUnit()->setTimestampReadSource(RecoveryUnit::ReadSource::kProvided,
targetClusterTime);
// The $_internalReadAtClusterTime option also causes any storage-layer cursors created
// during plan execution to block on prepared transactions. Since the dbhash command
// ignores prepare conflicts by default, change the behavior.
opCtx->recoveryUnit()->setPrepareConflictBehavior(PrepareConflictBehavior::kEnforce);
}
// We lock the entire database in S-mode in order to ensure that the contents will not
// change for the snapshot.
auto lockMode = LockMode::MODE_S;
boost::optional<ShouldNotConflictWithSecondaryBatchApplicationBlock> shouldNotConflictBlock;
if (opCtx->recoveryUnit()->getTimestampReadSource() ==
RecoveryUnit::ReadSource::kProvided) {
// However, if we are performing a read at a timestamp, then we only need to lock the
// database in intent mode and then collection in intent mode as well to ensure that
// none of the collections get dropped.
lockMode = LockMode::MODE_IS;
// Additionally, if we are performing a read at a timestamp, then we allow oplog
// application to proceed concurrently with the dbHash command. This is done
// to ensure a prepare conflict is able to eventually be resolved by processing a
// later commitTransaction or abortTransaction oplog entry.
shouldNotConflictBlock.emplace(opCtx->lockState());
}
AutoGetDb autoDb(opCtx, ns, lockMode);
Database* db = autoDb.getDb();
result.append("host", prettyHostName());
md5_state_t globalState;
md5_init(&globalState);
std::map<std::string, std::string> collectionToHashMap;
std::map<std::string, OptionalCollectionUUID> collectionToUUIDMap;
std::set<std::string> cappedCollectionSet;
bool noError = true;
catalog::forEachCollectionFromDb(opCtx, dbname, MODE_IS, [&](const Collection* collection) {
auto collNss = collection->ns();
if (collNss.size() - 1 <= dbname.size()) {
errmsg = str::stream() << "weird fullCollectionName [" << collNss.toString() << "]";
noError = false;
return false;
}
// Only hash replicated collections. In 4.4 we use a more general way of choosing what
// collections are replicated. This means that mixed 4.2-4.4 replica sets could hash the
// same database differently, even when all nodes are up-to-date. We only use the new
// method for choosing collections to hash in FCV 4.4 so that when all nodes are
// up-to-date, it is guaranteed that they hash the same set of collections.
if (serverGlobalParams.featureCompatibility.getVersion() ==
ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44) {
if (repl::ReplicationCoordinator::isOplogDisabledForNS(collNss)) {
return true;
}
} else {
// A set of 'system' collections that are replicated, and therefore included in the
// db hash.
const std::set<StringData> replicatedSystemCollections{"system.backup_users",
"system.js",
"system.new_users",
"system.roles",
"system.users",
"system.version",
"system.views"};
// Only include 'system' collections that are replicated.
bool isReplicatedSystemColl =
(replicatedSystemCollections.count(collNss.coll().toString()) > 0);
if (collNss.isSystem() && !isReplicatedSystemColl) {
return true;
}
}
if (collNss.coll().startsWith("tmp.mr.")) {
// We skip any incremental map reduce collections as they also aren't
// replicated.
return true;
}
if (desiredCollections.size() > 0 &&
desiredCollections.count(collNss.coll().toString()) == 0)
return true;
// Don't include 'drop pending' collections.
if (collNss.isDropPendingNamespace())
return true;
if (collection->isCapped()) {
cappedCollectionSet.insert(collNss.coll().toString());
}
if (OptionalCollectionUUID uuid = collection->uuid()) {
collectionToUUIDMap[collNss.coll().toString()] = uuid;
}
// Compute the hash for this collection.
std::string hash = _hashCollection(opCtx, db, collNss);
collectionToHashMap[collNss.coll().toString()] = hash;
return true;
});
if (!noError)
return false;
BSONObjBuilder bb(result.subobjStart("collections"));
BSONArrayBuilder cappedCollections;
BSONObjBuilder collectionsByUUID;
for (auto elem : cappedCollectionSet) {
cappedCollections.append(elem);
}
for (auto entry : collectionToUUIDMap) {
auto collName = entry.first;
auto uuid = entry.second;
uuid->appendToBuilder(&collectionsByUUID, collName);
}
for (auto entry : collectionToHashMap) {
auto collName = entry.first;
auto hash = entry.second;
bb.append(collName, hash);
md5_append(&globalState, (const md5_byte_t*)hash.c_str(), hash.size());
}
bb.done();
result.append("capped", BSONArray(cappedCollections.done()));
result.append("uuids", collectionsByUUID.done());
md5digest d;
md5_finish(&globalState, d);
std::string hash = digestToString(d);
result.append("md5", hash);
result.appendNumber("timeMillis", timer.millis());
return 1;
}
private:
std::string _hashCollection(OperationContext* opCtx, Database* db, const NamespaceString& nss) {
Collection* collection =
CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, nss);
invariant(collection);
boost::optional<Lock::CollectionLock> collLock;
if (opCtx->recoveryUnit()->getTimestampReadSource() ==
RecoveryUnit::ReadSource::kProvided) {
// When performing a read at a timestamp, we are only holding the database lock in
// intent mode. We need to also acquire the collection lock in intent mode to ensure
// reading from the consistent snapshot doesn't overlap with any catalog operations on
// the collection.
invariant(opCtx->lockState()->isCollectionLockedForMode(nss, MODE_IS));
auto minSnapshot = collection->getMinimumVisibleSnapshot();
auto mySnapshot = opCtx->recoveryUnit()->getPointInTimeReadTimestamp();
invariant(mySnapshot);
uassert(ErrorCodes::SnapshotUnavailable,
str::stream() << "Unable to read from a snapshot due to pending collection"
" catalog changes; please retry the operation. Snapshot"
" timestamp is "
<< mySnapshot->toString() << ". Collection minimum timestamp is "
<< minSnapshot->toString(),
!minSnapshot || *mySnapshot >= *minSnapshot);
} else {
invariant(opCtx->lockState()->isDbLockedForMode(db->name(), MODE_S));
}
auto desc = collection->getIndexCatalog()->findIdIndex(opCtx);
std::unique_ptr<PlanExecutor, PlanExecutor::Deleter> exec;
if (desc) {
exec = InternalPlanner::indexScan(opCtx,
collection,
desc,
BSONObj(),
BSONObj(),
BoundInclusion::kIncludeStartKeyOnly,
PlanExecutor::NO_YIELD,
InternalPlanner::FORWARD,
InternalPlanner::IXSCAN_FETCH);
} else if (collection->isCapped()) {
exec = InternalPlanner::collectionScan(
opCtx, nss.ns(), collection, PlanExecutor::NO_YIELD);
} else {
log() << "can't find _id index for: " << nss;
return "no _id _index";
}
md5_state_t st;
md5_init(&st);
long long n = 0;
PlanExecutor::ExecState state;
BSONObj c;
verify(nullptr != exec.get());
while (PlanExecutor::ADVANCED == (state = exec->getNext(&c, nullptr))) {
md5_append(&st, (const md5_byte_t*)c.objdata(), c.objsize());
n++;
}
if (PlanExecutor::IS_EOF != state) {
warning() << "error while hashing, db dropped? ns=" << nss;
uasserted(34371,
"Plan executor error while running dbHash command: " +
WorkingSetCommon::toStatusString(c));
}
md5digest d;
md5_finish(&st, d);
std::string hash = digestToString(d);
return hash;
}
} dbhashCmd;
} // namespace
} // namespace mongo
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