[lldb-dap] Adding support for well typed events.

ashgti · ashgti · commit b9fb9805f336 · 2025-03-06T14:25:27.000+01:00
This adds a mechanism for registering well typed events with the DAP.

For a proof of concept, this updates the 'exited' event to use the new
protocol serialization handlers and updates the call sites to use the
new helper.
diff --git a/lldb/tools/lldb-dap/DAP.h b/lldb/tools/lldb-dap/DAP.h
@@ -58,6 +58,9 @@ typedef llvm::StringMap<FunctionBreakpoint> FunctionBreakpointMap;
 typedef llvm::DenseMap<lldb::addr_t, InstructionBreakpoint>
     InstructionBreakpointMap;
 
+/// A debug adapter initiated event.
+template <typename T> using OutgoingEvent = std::function<void(const T &)>;
+
 enum class OutputType { Console, Stdout, Stderr, Telemetry };
 
 /// Buffer size for handling output events.
@@ -123,21 +126,21 @@ struct Variables {
 
 struct StartDebuggingRequestHandler : public lldb::SBCommandPluginInterface {
   DAP &dap;
-  explicit StartDebuggingRequestHandler(DAP &d) : dap(d) {};
+  explicit StartDebuggingRequestHandler(DAP &d) : dap(d){};
   bool DoExecute(lldb::SBDebugger debugger, char **command,
                  lldb::SBCommandReturnObject &result) override;
 };
 
 struct ReplModeRequestHandler : public lldb::SBCommandPluginInterface {
   DAP &dap;
-  explicit ReplModeRequestHandler(DAP &d) : dap(d) {};
+  explicit ReplModeRequestHandler(DAP &d) : dap(d){};
   bool DoExecute(lldb::SBDebugger debugger, char **command,
                  lldb::SBCommandReturnObject &result) override;
 };
 
 struct SendEventRequestHandler : public lldb::SBCommandPluginInterface {
   DAP &dap;
-  explicit SendEventRequestHandler(DAP &d) : dap(d) {};
+  explicit SendEventRequestHandler(DAP &d) : dap(d){};
   bool DoExecute(lldb::SBDebugger debugger, char **command,
                  lldb::SBCommandReturnObject &result) override;
 };
@@ -207,6 +210,14 @@ struct DAP {
   // will contain that expression.
   std::string last_nonempty_var_expression;
 
+  /// Typed Events Handlers
+  /// @{
+
+  /// onExited sends an event that the debuggee has exited.
+  OutgoingEvent<protocol::ExitedEventBody> onExited;
+
+  /// @}
+
   DAP(std::string name, llvm::StringRef path, std::ofstream *log,
       lldb::IOObjectSP input, lldb::IOObjectSP output, ReplMode repl_mode,
       std::vector<std::string> pre_init_commands);
@@ -345,6 +356,10 @@ struct DAP {
     request_handlers[Handler::getCommand()] = std::make_unique<Handler>(*this);
   }
 
+  /// Registeres an event handler for sending Debug Adapter Protocol events.
+  template <typename Body>
+  OutgoingEvent<Body> RegisterEvent(llvm::StringLiteral Event);
+
   /// Debuggee will continue from stopped state.
   void WillContinue() { variables.Clear(); }
 
@@ -378,6 +393,16 @@ struct DAP {
   InstructionBreakpoint *GetInstructionBPFromStopReason(lldb::SBThread &thread);
 };
 
+template <typename Body>
+OutgoingEvent<Body> DAP::RegisterEvent(llvm::StringLiteral Event) {
+  return [&, Event](const Body &B) {
+    protocol::Event Evt;
+    Evt.event = Event;
+    Evt.rawBody = std::move(B);
+    SendJSON(std::move(Evt));
+  };
+}
+
 } // namespace lldb_dap
 
 #endif
diff --git a/lldb/tools/lldb-dap/EventHelper.cpp b/lldb/tools/lldb-dap/EventHelper.cpp
@@ -10,6 +10,7 @@
 #include "DAP.h"
 #include "JSONUtils.h"
 #include "LLDBUtils.h"
+#include "Protocol.h"
 #include "lldb/API/SBFileSpec.h"
 
 #if defined(_WIN32)
@@ -235,13 +236,4 @@ void SendContinuedEvent(DAP &dap) {
   dap.SendJSON(llvm::json::Value(std::move(event)));
 }
 
-// Send a "exited" event to indicate the process has exited.
-void SendProcessExitedEvent(DAP &dap, lldb::SBProcess &process) {
-  llvm::json::Object event(CreateEventObject("exited"));
-  llvm::json::Object body;
-  body.try_emplace("exitCode", (int64_t)process.GetExitStatus());
-  event.try_emplace("body", std::move(body));
-  dap.SendJSON(llvm::json::Value(std::move(event)));
-}
-
 } // namespace lldb_dap
diff --git a/lldb/tools/lldb-dap/EventHelper.h b/lldb/tools/lldb-dap/EventHelper.h
@@ -26,8 +26,6 @@ void SendStdOutStdErr(DAP &dap, lldb::SBProcess &process);
 
 void SendContinuedEvent(DAP &dap);
 
-void SendProcessExitedEvent(DAP &dap, lldb::SBProcess &process);
-
 } // namespace lldb_dap
 
 #endif
diff --git a/lldb/tools/lldb-dap/Handler/InitializeRequestHandler.cpp b/lldb/tools/lldb-dap/Handler/InitializeRequestHandler.cpp
@@ -9,6 +9,7 @@
 #include "DAP.h"
 #include "EventHelper.h"
 #include "JSONUtils.h"
+#include "Protocol.h"
 #include "RequestHandler.h"
 #include "lldb/API/SBEvent.h"
 #include "lldb/API/SBListener.h"
@@ -178,7 +179,7 @@ static void EventThreadFunction(DAP &dap) {
               // Run any exit LLDB commands the user specified in the
               // launch.json
               dap.RunExitCommands();
-              SendProcessExitedEvent(dap, process);
+              dap.onExited(protocol::ExitedEventBody{/*exitCode=*/process.GetExitStatus()});
               dap.SendTerminatedEvent();
               done = true;
             }
diff --git a/lldb/tools/lldb-dap/Protocol.cpp b/lldb/tools/lldb-dap/Protocol.cpp
@@ -315,6 +315,10 @@ bool fromJSON(const llvm::json::Value &Params, Source &S, llvm::json::Path P) {
          O.mapOptional("sourceReference", S.sourceReference);
 }
 
+llvm::json::Value toJSON(const ExitedEventBody &EEB) {
+  return llvm::json::Object{{"exitCode", EEB.exitCode}};
+}
+
 bool fromJSON(const llvm::json::Value &Params, SourceArguments &SA,
               llvm::json::Path P) {
   llvm::json::ObjectMapper O(Params, P);
diff --git a/lldb/tools/lldb-dap/Protocol.h b/lldb/tools/lldb-dap/Protocol.h
@@ -316,6 +316,36 @@ struct Source {
 bool fromJSON(const llvm::json::Value &, Source &, llvm::json::Path);
 llvm::json::Value toJSON(const Source &);
 
+// MARK: Events
+
+// "ExitedEvent": {
+//   "allOf": [ { "$ref": "#/definitions/Event" }, {
+//     "type": "object",
+//     "description": "The event indicates that the debuggee has exited and
+//     returns its exit code.", "properties": {
+//       "event": {
+//         "type": "string",
+//         "enum": [ "exited" ]
+//       },
+//       "body": {
+//         "type": "object",
+//         "properties": {
+//           "exitCode": {
+//             "type": "integer",
+//             "description": "The exit code returned from the debuggee."
+//           }
+//         },
+//         "required": [ "exitCode" ]
+//       }
+//     },
+//     "required": [ "event", "body" ]
+//   }]
+// }
+struct ExitedEventBody {
+  int exitCode;
+};
+llvm::json::Value toJSON(const ExitedEventBody &);
+
 // MARK: Requests
 
 // "SourceArguments": {
diff --git a/lldb/tools/lldb-dap/lldb-dap.cpp b/lldb/tools/lldb-dap/lldb-dap.cpp
@@ -9,6 +9,7 @@
 #include "DAP.h"
 #include "EventHelper.h"
 #include "Handler/RequestHandler.h"
+#include "Protocol.h"
 #include "RunInTerminal.h"
 #include "lldb/API/SBDebugger.h"
 #include "lldb/API/SBStream.h"
@@ -151,6 +152,9 @@ static void RegisterRequestCallbacks(DAP &dap) {
 
   // Testing requests
   dap.RegisterRequest<TestGetTargetBreakpointsRequestHandler>();
+
+  // Event handlers
+  dap.onExited = dap.RegisterEvent<protocol::ExitedEventBody>("exited");
 }
 
 static void PrintHelp(LLDBDAPOptTable &table, llvm::StringRef tool_name) {
