[lldb-vscode] stop read loop after termination

[wallace]

Summary

On Linux, when executing lldb-vscode on a remote machine, lldb-vscode doesn't die after the debug session ends. It keeps trying to read JSON input to no avail.
This diff indicates lldb-vscode to stop reading after a termination event has been processed.

[clayborg]

Does this have something to do with a multiplexor that funnels traffic through one tunnel? I am curious as to why the ReadJSON() doesn't exit after the other side closes down?

LGTM, but needs a test.

[wallace]

As we discussed privately, some remote connections use a mutiplexor socket that doesn't die when the debug session ends.

[wallace]

add a test

[wallace]

nit

[clayborg]

lldb/test/API/tools/lldb-vscode/launch/TestVSCode_launch.py

46–48 ↗

(On Diff #251150)

I don't think we need to run a program. Just send the initialize packet and then the terminate packet, then sleep?

[wallace]

address comments

[clayborg]

lgtm.

[clayborg]

Just watch the build bots carefully when you check this in!

[labath]

lldb/test/API/tools/lldb-vscode/launch/TestVSCode_launch.py

50–53 ↗

(On Diff #251204)

1 second is pretty short, and I wouldn't be surprised if it causes spurious failures.

Using popen.wait() would be _much_ better -- you can use a much larger timeout, while still having the test terminate quickly in the common case.

[wallace]

address comments

[wallace]

support python2.7

[labath]

lldb/test/API/tools/lldb-vscode/launch/TestVSCode_launch.py

55–56 ↗

(On Diff #251428)

I'll add this to my list of reasons for dropping python2 support. :)

lldb/tools/lldb-vscode/lldb-vscode.cpp

if (portno != -1) {
     }
   } else {
     g_vsc.input.descriptor = StreamDescriptor::from_file(fileno(stdin), false);
     g_vsc.output.descriptor =
         StreamDescriptor::from_file(fileno(stdout), false);
   }
   auto request_handlers = GetRequestHandlers();
   uint32_t packet_idx = 0;
-  while (true) {
+  while (!g_vsc.sent_terminated_event) {
     std::string json = g_vsc.ReadJSON();
     if (json.empty())
       break;
 
     llvm::StringRef json_sref(json);
     llvm::Expected<llvm::json::Value> json_value = llvm::json::parse(json_sref);
     if (!json_value) {
       auto error = json_value.takeError();