SERVER-19004 Get rid of Shard::runCommand

30 files changed, 101 insertions, 320 deletions

diff --git a/src/mongo/client/SConscript b/src/mongo/client/SConscript
index d71678fe1f1..0b2d9cf7805 100644
--- a/src/mongo/client/SConscript
+++ b/src/mongo/client/SConscript
@@ -122,16 +122,6 @@ env.Library(
 )
 
 env.Library(
-    target='remote_command_runner_mock',
-    source=[
-        'remote_command_runner_mock.cpp',
-    ],
-    LIBDEPS=[
-         'remote_command_runner',
-    ]
-)
-
-env.Library(
     target='remote_command_targeter',
     source=[
         'remote_command_targeter_factory_impl.cpp',
diff --git a/src/mongo/client/remote_command_runner_mock.cpp b/src/mongo/client/remote_command_runner_mock.cpp
deleted file mode 100644
index c9df7c52bca..00000000000
--- a/src/mongo/client/remote_command_runner_mock.cpp
+++ /dev/null
@@ -1,70 +0,0 @@
-/**
- *    Copyright (C) 2015 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.
- */
-
-#include "mongo/platform/basic.h"
-
-#include "mongo/client/remote_command_runner_mock.h"
-
-#include "mongo/unittest/unittest.h"
-#include "mongo/util/mongoutils/str.h"
-
-namespace mongo {
-
-namespace {
-void noCheckerSet(const RemoteCommandRequest& request) {
-    FAIL(str::stream() << "runCommand not expected to be called. request: " << request.toString());
-}
-}
-
-RemoteCommandRunnerMock::RemoteCommandRunnerMock()
-    : _runCommandChecker(noCheckerSet),
-      _response(Status(ErrorCodes::InternalError, "response not set")) {}
-
-RemoteCommandRunnerMock::~RemoteCommandRunnerMock() = default;
-
-RemoteCommandRunnerMock* RemoteCommandRunnerMock::get(RemoteCommandRunner* runner) {
-    auto mock = dynamic_cast<RemoteCommandRunnerMock*>(runner);
-    invariant(mock);
-
-    return mock;
-}
-
-StatusWith<RemoteCommandResponse> RemoteCommandRunnerMock::runCommand(
-    const RemoteCommandRequest& request) {
-    _runCommandChecker(request);
-    _runCommandChecker = noCheckerSet;
-    return _response;
-}
-
-void RemoteCommandRunnerMock::setNextExpectedCommand(
-    stdx::function<void(const RemoteCommandRequest& request)> checkerFunc,
-    StatusWith<RemoteCommandResponse> returnThis) {
-    _runCommandChecker = checkerFunc;
-    _response = std::move(returnThis);
-}
-}
diff --git a/src/mongo/client/remote_command_runner_mock.h b/src/mongo/client/remote_command_runner_mock.h
deleted file mode 100644
index fb3b6bc26dd..00000000000
--- a/src/mongo/client/remote_command_runner_mock.h
+++ /dev/null
@@ -1,80 +0,0 @@
-/**
- *    Copyright (C) 2015 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.
- */
-
-#pragma once
-
-#include "mongo/client/remote_command_runner.h"
-#include "mongo/stdx/functional.h"
-
-namespace mongo {
-
-/**
- * Note: This is NOT thread-safe.
- *
- * Example usage:
- *
- * RemoteCommandRunnerMock executor;
- * executor.setNextExpectedCommand([](const RemoteCommandRequest& request) {
- *     ASSERT_EQUALS("config", request.dbname);
- * },
- * RemoteCommandResponse(BSON("ok" << 1), Milliseconds(0)));
- *
- * auto response = executor.runCommand(RemoteCommandRequest()); // Assertion error!
- */
-class RemoteCommandRunnerMock final : public RemoteCommandRunner {
-public:
-    RemoteCommandRunnerMock();
-    virtual ~RemoteCommandRunnerMock();
-
-    /**
-     * Shortcut for unit-tests.
-     */
-    static RemoteCommandRunnerMock* get(RemoteCommandRunner* runner);
-
-    /**
-     * Runs the function set by the last call to setNextExpectedCommand. Calling this more
-     * than once after a single call to setNextExpectedCommand will result in an assertion
-     * failure.
-     *
-     * Returns the value set on a previous call to setNextExpectedCommand.
-     */
-    StatusWith<RemoteCommandResponse> runCommand(const RemoteCommandRequest& request) override;
-
-    /**
-     * Sets the checker method to use and it's return value the next time runCommand is
-     * called.
-     */
-    void setNextExpectedCommand(
-        stdx::function<void(const RemoteCommandRequest& request)> checkerFunc,
-        StatusWith<RemoteCommandResponse> returnThis);
-
-private:
-    stdx::function<void(const RemoteCommandRequest& request)> _runCommandChecker;
-    StatusWith<RemoteCommandResponse> _response;
-};
-}
diff --git a/src/mongo/db/auth/authz_manager_external_state_s.cpp b/src/mongo/db/auth/authz_manager_external_state_s.cpp
index 91ca85ee3ef..6d6ae04db01 100644
--- a/src/mongo/db/auth/authz_manager_external_state_s.cpp
+++ b/src/mongo/db/auth/authz_manager_external_state_s.cpp
@@ -70,8 +70,7 @@ Status AuthzManagerExternalStateMongos::getStoredAuthorizationVersion(OperationC
     // that runs this command
     BSONObj getParameterCmd = BSON("getParameter" << 1 << authSchemaVersionServerParameter << 1);
     BSONObjBuilder builder;
-    const bool ok =
-        grid.catalogManager()->runUserManagementReadCommand("admin", getParameterCmd, &builder);
+    const bool ok = grid.catalogManager()->runReadCommand("admin", getParameterCmd, &builder);
     BSONObj cmdResult = builder.obj();
     if (!ok) {
         return Command::getStatusFromCommandResult(cmdResult);
@@ -96,8 +95,7 @@ Status AuthzManagerExternalStateMongos::getUserDescription(OperationContext* txn
                                             << userName.getDB())) << "showPrivileges" << true
                          << "showCredentials" << true);
     BSONObjBuilder builder;
-    const bool ok =
-        grid.catalogManager()->runUserManagementReadCommand("admin", usersInfoCmd, &builder);
+    const bool ok = grid.catalogManager()->runReadCommand("admin", usersInfoCmd, &builder);
     BSONObj cmdResult = builder.obj();
     if (!ok) {
         return Command::getStatusFromCommandResult(cmdResult);
@@ -126,8 +124,7 @@ Status AuthzManagerExternalStateMongos::getRoleDescription(const RoleName& roleN
                                 << roleName.getRole() << AuthorizationManager::ROLE_DB_FIELD_NAME
                                 << roleName.getDB())) << "showPrivileges" << showPrivileges);
     BSONObjBuilder builder;
-    const bool ok =
-        grid.catalogManager()->runUserManagementReadCommand("admin", rolesInfoCmd, &builder);
+    const bool ok = grid.catalogManager()->runReadCommand("admin", rolesInfoCmd, &builder);
     BSONObj cmdResult = builder.obj();
     if (!ok) {
         return Command::getStatusFromCommandResult(cmdResult);
@@ -154,8 +151,7 @@ Status AuthzManagerExternalStateMongos::getRoleDescriptionsForDB(const std::stri
     BSONObj rolesInfoCmd = BSON("rolesInfo" << 1 << "showPrivileges" << showPrivileges
                                             << "showBuiltinRoles" << showBuiltinRoles);
     BSONObjBuilder builder;
-    const bool ok =
-        grid.catalogManager()->runUserManagementReadCommand(dbname, rolesInfoCmd, &builder);
+    const bool ok = grid.catalogManager()->runReadCommand(dbname, rolesInfoCmd, &builder);
     BSONObj cmdResult = builder.obj();
     if (!ok) {
         return Command::getStatusFromCommandResult(cmdResult);
@@ -169,8 +165,7 @@ Status AuthzManagerExternalStateMongos::getRoleDescriptionsForDB(const std::stri
 bool AuthzManagerExternalStateMongos::hasAnyPrivilegeDocuments(OperationContext* txn) {
     BSONObj usersInfoCmd = BSON("usersInfo" << 1);
     BSONObjBuilder builder;
-    const bool ok =
-        grid.catalogManager()->runUserManagementReadCommand("admin", usersInfoCmd, &builder);
+    const bool ok = grid.catalogManager()->runReadCommand("admin", usersInfoCmd, &builder);
     if (!ok) {
         // If we were unable to complete the query,
         // it's best to assume that there _are_ privilege documents.  This might happen
diff --git a/src/mongo/db/auth/user_cache_invalidator_job.cpp b/src/mongo/db/auth/user_cache_invalidator_job.cpp
index dd44b200f60..2e44a9ff65a 100644
--- a/src/mongo/db/auth/user_cache_invalidator_job.cpp
+++ b/src/mongo/db/auth/user_cache_invalidator_job.cpp
@@ -91,7 +91,7 @@ public:
 StatusWith<OID> getCurrentCacheGeneration() {
     try {
         BSONObjBuilder result;
-        const bool ok = grid.catalogManager()->runUserManagementReadCommand(
+        const bool ok = grid.catalogManager()->runReadCommand(
             "admin", BSON("_getUserCacheGeneration" << 1), &result);
         if (!ok) {
             return Command::getStatusFromCommandResult(result.obj());
diff --git a/src/mongo/executor/network_test_env.h b/src/mongo/executor/network_test_env.h
index d5ec03b1226..5606d71d504 100644
--- a/src/mongo/executor/network_test_env.h
+++ b/src/mongo/executor/network_test_env.h
@@ -42,7 +42,6 @@ class BSONObj;
 class CatalogManagerReplicaSet;
 class DistLockManagerMock;
 struct RemoteCommandRequest;
-class RemoteCommandRunnerMock;
 class ShardRegistry;
 template <typename T>
 class StatusWith;
diff --git a/src/mongo/s/balance.cpp b/src/mongo/s/balance.cpp
index 29444e27953..7b836bb26d8 100644
--- a/src/mongo/s/balance.cpp
+++ b/src/mongo/s/balance.cpp
@@ -35,6 +35,7 @@
 #include <algorithm>
 
 #include "mongo/client/dbclientcursor.h"
+#include "mongo/client/remote_command_targeter.h"
 #include "mongo/db/client.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/namespace_string.h"
@@ -243,6 +244,7 @@ static BSONObj _buildDetails(bool didError,
         builder.append("candidateChunks", candidateChunks);
         builder.append("chunksMoved", chunksMoved);
     }
+
     return builder.obj();
 }
 
@@ -259,7 +261,11 @@ bool Balancer::_checkOIDs() {
             continue;
         }
 
-        BSONObj f = s->runCommand("admin", "features");
+        const auto shardHost = uassertStatusOK(
+            s->getTargeter()->findHost({ReadPreference::PrimaryOnly, TagSet::primaryOnly()}));
+
+        BSONObj f = uassertStatusOK(
+            grid.shardRegistry()->runCommand(shardHost, "admin", BSON("features" << 1)));
         if (f["oidMachine"].isNumber()) {
             int x = f["oidMachine"].numberInt();
             if (oids.count(x) == 0) {
@@ -267,18 +273,26 @@ bool Balancer::_checkOIDs() {
             } else {
                 log() << "error: 2 machines have " << x << " as oid machine piece: " << shardId
                       << " and " << oids[x];
-                s->runCommand("admin", BSON("features" << 1 << "oidReset" << 1));
+
+                uassertStatusOK(grid.shardRegistry()->runCommand(
+                    shardHost, "admin", BSON("features" << 1 << "oidReset" << 1)));
 
                 const auto otherShard = grid.shardRegistry()->getShard(oids[x]);
                 if (otherShard) {
-                    otherShard->runCommand("admin", BSON("features" << 1 << "oidReset" << 1));
+                    const auto otherShardHost = uassertStatusOK(otherShard->getTargeter()->findHost(
+                        {ReadPreference::PrimaryOnly, TagSet::primaryOnly()}));
+
+                    uassertStatusOK(grid.shardRegistry()->runCommand(
+                        otherShardHost, "admin", BSON("features" << 1 << "oidReset" << 1)));
                 }
+
                 return false;
             }
         } else {
             log() << "warning: oidMachine not set on: " << s->toString();
         }
     }
+
     return true;
 }
 
@@ -488,8 +502,8 @@ bool Balancer::_init() {
 void Balancer::run() {
     Client::initThread("Balancer");
 
-    // This is the body of a BackgroundJob so if we throw here we're basically ending the
-    // balancer thread prematurely.
+    // This is the body of a BackgroundJob so if we throw here we're basically ending the balancer
+    // thread prematurely.
     while (!inShutdown()) {
         if (!_init()) {
             log() << "will retry to initialize balancer in one minute";
diff --git a/src/mongo/s/catalog/SConscript b/src/mongo/s/catalog/SConscript
index f7a6265f5da..78bad9a62a9 100644
--- a/src/mongo/s/catalog/SConscript
+++ b/src/mongo/s/catalog/SConscript
@@ -128,7 +128,6 @@ env.CppUnitTest(
     LIBDEPS=[
         'catalog_manager_mock',
         'dist_lock_catalog_impl',
-        '$BUILD_DIR/mongo/client/remote_command_runner_mock',
         '$BUILD_DIR/mongo/client/remote_command_targeter_mock',
         '$BUILD_DIR/mongo/db/auth/authorization_manager_mock_init',
         '$BUILD_DIR/mongo/executor/network_test_env',
diff --git a/src/mongo/s/catalog/catalog_manager.h b/src/mongo/s/catalog/catalog_manager.h
index 04cc05c7d9a..e9f6ecac43f 100644
--- a/src/mongo/s/catalog/catalog_manager.h
+++ b/src/mongo/s/catalog/catalog_manager.h
@@ -276,7 +276,9 @@ public:
     virtual bool isShardHost(const ConnectionString& shardConnectionString) = 0;
 
     /**
-     * Runs a user management command on the config servers.
+     * Runs a user management command on the config servers, potentially synchronizing through
+     * a distributed lock. Do not use for general write command execution.
+     *
      * @param commandName: name of command
      * @param dbname: database for which the user management command is invoked
      * @param cmdObj: command obj
@@ -289,11 +291,11 @@ public:
                                                BSONObjBuilder* result) = 0;
 
     /**
-     * Runs a read-only user management command on a single config server.
+     * Runs a read-only command on a single config server.
      */
-    virtual bool runUserManagementReadCommand(const std::string& dbname,
-                                              const BSONObj& cmdObj,
-                                              BSONObjBuilder* result) = 0;
+    virtual bool runReadCommand(const std::string& dbname,
+                                const BSONObj& cmdObj,
+                                BSONObjBuilder* result) = 0;
 
     /**
      * Applies oplog entries to the config servers.
diff --git a/src/mongo/s/catalog/catalog_manager_mock.cpp b/src/mongo/s/catalog/catalog_manager_mock.cpp
index bbeab57f372..478f30c7141 100644
--- a/src/mongo/s/catalog/catalog_manager_mock.cpp
+++ b/src/mongo/s/catalog/catalog_manager_mock.cpp
@@ -148,9 +148,9 @@ bool CatalogManagerMock::runUserManagementWriteCommand(const string& commandName
     return true;
 }
 
-bool CatalogManagerMock::runUserManagementReadCommand(const string& dbname,
-                                                      const BSONObj& cmdObj,
-                                                      BSONObjBuilder* result) {
+bool CatalogManagerMock::runReadCommand(const string& dbname,
+                                        const BSONObj& cmdObj,
+                                        BSONObjBuilder* result) {
     return true;
 }
 
diff --git a/src/mongo/s/catalog/catalog_manager_mock.h b/src/mongo/s/catalog/catalog_manager_mock.h
index d208af32b79..eff3d2e10a0 100644
--- a/src/mongo/s/catalog/catalog_manager_mock.h
+++ b/src/mongo/s/catalog/catalog_manager_mock.h
@@ -106,9 +106,9 @@ public:
                                        const BSONObj& cmdObj,
                                        BSONObjBuilder* result) override;
 
-    bool runUserManagementReadCommand(const std::string& dbname,
-                                      const BSONObj& cmdObj,
-                                      BSONObjBuilder* result) override;
+    bool runReadCommand(const std::string& dbname,
+                        const BSONObj& cmdObj,
+                        BSONObjBuilder* result) override;
 
     Status applyChunkOpsDeprecated(const BSONArray& updateOps,
                                    const BSONArray& preCondition) override;
diff --git a/src/mongo/s/catalog/dist_lock_catalog_impl.h b/src/mongo/s/catalog/dist_lock_catalog_impl.h
index b496936d63c..e91217a6f91 100644
--- a/src/mongo/s/catalog/dist_lock_catalog_impl.h
+++ b/src/mongo/s/catalog/dist_lock_catalog_impl.h
@@ -37,7 +37,6 @@
 
 namespace mongo {
 
-class RemoteCommandRunner;
 class RemoteCommandTargeter;
 class ShardRegistry;
 
diff --git a/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp b/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
index 8f6026d6651..26979ed061e 100644
--- a/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
+++ b/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
@@ -33,7 +33,6 @@
 #include "mongo/base/status.h"
 #include "mongo/base/status_with.h"
 #include "mongo/bson/json.h"
-#include "mongo/client/remote_command_runner_mock.h"
 #include "mongo/client/remote_command_targeter_factory_mock.h"
 #include "mongo/client/remote_command_targeter_mock.h"
 #include "mongo/db/commands.h"
@@ -107,7 +106,6 @@ private:
 
         _shardRegistry =
             stdx::make_unique<ShardRegistry>(stdx::make_unique<RemoteCommandTargeterFactoryMock>(),
-                                             stdx::make_unique<RemoteCommandRunnerMock>(),
                                              std::move(executor),
                                              network,
                                              &_catalogMgr);
diff --git a/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp b/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp
index ecdd5775bf5..c364fa08045 100644
--- a/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp
+++ b/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp
@@ -1348,9 +1348,9 @@ bool CatalogManagerLegacy::runUserManagementWriteCommand(const string& commandNa
     return Command::appendCommandStatus(*result, status);
 }
 
-bool CatalogManagerLegacy::runUserManagementReadCommand(const string& dbname,
-                                                        const BSONObj& cmdObj,
-                                                        BSONObjBuilder* result) {
+bool CatalogManagerLegacy::runReadCommand(const string& dbname,
+                                          const BSONObj& cmdObj,
+                                          BSONObjBuilder* result) {
     try {
         // let SyncClusterConnection handle connecting to the first config server
         // that is reachable and returns data
diff --git a/src/mongo/s/catalog/legacy/catalog_manager_legacy.h b/src/mongo/s/catalog/legacy/catalog_manager_legacy.h
index 1067b98600d..2c625d9c76c 100644
--- a/src/mongo/s/catalog/legacy/catalog_manager_legacy.h
+++ b/src/mongo/s/catalog/legacy/catalog_manager_legacy.h
@@ -113,9 +113,9 @@ public:
                                        const BSONObj& cmdObj,
                                        BSONObjBuilder* result) override;
 
-    bool runUserManagementReadCommand(const std::string& dbname,
-                                      const BSONObj& cmdObj,
-                                      BSONObjBuilder* result) override;
+    bool runReadCommand(const std::string& dbname,
+                        const BSONObj& cmdObj,
+                        BSONObjBuilder* result) override;
 
     Status applyChunkOpsDeprecated(const BSONArray& updateOps,
                                    const BSONArray& preCondition) override;
diff --git a/src/mongo/s/catalog/replset/SConscript b/src/mongo/s/catalog/replset/SConscript
index c889cb36bcb..8324a7eaaf3 100644
--- a/src/mongo/s/catalog/replset/SConscript
+++ b/src/mongo/s/catalog/replset/SConscript
@@ -49,7 +49,6 @@ env.CppUnitTest(
     ],
     LIBDEPS=[
         'catalog_manager_replica_set',
-        '$BUILD_DIR/mongo/client/remote_command_runner_mock',
         '$BUILD_DIR/mongo/client/remote_command_targeter_mock',
         '$BUILD_DIR/mongo/db/auth/authorization_manager_mock_init',
         '$BUILD_DIR/mongo/executor/network_test_env',
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp
index c77532b89a4..795b822e0a2 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp
@@ -568,9 +568,9 @@ bool CatalogManagerReplicaSet::runUserManagementWriteCommand(const std::string&
     return Command::getStatusFromCommandResult(response.getValue()).isOK();
 }
 
-bool CatalogManagerReplicaSet::runUserManagementReadCommand(const std::string& dbname,
-                                                            const BSONObj& cmdObj,
-                                                            BSONObjBuilder* result) {
+bool CatalogManagerReplicaSet::runReadCommand(const std::string& dbname,
+                                              const BSONObj& cmdObj,
+                                              BSONObjBuilder* result) {
     auto targeter = grid.shardRegistry()->getShard("config")->getTargeter();
     auto target = targeter->findHost(kConfigReadSelector);
     if (!target.isOK()) {
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set.h b/src/mongo/s/catalog/replset/catalog_manager_replica_set.h
index 5756fbcf853..b66432fdd0f 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set.h
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set.h
@@ -113,9 +113,9 @@ public:
                                        const BSONObj& cmdObj,
                                        BSONObjBuilder* result) override;
 
-    bool runUserManagementReadCommand(const std::string& dbname,
-                                      const BSONObj& cmdObj,
-                                      BSONObjBuilder* result) override;
+    bool runReadCommand(const std::string& dbname,
+                        const BSONObj& cmdObj,
+                        BSONObjBuilder* result) override;
 
     Status applyChunkOpsDeprecated(const BSONArray& updateOps,
                                    const BSONArray& preCondition) override;
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp
index 6267fef1c8a..07da0c6d6a0 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp
@@ -549,8 +549,8 @@ TEST_F(CatalogManagerReplSetTestFixture, RunUserManagementReadCommand) {
 
     auto future = launchAsync([this] {
         BSONObjBuilder responseBuilder;
-        bool ok = catalogManager()->runUserManagementReadCommand(
-            "test", BSON("usersInfo" << 1), &responseBuilder);
+        bool ok =
+            catalogManager()->runReadCommand("test", BSON("usersInfo" << 1), &responseBuilder);
         ASSERT_TRUE(ok);
 
         BSONObj response = responseBuilder.obj();
@@ -566,7 +566,7 @@ TEST_F(CatalogManagerReplSetTestFixture, RunUserManagementReadCommand) {
         return BSON("ok" << 1 << "users" << BSONArrayBuilder().arr());
     });
 
-    // Now wait for the runUserManagementReadCommand call to return
+    // Now wait for the runReadCommand call to return
     future.wait_for(kFutureTimeout);
 }
 
@@ -577,8 +577,7 @@ TEST_F(CatalogManagerReplSetTestFixture, RunUserManagementReadCommandUnsatisfied
         Status(ErrorCodes::FailedToSatisfyReadPreference, "no nodes up"));
 
     BSONObjBuilder responseBuilder;
-    bool ok = catalogManager()->runUserManagementReadCommand(
-        "test", BSON("usersInfo" << 1), &responseBuilder);
+    bool ok = catalogManager()->runReadCommand("test", BSON("usersInfo" << 1), &responseBuilder);
     ASSERT_FALSE(ok);
 
     Status commandStatus = Command::getStatusFromCommandResult(responseBuilder.obj());
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp
index 8896b56327e..1fd46d42bde 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp
@@ -33,7 +33,6 @@
 #include <vector>
 
 #include "mongo/base/status_with.h"
-#include "mongo/client/remote_command_runner_mock.h"
 #include "mongo/client/remote_command_targeter_factory_mock.h"
 #include "mongo/db/repl/replication_executor.h"
 #include "mongo/executor/network_interface_mock.h"
@@ -73,7 +72,6 @@ void CatalogManagerReplSetTestFixture::setUp() {
 
     auto shardRegistry(
         stdx::make_unique<ShardRegistry>(stdx::make_unique<RemoteCommandTargeterFactoryMock>(),
-                                         stdx::make_unique<RemoteCommandRunnerMock>(),
                                          std::move(executor),
                                          _mockNetwork,
                                          cm.get()));
@@ -101,10 +99,6 @@ ShardRegistry* CatalogManagerReplSetTestFixture::shardRegistry() const {
     return grid.shardRegistry();
 }
 
-RemoteCommandRunnerMock* CatalogManagerReplSetTestFixture::commandRunner() const {
-    return RemoteCommandRunnerMock::get(shardRegistry()->getCommandRunner());
-}
-
 executor::NetworkInterfaceMock* CatalogManagerReplSetTestFixture::network() const {
     return _mockNetwork;
 }
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.h b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.h
index a5b22289e97..e95b9717c43 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.h
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.h
@@ -39,7 +39,6 @@ class BSONObj;
 class CatalogManagerReplicaSet;
 class DistLockManagerMock;
 struct RemoteCommandRequest;
-class RemoteCommandRunnerMock;
 class ShardRegistry;
 template <typename T>
 class StatusWith;
@@ -67,8 +66,6 @@ protected:
 
     ShardRegistry* shardRegistry() const;
 
-    RemoteCommandRunnerMock* commandRunner() const;
-
     executor::NetworkInterfaceMock* network() const;
 
     DistLockManagerMock* distLock() const;
diff --git a/src/mongo/s/client/shard.cpp b/src/mongo/s/client/shard.cpp
index 65aac08384f..5280a4107c5 100644
--- a/src/mongo/s/client/shard.cpp
+++ b/src/mongo/s/client/shard.cpp
@@ -36,10 +36,8 @@
 
 #include "mongo/client/replica_set_monitor.h"
 #include "mongo/client/read_preference.h"
-#include "mongo/client/remote_command_runner.h"
 #include "mongo/client/remote_command_targeter.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/rpc/get_status_from_command_result.h"
 #include "mongo/s/client/shard_registry.h"
 #include "mongo/s/grid.h"
 #include "mongo/util/log.h"
@@ -61,61 +59,19 @@ ShardPtr Shard::lookupRSName(const string& name) {
     return grid.shardRegistry()->lookupRSName(name);
 }
 
-BSONObj Shard::runCommand(const std::string& db, const std::string& simple) const {
-    return runCommand(db, BSON(simple << 1));
-}
-
-BSONObj Shard::runCommand(const string& db, const BSONObj& cmd) const {
-    BSONObj res;
-    bool ok = runCommand(db, cmd, res);
-    if (!ok) {
-        stringstream ss;
-        ss << "runCommand (" << cmd << ") on shard (" << _id << ") failed : " << res;
-        throw UserException(13136, ss.str());
-    }
-    res = res.getOwned();
-    return res;
-}
-
-bool Shard::runCommand(const std::string& db, const std::string& simple, BSONObj& res) const {
-    return runCommand(db, BSON(simple << 1), res);
-}
-
-bool Shard::runCommand(const string& db, const BSONObj& cmd, BSONObj& res) const {
-    const ReadPreferenceSetting readPref(ReadPreference::PrimaryOnly, TagSet::primaryOnly());
-    auto selectedHost = getTargeter()->findHost(readPref);
-    if (!selectedHost.isOK()) {
-        return false;
-    }
-
-    const RemoteCommandRequest request(selectedHost.getValue(), db, cmd);
-
-    auto statusCommand = grid.shardRegistry()->getCommandRunner()->runCommand(request);
-    if (!statusCommand.isOK()) {
-        return false;
-    }
-
-    res = statusCommand.getValue().data.getOwned();
-
-    return getStatusFromCommandResult(res).isOK();
-}
-
 ShardStatus Shard::getStatus() const {
-    BSONObj listDatabases;
-    uassert(28589,
-            str::stream() << "call to listDatabases on " << getConnString().toString()
-                          << " failed: " << listDatabases,
-            runCommand("admin", BSON("listDatabases" << 1), listDatabases));
+    const ReadPreferenceSetting readPref(ReadPreference::PrimaryOnly, TagSet::primaryOnly());
+    auto shardHost = uassertStatusOK(getTargeter()->findHost(readPref));
 
+    // List databases command
+    BSONObj listDatabases = uassertStatusOK(
+        grid.shardRegistry()->runCommand(shardHost, "admin", BSON("listDatabases" << 1)));
     BSONElement totalSizeElem = listDatabases["totalSize"];
     uassert(28590, "totalSize field not found in listDatabases", totalSizeElem.isNumber());
 
-    BSONObj serverStatus;
-    uassert(28591,
-            str::stream() << "call to serverStatus on " << getConnString().toString()
-                          << " failed: " << serverStatus,
-            runCommand("admin", BSON("serverStatus" << 1), serverStatus));
-
+    // Server status command
+    BSONObj serverStatus = uassertStatusOK(
+        grid.shardRegistry()->runCommand(shardHost, "admin", BSON("serverStatus" << 1)));
     BSONElement versionElement = serverStatus["version"];
     uassert(28599, "version field not found in serverStatus", versionElement.type() == String);
 
diff --git a/src/mongo/s/client/shard.h b/src/mongo/s/client/shard.h
index 077cd784000..d22e4d3fa83 100644
--- a/src/mongo/s/client/shard.h
+++ b/src/mongo/s/client/shard.h
@@ -95,12 +95,6 @@ public:
         return _targeter.get();
     }
 
-    BSONObj runCommand(const std::string& db, const std::string& simple) const;
-    BSONObj runCommand(const std::string& db, const BSONObj& cmd) const;
-
-    bool runCommand(const std::string& db, const std::string& simple, BSONObj& res) const;
-    bool runCommand(const std::string& db, const BSONObj& cmd, BSONObj& res) const;
-
     /**
      * Returns metadata and stats for this shard.
      */
diff --git a/src/mongo/s/client/shard_registry.cpp b/src/mongo/s/client/shard_registry.cpp
index 73db753262a..158fd48013b 100644
--- a/src/mongo/s/client/shard_registry.cpp
+++ b/src/mongo/s/client/shard_registry.cpp
@@ -34,7 +34,6 @@
 
 #include "mongo/client/connection_string.h"
 #include "mongo/client/query_fetcher.h"
-#include "mongo/client/remote_command_runner_impl.h"
 #include "mongo/client/remote_command_targeter.h"
 #include "mongo/client/remote_command_targeter_factory.h"
 #include "mongo/executor/task_executor.h"
@@ -61,12 +60,10 @@ const Seconds kConfigCommandTimeout{30};
 }  // unnamed namespace
 
 ShardRegistry::ShardRegistry(std::unique_ptr<RemoteCommandTargeterFactory> targeterFactory,
-                             std::unique_ptr<RemoteCommandRunner> commandRunner,
                              std::unique_ptr<executor::TaskExecutor> executor,
                              executor::NetworkInterface* network,
                              CatalogManager* catalogManager)
     : _targeterFactory(std::move(targeterFactory)),
-      _commandRunner(std::move(commandRunner)),
       _executor(std::move(executor)),
       _network(network),
       _catalogManager(catalogManager) {
diff --git a/src/mongo/s/client/shard_registry.h b/src/mongo/s/client/shard_registry.h
index 7251745d374..5bd91b42098 100644
--- a/src/mongo/s/client/shard_registry.h
+++ b/src/mongo/s/client/shard_registry.h
@@ -43,7 +43,6 @@ class BSONObjBuilder;
 class CatalogManager;
 struct HostAndPort;
 class NamespaceString;
-class RemoteCommandRunner;
 class RemoteCommandTargeterFactory;
 class Shard;
 class ShardType;
@@ -76,7 +75,6 @@ public:
      * @param catalogManager Used to retrieve the list of registered shard. TODO: remove.
      */
     ShardRegistry(std::unique_ptr<RemoteCommandTargeterFactory> targeterFactory,
-                  std::unique_ptr<RemoteCommandRunner> commandRunner,
                   std::unique_ptr<executor::TaskExecutor> executor,
                   executor::NetworkInterface* network,
                   CatalogManager* catalogManager);
@@ -94,10 +92,6 @@ public:
      */
     void shutdown();
 
-    RemoteCommandRunner* getCommandRunner() const {
-        return _commandRunner.get();
-    }
-
     executor::TaskExecutor* getExecutor() const {
         return _executor.get();
     }
@@ -165,9 +159,6 @@ private:
     // Factory to obtain remote command targeters for shards
     const std::unique_ptr<RemoteCommandTargeterFactory> _targeterFactory;
 
-    // API to run remote commands to shards in a synchronous manner
-    const std::unique_ptr<RemoteCommandRunner> _commandRunner;
-
     // Executor for scheduling work and remote commands to shards that run in an asynchronous
     // manner.
     const std::unique_ptr<executor::TaskExecutor> _executor;
diff --git a/src/mongo/s/commands/cluster_fsync_cmd.cpp b/src/mongo/s/commands/cluster_fsync_cmd.cpp
index f9dc78ee9d7..90735a25784 100644
--- a/src/mongo/s/commands/cluster_fsync_cmd.cpp
+++ b/src/mongo/s/commands/cluster_fsync_cmd.cpp
@@ -28,6 +28,8 @@
 
 #include "mongo/platform/basic.h"
 
+#include "mongo/client/read_preference.h"
+#include "mongo/client/remote_command_targeter.h"
 #include "mongo/db/commands.h"
 #include "mongo/s/client/shard.h"
 #include "mongo/s/client/shard_registry.h"
@@ -89,7 +91,12 @@ public:
                 continue;
             }
 
-            BSONObj x = s->runCommand("admin", "fsync");
+            const auto shardHost = uassertStatusOK(
+                s->getTargeter()->findHost({ReadPreference::PrimaryOnly, TagSet::primaryOnly()}));
+
+            BSONObj x = uassertStatusOK(
+                grid.shardRegistry()->runCommand(shardHost, "admin", BSON("fsync" << 1)));
+
             sub.append(s->getId(), x);
 
             if (!x["ok"].trueValue()) {
@@ -105,7 +112,7 @@ public:
         return ok;
     }
 
-} fsyncCmd;
+} clusterFsyncCmd;
 
 }  // namespace
 }  // namespace mongo
diff --git a/src/mongo/s/commands/cluster_list_databases_cmd.cpp b/src/mongo/s/commands/cluster_list_databases_cmd.cpp
index 248fb79f488..0e50c845df5 100644
--- a/src/mongo/s/commands/cluster_list_databases_cmd.cpp
+++ b/src/mongo/s/commands/cluster_list_databases_cmd.cpp
@@ -28,13 +28,14 @@
 
 #include "mongo/platform/basic.h"
 
-
 #include <map>
 #include <string>
 #include <vector>
 
 #include "mongo/client/connpool.h"
+#include "mongo/client/remote_command_targeter.h"
 #include "mongo/db/commands.h"
+#include "mongo/s/catalog/catalog_manager.h"
 #include "mongo/s/client/shard.h"
 #include "mongo/s/client/shard_registry.h"
 #include "mongo/s/grid.h"
@@ -98,7 +99,11 @@ public:
                 continue;
             }
 
-            BSONObj x = s->runCommand("admin", "listDatabases");
+            const auto shardHost = uassertStatusOK(
+                s->getTargeter()->findHost({ReadPreference::PrimaryOnly, TagSet::primaryOnly()}));
+
+            BSONObj x = uassertStatusOK(
+                grid.shardRegistry()->runCommand(shardHost, "admin", BSON("listDatabases" << 1)));
 
             BSONObjIterator j(x["databases"].Obj());
             while (j.more()) {
@@ -153,45 +158,45 @@ public:
             bb.append(temp.obj());
         }
 
-        // Obtain the cached config shard
-        const auto configShard = grid.shardRegistry()->getShard("config");
-
         {
-            // get config db from the config servers (first one)
-            BSONObj x;
-            if (configShard->runCommand("config", "dbstats", x)) {
+            // get config db from the config servers
+            BSONObjBuilder builder;
+
+            if (!grid.catalogManager()->runReadCommand("config", BSON("dbstats" << 1), &builder)) {
+                bb.append(BSON("name"
+                               << "config"));
+            } else {
+                BSONObj x = builder.obj();
                 BSONObjBuilder b;
                 b.append("name", "config");
                 b.appendBool("empty", false);
-                if (x["fileSize"].type())
+                if (x["fileSize"].type()) {
                     b.appendAs(x["fileSize"], "sizeOnDisk");
-                else
+                } else {
                     b.append("sizeOnDisk", 1);
+                }
                 bb.append(b.obj());
-            } else {
-                bb.append(BSON("name"
-                               << "config"));
             }
         }
 
         {
-            // get admin db from the config servers (first one)
-            BSONObj x;
-            if (configShard->runCommand("admin", "dbstats", x)) {
+            // get admin db from the config servers
+            BSONObjBuilder builder;
+
+            if (!grid.catalogManager()->runReadCommand("admin", BSON("dbstats" << 1), &builder)) {
+                bb.append(BSON("name"
+                               << "admin"));
+            } else {
+                BSONObj x = builder.obj();
                 BSONObjBuilder b;
                 b.append("name", "admin");
                 b.appendBool("empty", false);
-
                 if (x["fileSize"].type()) {
                     b.appendAs(x["fileSize"], "sizeOnDisk");
                 } else {
                     b.append("sizeOnDisk", 1);
                 }
-
                 bb.append(b.obj());
-            } else {
-                bb.append(BSON("name"
-                               << "admin"));
             }
         }
 
@@ -200,10 +205,10 @@ public:
         result.appendNumber("totalSize", totalSize);
         result.appendNumber("totalSizeMb", totalSize / (1024 * 1024));
 
-        return 1;
+        return true;
     }
 
-} cmdListDatabases;
+} clusterCmdListDatabases;
 
 }  // namespace
 }  // namespace mongo
diff --git a/src/mongo/s/commands/cluster_user_management_commands.cpp b/src/mongo/s/commands/cluster_user_management_commands.cpp
index d2a6ab667d4..0bb67e31c2a 100644
--- a/src/mongo/s/commands/cluster_user_management_commands.cpp
+++ b/src/mongo/s/commands/cluster_user_management_commands.cpp
@@ -352,7 +352,7 @@ public:
              int options,
              string& errmsg,
              BSONObjBuilder& result) {
-        return grid.catalogManager()->runUserManagementReadCommand(dbname, cmdObj, &result);
+        return grid.catalogManager()->runReadCommand(dbname, cmdObj, &result);
     }
 
 } cmdUsersInfo;
@@ -710,7 +710,7 @@ public:
              int options,
              string& errmsg,
              BSONObjBuilder& result) {
-        return grid.catalogManager()->runUserManagementReadCommand(dbname, cmdObj, &result);
+        return grid.catalogManager()->runReadCommand(dbname, cmdObj, &result);
     }
 
 } cmdRolesInfo;
diff --git a/src/mongo/s/d_state.cpp b/src/mongo/s/d_state.cpp
index aa5fcf51e5f..2cc3c99da8b 100644
--- a/src/mongo/s/d_state.cpp
+++ b/src/mongo/s/d_state.cpp
@@ -40,7 +40,6 @@
 
 #include "mongo/client/connpool.h"
 #include "mongo/client/global_conn_pool.h"
-#include "mongo/client/remote_command_runner_impl.h"
 #include "mongo/client/remote_command_targeter_factory_impl.h"
 #include "mongo/db/auth/action_set.h"
 #include "mongo/db/auth/action_type.h"
@@ -482,7 +481,6 @@ void ShardingState::_initialize(const string& server) {
 
     auto shardRegistry(
         stdx::make_unique<ShardRegistry>(stdx::make_unique<RemoteCommandTargeterFactoryImpl>(),
-                                         stdx::make_unique<RemoteCommandRunnerImpl>(0),
                                          stdx::make_unique<repl::ReplicationExecutor>(
                                              new executor::NetworkInterfaceImpl(), nullptr, 0),
                                          nullptr,
diff --git a/src/mongo/s/server.cpp b/src/mongo/s/server.cpp
index be3f6001398..2a03d2123b9 100644
--- a/src/mongo/s/server.cpp
+++ b/src/mongo/s/server.cpp
@@ -38,7 +38,6 @@
 #include "mongo/client/connpool.h"
 #include "mongo/client/dbclient_rs.h"
 #include "mongo/client/global_conn_pool.h"
-#include "mongo/client/remote_command_runner_impl.h"
 #include "mongo/client/remote_command_targeter_factory_impl.h"
 #include "mongo/client/replica_set_monitor.h"
 #include "mongo/config.h"
@@ -230,7 +229,6 @@ static ExitCode runMongosServer(bool doUpgrade) {
 
     auto shardRegistry(
         stdx::make_unique<ShardRegistry>(stdx::make_unique<RemoteCommandTargeterFactoryImpl>(),
-                                         stdx::make_unique<RemoteCommandRunnerImpl>(0),
                                          stdx::make_unique<repl::ReplicationExecutor>(
                                              new executor::NetworkInterfaceImpl(), nullptr, 0),
                                          nullptr,