From 79e8b3324d4dd318e454d81e753c3caa03b0c023 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Linse?= <bjorn.linse@gmail.com>
Date: Sun, 5 May 2019 19:42:33 +0200
Subject: [PATCH] WIP: coroutine and subprocess support

---
 pynvim/api/nvim.py                       | 50 ++++++++++++++++++++++++
 pynvim/msgpack_rpc/event_loop/asyncio.py |  6 +--
 pynvim/msgpack_rpc/session.py            | 19 +++++++++
 3 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/pynvim/api/nvim.py b/pynvim/api/nvim.py
index aa5f3bea..40690739 100644
--- a/pynvim/api/nvim.py
+++ b/pynvim/api/nvim.py
@@ -453,6 +453,56 @@ def handler():
                 raise
         self._session.threadsafe_call(handler)
 
+    if IS_PYTHON3:
+
+        def run_coroutine(self, coroutine):
+            """ Run a coroutine inside a response handler (or setup_cb)"""
+
+            return self._session.run_coroutine(coroutine)
+
+        def start_subprocess(self, cmd, on_data, on_exit, **args):
+             coro = self.loop.subprocess_exec(partial(NvimAsyncioProcess, self, on_data, on_exit),
+                                              *cmd, **args)
+             (transport, protocol) = self.run_coroutine(coro)
+             return transport
+
+if IS_PYTHON3:
+
+    import asyncio
+
+
+    class NvimAsyncioProcess(asyncio.SubprocessProtocol):
+
+        def __init__(self, session, on_data, on_exit):
+            self.session = session
+            self.on_data = on_data
+            self.on_exit = on_exit
+
+            self.call_point = ''.join(format_stack(None, 6)[:-2])
+
+        def _callback(self, cb, *args):
+
+            def handler():
+                try:
+                    cb(*args)
+                except Exception as err:
+                    msg = ("error caught while executing subprocess callback:\n"
+                           "{!r}\n{}\n \nthe process was created at\n{}"
+                           .format(err, format_exc_skip(1), self.call_point))
+                    self.session._err_cb(msg)
+                    raise
+
+            self.session._session.threadsafe_call(handler)
+
+
+        def connection_made(self, transport):
+            pass
+
+        def pipe_data_received(self, fd, data):
+            self._callback(self.on_data, fd, data)
+
+        def process_exited(self):
+            self._callback(self.on_exit)
 
 class Buffers(object):
 
diff --git a/pynvim/msgpack_rpc/event_loop/asyncio.py b/pynvim/msgpack_rpc/event_loop/asyncio.py
index 3674441b..0e1f7ac4 100644
--- a/pynvim/msgpack_rpc/event_loop/asyncio.py
+++ b/pynvim/msgpack_rpc/event_loop/asyncio.py
@@ -83,6 +83,9 @@ def _init(self):
         self._queued_data = deque()
         self._fact = lambda: self
         self._raw_transport = None
+        if os.name != 'nt':
+            self._child_watcher = asyncio.get_child_watcher()
+            self._child_watcher.attach_loop(self._loop)
 
     def _connect_tcp(self, address, port):
         coroutine = self._loop.create_connection(self._fact, address, port)
@@ -118,9 +121,6 @@ def _connect_stdio(self):
         debug("native stdout connection successful")
 
     def _connect_child(self, argv):
-        if os.name != 'nt':
-            self._child_watcher = asyncio.get_child_watcher()
-            self._child_watcher.attach_loop(self._loop)
         coroutine = self._loop.subprocess_exec(self._fact, *argv)
         self._loop.run_until_complete(coroutine)
 
diff --git a/pynvim/msgpack_rpc/session.py b/pynvim/msgpack_rpc/session.py
index a0923722..ba3c6c03 100644
--- a/pynvim/msgpack_rpc/session.py
+++ b/pynvim/msgpack_rpc/session.py
@@ -102,6 +102,25 @@ def request(self, method, *args, **kwargs):
             raise self.error_wrapper(err)
         return rv
 
+    def run_coroutine(self, coroutine):
+        if not self._is_running:
+            # TODO: can has return value?
+            return self.loop._loop.run_until_complete(coroutine)
+        gr = greenlet.getcurrent()
+        parent = gr.parent
+
+        def result_cb(future):
+            debug('coroutine result is available for greenlet %s, switching back', gr)
+            gr.switch(future)
+
+        task = self.loop._loop.create_task(coroutine)
+        task.add_done_callback(result_cb)
+
+        debug('yielding from greenlet %s to wait for coroutine', gr)
+        future = parent.switch()
+        return future.result() # should re-raise any exception
+
+
     def run(self, request_cb, notification_cb, setup_cb=None):
         """Run the event loop to receive requests and notifications from Nvim.