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/**
* Copyright (C) 2016 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::kSharding
#include "mongo/platform/basic.h"
#include "mongo/base/status_with.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/commands.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/repl/read_concern_args.h"
#include "mongo/db/s/chunk_move_write_concern_options.h"
#include "mongo/db/s/sharding_state.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/s/catalog/sharding_catalog_manager.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/s/catalog/type_locks.h"
#include "mongo/s/chunk_version.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/grid.h"
#include "mongo/s/request_types/commit_chunk_migration_request_type.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/fail_point_service.h"
#include "mongo/util/log.h"
namespace mongo {
namespace {
MONGO_FP_DECLARE(migrationCommitError); // delete this in 3.5
/**
* This command takes the chunk being migrated ("migratedChunk") and generates a new version for it
* that is written along with its new shard location ("toShard") to the chunks collection. It also
* takes a control chunk ("controlChunk") and assigns it a new version as well so that the source
* ("fromShard") shard's shardVersion will increases. If there is no control chunk, then the chunk
* being migrated is the source shard's only remaining chunk.
*
* The new chunk version is generated by querying the highest chunk version of the collection, and
* then incrementing that major value for both migrated and control chunks and setting the minor to
* 0 for the migrated chunk and 1 for the control chunk. A global exclusive lock is held for the
* duration of generating the new chunk version and writing to the chunks collection so that
* yielding cannot occur. This assures that generated ChunkVersions are strictly monotonically
* increasing -- a second process will not be able to query for max chunk version until the first
* finishes writing the new highest chunk version it generated.
*
* Command Format:
* {
* _configsvrCommitChunkMigration: <database>.<collection>,
* fromShard: "<from_shard_name>",
* toShard: "<to_shard_name>",
* migratedChunk: {min: <min_value>, max: <max_value>, etc. },
* controlChunk: {min: <min_value>, max: <max_value>, etc. }, (optional)
* fromShardCollectionVersion: { shardVersionField: <version> }, (for backward compatibility only)
* shardHasDistributedLock: true/false (for backward compatibility only)
* }
*
* Returns:
* {
* migratedChunkVersion: <ChunkVersion_BSON>,
* controlChunkVersion: <ChunkVersion_BSON>, (only present if a controlChunk is defined)
* }
*
*/
class ConfigSvrCommitChunkMigrationCommand : public Command {
public:
ConfigSvrCommitChunkMigrationCommand() : Command("_configsvrCommitChunkMigration") {}
void help(std::stringstream& help) const override {
help << "should not be calling this directly";
}
bool slaveOk() const override {
return false;
}
bool adminOnly() const override {
return true;
}
virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
return true;
}
Status checkAuthForCommand(Client* client,
const std::string& dbname,
const BSONObj& cmdObj) override {
if (!AuthorizationSession::get(client)->isAuthorizedForActionsOnResource(
ResourcePattern::forClusterResource(), ActionType::internal)) {
return Status(ErrorCodes::Unauthorized, "Unauthorized");
}
return Status::OK();
}
std::string parseNs(const std::string& dbname, const BSONObj& cmdObj) const override {
return parseNsFullyQualified(dbname, cmdObj);
}
/**
* Assures that the balancer still holds the collection distributed lock for this collection. If
* it no longer does, fail because we don't know if the collection state has changed -- e.g.
* whether it was/is dropping, whether another imcompatible migration is running, etc..
*/
static Status checkBalancerHasDistLock(OperationContext* txn,
const NamespaceString& nss,
const ChunkType& chunk) {
auto balancerDistLockProcessID =
Grid::get(txn)->catalogClient(txn)->getDistLockManager()->getProcessID();
// Must use local read concern because we're going to perform subsequent writes.
auto lockQueryResponseWith =
Grid::get(txn)->shardRegistry()->getConfigShard()->exhaustiveFindOnConfig(
txn,
ReadPreferenceSetting{ReadPreference::PrimaryOnly},
repl::ReadConcernLevel::kLocalReadConcern,
NamespaceString(LocksType::ConfigNS),
BSON(LocksType::process(balancerDistLockProcessID) << LocksType::name(nss.ns())),
BSONObj(),
boost::none);
if (!lockQueryResponseWith.isOK()) {
return lockQueryResponseWith.getStatus();
}
invariant(lockQueryResponseWith.getValue().docs.size() <= 1);
if (MONGO_FAIL_POINT(migrationCommitError)) {
lockQueryResponseWith.getValue().docs.clear();
}
if (lockQueryResponseWith.getValue().docs.size() != 1) {
return Status(
ErrorCodes::BalancerLostDistributedLock,
str::stream() << "The distributed lock for collection '" << nss.ns()
<< "' was lost by the balancer since this migration began. Cannot "
<< "proceed with the migration commit for chunk ("
<< chunk.getRange().toString()
<< ") because it could corrupt other operations.");
}
return Status::OK();
}
bool run(OperationContext* txn,
const std::string& dbName,
BSONObj& cmdObj,
int options,
std::string& errmsg,
BSONObjBuilder& result) override {
const NamespaceString nss = NamespaceString(parseNs(dbName, cmdObj));
auto commitRequest =
uassertStatusOK(CommitChunkMigrationRequest::createFromCommand(nss, cmdObj));
if (!commitRequest.shardHasDistributedLock()) {
auto check = checkBalancerHasDistLock(txn, nss, commitRequest.getMigratedChunk());
if (!check.isOK()) {
return appendCommandStatus(result, check);
}
}
StatusWith<BSONObj> response = Grid::get(txn)->catalogManager()->commitChunkMigration(
txn,
nss,
commitRequest.getMigratedChunk(),
commitRequest.getControlChunk(),
commitRequest.getCollectionEpoch(),
commitRequest.getFromShard(),
commitRequest.getToShard());
if (!response.isOK()) {
return appendCommandStatus(result, response.getStatus());
}
result.appendElements(response.getValue());
return true;
}
} configsvrCommitChunkMigrationCommand;
} // namespace
} // namespace mongo
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