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/**
* Copyright (C) 2014 10gen 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::kCommand
#include "mongo/platform/basic.h"
#include <string>
#include "mongo/base/init.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/commands/server_status.h"
#include "mongo/db/operation_context.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"
#include "mongo/util/time_support.h"
namespace mongo {
using std::string;
using std::stringstream;
using mongoutils::str::stream;
/**
* This command is required in v3.0 mongod to prevent v2.6 mongos from entering a tight loop and
* spamming the server with invalid writebacklisten requests. This command reports an error
* and pauses, which is safe because the original v2.6 WBL command was a long-poll (30s).
*/
class WriteBackCommand : public Command {
public:
WriteBackCommand() : Command("writebacklisten") {}
void help(stringstream& helpOut) const {
helpOut << "v3.0 disallowed internal command, present for compatibility only";
}
virtual bool isWriteCommandForConfigServer() const {
return false;
}
//
// Same as v2.6 settings
//
virtual bool adminOnly() const {
return true;
}
virtual bool slaveOk() const {
return true;
}
virtual void addRequiredPrivileges(const std::string& dbname,
const BSONObj& cmdObj,
std::vector<Privilege>* out) {
ActionSet actions;
actions.addAction(ActionType::internal);
out->push_back(Privilege(ResourcePattern::forClusterResource(), actions));
}
virtual bool run(
OperationContext* opCtx, const string&, BSONObj&, int, string&, BSONObjBuilder& result) {
string errMsg = stream() << "Writeback functionality is no longer present in v3.0 mongod, "
<< "a v2.6 mongos may be running in the v3.0 cluster at "
<< opCtx->getClient()->clientAddress(false);
error() << errMsg;
// Prevent v2.6 mongos from spamming writebacklisten retries
const int kSleepSecsBeforeMessage = 5;
sleepsecs(kSleepSecsBeforeMessage);
return appendCommandStatus(result, Status(ErrorCodes::CommandNotFound, errMsg));
}
};
/**
* The "writeBacksQueued" field is required in ServerStatus output to avoid v2.6 mongos crashing
* confusingly when upgrading a cluster.
*/
class WriteBacksQueuedSSM : public ServerStatusMetric {
public:
WriteBacksQueuedSSM() : ServerStatusMetric(".writeBacksQueued") {}
virtual void appendAtLeaf(BSONObjBuilder& b) const {
// always append false, we don't queue writebacks
b.appendBool(_leafName, false);
}
};
namespace {
MONGO_INITIALIZER(RegisterWriteBackShim)(InitializerContext* context) {
// Leaked intentionally: a Command registers itself when constructed.
new WriteBackCommand();
// Leaked intentionally: a SSM registers itself when constructed.
new WriteBacksQueuedSSM();
return Status::OK();
}
}
} // namespace
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