extmod/asyncio: Rename uasyncio to asyncio.

The asyncio module now has much better CPython compatibility and
deserves to be just called "asyncio".

This will avoid people having to write `from uasyncio import asyncio`.

Renames all files, and updates port manifests to use the new path. Also
renames the built-in _uasyncio to _asyncio.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

1 files changed, 177 insertions, 0 deletions

diff --git a/extmod/asyncio/task.py b/extmod/asyncio/task.py
new file mode 100644
index 0000000000..30be2170eb
--- /dev/null
+++ b/extmod/asyncio/task.py
@@ -0,0 +1,177 @@
+# MicroPython asyncio module
+# MIT license; Copyright (c) 2019-2020 Damien P. George
+
+# This file contains the core TaskQueue based on a pairing heap, and the core Task class.
+# They can optionally be replaced by C implementations.
+
+from . import core
+
+
+# pairing-heap meld of 2 heaps; O(1)
+def ph_meld(h1, h2):
+    if h1 is None:
+        return h2
+    if h2 is None:
+        return h1
+    lt = core.ticks_diff(h1.ph_key, h2.ph_key) < 0
+    if lt:
+        if h1.ph_child is None:
+            h1.ph_child = h2
+        else:
+            h1.ph_child_last.ph_next = h2
+        h1.ph_child_last = h2
+        h2.ph_next = None
+        h2.ph_rightmost_parent = h1
+        return h1
+    else:
+        h1.ph_next = h2.ph_child
+        h2.ph_child = h1
+        if h1.ph_next is None:
+            h2.ph_child_last = h1
+            h1.ph_rightmost_parent = h2
+        return h2
+
+
+# pairing-heap pairing operation; amortised O(log N)
+def ph_pairing(child):
+    heap = None
+    while child is not None:
+        n1 = child
+        child = child.ph_next
+        n1.ph_next = None
+        if child is not None:
+            n2 = child
+            child = child.ph_next
+            n2.ph_next = None
+            n1 = ph_meld(n1, n2)
+        heap = ph_meld(heap, n1)
+    return heap
+
+
+# pairing-heap delete of a node; stable, amortised O(log N)
+def ph_delete(heap, node):
+    if node is heap:
+        child = heap.ph_child
+        node.ph_child = None
+        return ph_pairing(child)
+    # Find parent of node
+    parent = node
+    while parent.ph_next is not None:
+        parent = parent.ph_next
+    parent = parent.ph_rightmost_parent
+    # Replace node with pairing of its children
+    if node is parent.ph_child and node.ph_child is None:
+        parent.ph_child = node.ph_next
+        node.ph_next = None
+        return heap
+    elif node is parent.ph_child:
+        child = node.ph_child
+        next = node.ph_next
+        node.ph_child = None
+        node.ph_next = None
+        node = ph_pairing(child)
+        parent.ph_child = node
+    else:
+        n = parent.ph_child
+        while node is not n.ph_next:
+            n = n.ph_next
+        child = node.ph_child
+        next = node.ph_next
+        node.ph_child = None
+        node.ph_next = None
+        node = ph_pairing(child)
+        if node is None:
+            node = n
+        else:
+            n.ph_next = node
+    node.ph_next = next
+    if next is None:
+        node.ph_rightmost_parent = parent
+        parent.ph_child_last = node
+    return heap
+
+
+# TaskQueue class based on the above pairing-heap functions.
+class TaskQueue:
+    def __init__(self):
+        self.heap = None
+
+    def peek(self):
+        return self.heap
+
+    def push(self, v, key=None):
+        assert v.ph_child is None
+        assert v.ph_next is None
+        v.data = None
+        v.ph_key = key if key is not None else core.ticks()
+        self.heap = ph_meld(v, self.heap)
+
+    def pop(self):
+        v = self.heap
+        assert v.ph_next is None
+        self.heap = ph_pairing(v.ph_child)
+        v.ph_child = None
+        return v
+
+    def remove(self, v):
+        self.heap = ph_delete(self.heap, v)
+
+
+# Task class representing a coroutine, can be waited on and cancelled.
+class Task:
+    def __init__(self, coro, globals=None):
+        self.coro = coro  # Coroutine of this Task
+        self.data = None  # General data for queue it is waiting on
+        self.state = True  # None, False, True, a callable, or a TaskQueue instance
+        self.ph_key = 0  # Pairing heap
+        self.ph_child = None  # Paring heap
+        self.ph_child_last = None  # Paring heap
+        self.ph_next = None  # Paring heap
+        self.ph_rightmost_parent = None  # Paring heap
+
+    def __iter__(self):
+        if not self.state:
+            # Task finished, signal that is has been await'ed on.
+            self.state = False
+        elif self.state is True:
+            # Allocated head of linked list of Tasks waiting on completion of this task.
+            self.state = TaskQueue()
+        elif type(self.state) is not TaskQueue:
+            # Task has state used for another purpose, so can't also wait on it.
+            raise RuntimeError("can't wait")
+        return self
+
+    def __next__(self):
+        if not self.state:
+            # Task finished, raise return value to caller so it can continue.
+            raise self.data
+        else:
+            # Put calling task on waiting queue.
+            self.state.push(core.cur_task)
+            # Set calling task's data to this task that it waits on, to double-link it.
+            core.cur_task.data = self
+
+    def done(self):
+        return not self.state
+
+    def cancel(self):
+        # Check if task is already finished.
+        if not self.state:
+            return False
+        # Can't cancel self (not supported yet).
+        if self is core.cur_task:
+            raise RuntimeError("can't cancel self")
+        # If Task waits on another task then forward the cancel to the one it's waiting on.
+        while isinstance(self.data, Task):
+            self = self.data
+        # Reschedule Task as a cancelled task.
+        if hasattr(self.data, "remove"):
+            # Not on the main running queue, remove the task from the queue it's on.
+            self.data.remove(self)
+            core._task_queue.push(self)
+        elif core.ticks_diff(self.ph_key, core.ticks()) > 0:
+            # On the main running queue but scheduled in the future, so bring it forward to now.
+            core._task_queue.remove(self)
+            core._task_queue.push(self)
+        self.data = core.CancelledError
+        return True