Add new queuing features to @futurize

- max_instances renamed to max_running

- consider_args parameter:
  if True, $max_running of this function with the same arguments can be
  running, else:
  $max_running of this function, no matter the arguments, can be running

- discard_if_max_running:
  if True and there are already the maximum possible number of running
  functions running, cancel this task (previous default behavior), else:
  Wait for a spot to be free before running

TODO.md

@@ -4,6 +4,7 @@
   - Cleanup unused icons
 
 - Bug fixes
+  - Local echo messages all have the same time
   - Something weird happening when nio store is created first time
   - 100% CPU usage when hitting top edge to trigger messages loading
   - Sending `![A picture](https://picsum.photos/256/256)` → not clickable?
@@ -38,6 +39,7 @@
   - Status message and presence
 
 - Client improvements
+  - Don't send setTypingState False when focus lost if nothing in sendbox
   - Initial sync filter and lazy load, see weechat-matrix `_handle_login()`
     - See also `handle_response()`'s `keys_query` request
   - HTTP/2

harmonyqml/backend/backend.py

@@ -60,7 +60,7 @@ class Backend(QObject):
 
     @pyqtSlot(str, result="QVariant")
     @pyqtSlot(str, bool, result="QVariant")
-    @futurize()
+    @futurize(max_running=1, consider_args=True)
     def getUserDisplayName(self, user_id: str, can_block: bool = True) -> str:
         if user_id in self._queried_displaynames:
             return self._queried_displaynames[user_id]

harmonyqml/backend/client.py

@@ -62,8 +62,6 @@ class Client(QObject):
         self.net      = NetworkManager(self.host, self.port, self.nio)
         self.net_sync = NetworkManager(self.host, self.port, self.nio_sync)
 
-        self._loading: bool = False
-
         self._stop_sync: Event = Event()
 
         # {room_id: (was_typing, at_timestamp_secs)}
@@ -81,15 +79,13 @@ class Client(QObject):
         return self.nio.user_id
 
 
-    @futurize(pyqt=False)
+    @futurize(max_running=1, discard_if_max_running=True, pyqt=False)
     def _keys_upload(self) -> None:
-        print("uploading key")
         self.net.talk(self.nio.keys_upload)
 
 
-    @futurize(max_instances=1, pyqt=False)
+    @futurize(max_running=1, discard_if_max_running=True, pyqt=False)
     def _keys_query(self) -> None:
-        print("querying keys")
         self.net.talk(self.nio.keys_query)
 
 
@@ -192,22 +188,17 @@ class Client(QObject):
                 self.roomLeft[str].emit(room_id)
 
 
-    @futurize()
+    @futurize(max_running=1, discard_if_max_running=True)
     def loadPastEvents(self, room_id: str, start_token: str, limit: int = 100
                       ) -> None:
         # From QML, use Backend.loastPastEvents instead
 
-        if self._loading:
-            return
-        self._loading = True
-
         self._on_past_events(
             room_id,
             self.net.talk(
                 self.nio.room_messages, room_id, start=start_token, limit=limit
             )
         )
-        self._loading = False
 
 
     def _on_past_events(self, room_id: str, response: nio.RoomMessagesResponse
@@ -221,7 +212,7 @@ class Client(QObject):
 
 
     @pyqtSlot(str, bool)
-    @futurize(max_instances=1)
+    @futurize(max_running=1, discard_if_max_running=True)
     def setTypingState(self, room_id: str, typing: bool) -> None:
         set_for_secs        = 5
         last_set, last_time = self._last_typing_set[room_id]
@@ -256,7 +247,7 @@ class Client(QObject):
         # If the thread pool workers are all occupied, and @futurize
         # wrapped sendMarkdown, the messageAboutToBeSent signal neccessary
         # for local echoes would not be sent until a thread is free.
-        @futurize()
+        @futurize(max_running=1)
         def send(self):
             return self.net.talk(
                 self.nio.room_send,

harmonyqml/backend/pyqt_future.py

@@ -2,11 +2,12 @@
 # This file is part of harmonyqml, licensed under GPLv3.
 
 import functools
-import logging
+import logging as log
 import sys
+import time
 import traceback
 from concurrent.futures import Executor, Future
-from typing import Callable, List, Optional, Tuple, Union
+from typing import Callable, Deque, Optional, Tuple, Union
 
 from PyQt5.QtCore import QObject, pyqtProperty, pyqtSignal, pyqtSlot
 
@@ -64,32 +65,79 @@ class PyQtFuture(QObject):
         self.future.add_done_callback(fn)
 
 
-_RUNNING: List[Tuple[Executor, Callable, tuple, dict]] = []
+_Task = Tuple[Executor, Callable, Optional[tuple], Optional[dict]]
+_RUNNING: Deque[_Task] = Deque()
+_PENDING: Deque[_Task] = Deque()
 
 
-def futurize(max_instances: Optional[int] = None, pyqt: bool = True
-            ) -> Callable:
+def futurize(max_running:            Optional[int] = None,
+             consider_args:          bool          = False,
+             discard_if_max_running: bool          = False,
+             pyqt:                   bool          = True) -> Callable:
 
     def decorator(func: Callable) -> Callable:
 
         @functools.wraps(func)
         def wrapper(self, *args, **kws) -> Optional[PyQtFuture]:
+            task: _Task = (
+                self.pool,
+                func,
+                args if consider_args else None,
+                kws  if consider_args else None,
+            )
+
+            def can_run_now() -> bool:
+                if max_running is not None and \
+                    _RUNNING.count(task) >= max_running:
+                    log.debug("!! Max %d tasks of this kind running: %r",
+                              max_running, task[1:])
+                    return False
+
+                if not consider_args or not _PENDING:
+                    return True
+
+                log.debug(".. Pending: %r\n  Queue: %r", task[1:],  _PENDING)
+                candidate_task = next((
+                    pending for pending in _PENDING
+                    if pending[0] == self.pool and pending[1] == func
+                ), None)
+
+                if candidate_task is None:
+                    log.debug(">> No other candidate, starting: %r", task[1:])
+                    return True
+
+                if candidate_task[2] == args and candidate_task[3] == kws:
+                    log.debug(">> Candidate is us: %r", candidate_task[1:])
+                    return True
+
+                log.debug("XX Other candidate: %r", candidate_task[1:])
+                return False
+
+            if not can_run_now() and discard_if_max_running:
+                log.debug("\\/ Discarding task: %r", task[1:])
+                return None
+
             def run_and_catch_errs():
+                if not can_run_now():
+                    log.debug("~~ Can't start now: %r", task[1:])
+                    _PENDING.append(task)
+
+                    while not can_run_now():
+                        time.sleep(0.05)
+
+                _RUNNING.append(task)
+                log.debug("Starting: %r", task[1:])
+
                 # Without this, exceptions are silently ignored
                 try:
                     return func(self, *args, **kws)
                 except Exception:
                     traceback.print_exc()
-                    logging.error("Exiting thread/process due to exception.")
+                    log.error("Exiting thread/process due to exception.")
                     sys.exit(1)
                 finally:
-                    del _RUNNING[_RUNNING.index((self.pool, func, args, kws))]
+                    del _RUNNING[_RUNNING.index(task)]
 
-            if max_instances is not None and \
-               _RUNNING.count((self.pool, func, args, kws)) >= max_instances:
-                return None
-
-            _RUNNING.append((self.pool, func, args, kws))
             future = self.pool.submit(run_and_catch_errs)
             return PyQtFuture(future, self) if pyqt else future