expose main-loop file descriptor hooks

(cherry picked from commit 92d39cd077)

docs/plugin-api-additions/async.md

@@ -1,30 +0,0 @@
-# Optional Python asyncio integration
-
-`run_async(coroutine, context=None, interval=10)` returns an AsyncTask with
-`done()`, `cancel()` and `result()`. Each invocation owns a separate event loop
-pumped by an existing main-loop timer. A ready stop callback ensures selector
-polling never blocks the UI. The captured context is restored after every pump;
-a closed context cancels the work. No process-wide event-loop policy is changed.
-
-Existing synchronous scripts are unaffected. Use `asyncio.get_running_loop()`
-inside the coroutine. Child tasks use the same loop/context and are cancelled
-when the main coroutine finishes or the script unloads. Cancellation cleanup is
-bounded; tasks must not suppress cancellation indefinitely. Cleanup uses the
-captured context while it remains open; after it closes, cancellation cleanup uses
-the current valid context. Use explicit Context methods for context-specific
-output in finally blocks, and do not issue context-dependent commands there. This provides normal
-asyncio sockets/timers, not Windows subprocess support or a new HTTP library.
-Asyncio hostname resolution can use its executor; use a resolver appropriate to
-your library if you require no worker threads. Blocking work inside a coroutine
-still blocks the client and must be avoided.
-
-```python
-import asyncio
-import zoitechat
-
-async def later():
-    await asyncio.sleep(1)
-    zoitechat.prnt('Still in the context where this task was started')
-
-task = zoitechat.run_async(later())
-```

docs/plugin-api-additions/fd.md

@@ -0,0 +1,19 @@
+# Python descriptor hooks
+
+`hook_fd(fd, callback, userdata=None, flags=FD_READ)` returns an ordinary hook
+handle accepted by `unhook()`. Callback arguments are `(fd, ready_flags, userdata)`;
+return True to retain the watch and False/None to remove it. Exceptions print a
+traceback and remove the watch. Unloading the script removes its watches.
+The callback runs in the context captured during registration, and that context
+is restored afterwards. A closed context removes the watch.
+
+Use nonblocking IO and bounded reads/writes. The descriptor belongs to the script;
+unhook before closing it. On Windows socket descriptors use the default flags;
+CRT descriptors need FD_NOTSOCKET. The existing C API uses int descriptors: values
+outside its range are rejected rather than truncated. This does not add threads.
+
+Example:
+```python
+watch = zoitechat.hook_fd(sock.fileno(), on_readable, flags=zoitechat.FD_READ)
+# def on_readable(fd, flags, userdata): ...; return True
+```

plugins/python/_zoitechat_async.py

@@ -1,100 +0,0 @@
-"""Opt-in asyncio tasks pumped without blocking the client main loop."""
-import asyncio
-import operator
-import traceback
-import _zoitechat as api
-
-__all__ = ['AsyncTask', 'run_async']
-
-
-class AsyncTask:
-    """A script-owned task and isolated event loop; cancel() is cooperative."""
-    def __init__(self, coroutine, plugin, context, interval):
-        self._plugin = plugin
-        self._context = context
-        self._loop = asyncio.new_event_loop()
-        self._task = self._loop.create_task(coroutine)
-        self._closed = False
-        self._unload_hook = api.hook_unload(lambda data: self._close())
-        self._timer_hook = api.hook_timer(interval, self._tick)
-
-    def done(self):
-        return self._task.done()
-
-    def cancel(self):
-        if not self._closed:
-            return self._task.cancel()
-        return False
-
-    def result(self):
-        return self._task.result()
-
-    def _pump(self):
-        # A ready stop callback forces the selector's timeout to zero.
-        self._loop.call_soon(self._loop.stop)
-        self._loop.run_forever()
-
-    def _close(self):
-        if self._closed:
-            return
-        self._closed = True
-        previous = api.get_context()
-        self._context.set()
-        try:
-            pending = asyncio.all_tasks(self._loop)
-            for task in pending:
-                task.cancel()
-            # Bound cleanup work; tasks must cooperate with cancellation.
-            for unused in range(3):
-                if not any(not task.done() for task in pending):
-                    break
-                self._pump()
-            for task in pending:
-                if not task.done():
-                    self._loop.call_exception_handler({
-                        'message': 'Script task ignored cancellation during unload',
-                        'task': task,
-                    })
-        finally:
-            self._loop.close()
-            previous.set()
-
-    def _tick(self, userdata):
-        if self._closed:
-            return False
-        previous = api.get_context()
-        if not self._context.set():
-            self._close()
-            self._plugin.remove_hook(self._unload_hook)
-            return False
-        try:
-            self._pump()
-            if not self._task.done():
-                return True
-            try:
-                self._task.result()
-            except asyncio.CancelledError:
-                pass
-            except Exception:
-                traceback.print_exc()
-            self._close()
-            self._plugin.remove_hook(self._unload_hook)
-            return False
-        except Exception:
-            traceback.print_exc()
-            self._close()
-            self._plugin.remove_hook(self._unload_hook)
-            return False
-        finally:
-            previous.set()
-
-
-def run_async(coroutine, context=None, interval=10):
-    """Schedule a coroutine in a captured context; return an AsyncTask handle."""
-    interval = operator.index(interval)
-    if interval < 1 or interval > 2147483647:
-        raise ValueError('interval must be a positive C int in milliseconds')
-    if not asyncio.iscoroutine(coroutine):
-        raise TypeError('run_async expects a coroutine object')
-    plugin = api.__get_current_plugin()
-    return AsyncTask(coroutine, plugin, context or api.get_context(), interval)

plugins/python/_zoitechat_fd.py

@@ -0,0 +1,39 @@
+"""File descriptor readiness hooks; callbacks execute on the main thread."""
+import operator
+import _zoitechat as api
+from _zoitechat_embedded import ffi, lib
+
+__all__ = ['FD_READ', 'FD_WRITE', 'FD_EXCEPTION', 'FD_NOTSOCKET', 'hook_fd']
+FD_READ, FD_WRITE, FD_EXCEPTION, FD_NOTSOCKET = 1, 2, 4, 8
+
+
+def hook_fd(fd, callback, userdata=None, flags=FD_READ):
+    """callback(fd, ready_flags, userdata): True keeps the watch, False removes it."""
+    fd = operator.index(fd)
+    flags = operator.index(flags)
+    if fd < 0 or fd > 2147483647:
+        raise ValueError('fd must fit the C API nonnegative int descriptor')
+    if flags & ~15 or not flags & 7:
+        raise ValueError('flags must select READ, WRITE or EXCEPTION')
+    if not callable(callback):
+        raise TypeError('callback must be callable')
+    plugin = api.__get_current_plugin()
+    context = api.get_context()
+
+    def dispatch(descriptor, ready, data):
+        previous = api.get_context()
+        if not context.set():
+            return False
+        try:
+            return callback(descriptor, ready, data)
+        finally:
+            previous.set()
+
+    hook = plugin.add_hook(dispatch, userdata)
+    handle = lib.zoitechat_hook_fd(lib.ph, fd, flags, lib._on_fd_hook, hook.handle)
+    if handle == ffi.NULL:
+        hook.is_unload = True
+        plugin.remove_hook(id(hook))
+        raise RuntimeError('unable to watch descriptor')
+    hook.zoitechat_hook = handle
+    return id(hook)

plugins/python/generate_plugin.py

@@ -38,6 +38,7 @@ extern "Python" int _on_print_attrs_hook(char **, zoitechat_event_attrs *, void
 extern "Python" int _on_server_hook(char **, char **, void *);
 extern "Python" int _on_server_attrs_hook(char **, char **, zoitechat_event_attrs *, void *);
 extern "Python" int _on_timer_hook(void *);
+extern "Python" int _on_fd_hook(int, int, void *);
 
 extern "Python" int _on_plugin_init(char **, char **, char **, char *, char *);
 extern "Python" int _on_plugin_deinit(void);

plugins/python/python.py

@@ -304,6 +304,28 @@ def _on_timer_hook(userdata):
     return 0
 
 
+@ffi.def_extern()
+def _on_fd_hook(fd, flags, userdata):
+    hook = ffi.from_handle(userdata)
+    keep = False
+    try:
+        keep = bool(hook.callback(fd, flags, hook.userdata))
+    except Exception:
+        traceback.print_exc()
+    if not keep:
+        # The C watch removes itself on return; do not unhook it a second time.
+        try:
+            hook.is_unload = True
+            # from_handle() yields a weak proxy: id(proxy) is not id(Hook).
+            for existing in hook.plugin.hooks:
+                if existing == hook:
+                    hook.plugin.remove_hook(id(existing))
+                    break
+        except ReferenceError:
+            pass  # the callback already unhooked itself
+    return int(keep)
+
+
 @ffi.def_extern()
 def _on_say_command(word, word_eol, userdata):
     """Handle input in the special >>python<< tab.