SERVER-22672 Move the sharding balancer to the CSRS primary

This change moves the sharding balancer to run on the primary of the CSRS
config server and removes it from the mongos instances.

2 files changed, 232 insertions, 0 deletions

diff --git a/src/mongo/db/s/config/configsvr_control_balancer_command.cpp b/src/mongo/db/s/config/configsvr_control_balancer_command.cpp
new file mode 100644
index 00000000000..312c8f0c5c8
--- /dev/null
+++ b/src/mongo/db/s/config/configsvr_control_balancer_command.cpp
@@ -0,0 +1,126 @@
+/**
+ *    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/db/auth/action_type.h"
+#include "mongo/db/auth/authorization_session.h"
+#include "mongo/db/auth/privilege.h"
+#include "mongo/db/commands.h"
+#include "mongo/s/balancer/balancer.h"
+#include "mongo/s/balancer/balancer_configuration.h"
+#include "mongo/s/grid.h"
+#include "mongo/s/request_types/control_balancer_request_type.h"
+#include "mongo/util/log.h"
+#include "mongo/util/mongoutils/str.h"
+
+namespace mongo {
+namespace {
+
+class ConfigSvrControlBalancerCommand : public Command {
+public:
+    ConfigSvrControlBalancerCommand() : Command("_configsvrControlBalancer") {}
+
+    void help(std::stringstream& help) const override {
+        help << "Internal command, which is exported by the sharding config server. Do not call "
+                "directly. Controls the balancer state.";
+    }
+
+    bool slaveOk() const override {
+        return false;
+    }
+
+    bool adminOnly() const override {
+        return true;
+    }
+
+    bool supportsWriteConcern(const BSONObj& cmd) const override {
+        return false;
+    }
+
+    Status checkAuthForCommand(ClientBasic* 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();
+    }
+
+    bool run(OperationContext* txn,
+             const std::string& unusedDbName,
+             BSONObj& cmdObj,
+             int options,
+             std::string& errmsg,
+             BSONObjBuilder& result) override {
+        if (serverGlobalParams.clusterRole != ClusterRole::ConfigServer) {
+            return appendCommandStatus(
+                result,
+                Status(ErrorCodes::IllegalOperation,
+                       "_configsvrControlBalancer can only be run on config servers"));
+        }
+
+        const auto request =
+            uassertStatusOK(ControlBalancerRequest::parseFromConfigCommand(cmdObj));
+        auto balancerConfig = Grid::get(txn)->getBalancerConfiguration();
+
+        Status writeBalancerConfigStatus{ErrorCodes::InternalError, "Not initialized"};
+
+        switch (request.getAction()) {
+            case ControlBalancerRequest::kStart:
+                writeBalancerConfigStatus = balancerConfig->setBalancerActive(txn, true);
+                uassertStatusOK(Balancer::get(txn)->startThread(txn));
+                break;
+            case ControlBalancerRequest::kStop:
+                writeBalancerConfigStatus = balancerConfig->setBalancerActive(txn, false);
+                Balancer::get(txn)->stopThread();
+                Balancer::get(txn)->joinThread();
+                break;
+            default:
+                MONGO_UNREACHABLE;
+        }
+
+        if (!writeBalancerConfigStatus.isOK()) {
+            uasserted(writeBalancerConfigStatus.code(),
+                      str::stream()
+                          << "Balancer thread state was changed successfully, but the balancer "
+                             "configuration setting could not be persisted due to error '"
+                          << writeBalancerConfigStatus.reason()
+                          << "'");
+        }
+
+        return true;
+    }
+
+} configSvrControlBalancerCmd;
+
+}  // namespace
+}  // namespace mongo
diff --git a/src/mongo/db/s/config/configsvr_move_chunk_command.cpp b/src/mongo/db/s/config/configsvr_move_chunk_command.cpp
new file mode 100644
index 00000000000..d85f29b7417
--- /dev/null
+++ b/src/mongo/db/s/config/configsvr_move_chunk_command.cpp
@@ -0,0 +1,106 @@
+/**
+ *    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/bson/util/bson_extract.h"
+#include "mongo/db/auth/action_type.h"
+#include "mongo/db/auth/authorization_session.h"
+#include "mongo/db/auth/privilege.h"
+#include "mongo/db/commands.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/s/balancer/balancer.h"
+#include "mongo/s/request_types/balance_chunk_request_type.h"
+#include "mongo/util/log.h"
+#include "mongo/util/mongoutils/str.h"
+
+namespace mongo {
+namespace {
+
+using std::string;
+using str::stream;
+
+class ConfigSvrMoveChunkCommand : public Command {
+public:
+    ConfigSvrMoveChunkCommand() : Command("_configsvrMoveChunk") {}
+
+    void help(std::stringstream& help) const override {
+        help << "Internal command, which is exported by the sharding config server. Do not call "
+                "directly. Requests the balancer to move or rebalance a single chunk.";
+    }
+
+    bool slaveOk() const override {
+        return false;
+    }
+
+    bool adminOnly() const override {
+        return true;
+    }
+
+    bool supportsWriteConcern(const BSONObj& cmd) const override {
+        return false;
+    }
+
+    Status checkAuthForCommand(ClientBasic* 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();
+    }
+
+    bool run(OperationContext* txn,
+             const std::string& unusedDbName,
+             BSONObj& cmdObj,
+             int options,
+             std::string& errmsg,
+             BSONObjBuilder& result) override {
+        auto request = uassertStatusOK(BalanceChunkRequest::parseFromConfigCommand(cmdObj));
+
+        if (request.hasToShardId()) {
+            uassertStatusOK(Balancer::get(txn)->moveSingleChunk(txn,
+                                                                request.getChunk(),
+                                                                request.getToShardId(),
+                                                                request.getMaxChunkSizeBytes(),
+                                                                request.getSecondaryThrottle(),
+                                                                request.getWaitForDelete()));
+        } else {
+            uassertStatusOK(Balancer::get(txn)->rebalanceSingleChunk(txn, request.getChunk()));
+        }
+
+        return true;
+    }
+
+} configSvrMoveChunk;
+
+}  // namespace
+}  // namespace mongo