diff --git a/src/atomic_object.h b/src/atomic_object.h
deleted file mode 100644
index a953f37c..00000000
--- a/src/atomic_object.h
+++ /dev/null
@@ -1,51 +0,0 @@
-#pragma once
-
-#include <algorithm>
-#include <condition_variable>
-#include <memory>
-#include <mutex>
-
-// A object which can be stored and taken from atomically.
-template <class T>
-struct AtomicObject {
-  void Set(std::unique_ptr<T> t) {
-    std::lock_guard<std::mutex> lock(mutex_);
-    value_ = std::move(t);
-    cv_.notify_one();
-  }
-
-  void SetIfEmpty(std::unique_ptr<T> t) {
-    std::lock_guard<std::mutex> lock(mutex_);
-    if (value_)
-      return;
-
-    value_ = std::move(t);
-    cv_.notify_one();
-  }
-
-  std::unique_ptr<T> Take() {
-    std::unique_lock<std::mutex> lock(mutex_);
-    while (!value_) {
-      // release lock as long as the wait and reaquire it afterwards.
-      cv_.wait(lock);
-    }
-
-    return std::move(value_);
-  }
-
-  template <typename TAction>
-  void WithLock(TAction action) {
-    std::unique_lock<std::mutex> lock(mutex_);
-    bool had_value = !!value_;
-    action(value_);
-    bool has_value = !!value_;
-
-    if (had_value != has_value)
-      cv_.notify_one();
-  }
-
- private:
-  std::unique_ptr<T> value_;
-  mutable std::mutex mutex_;
-  std::condition_variable cv_;
-};
diff --git a/src/clang_complete.h b/src/clang_complete.h
index 5df97256..cf752417 100644
--- a/src/clang_complete.h
+++ b/src/clang_complete.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include "atomic_object.h"
 #include "clang_index.h"
 #include "clang_translation_unit.h"
 #include "lsp_completion.h"
diff --git a/src/indexer.cc b/src/clang_indexer.cc
similarity index 100%
rename from src/indexer.cc
rename to src/clang_indexer.cc
diff --git a/src/command_line.cc b/src/command_line.cc
index 070d19e1..837a9f61 100644
--- a/src/command_line.cc
+++ b/src/command_line.cc
@@ -339,6 +339,7 @@ void LaunchStdinLoop(Config* config,
         case IpcId::TextDocumentDocumentLink:
         case IpcId::TextDocumentCodeAction:
         case IpcId::TextDocumentCodeLens:
+        case IpcId::WorkspaceDidChangeConfiguration:
         case IpcId::WorkspaceDidChangeWatchedFiles:
         case IpcId::WorkspaceSymbol:
         case IpcId::CqueryFileInfo:
diff --git a/src/ipc.cc b/src/ipc.cc
index f208d260..0c86e432 100644
--- a/src/ipc.cc
+++ b/src/ipc.cc
@@ -14,6 +14,8 @@ const char* IpcIdToString(IpcId id) {
       return "shutdown";
     case IpcId::Exit:
       return "exit";
+    case IpcId::CodeLensResolve:
+      return "codeLens/resolve";
     case IpcId::TextDocumentDidOpen:
       return "textDocument/didOpen";
     case IpcId::TextDocumentDidChange:
@@ -52,8 +54,8 @@ const char* IpcIdToString(IpcId id) {
       return "textDocument/codeAction";
     case IpcId::TextDocumentCodeLens:
       return "textDocument/codeLens";
-    case IpcId::CodeLensResolve:
-      return "codeLens/resolve";
+    case IpcId::WorkspaceDidChangeConfiguration:
+      return "workspace/didChangeConfiguration";
     case IpcId::WorkspaceDidChangeWatchedFiles:
       return "workspace/didChangeWatchedFiles";
     case IpcId::WorkspaceSymbol:
diff --git a/src/ipc.h b/src/ipc.h
index 93a57b00..97813fba 100644
--- a/src/ipc.h
+++ b/src/ipc.h
@@ -12,8 +12,10 @@ enum class IpcId : int {
   CancelRequest = 0,
   Initialize,
   Initialized,
-  Shutdown,
   Exit,
+  Shutdown,
+
+  CodeLensResolve,
   TextDocumentDidOpen,
   TextDocumentDidChange,
   TextDocumentDidClose,
@@ -33,7 +35,7 @@ enum class IpcId : int {
   TextDocumentDocumentLink,
   TextDocumentCodeAction,
   TextDocumentCodeLens,
-  CodeLensResolve,
+  WorkspaceDidChangeConfiguration,
   WorkspaceDidChangeWatchedFiles,
   WorkspaceSymbol,
 
@@ -51,7 +53,7 @@ enum class IpcId : int {
   CqueryCallHierarchy,
   CqueryInheritanceHierarchy,
   CqueryMemberHierarchy,
-  // These are like DocumentReferences but show different types of data.
+  // cquery cross reference extension.
   CqueryVars,     // Show all variables of a type.
   CqueryCallers,  // Show all callers of a function.
   CqueryBase,     // Show base types/method.
diff --git a/src/lsp.cc b/src/lsp.cc
index 32bc3844..47d869ea 100644
--- a/src/lsp.cc
+++ b/src/lsp.cc
@@ -195,10 +195,6 @@ void lsResponseError::Write(Writer& visitor) {
   visitor.StartObject();
   REFLECT_MEMBER2("code", code2);
   REFLECT_MEMBER(message);
-  if (data) {
-    visitor.Key("data");
-    data->Write(visitor);
-  }
   visitor.EndObject();
 }
 
diff --git a/src/lsp.h b/src/lsp.h
index 2a7fbfd2..55527a2c 100644
--- a/src/lsp.h
+++ b/src/lsp.h
@@ -73,10 +73,6 @@ struct lsOutMessage : lsBaseOutMessage {
 };
 
 struct lsResponseError {
-  struct Data {
-    virtual void Write(Writer& writer) = 0;
-  };
-
   enum class lsErrorCodes : int {
     ParseError = -32700,
     InvalidRequest = -32600,
@@ -86,13 +82,13 @@ struct lsResponseError {
     serverErrorStart = -32099,
     serverErrorEnd = -32000,
     ServerNotInitialized = -32002,
-    UnknownErrorCode = -32001
+    UnknownErrorCode = -32001,
+    RequestCancelled = -32800,
   };
 
   lsErrorCodes code;
   // Short description.
   std::string message;
-  std::unique_ptr<Data> data;
 
   void Write(Writer& visitor);
 };
diff --git a/src/messages/workspace_did_change_configuration.cc b/src/messages/workspace_did_change_configuration.cc
new file mode 100644
index 00000000..2e672996
--- /dev/null
+++ b/src/messages/workspace_did_change_configuration.cc
@@ -0,0 +1,27 @@
+#include "cache_manager.h"
+#include "message_handler.h"
+#include "project.h"
+#include "queue_manager.h"
+#include "working_files.h"
+
+namespace {
+struct lsDidChangeConfigurationParams {
+  bool placeholder;
+};
+MAKE_REFLECT_STRUCT(lsDidChangeConfigurationParams, placeholder);
+
+struct Ipc_WorkspaceDidChangeConfiguration
+    : public NotificationMessage<Ipc_WorkspaceDidChangeConfiguration> {
+  const static IpcId kIpcId = IpcId::WorkspaceDidChangeConfiguration;
+  lsDidChangeConfigurationParams params;
+};
+MAKE_REFLECT_STRUCT(Ipc_WorkspaceDidChangeConfiguration, params);
+REGISTER_IPC_MESSAGE(Ipc_WorkspaceDidChangeConfiguration);
+
+struct WorkspaceDidChangeConfigurationHandler
+    : BaseMessageHandler<Ipc_WorkspaceDidChangeConfiguration> {
+  void Run(Ipc_WorkspaceDidChangeConfiguration* request) override {
+  }
+};
+REGISTER_MESSAGE_HANDLER(WorkspaceDidChangeConfigurationHandler);
+}  // namespace