[lldb-dap] Fix flaky test

[DrSergei]

This patch fixes a possible data race between main and event handler threads. Terminated event can be sent from Disconnect function or event handler. Consequently, there are some possible sequences of events. We must check events twice, because without getting an exited event, exit_status will be None. But, we don't know the order of events (for example, we can get terminated event before exited event), so we check events by filter. It is correct, because terminated event will be sent only once (guarded by llvm::call_once).

This patch moved from 145010 and based on idea from this comment.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: None (DrSergei)

Changes

This patch fixes a possible data race between main and event handler threads. Terminated event can be sent from Disconnect function or event handler. Consequently, there are some possible sequences of events. We must check events twice, because without getting an exited event, exit_status will be None. But, we don't know the order of events (for example, we can get terminated event before exited event), so we check events by filter. It is correct, because terminated event will be sent only once (guarded by llvm::call_once).

This patch moved from 145010 and based on idea from this comment.

---

Full diff: https://github.com/llvm/llvm-project/pull/145231.diff

2 Files Affected:

• (modified) lldb/test/API/tools/lldb-dap/server/TestDAP_server.py (+2-1)
• (modified) lldb/tools/lldb-dap/tool/lldb-dap.cpp (+1-3)

diff --git a/lldb/test/API/tools/lldb-dap/server/TestDAP_server.py b/lldb/test/API/tools/lldb-dap/server/TestDAP_server.py
index ed17044a220d4..116bc53a2dde0 100644
--- a/lldb/test/API/tools/lldb-dap/server/TestDAP_server.py
+++ b/lldb/test/API/tools/lldb-dap/server/TestDAP_server.py
@@ -101,7 +101,8 @@ def test_server_interrupt(self):
         # Interrupt the server which should disconnect all clients.
         process.send_signal(signal.SIGINT)
 
-        self.dap_server.wait_for_terminated()
+        self.dap_server.wait_for_event(["terminated", "exited"])
+        self.dap_server.wait_for_event(["terminated", "exited"])
         self.assertIsNotNone(
             self.dap_server.exit_status,
             "Process exited before interrupting lldb-dap server",
diff --git a/lldb/tools/lldb-dap/tool/lldb-dap.cpp b/lldb/tools/lldb-dap/tool/lldb-dap.cpp
index 9b9de5e21a742..9de6283319bb6 100644
--- a/lldb/tools/lldb-dap/tool/lldb-dap.cpp
+++ b/lldb/tools/lldb-dap/tool/lldb-dap.cpp
@@ -310,7 +310,7 @@ serveConnection(const Socket::SocketProtocol &protocol, const std::string &name,
                                     "DAP session (" + client_name +
                                         ") error: ");
       }
-
+      io->Close();
       DAP_LOG(log, "({0}) client disconnected", client_name);
       std::unique_lock<std::mutex> lock(dap_sessions_mutex);
       dap_sessions.erase(io.get());
@@ -342,8 +342,6 @@ serveConnection(const Socket::SocketProtocol &protocol, const std::string &name,
                      << " disconnected failed: "
                      << llvm::toString(std::move(error)) << "\n";
       }
-      // Close the socket to ensure the DAP::Loop read finishes.
-      sock->Close();
     }
   }