SERVER-34798 Remove ServiceContext subclasses and use new ServiceContext in every unit test.

This patch does several loosely related and surprisingly hard to separate things.

1.) Make the ServiceContext class final

2.) Create a mechanism, called ConstructorActions, for running methods on
ServiceContexts immediately after they're built and immediately before they're
destroyed.

3.) Introduce / improve test fixture base classes for tests, giving them fresh
ServiceContext instances for each test case. There is one fixture for tests that
need a storage engine and another for those that do not.

4.) Make several remaining global variables SC decorations in support of (3)

5.) Replace many MONGO_INITIALIZERS that access getGlobalServiceContext with the
new constructor-actions system, which is needed for (3.)

6.) Fix up tests to use the fixtures from (3) and fix tests that silently used
different service contexts in together in a technically illegal fashion that now
breaks.

7.) Utilize (2) as necessary to simplify initialization of new ServiceContexts,
simplifying the fixtures in (3).

5 files changed, 22 insertions, 27 deletions

diff --git a/src/mongo/transport/SConscript b/src/mongo/transport/SConscript
index d12800b3273..0f61fbcf12c 100644
--- a/src/mongo/transport/SConscript
+++ b/src/mongo/transport/SConscript
@@ -74,7 +74,6 @@ env.Library(
     ],
     LIBDEPS_PRIVATE=[
         'transport_layer',
-        '$BUILD_DIR/mongo/db/service_context_noop_init',
     ]
 )
 
@@ -86,7 +85,6 @@ tlEnv.CppUnitTest(
     LIBDEPS=[
         'transport_layer',
         '$BUILD_DIR/mongo/base',
-        '$BUILD_DIR/mongo/db/service_context_noop_init',
         '$BUILD_DIR/mongo/rpc/protocol',
         '$BUILD_DIR/mongo/util/net/socket',
     ],
diff --git a/src/mongo/transport/service_executor_adaptive_test.cpp b/src/mongo/transport/service_executor_adaptive_test.cpp
index c851c738ac2..30227edf3b9 100644
--- a/src/mongo/transport/service_executor_adaptive_test.cpp
+++ b/src/mongo/transport/service_executor_adaptive_test.cpp
@@ -32,7 +32,7 @@
 
 #include "boost/optional.hpp"
 
-#include "mongo/db/service_context_noop.h"
+#include "mongo/db/service_context.h"
 #include "mongo/transport/service_executor_adaptive.h"
 #include "mongo/unittest/unittest.h"
 #include "mongo/util/log.h"
@@ -107,8 +107,7 @@ struct RecursionOptions : public ServiceExecutorAdaptive::Options {
 class ServiceExecutorAdaptiveFixture : public unittest::Test {
 protected:
     void setUp() override {
-        auto scOwned = stdx::make_unique<ServiceContextNoop>();
-        setGlobalServiceContext(std::move(scOwned));
+        setGlobalServiceContext(ServiceContext::make());
         asioIoCtx = std::make_shared<asio::io_context>();
     }
 
diff --git a/src/mongo/transport/service_executor_test.cpp b/src/mongo/transport/service_executor_test.cpp
index 8e749228631..86e7187a37f 100644
--- a/src/mongo/transport/service_executor_test.cpp
+++ b/src/mongo/transport/service_executor_test.cpp
@@ -32,7 +32,7 @@
 
 #include "boost/optional.hpp"
 
-#include "mongo/db/service_context_noop.h"
+#include "mongo/db/service_context.h"
 #include "mongo/transport/service_executor_adaptive.h"
 #include "mongo/transport/service_executor_synchronous.h"
 #include "mongo/transport/service_executor_task_names.h"
@@ -135,7 +135,7 @@ private:
 class ServiceExecutorAdaptiveFixture : public unittest::Test {
 protected:
     void setUp() override {
-        auto scOwned = stdx::make_unique<ServiceContextNoop>();
+        auto scOwned = ServiceContext::make();
         setGlobalServiceContext(std::move(scOwned));
 
         auto configOwned = stdx::make_unique<TestOptions>();
@@ -152,7 +152,7 @@ protected:
 class ServiceExecutorSynchronousFixture : public unittest::Test {
 protected:
     void setUp() override {
-        auto scOwned = stdx::make_unique<ServiceContextNoop>();
+        auto scOwned = ServiceContext::make();
         setGlobalServiceContext(std::move(scOwned));
 
         executor = stdx::make_unique<ServiceExecutorSynchronous>(getGlobalServiceContext());
diff --git a/src/mongo/transport/service_state_machine_test.cpp b/src/mongo/transport/service_state_machine_test.cpp
index 7ea13eaf12f..e29c33627a6 100644
--- a/src/mongo/transport/service_state_machine_test.cpp
+++ b/src/mongo/transport/service_state_machine_test.cpp
@@ -35,7 +35,7 @@
 #include "mongo/bson/bsonobjbuilder.h"
 #include "mongo/db/client.h"
 #include "mongo/db/dbmessage.h"
-#include "mongo/db/service_context_noop.h"
+#include "mongo/db/service_context.h"
 #include "mongo/rpc/op_msg.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/transport/mock_session.h"
@@ -272,7 +272,7 @@ class ServiceStateMachineFixture : public unittest::Test {
 protected:
     void setUp() override {
 
-        auto scOwned = stdx::make_unique<ServiceContextNoop>();
+        auto scOwned = ServiceContext::make();
         auto sc = scOwned.get();
         setGlobalServiceContext(std::move(scOwned));
 
diff --git a/src/mongo/transport/transport_layer_egress_init.cpp b/src/mongo/transport/transport_layer_egress_init.cpp
index 628cf6c2dfc..ec8dd262515 100644
--- a/src/mongo/transport/transport_layer_egress_init.cpp
+++ b/src/mongo/transport/transport_layer_egress_init.cpp
@@ -34,25 +34,23 @@
 #include "mongo/db/service_context.h"
 #include "mongo/transport/transport_layer_asio.h"
 
+#include <iostream>
+
 namespace mongo {
 namespace {
-// Linking with this file will configure an egress-only TransportLayer on a ServiceContextNoop.
+// Linking with this file will configure an egress-only TransportLayer on all new ServiceContexts.
 // Use this for unit/integration tests that require only egress networking.
-MONGO_INITIALIZER_WITH_PREREQUISITES(ConfigureEgressTransportLayer, ("ServiceContext"))
-(InitializerContext* context) {
-    auto sc = getGlobalServiceContext();
-    invariant(!sc->getTransportLayer());
-
-    transport::TransportLayerASIO::Options opts;
-    opts.mode = transport::TransportLayerASIO::Options::kEgress;
-    sc->setTransportLayer(std::make_unique<transport::TransportLayerASIO>(opts, nullptr));
-    auto status = sc->getTransportLayer()->setup();
-    if (!status.isOK()) {
-        return status;
-    }
-
-    return sc->getTransportLayer()->start();
-}
+
+ServiceContext::ConstructorActionRegisterer registerEgressTransportLayer{
+    "ConfigureEgressTransportLayer", [](ServiceContext* sc) {
+
+        invariant(!sc->getTransportLayer());
+        transport::TransportLayerASIO::Options opts;
+        opts.mode = transport::TransportLayerASIO::Options::kEgress;
+        sc->setTransportLayer(std::make_unique<transport::TransportLayerASIO>(opts, nullptr));
+        uassertStatusOK(sc->getTransportLayer()->setup());
+        uassertStatusOK(sc->getTransportLayer()->start());
+    }};
 
 }  // namespace
-}  // namespace
+}  // namespace mongo