Circuitpython build

libs/circuitpython/asyncio/event.py

@@ -0,0 +1,92 @@
+# SPDX-FileCopyrightText: 2019-2020 Damien P. George
+#
+# SPDX-License-Identifier: MIT
+#
+# MicroPython uasyncio module
+# MIT license; Copyright (c) 2019-2020 Damien P. George
+#
+# This code comes from MicroPython, and has not been run through black or pylint there.
+# Altering these files significantly would make merging difficult, so we will not use
+# pylint or black.
+# pylint: skip-file
+# fmt: off
+"""
+Events
+======
+"""
+
+from . import core
+
+# Event class for primitive events that can be waited on, set, and cleared
+class Event:
+    """Create a new event which can be used to synchronize tasks. Events
+    start in the cleared state.
+    """
+
+    def __init__(self):
+        self.state = False  # False=unset; True=set
+        self.waiting = core.TaskQueue()  # Queue of Tasks waiting on completion of this event
+
+    def is_set(self):
+        """Returns ``True`` if the event is set, ``False`` otherwise."""
+
+        return self.state
+
+    def set(self):
+        """Set the event. Any tasks waiting on the event will be scheduled to run.
+        """
+
+        # Event becomes set, schedule any tasks waiting on it
+        # Note: This must not be called from anything except the thread running
+        # the asyncio loop (i.e. neither hard or soft IRQ, or a different thread).
+        while self.waiting.peek():
+            core._task_queue.push_head(self.waiting.pop_head())
+        self.state = True
+
+    def clear(self):
+        """Clear the event."""
+
+        self.state = False
+
+    async def wait(self):
+        """Wait for the event to be set. If the event is already set then it returns
+        immediately.
+
+        This is a coroutine.
+        """
+
+        if not self.state:
+            # Event not set, put the calling task on the event's waiting queue
+            self.waiting.push_head(core.cur_task)
+            # Set calling task's data to the event's queue so it can be removed if needed
+            core.cur_task.data = self.waiting
+            await core._never()
+        return True
+
+
+# MicroPython-extension: This can be set from outside the asyncio event loop,
+# such as other threads, IRQs or scheduler context. Implementation is a stream
+# that asyncio will poll until a flag is set.
+# Note: Unlike Event, this is self-clearing.
+try:
+    import uio
+
+    class ThreadSafeFlag(uio.IOBase):
+        def __init__(self):
+            self._flag = 0
+
+        def ioctl(self, req, flags):
+            if req == 3:  # MP_STREAM_POLL
+                return self._flag * flags
+            return None
+
+        def set(self):
+            self._flag = 1
+
+        async def wait(self):
+            if not self._flag:
+                yield core._io_queue.queue_read(self)
+            self._flag = 0
+
+except ImportError:
+    pass