SERVER-29731 Unify logic around directly invoking a command

11 files changed, 71 insertions, 73 deletions

diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index b431751dc9f..2e4b0116afd 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -50,6 +50,7 @@
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/rpc/write_concern_error_detail.h"
+#include "mongo/s/stale_exception.h"
 #include "mongo/util/log.h"
 
 namespace mongo {
@@ -182,6 +183,26 @@ Status Command::explain(OperationContext* opCtx,
     return {ErrorCodes::IllegalOperation, str::stream() << "Cannot explain cmd: " << getName()};
 }
 
+BSONObj Command::runCommandDirectly(OperationContext* opCtx, const OpMsgRequest& request) {
+    auto command = Command::findCommand(request.getCommandName());
+    invariant(command);
+
+    BSONObjBuilder out;
+    try {
+        std::string errmsg;
+        bool ok = command->enhancedRun(opCtx, request, errmsg, out);
+        appendCommandStatus(out, ok, errmsg);
+    } catch (const StaleConfigException& ex) {
+        // These exceptions are intended to be handled at a higher level and cannot losslessly
+        // round-trip through Status.
+        throw;
+    } catch (const DBException& ex) {
+        out.resetToEmpty();
+        appendCommandStatus(out, ex.toStatus());
+    }
+    return out.obj();
+}
+
 Command* Command::findCommand(StringData name) {
     CommandMap::const_iterator i = _commands->find(name);
     if (i == _commands->end())
diff --git a/src/mongo/db/commands.h b/src/mongo/db/commands.h
index 1efd437d3ef..96cf930d4c0 100644
--- a/src/mongo/db/commands.h
+++ b/src/mongo/db/commands.h
@@ -401,6 +401,13 @@ public:
     // Counter for unknown commands
     static Counter64 unknownCommands;
 
+    /**
+     * Runs a command directly and returns the result. Does not do any other work normally handled
+     * by command dispatch, such as checking auth, dealing with CurOp or waiting for write concern.
+     * It is illegal to call this if the command does not exist.
+     */
+    static BSONObj runCommandDirectly(OperationContext* txn, const OpMsgRequest& request);
+
     static Command* findCommand(StringData name);
 
     // Helper for setting errmsg and ok field in command result object.
diff --git a/src/mongo/db/commands/count_cmd.cpp b/src/mongo/db/commands/count_cmd.cpp
index b34eb049b0b..2a3db9a0341 100644
--- a/src/mongo/db/commands/count_cmd.cpp
+++ b/src/mongo/db/commands/count_cmd.cpp
@@ -177,16 +177,15 @@ public:
                 return appendCommandStatus(result, viewAggregation.getStatus());
             }
 
-            BSONObjBuilder aggResult;
-            (void)Command::findCommand("aggregate")
-                ->run(opCtx, dbname, viewAggregation.getValue(), errmsg, aggResult);
+            BSONObj aggResult = Command::runCommandDirectly(
+                opCtx, OpMsgRequest::fromDBAndBody(dbname, std::move(viewAggregation.getValue())));
 
-            if (ResolvedView::isResolvedViewErrorResponse(aggResult.asTempObj())) {
-                result.appendElements(aggResult.obj());
+            if (ResolvedView::isResolvedViewErrorResponse(aggResult)) {
+                result.appendElements(aggResult);
                 return false;
             }
 
-            ViewResponseFormatter formatter(aggResult.obj());
+            ViewResponseFormatter formatter(aggResult);
             Status formatStatus = formatter.appendAsCountResponse(&result);
             if (!formatStatus.isOK()) {
                 return appendCommandStatus(result, formatStatus);
diff --git a/src/mongo/db/commands/distinct.cpp b/src/mongo/db/commands/distinct.cpp
index 521862f0ccf..ba72b5cd7a6 100644
--- a/src/mongo/db/commands/distinct.cpp
+++ b/src/mongo/db/commands/distinct.cpp
@@ -178,17 +178,16 @@ public:
             if (!viewAggregation.isOK()) {
                 return appendCommandStatus(result, viewAggregation.getStatus());
             }
-            BSONObjBuilder aggResult;
 
-            (void)Command::findCommand("aggregate")
-                ->run(opCtx, dbname, viewAggregation.getValue(), errmsg, aggResult);
+            BSONObj aggResult = Command::runCommandDirectly(
+                opCtx, OpMsgRequest::fromDBAndBody(dbname, std::move(viewAggregation.getValue())));
 
-            if (ResolvedView::isResolvedViewErrorResponse(aggResult.asTempObj())) {
-                result.appendElements(aggResult.obj());
+            if (ResolvedView::isResolvedViewErrorResponse(aggResult)) {
+                result.appendElements(aggResult);
                 return false;
             }
 
-            ViewResponseFormatter formatter(aggResult.obj());
+            ViewResponseFormatter formatter(aggResult);
             Status formatStatus = formatter.appendAsDistinctResponse(&result);
             if (!formatStatus.isOK()) {
                 return appendCommandStatus(result, formatStatus);
diff --git a/src/mongo/db/commands/find_cmd.cpp b/src/mongo/db/commands/find_cmd.cpp
index e7d40b08c70..c597fbcc0e9 100644
--- a/src/mongo/db/commands/find_cmd.cpp
+++ b/src/mongo/db/commands/find_cmd.cpp
@@ -53,6 +53,7 @@
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/service_context.h"
 #include "mongo/db/stats/counters.h"
+#include "mongo/rpc/get_status_from_command_result.h"
 #include "mongo/util/log.h"
 
 namespace mongo {
@@ -284,19 +285,19 @@ public:
             if (!viewAggregationCommand.isOK())
                 return appendCommandStatus(result, viewAggregationCommand.getStatus());
 
-            Command* agg = Command::findCommand("aggregate");
-            try {
-                agg->run(opCtx, dbname, viewAggregationCommand.getValue(), errmsg, result);
-            } catch (DBException& error) {
-                if (error.getCode() == ErrorCodes::InvalidPipelineOperator) {
-                    return appendCommandStatus(
-                        result,
-                        {ErrorCodes::InvalidPipelineOperator,
-                         str::stream() << "Unsupported in view pipeline: " << error.what()});
-                }
-                return appendCommandStatus(result, error.toStatus());
+            BSONObj aggResult = Command::runCommandDirectly(
+                opCtx,
+                OpMsgRequest::fromDBAndBody(dbname, std::move(viewAggregationCommand.getValue())));
+            auto status = getStatusFromCommandResult(aggResult);
+            if (status.code() == ErrorCodes::InvalidPipelineOperator) {
+                return appendCommandStatus(
+                    result,
+                    {ErrorCodes::InvalidPipelineOperator,
+                     str::stream() << "Unsupported in view pipeline: " << status.reason()});
             }
-            return true;
+            result.resetToEmpty();
+            result.appendElements(aggResult);
+            return status.isOK();
         }
 
         // Get the execution plan for the query.
diff --git a/src/mongo/db/dbdirectclient.cpp b/src/mongo/db/dbdirectclient.cpp
index b85be86dd0d..6609d69a642 100644
--- a/src/mongo/db/dbdirectclient.cpp
+++ b/src/mongo/db/dbdirectclient.cpp
@@ -164,23 +164,12 @@ unsigned long long DBDirectClient::count(
     BSONObj cmdObj = _countCmd(ns, query, options, limit, skip);
 
     NamespaceString nsString(ns);
-    std::string dbname = nsString.db().toString();
-
-    Command* countCmd = Command::findCommand("count");
-    invariant(countCmd);
-
-    std::string errmsg;
-    BSONObjBuilder result;
-    bool runRetval = countCmd->run(_opCtx, dbname, cmdObj, errmsg, result);
-    if (!runRetval) {
-        Command::appendCommandStatus(result, runRetval, errmsg);
-        Status commandStatus = getStatusFromCommandResult(result.obj());
-        invariant(!commandStatus.isOK());
-        uassertStatusOK(commandStatus);
-    }
 
-    BSONObj resultObj = result.obj();
-    return static_cast<unsigned long long>(resultObj["n"].numberLong());
+    auto result = Command::runCommandDirectly(
+        _opCtx, OpMsgRequest::fromDBAndBody(nsString.db(), std::move(cmdObj)));
+
+    uassertStatusOK(getStatusFromCommandResult(result));
+    return static_cast<unsigned long long>(result["n"].numberLong());
 }
 
 }  // namespace mongo
diff --git a/src/mongo/db/ftdc/ftdc_server.cpp b/src/mongo/db/ftdc/ftdc_server.cpp
index 534cbf37650..a4bb5572c7c 100644
--- a/src/mongo/db/ftdc/ftdc_server.cpp
+++ b/src/mongo/db/ftdc/ftdc_server.cpp
@@ -247,21 +247,14 @@ FTDCSimpleInternalCommandCollector::FTDCSimpleInternalCommandCollector(StringDat
                                                                        StringData name,
                                                                        StringData ns,
                                                                        BSONObj cmdObj)
-    : _name(name.toString()), _ns(ns.toString()), _cmdObj(std::move(cmdObj)) {
-    _command = Command::findCommand(command);
-    invariant(_command);
+    : _name(name.toString()), _request(OpMsgRequest::fromDBAndBody(ns, std::move(cmdObj))) {
+    invariant(command == _request.getCommandName());
+    invariant(Command::findCommand(command));  // Fail early if it doesn't exist.
 }
 
 void FTDCSimpleInternalCommandCollector::collect(OperationContext* opCtx, BSONObjBuilder& builder) {
-    std::string errmsg;
-
-    bool ret = _command->run(opCtx, _ns, _cmdObj, errmsg, builder);
-
-    // Some commands return errmsgs when they return false (collstats)
-    // Some commands return bson objs when they return false (replGetStatus)
-    // We append the status as needed to ensure readers of the collected data can check the
-    // status of any individual command.
-    _command->appendCommandStatus(builder, ret, errmsg);
+    auto result = Command::runCommandDirectly(opCtx, _request);
+    builder.appendElements(result);
 }
 
 std::string FTDCSimpleInternalCommandCollector::name() const {
diff --git a/src/mongo/db/ftdc/ftdc_server.h b/src/mongo/db/ftdc/ftdc_server.h
index 4b4583ae153..02357c24e6f 100644
--- a/src/mongo/db/ftdc/ftdc_server.h
+++ b/src/mongo/db/ftdc/ftdc_server.h
@@ -93,11 +93,7 @@ public:
 
 private:
     std::string _name;
-    std::string _ns;
-    BSONObj _cmdObj;
-
-    // Not owned
-    Command* _command;
+    const OpMsgRequest _request;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/ops/write_ops_exec.cpp b/src/mongo/db/ops/write_ops_exec.cpp
index 76e1d9a0acc..17ffdead6b5 100644
--- a/src/mongo/db/ops/write_ops_exec.cpp
+++ b/src/mongo/db/ops/write_ops_exec.cpp
@@ -252,14 +252,9 @@ SingleWriteResult createIndex(OperationContext* opCtx,
     BSONObjBuilder cmdBuilder;
     cmdBuilder << "createIndexes" << ns.coll();
     cmdBuilder << "indexes" << BSON_ARRAY(spec);
-    auto cmd = cmdBuilder.obj();
-
-    BSONObjBuilder cmdReplyBuilder;
-    std::string errMsg;
-    bool ok = Command::findCommand("createIndexes")
-                  ->run(opCtx, systemIndexes.db().toString(), cmd, errMsg, cmdReplyBuilder);
-    Command::appendCommandStatus(cmdReplyBuilder, ok, errMsg);
-    auto cmdResult = cmdReplyBuilder.obj();
+
+    auto cmdResult = Command::runCommandDirectly(
+        opCtx, OpMsgRequest::fromDBAndBody(systemIndexes.db(), cmdBuilder.obj()));
     uassertStatusOK(getStatusFromCommandResult(cmdResult));
 
     // Unlike normal inserts, it is not an error to "insert" a duplicate index.
diff --git a/src/mongo/s/commands/cluster_count_cmd.cpp b/src/mongo/s/commands/cluster_count_cmd.cpp
index e21dc7bad41..6736d6c4174 100644
--- a/src/mongo/s/commands/cluster_count_cmd.cpp
+++ b/src/mongo/s/commands/cluster_count_cmd.cpp
@@ -184,12 +184,11 @@ public:
                 resolvedView.asExpandedViewAggregation(aggRequestOnView.getValue());
             auto resolvedAggCmd = resolvedAggRequest.serializeToCommandObj().toBson();
 
-            BSONObjBuilder aggResult;
-            Command::findCommand("aggregate")
-                ->run(opCtx, dbname, resolvedAggCmd, errmsg, aggResult);
+            BSONObj aggResult = Command::runCommandDirectly(
+                opCtx, OpMsgRequest::fromDBAndBody(dbname, std::move(resolvedAggCmd)));
 
             result.resetToEmpty();
-            ViewResponseFormatter formatter(aggResult.obj());
+            ViewResponseFormatter formatter(aggResult);
             auto formatStatus = formatter.appendAsCountResponse(&result);
             if (!formatStatus.isOK()) {
                 return appendCommandStatus(result, formatStatus);
diff --git a/src/mongo/s/commands/commands_public.cpp b/src/mongo/s/commands/commands_public.cpp
index bdc73bd5adc..9ba05a7298b 100644
--- a/src/mongo/s/commands/commands_public.cpp
+++ b/src/mongo/s/commands/commands_public.cpp
@@ -1041,11 +1041,10 @@ public:
                     resolvedView.asExpandedViewAggregation(aggRequestOnView.getValue());
                 auto resolvedAggCmd = resolvedAggRequest.serializeToCommandObj().toBson();
 
-                BSONObjBuilder aggResult;
-                Command::findCommand("aggregate")
-                    ->run(opCtx, dbName, resolvedAggCmd, errmsg, aggResult);
+                BSONObj aggResult = Command::runCommandDirectly(
+                    opCtx, OpMsgRequest::fromDBAndBody(dbName, std::move(resolvedAggCmd)));
 
-                ViewResponseFormatter formatter(aggResult.obj());
+                ViewResponseFormatter formatter(aggResult);
                 auto formatStatus = formatter.appendAsDistinctResponse(&result);
                 if (!formatStatus.isOK()) {
                     return appendCommandStatus(result, formatStatus);