Log KoreServer output (#4501)

Stream output from `kore-rpc` and `kore-rpc-booster` into a `Logger`,
instead of the standard output / error stream of the parent.

pyk/src/pyk/kore/rpc.py

@@ -12,7 +12,8 @@
 from enum import Enum, auto
 from pathlib import Path
 from signal import SIGINT
-from subprocess import Popen
+from subprocess import DEVNULL, PIPE, Popen
+from threading import Thread
 from time import sleep
 from typing import ClassVar  # noqa: TC003
 from typing import TYPE_CHECKING, ContextManager, NamedTuple, TypedDict, final
@@ -26,7 +27,7 @@
 
 if TYPE_CHECKING:
     from collections.abc import Iterable, Mapping
-    from typing import Any, Final, TextIO, TypeVar
+    from typing import IO, Any, Final, TypeVar
 
     from typing_extensions import Required
 
@@ -115,7 +116,7 @@ class SingleSocketTransport(Transport):
     _host: str
     _port: int
     _sock: socket.socket
-    _file: TextIO
+    _file: IO[str]
 
     def __init__(
         self,
@@ -1129,6 +1130,8 @@ class KoreServerInfo(NamedTuple):
 
 class KoreServer(ContextManager['KoreServer']):
     _proc: Popen
+    _stdout_reader: Thread
+    _stderr_reader: Thread
     _info: KoreServerInfo
 
     _kompiled_dir: Path
@@ -1208,21 +1211,41 @@ def start(self) -> None:
         new_env['GHCRTS'] = f'-N{self._haskell_threads}'
 
         _LOGGER.info(f'Starting KoreServer: {" ".join(cli_args)}')
-        self._proc = Popen(cli_args, env=new_env)
+        self._proc, self._stdout_reader, self._stderr_reader = self._create_proc(cli_args, new_env)
         pid = self._proc.pid
         host, port = self._get_host_and_port(pid)
         if self._port:
             assert port == self._port
         self._info = KoreServerInfo(pid=pid, host=host, port=port)
         _LOGGER.info(f'KoreServer started: {self.host}:{self.port}, pid={self.pid}')
 
+    @staticmethod
+    def _create_proc(args: list[str], env: dict[str, str]) -> tuple[Popen, Thread, Thread]:
+        popen = Popen(args, env=env, stdin=DEVNULL, stdout=PIPE, stderr=PIPE, text=True)
+
+        def reader(fh: IO[str], prefix: str) -> None:
+            for line in fh:
+                _LOGGER.info(f'[PID={popen.pid}][{prefix}] {line.rstrip()}')
+
+        stdout_reader = Thread(target=reader, args=(popen.stdout, 'stdo'))
+        stdout_reader.daemon = True
+        stdout_reader.start()
+
+        stderr_reader = Thread(target=reader, args=(popen.stderr, 'stde'))
+        stderr_reader.daemon = True
+        stderr_reader.start()
+
+        return popen, stdout_reader, stderr_reader
+
     def close(self) -> None:
         _LOGGER.info(f'Stopping KoreServer: {self.host}:{self.port}, pid={self.pid}')
         if '--solver-transcript' in self._command:
             self._proc.send_signal(SIGINT)
         else:
             self._proc.terminate()
         self._proc.wait()
+        self._stdout_reader.join()
+        self._stderr_reader.join()
         _LOGGER.info(f'KoreServer stopped: {self.host}:{self.port}, pid={self.pid}')
 
     def _validate(self) -> None: