server: breaking into base and impl class (envoyproxy#30693)

Also moving out the heap checker for E-M as an example of why we want to do this

Risk Level: low
Testing: n/a
Docs Changes: n/a
Release Notes: n/a

Signed-off-by: Alyssa Wilk <alyssar@chromium.org>

mobile/library/common/engine_common.cc

@@ -54,6 +54,12 @@ void registerMobileProtoDescriptors() {
 
 namespace Envoy {
 
+class ServerLite : public Server::InstanceBase {
+public:
+  using Server::InstanceBase::InstanceBase;
+  void maybeCreateHeapShrinker() override {}
+};
+
 EngineCommon::EngineCommon(std::unique_ptr<Envoy::OptionsImpl>&& options)
     : options_(std::move(options)) {
 
@@ -69,9 +75,8 @@ EngineCommon::EngineCommon(std::unique_ptr<Envoy::OptionsImpl>&& options)
          ThreadLocal::Instance& tls, Thread::ThreadFactory& thread_factory,
          Filesystem::Instance& file_system, std::unique_ptr<ProcessContext> process_context,
          Buffer::WatermarkFactorySharedPtr watermark_factory) {
-        // TODO(alyssawilk) use InstanceLite not InstanceImpl.
         auto local_address = Network::Utility::getLocalAddress(options.localAddressIpVersion());
-        auto server = std::make_unique<Server::InstanceImpl>(
+        auto server = std::make_unique<ServerLite>(
             init_manager, options, time_system, hooks, restarter, store, access_log_lock,
             std::move(random_generator), tls, thread_factory, file_system,
             std::move(process_context), watermark_factory);

source/exe/BUILD

@@ -42,7 +42,7 @@ envoy_cc_library(
         "//source/server:drain_manager_lib",
         "//source/server:listener_hooks_lib",
         "//source/server:options_lib",
-        "//source/server:server_lib",
+        "//source/server:server_base_lib",
     ] + select({
         "//bazel:windows_x86_64": envoy_all_extensions(WINDOWS_SKIP_TARGETS),
         "//bazel:linux_ppc": envoy_all_extensions(PPC_SKIP_TARGETS),
@@ -144,7 +144,7 @@ envoy_cc_library(
                "//source/server:drain_manager_lib",
                "//source/server:listener_hooks_lib",
                "//source/server:options_lib",
-               "//source/server:server_lib",
+               "//source/server:server_base_lib",
            ] + envoy_all_core_extensions() +
            # TODO(rojkov): drop io_uring dependency when it's fully integrated.
            select({
@@ -175,6 +175,7 @@ envoy_cc_library(
         "//source/extensions/listener_managers/validation_listener_manager:validation_listener_manager_lib",
         "//source/server:hot_restart_lib",
         "//source/server:hot_restart_nop_lib",
+        "//source/server:server_lib",
         "//source/server/config_validation:server_lib",
     ] + envoy_select_signal_trace([
         "//source/common/signal:sigaction_lib",

source/exe/main_common.cc

@@ -16,9 +16,9 @@
 #include "source/server/config_validation/server.h"
 #include "source/server/drain_manager_impl.h"
 #include "source/server/hot_restart_nop_impl.h"
+#include "source/server/instance_impl.h"
 #include "source/server/listener_hooks.h"
 #include "source/server/options_impl.h"
-#include "source/server/server.h"
 
 #include "absl/debugging/symbolize.h"
 #include "absl/strings/str_split.h"

source/server/BUILD

@@ -376,7 +376,7 @@ envoy_cc_library(
 )
 
 envoy_cc_library(
-    name = "server_lib",
+    name = "server_base_lib",
     srcs = ["server.cc"],
     hdrs = ["server.h"],
     external_deps = [
@@ -424,7 +424,6 @@ envoy_cc_library(
         "//source/common/http:headers_lib",
         "//source/common/init:manager_lib",
         "//source/common/local_info:local_info_lib",
-        "//source/common/memory:heap_shrinker_lib",
         "//source/common/memory:stats_lib",
         "//source/common/protobuf:utility_lib",
         "//source/common/quic:quic_stat_names_lib",
@@ -444,6 +443,16 @@ envoy_cc_library(
     ],
 )
 
+envoy_cc_library(
+    name = "server_lib",
+    srcs = ["instance_impl.cc"],
+    hdrs = ["instance_impl.h"],
+    deps = [
+        ":server_base_lib",
+        "//source/common/memory:heap_shrinker_lib",
+    ],
+)
+
 envoy_cc_library(
     name = "ssl_context_manager_lib",
     srcs = ["ssl_context_manager.cc"],

source/server/instance_impl.cc

@@ -0,0 +1,11 @@
+#include "source/server/instance_impl.h"
+
+namespace Envoy {
+namespace Server {
+void InstanceImpl::maybeCreateHeapShrinker() {
+  heap_shrinker_ =
+      std::make_unique<Memory::HeapShrinker>(dispatcher(), overloadManager(), *stats().rootScope());
+}
+
+} // namespace Server
+} // namespace Envoy

source/server/instance_impl.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "source/common/memory/heap_shrinker.h"
+#include "source/server/server.h"
+
+namespace Envoy {
+namespace Server {
+
+// The production server instance, which creates all of the required components.
+class InstanceImpl : public InstanceBase {
+public:
+  using InstanceBase::InstanceBase;
+
+protected:
+  void maybeCreateHeapShrinker() override;
+
+private:
+  std::unique_ptr<Memory::HeapShrinker> heap_shrinker_;
+};
+
+} // namespace Server
+} // namespace Envoy