[lldb] Stop the protocol servers when terminating the plugin (#156101)

Currently, the server keeps running until we call Stop from its dtor in
the static destruction chain. This is too late: the server should stop
when the plugin gets terminated.

Author: JDevlieghere

lldb/include/lldb/Core/ProtocolServer.h

@@ -22,6 +22,8 @@ class ProtocolServer : public PluginInterface {
 
   static ProtocolServer *GetOrCreate(llvm::StringRef name);
 
+  static llvm::Error Terminate();
+
   static std::vector<llvm::StringRef> GetSupportedProtocols();
 
   struct Connection {

lldb/source/Core/ProtocolServer.cpp

@@ -8,24 +8,29 @@
 
 #include "lldb/Core/ProtocolServer.h"
 #include "lldb/Core/PluginManager.h"
+#include "llvm/Support/Error.h"
 
 using namespace lldb_private;
 using namespace lldb;
 
-ProtocolServer *ProtocolServer::GetOrCreate(llvm::StringRef name) {
-  static std::mutex g_mutex;
+static std::pair<llvm::StringMap<ProtocolServerUP> &, std::mutex &> Servers() {
   static llvm::StringMap<ProtocolServerUP> g_protocol_server_instances;
+  static std::mutex g_mutex;
+  return {g_protocol_server_instances, g_mutex};
+}
+
+ProtocolServer *ProtocolServer::GetOrCreate(llvm::StringRef name) {
+  auto [protocol_server_instances, mutex] = Servers();
 
-  std::lock_guard<std::mutex> guard(g_mutex);
+  std::lock_guard<std::mutex> guard(mutex);
 
-  auto it = g_protocol_server_instances.find(name);
-  if (it != g_protocol_server_instances.end())
+  auto it = protocol_server_instances.find(name);
+  if (it != protocol_server_instances.end())
     return it->second.get();
 
   if (ProtocolServerCreateInstance create_callback =
           PluginManager::GetProtocolCreateCallbackForPluginName(name)) {
-    auto pair =
-        g_protocol_server_instances.try_emplace(name, create_callback());
+    auto pair = protocol_server_instances.try_emplace(name, create_callback());
     return pair.first->second.get();
   }
 
@@ -45,3 +50,18 @@ std::vector<llvm::StringRef> ProtocolServer::GetSupportedProtocols() {
 
   return supported_protocols;
 }
+
+llvm::Error ProtocolServer::Terminate() {
+  llvm::Error error = llvm::Error::success();
+
+  auto [protocol_server_instances, mutex] = Servers();
+  std::lock_guard<std::mutex> guard(mutex);
+  for (auto &instance : protocol_server_instances) {
+    if (llvm::Error instance_error = instance.second->Stop())
+      error = llvm::joinErrors(std::move(error), std::move(instance_error));
+  }
+
+  protocol_server_instances.clear();
+
+  return error;
+}

lldb/source/Plugins/Protocol/MCP/ProtocolServerMCP.cpp

@@ -39,6 +39,8 @@ void ProtocolServerMCP::Initialize() {
 }
 
 void ProtocolServerMCP::Terminate() {
+  if (llvm::Error error = ProtocolServer::Terminate())
+    LLDB_LOG_ERROR(GetLog(LLDBLog::Host), std::move(error), "{0}");
   PluginManager::UnregisterPlugin(CreateInstance);
 }