SERVER-49336 Set ClientMetadata before CommandInvocations are run

This patch does the following:
- Always parses ClientMetadata before command implementations are run.
- Marks general ClientMetadata as final in the first hello.
- Removes client_metadata_ismaster.* (SERVER-50517)
- Switches references to "isMaster" to "hello" (SERVER-50517)
- Binds "$client" metadata as a decoration (SERVER-50804)

23 files changed, 329 insertions, 441 deletions

diff --git a/src/mongo/db/client_metadata_propagation_egress_hook.cpp b/src/mongo/db/client_metadata_propagation_egress_hook.cpp
index 2da3c615fd5..3da25eaf5e4 100644
--- a/src/mongo/db/client_metadata_propagation_egress_hook.cpp
+++ b/src/mongo/db/client_metadata_propagation_egress_hook.cpp
@@ -29,7 +29,7 @@
 
 #include "mongo/db/client_metadata_propagation_egress_hook.h"
 
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/rpc/metadata/impersonated_user_metadata.h"
 
 namespace mongo {
@@ -37,9 +37,16 @@ namespace rpc {
 
 Status ClientMetadataPropagationEgressHook::writeRequestMetadata(OperationContext* opCtx,
                                                                  BSONObjBuilder* metadataBob) {
+    if (!opCtx) {
+        return Status::OK();
+    }
+
     try {
         writeAuthDataToImpersonatedUserMetadata(opCtx, metadataBob);
-        ClientMetadataIsMasterState::writeToMetadata(opCtx, metadataBob);
+
+        if (auto metadata = ClientMetadata::get(opCtx->getClient())) {
+            metadata->writeToMetadata(metadataBob);
+        }
         return Status::OK();
     } catch (...) {
         return exceptionToStatus();
diff --git a/src/mongo/db/commands.cpp b/src/mongo/db/commands.cpp
index 8d9a8de296b..2232eee33ce 100644
--- a/src/mongo/db/commands.cpp
+++ b/src/mongo/db/commands.cpp
@@ -56,7 +56,7 @@
 #include "mongo/db/read_write_concern_defaults.h"
 #include "mongo/logv2/log.h"
 #include "mongo/rpc/factory.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/rpc/op_msg_rpc_impls.h"
 #include "mongo/rpc/protocol.h"
 #include "mongo/rpc/write_concern_error_detail.h"
@@ -553,8 +553,8 @@ bool CommandHelpers::shouldActivateFailCommandFailPoint(const BSONObj& data,
 
     auto threadName = client->desc();
     auto appName = StringData();
-    if (const auto& clientMetadata = ClientMetadataIsMasterState::get(client).getClientMetadata()) {
-        appName = clientMetadata.get().getApplicationName();
+    if (auto clientMetadata = ClientMetadata::get(client)) {
+        appName = clientMetadata->getApplicationName();
     }
     auto isInternalClient = client->session()->getTags() & transport::Session::kInternalClient;
 
@@ -703,8 +703,7 @@ void CommandHelpers::handleMarkKillOnClientDisconnect(OperationContext* opCtx,
     waitInCommandMarkKillOnClientDisconnect.executeIf(
         [&](const BSONObj&) { waitInCommandMarkKillOnClientDisconnect.pauseWhileSet(opCtx); },
         [&](const BSONObj& obj) {
-            const auto& md =
-                ClientMetadataIsMasterState::get(opCtx->getClient()).getClientMetadata();
+            auto md = ClientMetadata::get(opCtx->getClient());
             return md && (md->getApplicationName() == obj["appName"].str());
         });
 }
diff --git a/src/mongo/db/commands/authentication_commands.cpp b/src/mongo/db/commands/authentication_commands.cpp
index 4bdb7f67b62..b9c48b18495 100644
--- a/src/mongo/db/commands/authentication_commands.cpp
+++ b/src/mongo/db/commands/authentication_commands.cpp
@@ -58,7 +58,6 @@
 #include "mongo/logv2/log.h"
 #include "mongo/platform/random.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 #include "mongo/transport/session.h"
 #include "mongo/util/concurrency/mutex.h"
 #include "mongo/util/net/ssl_manager.h"
@@ -114,9 +113,7 @@ Status _authenticateX509(OperationContext* opCtx, const UserName& user, const BS
                               "authentication. The current configuration does not allow "
                               "x.509 cluster authentication, check the --clusterAuthMode flag");
             }
-            auto& clientMetadata =
-                ClientMetadataIsMasterState::get(opCtx->getClient()).getClientMetadata();
-            if (clientMetadata) {
+            if (auto clientMetadata = ClientMetadata::get(opCtx->getClient())) {
                 auto clientMetadataDoc = clientMetadata->getDocument();
                 auto driverName = clientMetadataDoc.getObjectField("driver"_sd)
                                       .getField("name"_sd)
diff --git a/src/mongo/db/curop.cpp b/src/mongo/db/curop.cpp
index 78af5154bae..e00d6a3b6ba 100644
--- a/src/mongo/db/curop.cpp
+++ b/src/mongo/db/curop.cpp
@@ -52,7 +52,6 @@
 #include "mongo/db/query/plan_summary_stats.h"
 #include "mongo/logv2/log.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 #include "mongo/rpc/metadata/impersonated_user_metadata.h"
 #include "mongo/util/hex.h"
 #include "mongo/util/log_with_sampling.h"
@@ -261,15 +260,13 @@ void CurOp::reportCurrentOpForClient(OperationContext* opCtx,
     infoBuilder->append("host", hostName);
 
     client->reportState(*infoBuilder);
-    const auto& clientMetadata = ClientMetadataIsMasterState::get(client).getClientMetadata();
-
-    if (clientMetadata) {
-        auto appName = clientMetadata.get().getApplicationName();
+    if (auto clientMetadata = ClientMetadata::get(client)) {
+        auto appName = clientMetadata->getApplicationName();
         if (!appName.empty()) {
             infoBuilder->append("appName", appName);
         }
 
-        auto clientMetadataDocument = clientMetadata.get().getDocument();
+        auto clientMetadataDocument = clientMetadata->getDocument();
         infoBuilder->append("clientMetadata", clientMetadataDocument);
     }
 
@@ -784,9 +781,8 @@ string OpDebug::report(OperationContext* opCtx, const SingleThreadedLockStats* l
 
     s << curop.getNS();
 
-    const auto& clientMetadata = ClientMetadataIsMasterState::get(client).getClientMetadata();
-    if (clientMetadata) {
-        auto appName = clientMetadata.get().getApplicationName();
+    if (auto clientMetadata = ClientMetadata::get(client)) {
+        auto appName = clientMetadata->getApplicationName();
         if (!appName.empty()) {
             s << " appName: \"" << str::escape(appName) << '\"';
         }
@@ -956,9 +952,8 @@ void OpDebug::report(OperationContext* opCtx,
 
     pAttrs->addDeepCopy("ns", curop.getNS());
 
-    const auto& clientMetadata = ClientMetadataIsMasterState::get(client).getClientMetadata();
-    if (clientMetadata) {
-        StringData appName = clientMetadata.get().getApplicationName();
+    if (auto clientMetadata = ClientMetadata::get(client)) {
+        StringData appName = clientMetadata->getApplicationName();
         if (!appName.empty()) {
             pAttrs->add("appName", appName);
         }
@@ -1299,10 +1294,8 @@ std::function<BSONObj(ProfileFilter::Args)> OpDebug::appendStaged(StringSet requ
         b.append(field, args.opCtx->getClient()->clientAddress());
     });
     addIfNeeded("appName", [](auto field, auto args, auto& b) {
-        const auto& clientMetadata =
-            ClientMetadataIsMasterState::get(args.opCtx->getClient()).getClientMetadata();
-        if (clientMetadata) {
-            auto appName = clientMetadata.get().getApplicationName();
+        if (auto clientMetadata = ClientMetadata::get(args.opCtx->getClient())) {
+            auto appName = clientMetadata->getApplicationName();
             if (!appName.empty()) {
                 b.append(field, appName);
             }
diff --git a/src/mongo/db/introspect.cpp b/src/mongo/db/introspect.cpp
index 307723838fd..89fea0c89cb 100644
--- a/src/mongo/db/introspect.cpp
+++ b/src/mongo/db/introspect.cpp
@@ -46,7 +46,6 @@
 #include "mongo/db/stats/resource_consumption_metrics.h"
 #include "mongo/logv2/log.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 #include "mongo/util/scopeguard.h"
 
 namespace mongo {
@@ -79,10 +78,8 @@ void profile(OperationContext* opCtx, NetworkOp op) {
     b.appendDate("ts", jsTime());
     b.append("client", opCtx->getClient()->clientAddress());
 
-    const auto& clientMetadata =
-        ClientMetadataIsMasterState::get(opCtx->getClient()).getClientMetadata();
-    if (clientMetadata) {
-        auto appName = clientMetadata.get().getApplicationName();
+    if (auto clientMetadata = ClientMetadata::get(opCtx->getClient())) {
+        auto appName = clientMetadata->getApplicationName();
         if (!appName.empty()) {
             b.append("appName", appName);
         }
diff --git a/src/mongo/db/pipeline/pipeline_d.cpp b/src/mongo/db/pipeline/pipeline_d.cpp
index a2a383ed0fe..2915c9c99f6 100644
--- a/src/mongo/db/pipeline/pipeline_d.cpp
+++ b/src/mongo/db/pipeline/pipeline_d.cpp
@@ -77,7 +77,7 @@
 #include "mongo/db/stats/top.h"
 #include "mongo/db/storage/record_store.h"
 #include "mongo/db/storage/sorted_data_interface.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/s/query/document_source_merge_cursors.h"
 #include "mongo/util/time_support.h"
 
diff --git a/src/mongo/db/repl/replication_info.cpp b/src/mongo/db/repl/replication_info.cpp
index 183888255a3..3a024c8450a 100644
--- a/src/mongo/db/repl/replication_info.cpp
+++ b/src/mongo/db/repl/replication_info.cpp
@@ -61,7 +61,6 @@
 #include "mongo/executor/network_interface.h"
 #include "mongo/logv2/log.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 #include "mongo/transport/ismaster_metrics.h"
 #include "mongo/util/decimal_counter.h"
 #include "mongo/util/fail_point.h"
@@ -289,33 +288,11 @@ public:
             sessionTagsToSet |= transport::Session::kKeepOpen;
         }
 
-        auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx->getClient());
-        bool seenIsMaster = clientMetadataIsMasterState.hasSeenIsMaster();
-
-        if (!seenIsMaster) {
-            clientMetadataIsMasterState.setSeenIsMaster();
-        }
-
-        BSONElement element = cmdObj[kMetadataDocumentName];
-        if (!element.eoo()) {
-            if (seenIsMaster) {
-                uasserted(ErrorCodes::ClientMetadataCannotBeMutated,
-                          "The client metadata document may only be sent in the first isMaster");
-            }
-
-            auto parsedClientMetadata = uassertStatusOK(ClientMetadata::parse(element));
-
-            invariant(parsedClientMetadata);
-
-            parsedClientMetadata->logClientMetadata(opCtx->getClient());
-
-            clientMetadataIsMasterState.setClientMetadata(opCtx->getClient(),
-                                                          std::move(parsedClientMetadata));
-        }
-
-        if (!seenIsMaster) {
-            auto sniName = opCtx->getClient()->getSniNameForSession();
-            SplitHorizon::setParameters(opCtx->getClient(), std::move(sniName));
+        auto client = opCtx->getClient();
+        if (ClientMetadata::tryFinalize(client)) {
+            // If we are the first hello, then set split horizon parameters.
+            auto sniName = client->getSniNameForSession();
+            SplitHorizon::setParameters(client, std::move(sniName));
         }
 
         // Parse the optional 'internalClient' field. This is provided by incoming connections from
diff --git a/src/mongo/db/s/single_transaction_coordinator_stats.h b/src/mongo/db/s/single_transaction_coordinator_stats.h
index a6d8be9b54f..9f7349cf3ed 100644
--- a/src/mongo/db/s/single_transaction_coordinator_stats.h
+++ b/src/mongo/db/s/single_transaction_coordinator_stats.h
@@ -30,7 +30,7 @@
 #pragma once
 
 #include "mongo/db/client.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/util/tick_source.h"
 #include "mongo/util/time_support.h"
 
@@ -56,10 +56,9 @@ public:
                 clientHostAndPort = client->getRemote().toString();
             }
             connectionId = client->getConnectionId();
-            if (const auto& metadata =
-                    ClientMetadataIsMasterState::get(client).getClientMetadata()) {
-                clientMetadata = metadata.get().getDocument();
-                appName = metadata.get().getApplicationName().toString();
+            if (auto metadata = ClientMetadata::get(client)) {
+                clientMetadata = metadata->getDocument();
+                appName = metadata->getApplicationName().toString();
             }
         }
     };
diff --git a/src/mongo/db/s/transaction_coordinator_test_fixture.cpp b/src/mongo/db/s/transaction_coordinator_test_fixture.cpp
index 256d0905278..377a1993213 100644
--- a/src/mongo/db/s/transaction_coordinator_test_fixture.cpp
+++ b/src/mongo/db/s/transaction_coordinator_test_fixture.cpp
@@ -39,7 +39,6 @@
 #include "mongo/db/operation_context.h"
 #include "mongo/db/repl/wait_for_majority_service.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 #include "mongo/s/catalog/sharding_catalog_client_mock.h"
 #include "mongo/s/catalog/type_shard.h"
 #include "mongo/unittest/unittest.h"
@@ -137,7 +136,6 @@ void TransactionCoordinatorTestFixture::associateClientMetadata(Client* client,
                                                &metadataBuilder));
     auto clientMetadata = metadataBuilder.obj();
     auto clientMetadataParse = ClientMetadata::parse(clientMetadata["client"]);
-    ClientMetadataIsMasterState::setClientMetadata(client,
-                                                   std::move(clientMetadataParse.getValue()));
+    ClientMetadata::setAndFinalize(client, std::move(clientMetadataParse.getValue()));
 }
 }  // namespace mongo
diff --git a/src/mongo/db/service_entry_point_common.cpp b/src/mongo/db/service_entry_point_common.cpp
index b4fa419ce16..540a4480ca1 100644
--- a/src/mongo/db/service_entry_point_common.cpp
+++ b/src/mongo/db/service_entry_point_common.cpp
@@ -91,6 +91,7 @@
 #include "mongo/rpc/get_status_from_command_result.h"
 #include "mongo/rpc/message.h"
 #include "mongo/rpc/metadata.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/rpc/metadata/oplog_query_metadata.h"
 #include "mongo/rpc/metadata/repl_set_metadata.h"
 #include "mongo/rpc/metadata/tracking_metadata.h"
@@ -990,6 +991,8 @@ void execCommandDatabase(OperationContext* opCtx,
     const auto isInternalClient = opCtx->getClient()->session() &&
         (opCtx->getClient()->session()->getTags() & transport::Session::kInternalClient);
 
+    const auto isHello = command->getName() == "hello"_sd || command->getName() == "isMaster"_sd;
+
     try {
         const auto apiParamsFromClient = initializeAPIParameters(opCtx, request.body, command);
         Client* client = opCtx->getClient();
@@ -1000,11 +1003,17 @@ void execCommandDatabase(OperationContext* opCtx,
             APIParameters::get(opCtx) = APIParameters::fromClient(apiParamsFromClient);
         }
 
+        if (isHello) {
+            // Preload generic ClientMetadata ahead of our first hello request. After the first
+            // request, metaElement should always be empty.
+            auto metaElem = request.body[kMetadataDocumentName];
+            ClientMetadata::setFromMetadata(opCtx->getClient(), metaElem);
+        }
+
         auto& apiParams = APIParameters::get(opCtx);
         auto& apiVersionMetrics = APIVersionMetrics::get(opCtx->getServiceContext());
-        const auto& clientMetadata = ClientMetadataIsMasterState::get(client).getClientMetadata();
-        if (clientMetadata) {
-            auto appName = clientMetadata.get().getApplicationName().toString();
+        if (auto clientMetadata = ClientMetadata::get(client)) {
+            auto appName = clientMetadata->getApplicationName().toString();
             apiVersionMetrics.update(appName, apiParams);
         }
 
@@ -1166,8 +1175,7 @@ void execCommandDatabase(OperationContext* opCtx,
         // The "hello" or "isMaster" commands should not inherit the deadline from the user op it is
         // operating as a part of as that can interfere with replica set monitoring and host
         // selection.
-        bool ignoreMaxTimeMSOpOnly =
-            command->getName() == "hello"_sd || command->getName() == "isMaster"_sd;
+        const bool ignoreMaxTimeMSOpOnly = isHello;
 
         if ((maxTimeMS > 0 || maxTimeMSOpOnly > 0) &&
             command->getLogicalOp() != LogicalOp::opGetMore) {
diff --git a/src/mongo/db/stats/single_transaction_stats.h b/src/mongo/db/stats/single_transaction_stats.h
index 0afdb7f3d24..51524c8d01c 100644
--- a/src/mongo/db/stats/single_transaction_stats.h
+++ b/src/mongo/db/stats/single_transaction_stats.h
@@ -31,7 +31,6 @@
 
 #include "mongo/db/curop.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 
 namespace mongo {
 
@@ -56,10 +55,9 @@ public:
                 clientHostAndPort = client->getRemote().toString();
             }
             connectionId = client->getConnectionId();
-            if (const auto& metadata =
-                    ClientMetadataIsMasterState::get(client).getClientMetadata()) {
-                clientMetadata = metadata.get().getDocument();
-                appName = metadata.get().getApplicationName().toString();
+            if (auto metadata = ClientMetadata::get(client)) {
+                clientMetadata = metadata->getDocument();
+                appName = metadata->getApplicationName().toString();
             }
         }
     };
diff --git a/src/mongo/db/transaction_participant_test.cpp b/src/mongo/db/transaction_participant_test.cpp
index c2c18a05c8f..831cab5b825 100644
--- a/src/mongo/db/transaction_participant_test.cpp
+++ b/src/mongo/db/transaction_participant_test.cpp
@@ -2704,7 +2704,7 @@ TEST_F(TransactionsMetricsTest, ReportStashedResources) {
 
     auto sessionCheckout = checkOutSession();
 
-    // Create a ClientMetadata object and set it on ClientMetadataIsMasterState.
+    // Create a ClientMetadata object and set it.
     BSONObjBuilder builder;
     ASSERT_OK(ClientMetadata::serializePrivate("driverName",
                                                "driverVersion",
@@ -2716,9 +2716,7 @@ TEST_F(TransactionsMetricsTest, ReportStashedResources) {
                                                &builder));
     auto obj = builder.obj();
     auto clientMetadata = ClientMetadata::parse(obj["client"]);
-    auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx()->getClient());
-    clientMetadataIsMasterState.setClientMetadata(opCtx()->getClient(),
-                                                  std::move(clientMetadata.getValue()));
+    ClientMetadata::setAndFinalize(opCtx()->getClient(), std::move(clientMetadata.getValue()));
 
     repl::ReadConcernArgs readConcernArgs;
     ASSERT_OK(
@@ -2948,12 +2946,10 @@ BSONObj constructClientMetadata(StringData appName) {
 }  // namespace
 
 TEST_F(TransactionsMetricsTest, LastClientInfoShouldUpdateUponStash) {
-    // Create a ClientMetadata object and set it on ClientMetadataIsMasterState.
+    // Create a ClientMetadata object and set it.
     auto obj = constructClientMetadata("appName");
     auto clientMetadata = ClientMetadata::parse(obj["client"]);
-    auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx()->getClient());
-    clientMetadataIsMasterState.setClientMetadata(opCtx()->getClient(),
-                                                  std::move(clientMetadata.getValue()));
+    ClientMetadata::setAndFinalize(opCtx()->getClient(), std::move(clientMetadata.getValue()));
 
     auto sessionCheckout = checkOutSession();
     auto txnParticipant = TransactionParticipant::get(opCtx());
@@ -2972,8 +2968,7 @@ TEST_F(TransactionsMetricsTest, LastClientInfoShouldUpdateUponStash) {
     // Create another ClientMetadata object.
     auto newObj = constructClientMetadata("newAppName");
     auto newClientMetadata = ClientMetadata::parse(newObj["client"]);
-    clientMetadataIsMasterState.setClientMetadata(opCtx()->getClient(),
-                                                  std::move(newClientMetadata.getValue()));
+    ClientMetadata::setAndFinalize(opCtx()->getClient(), std::move(newClientMetadata.getValue()));
 
     txnParticipant.unstashTransactionResources(opCtx(), "insert");
     txnParticipant.stashTransactionResources(opCtx());
@@ -2985,12 +2980,10 @@ TEST_F(TransactionsMetricsTest, LastClientInfoShouldUpdateUponStash) {
 }
 
 TEST_F(TransactionsMetricsTest, LastClientInfoShouldUpdateUponCommit) {
-    // Create a ClientMetadata object and set it on ClientMetadataIsMasterState.
+    // Create a ClientMetadata object and set it.
     auto obj = constructClientMetadata("appName");
     auto clientMetadata = ClientMetadata::parse(obj["client"]);
-    auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx()->getClient());
-    clientMetadataIsMasterState.setClientMetadata(opCtx()->getClient(),
-                                                  std::move(clientMetadata.getValue()));
+    ClientMetadata::setAndFinalize(opCtx()->getClient(), std::move(clientMetadata.getValue()));
 
     auto sessionCheckout = checkOutSession();
     auto txnParticipant = TransactionParticipant::get(opCtx());
@@ -3008,13 +3001,10 @@ TEST_F(TransactionsMetricsTest, LastClientInfoShouldUpdateUponCommit) {
 }
 
 TEST_F(TransactionsMetricsTest, LastClientInfoShouldUpdateUponAbort) {
-    // Create a ClientMetadata object and set it on ClientMetadataIsMasterState.
+    // Create a ClientMetadata object and set it.
     auto obj = constructClientMetadata("appName");
     auto clientMetadata = ClientMetadata::parse(obj["client"]);
-
-    auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx()->getClient());
-    clientMetadataIsMasterState.setClientMetadata(opCtx()->getClient(),
-                                                  std::move(clientMetadata.getValue()));
+    ClientMetadata::setAndFinalize(opCtx()->getClient(), std::move(clientMetadata.getValue()));
 
     auto sessionCheckout = checkOutSession();
     auto txnParticipant = TransactionParticipant::get(opCtx());
diff --git a/src/mongo/embedded/embedded_ismaster.cpp b/src/mongo/embedded/embedded_ismaster.cpp
index b304a7a9148..94f1a557ee1 100644
--- a/src/mongo/embedded/embedded_ismaster.cpp
+++ b/src/mongo/embedded/embedded_ismaster.cpp
@@ -33,7 +33,6 @@
 #include "mongo/db/commands.h"
 #include "mongo/db/ops/write_ops.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 
 namespace mongo {
 namespace {
@@ -69,29 +68,10 @@ public:
                      BSONObjBuilder& result) {
 
         auto wireSpec = WireSpec::instance().get();
-        auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx->getClient());
-        bool seenIsMaster = clientMetadataIsMasterState.hasSeenIsMaster();
-        if (!seenIsMaster) {
-            clientMetadataIsMasterState.setSeenIsMaster();
-        }
 
-        BSONElement element = cmdObj[kMetadataDocumentName];
-        if (!element.eoo()) {
-            if (seenIsMaster) {
-                uasserted(ErrorCodes::ClientMetadataCannotBeMutated,
-                          "The client metadata document may only be sent in the first isMaster");
-            }
-
-            auto swParseClientMetadata = ClientMetadata::parse(element);
-            uassertStatusOK(swParseClientMetadata.getStatus());
-
-            invariant(swParseClientMetadata.getValue());
-
-            swParseClientMetadata.getValue().get().logClientMetadata(opCtx->getClient());
-
-            clientMetadataIsMasterState.setClientMetadata(
-                opCtx->getClient(), std::move(swParseClientMetadata.getValue()));
-        }
+        auto metaElem = cmdObj[kMetadataDocumentName];
+        ClientMetadata::setFromMetadata(opCtx->getClient(), metaElem);
+        ClientMetadata::tryFinalize(opCtx->getClient());
 
         result.appendBool("ismaster", true);
 
diff --git a/src/mongo/rpc/SConscript b/src/mongo/rpc/SConscript
index e5d6a85c1bc..aeec34c5414 100644
--- a/src/mongo/rpc/SConscript
+++ b/src/mongo/rpc/SConscript
@@ -134,7 +134,6 @@ env.Library(
     target='client_metadata',
     source=[
         'metadata/client_metadata.cpp',
-        'metadata/client_metadata_ismaster.cpp',
     ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
diff --git a/src/mongo/rpc/metadata.cpp b/src/mongo/rpc/metadata.cpp
index a9747811af1..a6e9bde0ebf 100644
--- a/src/mongo/rpc/metadata.cpp
+++ b/src/mongo/rpc/metadata.cpp
@@ -37,7 +37,7 @@
 #include "mongo/db/jsobj.h"
 #include "mongo/db/logical_time_validator.h"
 #include "mongo/db/vector_clock.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/rpc/metadata/config_server_metadata.h"
 #include "mongo/rpc/metadata/impersonated_user_metadata.h"
 #include "mongo/rpc/metadata/sharding_metadata.h"
@@ -59,6 +59,7 @@ void readRequestMetadata(OperationContext* opCtx,
     BSONElement configSvrElem;
     BSONElement trackingElem;
     BSONElement clientElem;
+    BSONElement helloClientElem;
     BSONElement impersonationElem;
     BSONElement clientOperationKeyElem;
 
@@ -96,7 +97,13 @@ void readRequestMetadata(OperationContext* opCtx,
 
     readImpersonatedUserMetadata(impersonationElem, opCtx);
 
-    uassertStatusOK(ClientMetadataIsMasterState::readFromMetadata(opCtx, clientElem));
+    // We check for "$client" but not "client" here, because currentOp can filter on "client" as
+    // a top-level field.
+    if (clientElem) {
+        // The '$client' field is populated by mongos when it sends requests to shards on behalf of
+        // its own requests. This may or may not be relevant for SERVER-50804.
+        ClientMetadata::setFromMetadataForOperation(opCtx, clientElem);
+    }
 
     ConfigServerMetadata::get(opCtx) =
         uassertStatusOK(ConfigServerMetadata::readFromMetadata(configSvrElem));
diff --git a/src/mongo/rpc/metadata/client_metadata.cpp b/src/mongo/rpc/metadata/client_metadata.cpp
index e9203e66bb2..a4b78080ec9 100644
--- a/src/mongo/rpc/metadata/client_metadata.cpp
+++ b/src/mongo/rpc/metadata/client_metadata.cpp
@@ -44,8 +44,11 @@
 #include "mongo/logv2/log.h"
 #include "mongo/s/is_mongos.h"
 #include "mongo/util/debug_util.h"
+#include "mongo/util/net/socket_utils.h"
 #include "mongo/util/processinfo.h"
 #include "mongo/util/str.h"
+#include "mongo/util/testing_proctor.h"
+#include "mongo/util/version.h"
 
 namespace mongo {
 
@@ -72,6 +75,13 @@ constexpr uint32_t kMaxMongoSMetadataDocumentByteLength = 512U;
 constexpr uint32_t kMaxMongoDMetadataDocumentByteLength = 1024U;
 constexpr uint32_t kMaxApplicationNameByteLength = 128U;
 
+struct ClientMetadataState {
+    bool isFinalized = false;
+    boost::optional<ClientMetadata> meta;
+};
+const auto getClientState = Client::declareDecoration<ClientMetadataState>();
+const auto getOperationState = OperationContext::declareDecoration<ClientMetadataState>();
+
 }  // namespace
 
 StatusWith<boost::optional<ClientMetadata>> ClientMetadata::parse(const BSONElement& element) {
@@ -442,4 +452,110 @@ StringData ClientMetadata::fieldName() {
     return kClientMetadataFieldName;
 }
 
+bool ClientMetadata::tryFinalize(Client* client) {
+    auto lk = stdx::unique_lock(*client);
+    auto& state = getClientState(client);
+    if (std::exchange(state.isFinalized, true)) {
+        return false;
+    }
+
+    lk.unlock();
+
+    if (state.meta) {
+        // If we reach this point, the ClientMetadata is effectively immutable because isFinalized
+        // is true.
+        state.meta->logClientMetadata(client);
+    }
+
+    return true;
+}
+
+const ClientMetadata* ClientMetadata::getForClient(Client* client) noexcept {
+    auto& state = getClientState(client);
+    if (!state.isFinalized || !state.meta) {
+        return nullptr;
+    }
+    return &state.meta.get();
+}
+
+const ClientMetadata* ClientMetadata::getForOperation(OperationContext* opCtx) noexcept {
+    auto& state = getOperationState(opCtx);
+    if (!state.isFinalized) {
+        return nullptr;
+    }
+    invariant(state.meta);
+    return &state.meta.get();
+}
+
+const ClientMetadata* ClientMetadata::get(Client* client) noexcept {
+    if (auto opCtx = client->getOperationContext()) {
+        if (auto meta = getForOperation(opCtx)) {
+            return meta;
+        }
+    }
+
+    return getForClient(client);
+}
+
+void ClientMetadata::setAndFinalize(Client* client, boost::optional<ClientMetadata> meta) {
+    invariant(TestingProctor::instance().isEnabled());
+
+    auto lk = stdx::lock_guard(*client);
+
+    auto& state = getClientState(client);
+    state.isFinalized = true;
+    state.meta = std::move(meta);
+}
+
+void ClientMetadata::setFromMetadataForOperation(OperationContext* opCtx, BSONElement& elem) {
+    auto lk = stdx::lock_guard(*opCtx->getClient());
+
+    auto& state = getOperationState(opCtx);
+    auto wasFinalized = std::exchange(state.isFinalized, true);
+    uassert(ErrorCodes::ClientMetadataCannotBeMutated,
+            "The client metadata document may only be set once per operation",
+            !wasFinalized);
+
+    state.meta = ClientMetadata::readFromMetadata(elem);
+}
+
+void ClientMetadata::setFromMetadata(Client* client, BSONElement& elem) {
+    auto& state = getClientState(client);
+
+    {
+        auto lk = stdx::lock_guard(*client);
+        if (state.isFinalized) {
+            uassert(ErrorCodes::ClientMetadataCannotBeMutated,
+                    "The client metadata document may only be sent in the first hello",
+                    elem.eoo());
+            return;
+        }
+    }
+
+    auto meta = ClientMetadata::readFromMetadata(elem);
+    if (meta && isMongos()) {
+        // If we had a full ClientMetadata and we're on mongos, attach some additional client data.
+        meta->setMongoSMetadata(getHostNameCachedAndPort(),
+                                client->clientAddress(true),
+                                VersionInfoInterface::instance().version());
+    }
+
+    auto lk = stdx::lock_guard(*client);
+    state.meta = std::move(meta);
+}
+
+boost::optional<ClientMetadata> ClientMetadata::readFromMetadata(BSONElement& element) {
+    return uassertStatusOK(ClientMetadata::parse(element));
+}
+
+void ClientMetadata::writeToMetadata(BSONObjBuilder* builder) const noexcept {
+    auto& document = getDocument();
+    if (document.isEmpty()) {
+        // Skip appending metadata if there is none
+        return;
+    }
+
+    builder->append(ClientMetadata::fieldName(), document);
+}
+
 }  // namespace mongo
diff --git a/src/mongo/rpc/metadata/client_metadata.h b/src/mongo/rpc/metadata/client_metadata.h
index 524fdda3710..ff17cf60720 100644
--- a/src/mongo/rpc/metadata/client_metadata.h
+++ b/src/mongo/rpc/metadata/client_metadata.h
@@ -46,38 +46,35 @@ constexpr auto kMetadataDocumentName = "client"_sd;
 
 /**
  * The ClientMetadata class is responsible for parsing the client metadata document that is received
- * in isMaster from clients. This class also provides static methods for client libraries to create
- * a valid client metadata document.
+ * in the "client" field of the first hello from clients. The client metadata document can also be
+ * parsed from the "$client" field of any operation. This class also provides static methods for
+ * client libraries to write a valid client metadata document.
  *
- * Example document of isMaster request with client metadata document:
+ * Example client metadata document:
  * {
- *    "isMaster" : 1,
- *    "client" : {
- *        "application" : {              // Optional
- *            "name" : "string"          // Optional with caveats
- *        },
- *        "driver" : {                   // Required, Informational Only
- *            "name" : "string",         // Required, Informational Only
- *            "version" : "string"       // Required, Informational Only
- *        },
- *        "os" : {                       // Required, Informational Only
- *            "type" : "string",         // Required, Informational Only, See note
- *            "name" : "string",         // Optional, Informational Only
- *            "architecture" : "string", // Optional, Informational Only
- *            "version" : "string"       // Optional, Informational Only
- *        }
- *        "mongos" : {                   // Optional, Informational Only
- *            "host" : "string",         // Optional, Informational Only
- *            "client" : "string",       // Optional, Informational Only
- *            "version" : "string"       // Optional, Informational Only
- *        }
- *    }
+ *     "application" : {              // Optional
+ *         "name" : "string"          // Optional with caveats
+ *     },
+ *     "driver" : {                   // Required, Informational Only
+ *         "name" : "string",         // Required, Informational Only
+ *         "version" : "string"       // Required, Informational Only
+ *     },
+ *     "os" : {                       // Required, Informational Only
+ *         "type" : "string",         // Required, Informational Only, See note
+ *         "name" : "string",         // Optional, Informational Only
+ *         "architecture" : "string", // Optional, Informational Only
+ *         "version" : "string"       // Optional, Informational Only
+ *     }
+ *     "mongos" : {                   // Optional, Informational Only
+ *         "host" : "string",         // Optional, Informational Only
+ *         "client" : "string",       // Optional, Informational Only
+ *         "version" : "string"       // Optional, Informational Only
+ *     }
  * }
  *
- * For this classes' purposes, the client metadata document is the sub-document in "client". It is
- * allowed to contain additional fields that are not listed in the example above. These additional
- * fields are ignore by this class. The "os" document "type" field is required (defaults to
- * "unknown" in Mongo Drivers). The "driver", and "os" documents while required, are for
+ * It is allowed to contain additional fields that are not listed in the example above. These
+ * additional fields are ignore by this class. The "os" document "type" field is required (defaults
+ * to "unknown" in Mongo Drivers). The "driver", and "os" documents while required, are for
  * informational purposes only. The content is logged to disk but otherwise ignored.
  *
  * See Driver Specification: "MongoDB Handshake" for more information.
@@ -91,7 +88,55 @@ public:
     ClientMetadata& operator=(ClientMetadata&&) = default;
 
     /**
-     * Parse and validate a client metadata document contained in an isMaster request.
+     * Get the ClientMetadata for the Client.
+     *
+     * This function may return nullptr for either of two reasons:
+     * - The ClientMetadata hasn't been finalized yet via tryFinalize().
+     * - The ClientMetadata wasn't provided at all.
+     *
+     * The pointer to ClientMetadata is valid to use if:
+     * - You hold the Client lock.
+     * - You are on the Client's thread.
+     */
+    static const ClientMetadata* getForClient(Client* client) noexcept;
+
+    /**
+     * Get the ClientMetadata for the OperationContext.
+     *
+     * This function may return nullptr if there was no ClientMetadata provided for the
+     * OperationContext.
+     *
+     * The pointer to ClientMetadata is valid to use if:
+     * - You hold the Client lock.
+     * - You are on the Client's thread.
+     */
+    static const ClientMetadata* getForOperation(OperationContext* opCtx) noexcept;
+
+    /**
+     * Get the prioritized ClientMetadata for the Client.
+     *
+     * This function returns getForOperation() if it returns a valid pointer, otherwise it returns
+     * getForClient().
+     *
+     * The pointer to ClientMetadata is valid to use if:
+     * - You hold the Client lock.
+     * - You are on the Client's thread.
+     */
+    static const ClientMetadata* get(Client* client) noexcept;
+
+    /**
+     * Set the ClientMetadata for the Client directly.
+     *
+     * This should only be used in testing. It sets the ClientMetadata as finalized but does not
+     * check if it was previously finalized. It allows the user to replace the ClientMetadata for
+     * a Client, which is disallowed if done via setFromMetadata().
+     *
+     * This function takes the Client lock.
+     */
+    static void setAndFinalize(Client* client, boost::optional<ClientMetadata> meta);
+
+    /**
+     * Parse and validate a client metadata document contained in a hello request.
      *
      * Empty or non-existent sub-documents are permitted. Non-empty documents are required to have
      * the fields driver.name, driver.version, and os.type which must be strings.
@@ -155,6 +200,47 @@ public:
                             BSONObjBuilder* builder);
 
     /**
+     * Mark the ClientMetadata as finalized.
+     *
+     * Once this function is called, no future hello can mutate the ClientMetadata.
+     *
+     * This function takes the Client lock.
+     */
+    static bool tryFinalize(Client* client);
+
+    /**
+     * Set the ClientMetadata for the Client by reading it from the given BSONElement.
+     *
+     * This function throws if the ClientMetadata has already been finalized but the BSONElement is
+     * an object. ClientMetadata is allowed to be set via the first hello only.
+     *
+     * This function takes the Client lock.
+     */
+    static void setFromMetadata(Client* client, BSONElement& elem);
+
+    /**
+     * Set the ClientMetadata for the OperationContext by reading it from the given BSONElement.
+     *
+     * This function throws if called more than once for the same OperationContext.
+     *
+     * This function takes the Client lock.
+     */
+    static void setFromMetadataForOperation(OperationContext* opCtx, BSONElement& elem);
+
+    /**
+     * Read from the $client field in requests.
+     *
+     * Throws an error if the $client section is not valid. It is valid for it to not exist though.
+     */
+    static boost::optional<ClientMetadata> readFromMetadata(BSONElement& elem);
+
+    /**
+     * Write the $client section to request bodies if there is a non-empty client metadata
+     * connection with the current client.
+     */
+    void writeToMetadata(BSONObjBuilder* builder) const noexcept;
+
+    /**
      * Modify the existing client metadata document to include a mongos section.
      *
      * hostAndPort is "host:port" of the running MongoS.
diff --git a/src/mongo/rpc/metadata/client_metadata_ismaster.cpp b/src/mongo/rpc/metadata/client_metadata_ismaster.cpp
deleted file mode 100644
index 15a3dc7482d..00000000000
--- a/src/mongo/rpc/metadata/client_metadata_ismaster.cpp
+++ /dev/null
@@ -1,128 +0,0 @@
-/**
- *    Copyright (C) 2018-present MongoDB, Inc.
- *
- *    This program is free software: you can redistribute it and/or modify
- *    it under the terms of the Server Side Public License, version 1,
- *    as published by MongoDB, Inc.
- *
- *    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
- *    Server Side Public License for more details.
- *
- *    You should have received a copy of the Server Side Public License
- *    along with this program. If not, see
- *    <http://www.mongodb.com/licensing/server-side-public-license>.
- *
- *    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 Server Side 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/rpc/metadata/client_metadata_ismaster.h"
-
-#include <memory>
-#include <string>
-
-#include "mongo/base/init.h"
-#include "mongo/base/status.h"
-#include "mongo/db/client.h"
-#include "mongo/db/operation_context.h"
-#include "mongo/db/service_context.h"
-
-namespace mongo {
-
-namespace {
-
-const auto getClientMetadataIsMasterState =
-    Client::declareDecoration<ClientMetadataIsMasterState>();
-
-}  // namespace
-
-ClientMetadataIsMasterState& ClientMetadataIsMasterState::get(Client* client) {
-    return getClientMetadataIsMasterState(*client);
-}
-
-bool ClientMetadataIsMasterState::hasSeenIsMaster() const {
-    return _hasSeenIsMaster;
-}
-
-void ClientMetadataIsMasterState::setSeenIsMaster() {
-    invariant(!_hasSeenIsMaster);
-    _hasSeenIsMaster = true;
-}
-
-const boost::optional<ClientMetadata>& ClientMetadataIsMasterState::getClientMetadata() const {
-    return _clientMetadata;
-}
-
-void ClientMetadataIsMasterState::setClientMetadata(Client* client,
-                                                    boost::optional<ClientMetadata> clientMetadata,
-                                                    bool setViaMetadata) {
-    auto& state = get(client);
-
-    stdx::lock_guard<Client> lk(*client);
-    state._clientMetadata = std::move(clientMetadata);
-    state._setViaMetadata = setViaMetadata;
-}
-
-
-Status ClientMetadataIsMasterState::readFromMetadata(OperationContext* opCtx,
-                                                     BSONElement& element) {
-    auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx->getClient());
-
-    // If client metadata is not present in network requests, reset the in-memory metadata to be
-    // blank so that the wrong
-    // app name is not propagated.
-    if (element.eoo()) {
-        auto client = opCtx->getClient();
-
-        if (clientMetadataIsMasterState._setViaMetadata && !client->isInDirectClient()) {
-            clientMetadataIsMasterState.setClientMetadata(client, boost::none, true);
-        }
-
-        return Status::OK();
-    }
-
-    auto swParseClientMetadata = ClientMetadata::parse(element);
-
-    if (!swParseClientMetadata.getStatus().isOK()) {
-        return swParseClientMetadata.getStatus();
-    }
-
-    clientMetadataIsMasterState.setClientMetadata(
-        opCtx->getClient(), std::move(swParseClientMetadata.getValue()), true);
-
-    return Status::OK();
-}
-
-void ClientMetadataIsMasterState::writeToMetadata(OperationContext* opCtx,
-                                                  BSONObjBuilder* builder) {
-    // We may be asked to write metadata on background threads that are not associated with an
-    // operation context
-    if (!opCtx) {
-        return;
-    }
-
-    const auto& clientMetadata =
-        ClientMetadataIsMasterState::get(opCtx->getClient()).getClientMetadata();
-
-    // Skip appending metadata if there is none
-    if (!clientMetadata || clientMetadata.get().getDocument().isEmpty()) {
-        return;
-    }
-
-    builder->append(ClientMetadata::fieldName(), clientMetadata.get().getDocument());
-}
-
-}  // namespace mongo
diff --git a/src/mongo/rpc/metadata/client_metadata_ismaster.h b/src/mongo/rpc/metadata/client_metadata_ismaster.h
deleted file mode 100644
index 91214a8ccab..00000000000
--- a/src/mongo/rpc/metadata/client_metadata_ismaster.h
+++ /dev/null
@@ -1,115 +0,0 @@
-/**
- *    Copyright (C) 2018-present MongoDB, Inc.
- *
- *    This program is free software: you can redistribute it and/or modify
- *    it under the terms of the Server Side Public License, version 1,
- *    as published by MongoDB, Inc.
- *
- *    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
- *    Server Side Public License for more details.
- *
- *    You should have received a copy of the Server Side Public License
- *    along with this program. If not, see
- *    <http://www.mongodb.com/licensing/server-side-public-license>.
- *
- *    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 Server Side 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 <boost/optional.hpp>
-#include <memory>
-#include <string>
-
-#include "mongo/rpc/metadata/client_metadata.h"
-
-namespace mongo {
-
-class Client;
-
-/**
- * ClientMetadataIsMasterState is responsible for tracking whether the client metadata document has
- * been received by the specified Client object.
- */
-class ClientMetadataIsMasterState {
-    ClientMetadataIsMasterState(const ClientMetadataIsMasterState&) = delete;
-    ClientMetadataIsMasterState& operator=(const ClientMetadataIsMasterState&) = delete;
-
-public:
-    ClientMetadataIsMasterState() = default;
-
-    static ClientMetadataIsMasterState& get(Client* client);
-
-    /**
-     * Get the optional client metadata object.
-     */
-    const boost::optional<ClientMetadata>& getClientMetadata() const;
-
-    /**
-     * Set the optional client metadata object.
-     */
-    static void setClientMetadata(Client* client,
-                                  boost::optional<ClientMetadata> clientMetadata,
-                                  bool setViaMetadata = false);
-
-    /**
-     * Check a flag to indicate that isMaster has been seen for this Client.
-     */
-    bool hasSeenIsMaster() const;
-
-    /**
-     * Set a flag to indicate that isMaster has been seen for this Client.
-     */
-    void setSeenIsMaster();
-
-    /**
-     * Read from the $client field in requests.
-     *
-     * Returns an error if the $client section is not valid. It is valid for it to not exist though.
-     *
-     * Thread-Safety:
-     *   None - must be only be read and written from the thread owning "Client".
-     */
-    static Status readFromMetadata(OperationContext* opCtx, BSONElement& elem);
-
-    /**
-     * Write the $client section to request bodies if there is a non-empty client metadata
-     * connection with the current client.
-     *
-     * Thread-Safety:
-     *   None - must be only be read and written from the thread owning "Client".
-     */
-    static void writeToMetadata(OperationContext* opCtx, BSONObjBuilder* builder);
-
-private:
-    // Optional client metadata document.
-    // Set if client sees isMaster cmd or the $client field.
-    // Thread-Safety:
-    //   Can be read and written from the thread owning "Client".
-    //   Can be read from other threads if they hold the "Client" lock.
-    boost::optional<ClientMetadata> _clientMetadata{boost::none};
-
-    // Indicates whether we have seen an is master for this client.
-    // Thread-Safety:
-    //   None - must be only be read and written from the thread owning "Client".
-    bool _hasSeenIsMaster{false};
-
-    // Indicates whether we have set isMaster based on metadata or via isMaster
-    // Thread-Safety:
-    //   None - must be only be read and written from the thread owning "Client".
-    bool _setViaMetadata{false};
-};
-
-}  // namespace mongo
diff --git a/src/mongo/s/commands/cluster_is_master_cmd.cpp b/src/mongo/s/commands/cluster_is_master_cmd.cpp
index 532f29c7e04..1ae4b497576 100644
--- a/src/mongo/s/commands/cluster_is_master_cmd.cpp
+++ b/src/mongo/s/commands/cluster_is_master_cmd.cpp
@@ -42,7 +42,6 @@
 #include "mongo/db/wire_version.h"
 #include "mongo/logv2/log.h"
 #include "mongo/rpc/metadata/client_metadata.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
 #include "mongo/rpc/topology_version_gen.h"
 #include "mongo/s/mongos_topology_coordinator.h"
 #include "mongo/transport/message_compressor_manager.h"
@@ -99,34 +98,8 @@ public:
 
         waitInHello.pauseWhileSet(opCtx);
 
-        auto& clientMetadataIsMasterState = ClientMetadataIsMasterState::get(opCtx->getClient());
-        bool seenIsMaster = clientMetadataIsMasterState.hasSeenIsMaster();
-        if (!seenIsMaster) {
-            clientMetadataIsMasterState.setSeenIsMaster();
-        }
-
-        BSONElement element = cmdObj[kMetadataDocumentName];
-        if (!element.eoo()) {
-            if (seenIsMaster) {
-                uasserted(ErrorCodes::ClientMetadataCannotBeMutated,
-                          "The client metadata document may only be sent in the first isMaster");
-            }
-
-            auto swParseClientMetadata = ClientMetadata::parse(element);
-            uassertStatusOK(swParseClientMetadata.getStatus());
-
-            invariant(swParseClientMetadata.getValue());
-
-            swParseClientMetadata.getValue().get().logClientMetadata(opCtx->getClient());
-
-            swParseClientMetadata.getValue().get().setMongoSMetadata(
-                getHostNameCachedAndPort(),
-                opCtx->getClient()->clientAddress(true),
-                VersionInfoInterface::instance().version());
-
-            clientMetadataIsMasterState.setClientMetadata(
-                opCtx->getClient(), std::move(swParseClientMetadata.getValue()));
-        }
+        auto client = opCtx->getClient();
+        ClientMetadata::tryFinalize(client);
 
         // If a client is following the awaitable isMaster protocol, maxAwaitTimeMS should be
         // present if and only if topologyVersion is present in the request.
diff --git a/src/mongo/s/commands/strategy.cpp b/src/mongo/s/commands/strategy.cpp
index d2b88b8c78f..364b385ec8d 100644
--- a/src/mongo/s/commands/strategy.cpp
+++ b/src/mongo/s/commands/strategy.cpp
@@ -68,6 +68,7 @@
 #include "mongo/logv2/log.h"
 #include "mongo/rpc/factory.h"
 #include "mongo/rpc/get_status_from_command_result.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/rpc/metadata/tracking_metadata.h"
 #include "mongo/rpc/op_msg.h"
 #include "mongo/rpc/op_msg_rpc_impls.h"
@@ -312,11 +313,12 @@ void runCommand(OperationContext* opCtx,
         return;
     }
 
+    const auto isHello = command->getName() == "hello"_sd || command->getName() == "isMaster"_sd;
+
     opCtx->setExhaust(OpMsg::isFlagSet(m, OpMsg::kExhaustSupported));
     const auto session = opCtx->getClient()->session();
     if (session) {
-        if (!opCtx->isExhaust() ||
-            (command->getName() != "hello"_sd && command->getName() != "isMaster"_sd)) {
+        if (!opCtx->isExhaust() || !isHello) {
             InExhaustHello::get(session.get())->setInExhaust(false, commandName);
         }
     }
@@ -390,19 +392,26 @@ void runCommand(OperationContext* opCtx,
         return;
     }
 
-    auto& apiParams = APIParameters::get(opCtx);
-    auto& apiVersionMetrics = APIVersionMetrics::get(opCtx->getServiceContext());
-    const auto& clientMetadata = ClientMetadataIsMasterState::get(client).getClientMetadata();
-    if (clientMetadata) {
-        auto appName = clientMetadata.get().getApplicationName().toString();
-        apiVersionMetrics.update(appName, apiParams);
-    }
-
-    boost::optional<RouterOperationContextSession> routerSession;
     try {
+        if (isHello) {
+            // Preload generic ClientMetadata ahead of our first hello request. After the first
+            // request, metaElement should always be empty.
+            auto metaElem = request.body[kMetadataDocumentName];
+            ClientMetadata::setFromMetadata(opCtx->getClient(), metaElem);
+        }
+
+        auto& apiParams = APIParameters::get(opCtx);
+        auto& apiVersionMetrics = APIVersionMetrics::get(opCtx->getServiceContext());
+        if (auto clientMetadata = ClientMetadata::get(client)) {
+            auto appName = clientMetadata->getApplicationName().toString();
+            apiVersionMetrics.update(appName, apiParams);
+        }
+
         rpc::readRequestMetadata(opCtx, request.body, command->requiresAuth());
 
         CommandHelpers::evaluateFailCommandFailPoint(opCtx, invocation.get());
+
+        boost::optional<RouterOperationContextSession> routerSession;
         bool startTransaction = false;
         if (osi.getAutocommit()) {
             routerSession.emplace(opCtx);
diff --git a/src/mongo/s/sharding_egress_metadata_hook.cpp b/src/mongo/s/sharding_egress_metadata_hook.cpp
index 3db174e499e..9f0d11eeff7 100644
--- a/src/mongo/s/sharding_egress_metadata_hook.cpp
+++ b/src/mongo/s/sharding_egress_metadata_hook.cpp
@@ -35,7 +35,7 @@
 
 #include "mongo/base/status.h"
 #include "mongo/db/service_context.h"
-#include "mongo/rpc/metadata/client_metadata_ismaster.h"
+#include "mongo/rpc/metadata/client_metadata.h"
 #include "mongo/rpc/metadata/config_server_metadata.h"
 #include "mongo/rpc/metadata/impersonated_user_metadata.h"
 #include "mongo/rpc/metadata/metadata_hook.h"
diff --git a/src/mongo/s/transaction_router_test.cpp b/src/mongo/s/transaction_router_test.cpp
index bd6e503c0e1..964c8a38994 100644
--- a/src/mongo/s/transaction_router_test.cpp
+++ b/src/mongo/s/transaction_router_test.cpp
@@ -4848,10 +4848,8 @@ TEST_F(TransactionRouterMetricsTest, ReportResources) {
 
     auto obj = builder.obj();
     auto clientMetadata = ClientMetadata::parse(obj["client"]);
-    auto& clientMetadataIsMasterState =
-        ClientMetadataIsMasterState::get(operationContext()->getClient());
-    clientMetadataIsMasterState.setClientMetadata(operationContext()->getClient(),
-                                                  std::move(clientMetadata.getValue()));
+    ClientMetadata::setAndFinalize(operationContext()->getClient(),
+                                   std::move(clientMetadata.getValue()));
 
     repl::ReadConcernArgs readConcernArgs;
     ASSERT_OK(