This abstracts the base Transport handler to have a MessageHandler
component and allows us to generalize both JSON-RPC 2.0 for MCP (or an
LSP) and DAP format.
This should allow us to create clearly defined clients and servers for
protocols, both for testing and for RPC between the lldb instances and
an lldb-mcp multiplexer.
This basic model is inspiried by the clangd/Transport.h file and the
mlir/lsp-server-support/Transport.h that are both used for LSP servers
within the llvm project.
Additionally, this helps with testing by subclassing `Transport` to
allow us to simplify sending/receiving messages without needing to use a
toJSON/fromJSON and a pair of pipes, see `TestTransport` in
DAP/TestBase.h.
Reapply "[lldb] Update JSONTransport to use MainLoop for reading."
(#152155)
This reverts commit cd40281685f642ad879e33f3fda8d1faa136ebf4.
This also includes some updates to try to address the platforms with
failing tests.
I updated the JSONTransport and tests to use std::function instead of
llvm:unique_function. I think the tests were failing due to the
unique_function not being moved correctly in the loop on some platforms.
This updates JSONTransport to use a MainLoop for reading messages.
This also allows us to read in larger chunks than we did previously.
With the event driven reading operations we can read in chunks and store
the contents in an internal buffer. Separately we can parse the buffer
and split the contents up into messages.
Our previous version approach would read a byte at a time, which is less
efficient.
We had two classes named `PipeTest`: one in `PipeTestUtilities.h` and
one in `PipeTest.cpp`. The latter was unintentionally using the wrong
class (from the header) which didn't initialize the HostInfo subsystem.
This resulted in a crash due to a nullptr dereference (`g_fields`) when
`PipePosix::CreateWithUniqueName` called `HostInfoBase::GetProcessTempDir`.
These were failing on our Windows on Arm bot, or more precisely,
not even completing.
This is because Microsoft's C runtime does extra parameter validation.
So when we called _read with an invalid fd, it called an invalid
parameter handler instead of returning an error.
https://learn.microsoft.com/en-us/%20cpp/c-runtime-library/reference/read?view=msvc-170https://learn.microsoft.com/en-us/%20cpp/c-runtime-library/parameter-validation?view=msvc-170
(lldb) run
Process 8440 launched: 'C:\Users\tcwg\llvm-worker\lldb-aarch64-windows\build\tools\lldb\unittests\Host\HostTests.exe' (aarch64)
Process 8440 stopped
* thread #1, stop reason = Exception 0xc0000409 encountered at address 0x7ffb7453564c
frame #0: 0x00007ffb7453564c ucrtbase.dll`_get_thread_local_invalid_parameter_handler + 652
ucrtbase.dll`_get_thread_local_invalid_parameter_handler:
-> 0x7ffb7453564c <+652>: brk #0xf003
ucrtbase.dll`_invalid_parameter_noinfo:
0x7ffb74535650 <+0>: b 0x7ffb745354d8 ; _get_thread_local_invalid_parameter_handler + 280
0x7ffb74535654 <+4>: nop
0x7ffb74535658 <+8>: nop
You can override this handler but I'm assuming that this reading
after close isn't a crucial feature, so disabling the tests seems
like the way to go.
If it is crucial, we can check the fd before we use it.
Tests added by https://github.com/llvm/llvm-project/pull/143946.
This PR implements JSON RPC-style (i.e. newline delimited) JSON
transport. I moved the existing transport tests from DAP to Host and
moved the PipeTest base class into TestingSupport so it can be shared by
both.
