[lldb-dap] Send terminated event only once

[labath]

This is a regression from #91591. Turns out std::mutex does not prevent code from running twice. 🤦

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Pavel Labath (labath)

Changes

This is a regression from #91591. Turns out std::mutex does not prevent code from running twice. 🤦

---

Full diff: https://github.com/llvm/llvm-project/pull/93172.diff

2 Files Affected:

• (modified) lldb/tools/lldb-dap/DAP.h (+2)
• (modified) lldb/tools/lldb-dap/lldb-dap.cpp (+6-7)

diff --git a/lldb/tools/lldb-dap/DAP.h b/lldb/tools/lldb-dap/DAP.h
index bbd9d46ba3a04..a88ee3e1dec6b 100644
--- a/lldb/tools/lldb-dap/DAP.h
+++ b/lldb/tools/lldb-dap/DAP.h
@@ -26,6 +26,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/JSON.h"
+#include "llvm/Support/Threading.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include "lldb/API/SBAttachInfo.h"
@@ -169,6 +170,7 @@ struct DAP {
   std::optional<llvm::json::Object> last_launch_or_attach_request;
   lldb::tid_t focus_tid;
   bool disconnecting = false;
+  llvm::once_flag terminated_event_flag;
   bool stop_at_entry;
   bool is_attach;
   bool enable_auto_variable_summaries;
diff --git a/lldb/tools/lldb-dap/lldb-dap.cpp b/lldb/tools/lldb-dap/lldb-dap.cpp
index 170fa88f1e8b8..7746afb6cbbf3 100644
--- a/lldb/tools/lldb-dap/lldb-dap.cpp
+++ b/lldb/tools/lldb-dap/lldb-dap.cpp
@@ -227,13 +227,12 @@ void SendContinuedEvent() {
 // debugged.
 void SendTerminatedEvent() {
   // Prevent races if the process exits while we're being asked to disconnect.
-  static std::mutex mutex;
-  std::lock_guard<std::mutex> locker(mutex);
-
-  g_dap.RunTerminateCommands();
-  // Send a "terminated" event
-  llvm::json::Object event(CreateTerminatedEventObject());
-  g_dap.SendJSON(llvm::json::Value(std::move(event)));
+  llvm::call_once(g_dap.terminated_event_flag, [&] {
+    g_dap.RunTerminateCommands();
+    // Send a "terminated" event
+    llvm::json::Object event(CreateTerminatedEventObject());
+    g_dap.SendJSON(llvm::json::Value(std::move(event)));
+  });
 }
 
 // Send a thread stopped event for all threads as long as the process

[kusmour]

Thanks for fixing it :)
Just tested this patch from my side, worked well!