[Lldb-commits] [lldb] [lldb-dap] Adding support for cancelling a request. (PR #130169)

[John Harrison via lldb-commits]

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@@ -96,7 +115,7 @@ Expected<std::optional<Message>> Transport::Read() {
     return createStringError(
         formatv("invalid content length {0}", *raw_length).str());
 
-  Expected<std::string> raw_json = ReadFull(*input, length);
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ashgti wrote:

> I don't know if this helps you (since you still have to use a dedicated API instead of `select(2)`), but `lldb_private::Pipe` works around this by creating a named pipe with an random name (from what I've read, that's actually how windows implements anonymous pipes internally).

The trouble is that when we run the debugger as an [DebugAdapterExecutable](https://code.visualstudio.com/api/references/vscode-api#DebugAdapterExecutable) the input stream is `stdin`. Unless we want to make Windows always use a local socket [DebugAdapterServer](https://code.visualstudio.com/api/references/vscode-api#DebugAdapterServer) or named pipes [DebugAdapterNamedPipeServer](https://code.visualstudio.com/api/references/vscode-api#DebugAdapterNamedPipeServer) we'd need to have some other mechanism for supporting reading with a timeout on Windows.

But I'm also not sure if that actually matters. VSCode never closes stdin, so it never gets an EOF. When the debug session ends, it sends a `kill -15` https://github.com/microsoft/vscode/blob/main/src/vs/workbench/contrib/debug/node/debugAdapter.ts#L290-L303   so I'm not sure if we need to ensure the Transport returns, but we do have an existing test that we shutdown after the `disconnect` request is sent.

https://github.com/llvm/llvm-project/pull/130169