Make python language server exit when parent process dies (palantir#410)

Author: JiahuiJiang

pyls/_utils.py

@@ -113,3 +113,21 @@ def clip_column(column, lines, line_number):
     # https://github.com/Microsoft/language-server-protocol/blob/master/protocol.md#position
     max_column = len(lines[line_number].rstrip('\r\n')) if len(lines) > line_number else 0
     return min(column, max_column)
+
+
+def is_process_alive(pid):
+    """ Check whether the process with the given pid is still alive.
+
+    Args:
+        pid (int): process ID
+
+    Returns:
+        bool: False if the process is not alive or don't have permission to check, True otherwise.
+    """
+    try:
+        os.kill(pid, 0)
+    except OSError:
+        # no such process or process is already dead
+        return False
+    else:
+        return True

pyls/config/config.py

@@ -14,10 +14,11 @@
 
 class Config(object):
 
-    def __init__(self, root_uri, init_opts):
+    def __init__(self, root_uri, init_opts, process_id):
         self._root_path = uris.to_fs_path(root_uri)
         self._root_uri = root_uri
         self._init_opts = init_opts
+        self._process_id = process_id
 
         self._settings = {}
         self._plugin_settings = {}
@@ -77,6 +78,10 @@ def init_opts(self):
     def root_uri(self):
         return self._root_uri
 
+    @property
+    def process_id(self):
+        return self._process_id
+
     def settings(self, document_path=None):
         """Settings are constructed from a few sources:
 

pyls/python_ls.py

@@ -1,6 +1,7 @@
 # Copyright 2017 Palantir Technologies, Inc.
 import logging
 import socketserver
+import threading
 
 from jsonrpc.dispatchers import MethodDispatcher
 from jsonrpc.endpoint import Endpoint
@@ -14,6 +15,7 @@
 
 
 LINT_DEBOUNCE_S = 0.5  # 500 ms
+PARENT_PROCESS_WATCH_INTERVAL = 10  # 10 s
 
 
 class _StreamHandlerWrapper(socketserver.StreamRequestHandler, object):
@@ -149,10 +151,23 @@ def m_initialize(self, processId=None, rootUri=None, rootPath=None, initializati
             rootUri = uris.from_fs_path(rootPath) if rootPath is not None else ''
 
         self.workspace = Workspace(rootUri, self._endpoint)
-        self.config = config.Config(rootUri, initializationOptions or {})
+        self.config = config.Config(rootUri, initializationOptions or {}, processId)
         self._dispatchers = self._hook('pyls_dispatchers')
         self._hook('pyls_initialize')
 
+        if processId is not None:
+            def watch_parent_process(pid):
+                # exist when the given pid is not alive
+                if not _utils.is_process_alive(pid):
+                    log.info("parent process %s is not alive", pid)
+                    self.m_exit()
+                log.debug("parent process %s is still alive", pid)
+                threading.Timer(PARENT_PROCESS_WATCH_INTERVAL, watch_parent_process(pid)).start()
+
+            watching_thread = threading.Thread(target=watch_parent_process, args=[processId])
+            watching_thread.daemon = True
+            watching_thread.start()
+
         # Get our capabilities
         return {'capabilities': self.capabilities()}
 

test/fixtures.py

@@ -44,7 +44,7 @@ def workspace(tmpdir):
 @pytest.fixture
 def config(workspace):  # pylint: disable=redefined-outer-name
     """Return a config object."""
-    return Config(workspace.root_uri, {})
+    return Config(workspace.root_uri, {}, 0)
 
 
 @pytest.fixture

test/plugins/test_pycodestyle_lint.py

@@ -67,7 +67,7 @@ def test_pycodestyle_config(workspace):
     doc_uri = uris.from_fs_path(os.path.join(workspace.root_path, 'test.py'))
     workspace.put_document(doc_uri, DOC)
     doc = workspace.get_document(doc_uri)
-    config = Config(workspace.root_uri, {})
+    config = Config(workspace.root_uri, {}, 1234)
 
     # Make sure we get a warning for 'indentation contains tabs'
     diags = pycodestyle_lint.pyls_lint(config, doc)

test/test_language_server.py

@@ -14,42 +14,66 @@ def start_client(client):
     client.start()
 
 
+class _ClientServer(object):
+    """ A class to setup a client/server pair """
+    def __init__(self):
+        # Client to Server pipe
+        csr, csw = os.pipe()
+        # Server to client pipe
+        scr, scw = os.pipe()
+
+        self.server_thread = Thread(target=start_io_lang_server, args=(
+            os.fdopen(csr, 'rb'), os.fdopen(scw, 'wb'), PythonLanguageServer
+        ))
+        self.server_thread.daemon = True
+        self.server_thread.start()
+
+        self.client = PythonLanguageServer(os.fdopen(scr, 'rb'), os.fdopen(csw, 'wb'))
+        self.client_thread = Thread(target=start_client, args=[self.client])
+        self.client_thread.daemon = True
+        self.client_thread.start()
+
+
 @pytest.fixture
 def client_server():
-    """ A fixture to setup a client/server """
+    """ A fixture that sets up a client/server pair and shuts down the server """
+    client_server_pair = _ClientServer()
 
-    # Client to Server pipe
-    csr, csw = os.pipe()
-    # Server to client pipe
-    scr, scw = os.pipe()
+    yield client_server_pair.client
+
+    shutdown_response = client_server_pair.client._endpoint.request('shutdown').result(timeout=CALL_TIMEOUT)
+    assert shutdown_response is None
+    client_server_pair.client._endpoint.notify('exit')
 
-    server_thread = Thread(target=start_io_lang_server, args=(
-        os.fdopen(csr, 'rb'), os.fdopen(scw, 'wb'), PythonLanguageServer
-    ))
-    server_thread.daemon = True
-    server_thread.start()
 
-    client = PythonLanguageServer(os.fdopen(scr, 'rb'), os.fdopen(csw, 'wb'))
-    client_thread = Thread(target=start_client, args=[client])
-    client_thread.daemon = True
-    client_thread.start()
+@pytest.fixture
+def client_exited_server():
+    """ A fixture that sets up a client/server pair and assert the server has already exited """
+    client_server_pair = _ClientServer()
 
-    yield client
+    yield client_server_pair.client
 
-    shutdown_response = client._endpoint.request('shutdown').result(timeout=CALL_TIMEOUT)
-    assert shutdown_response is None
-    client._endpoint.notify('exit')
+    assert client_server_pair.server_thread.is_alive() is False
 
 
 def test_initialize(client_server):  # pylint: disable=redefined-outer-name
     response = client_server._endpoint.request('initialize', {
-        'processId': 1234,
         'rootPath': os.path.dirname(__file__),
         'initializationOptions': {}
     }).result(timeout=CALL_TIMEOUT)
     assert 'capabilities' in response
 
 
+def test_exit_with_parent_process_died(client_exited_server):  # pylint: disable=redefined-outer-name
+    # language server should have already exited before responding
+    with pytest.raises(Exception):
+        client_exited_server._endpoint.request('initialize', {
+            'processId': 1234,
+            'rootPath': os.path.dirname(__file__),
+            'initializationOptions': {}
+        }).result(timeout=CALL_TIMEOUT)
+
+
 def test_missing_message(client_server):  # pylint: disable=redefined-outer-name
     with pytest.raises(JsonRpcMethodNotFound):
         client_server._endpoint.request('unknown_method').result(timeout=CALL_TIMEOUT)