From 9e4b6e5c2f9e266ed05ce7c913631f12548e4160 Mon Sep 17 00:00:00 2001
From: Pavi Vetriselvan <pavithra.vetriselvan@mongodb.com>
Date: Tue, 4 Aug 2020 12:51:12 -0400
Subject: SERVER-50097 isMaster aliases should correctly populate
 exhaustIsMasterMetrics

---
 src/mongo/rpc/op_msg_integration_test.cpp | 59 +++++++++++++++++++++++++++++++
 src/mongo/s/commands/strategy.cpp         | 23 ++++++------
 2 files changed, 71 insertions(+), 11 deletions(-)

diff --git a/src/mongo/rpc/op_msg_integration_test.cpp b/src/mongo/rpc/op_msg_integration_test.cpp
index 1c6400e2cba..0b2b4de6c31 100644
--- a/src/mongo/rpc/op_msg_integration_test.cpp
+++ b/src/mongo/rpc/op_msg_integration_test.cpp
@@ -767,6 +767,65 @@ TEST(OpMsg, ServerStatusCorrectlyShowsExhaustIsMasterMetrics) {
     // The exhaust stream would continue indefinitely.
 }
 
+TEST(OpMsg, ServerStatusCorrectlyShowsExhaustIsMasterMetricsWithIsMasterAlias) {
+    std::string errMsg;
+    auto conn = std::unique_ptr<DBClientBase>(
+        unittest::getFixtureConnectionString().connect("integration_test", errMsg));
+    uassert(ErrorCodes::SocketException, errMsg, conn);
+
+    if (conn->isReplicaSetMember()) {
+        // Don't run on replica sets as the RSM will use the streamable isMaster protocol by
+        // default. This can cause inconsistencies in our metrics tests.
+        return;
+    }
+
+    // Wait for stale exhuast streams to finish closing before testing the exhaust isMaster metrics.
+    ASSERT(waitForCondition([&] {
+        auto serverStatusCmd = BSON("serverStatus" << 1);
+        BSONObj serverStatusReply;
+        ASSERT(conn->runCommand("admin", serverStatusCmd, serverStatusReply));
+        return serverStatusReply["connections"]["exhaustIsMaster"].numberInt() == 0;
+    }));
+
+    // Issue an isMaster command with the "ismaster" alias without a topology version.
+    auto lowerCaseIsMasterCmd = BSON("ismaster" << 1);
+    auto opMsgRequest = OpMsgRequest::fromDBAndBody("admin", lowerCaseIsMasterCmd);
+    auto request = opMsgRequest.serialize();
+
+    Message reply;
+    ASSERT(conn->call(request, reply));
+    auto res = OpMsg::parse(reply).body;
+    ASSERT_OK(getStatusFromCommandResult(res));
+    auto topologyVersion = res["topologyVersion"].Obj().getOwned();
+    ASSERT(!OpMsg::isFlagSet(reply, OpMsg::kMoreToCome));
+
+    lowerCaseIsMasterCmd =
+        BSON("ismaster" << 1 << "topologyVersion" << topologyVersion << "maxAwaitTimeMS" << 100);
+    opMsgRequest = OpMsgRequest::fromDBAndBody("admin", lowerCaseIsMasterCmd);
+    request = opMsgRequest.serialize();
+    OpMsg::setFlag(&request, OpMsg::kExhaustSupported);
+
+    // Run the isMaster command with the "ismaster" alias. The aliased command should work
+    // identically to the default "isMaster" command name and initiate the the exhaust stream.
+    ASSERT(conn->call(request, reply));
+    ASSERT(OpMsg::isFlagSet(reply, OpMsg::kMoreToCome));
+    res = OpMsg::parse(reply).body;
+    ASSERT_OK(getStatusFromCommandResult(res));
+
+    // Start a new connection to the server to check the serverStatus metrics.
+    std::string newErrMsg;
+    auto conn2 = std::unique_ptr<DBClientBase>(
+        unittest::getFixtureConnectionString().connect("integration_test", newErrMsg));
+    uassert(ErrorCodes::SocketException, newErrMsg, conn2);
+
+    auto serverStatusCmd = BSON("serverStatus" << 1);
+    BSONObj serverStatusReply;
+    ASSERT(conn2->runCommand("admin", serverStatusCmd, serverStatusReply));
+    ASSERT_EQUALS(1, serverStatusReply["connections"]["exhaustIsMaster"].numberInt());
+
+    // The exhaust stream would continue indefinitely.
+}
+
 TEST(OpMsg, ExhaustIsMasterMetricDecrementsOnNewOpAfterTerminatingExhaustStream) {
     std::string errMsg;
     const auto conn1AppName = "integration_test";
diff --git a/src/mongo/s/commands/strategy.cpp b/src/mongo/s/commands/strategy.cpp
index 81eee3ef4bc..f90d6d1beb6 100644
--- a/src/mongo/s/commands/strategy.cpp
+++ b/src/mongo/s/commands/strategy.cpp
@@ -296,9 +296,10 @@ MONGO_FAIL_POINT_DEFINE(doNotRefreshShardsOnRetargettingError);
  */
 void runCommand(OperationContext* opCtx,
                 const OpMsgRequest& request,
-                const NetworkOp opType,
+                const Message& m,
                 rpc::ReplyBuilderInterface* replyBuilder,
                 BSONObjBuilder* errorBuilder) {
+    auto const opType = m.operation();
     auto const commandName = request.getCommandName();
     auto const command = CommandHelpers::findCommand(commandName);
     if (!command) {
@@ -311,6 +312,14 @@ void runCommand(OperationContext* opCtx,
         return;
     }
 
+    opCtx->setExhaust(OpMsg::isFlagSet(m, OpMsg::kExhaustSupported));
+    const auto session = opCtx->getClient()->session();
+    if (session) {
+        if (!opCtx->isExhaust() || command->getName() != "isMaster"_sd) {
+            InExhaustIsMaster::get(session.get())->setInExhaustIsMaster(false);
+        }
+    }
+
     CommandHelpers::uassertShouldAttemptParse(opCtx, command, request);
 
     // Parse the 'maxTimeMS' command option, and use it to set a deadline for the operation on
@@ -1023,14 +1032,6 @@ DbResponse Strategy::clientCommand(OperationContext* opCtx, const Message& m) {
             }
         }();
 
-        opCtx->setExhaust(OpMsg::isFlagSet(m, OpMsg::kExhaustSupported));
-        const auto session = opCtx->getClient()->session();
-        if (session) {
-            if (!opCtx->isExhaust() || request.getCommandName() != "isMaster"_sd) {
-                InExhaustIsMaster::get(session.get())->setInExhaustIsMaster(false);
-            }
-        }
-
         // Execute.
         std::string db = request.getDatabase().toString();
         try {
@@ -1040,7 +1041,7 @@ DbResponse Strategy::clientCommand(OperationContext* opCtx, const Message& m) {
                         "Command begin",
                         "db"_attr = db,
                         "headerId"_attr = m.header().getId());
-            runCommand(opCtx, request, m.operation(), reply.get(), &errorBuilder);
+            runCommand(opCtx, request, m, reply.get(), &errorBuilder);
             LOGV2_DEBUG(22771,
                         3,
                         "Command end db: {db} msg id: {headerId}",
@@ -1232,7 +1233,7 @@ void Strategy::writeOp(OperationContext* opCtx, DbMessage* dbm) {
                            MONGO_UNREACHABLE;
                    }
                }(),
-               msg.operation(),
+               msg,
                &reply,
                &errorBuilder);  // built objects are ignored
 }
-- 
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