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>

extmod/asyncio/stream.py

@@ -0,0 +1,189 @@
+# MicroPython asyncio module
+# MIT license; Copyright (c) 2019-2020 Damien P. George
+
+from . import core
+
+
+class Stream:
+    def __init__(self, s, e={}):
+        self.s = s
+        self.e = e
+        self.out_buf = b""
+
+    def get_extra_info(self, v):
+        return self.e[v]
+
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, exc, tb):
+        await self.close()
+
+    def close(self):
+        pass
+
+    async def wait_closed(self):
+        # TODO yield?
+        self.s.close()
+
+    # async
+    def read(self, n=-1):
+        r = b""
+        while True:
+            yield core._io_queue.queue_read(self.s)
+            r2 = self.s.read(n)
+            if r2 is not None:
+                if n >= 0:
+                    return r2
+                if not len(r2):
+                    return r
+                r += r2
+
+    # async
+    def readinto(self, buf):
+        yield core._io_queue.queue_read(self.s)
+        return self.s.readinto(buf)
+
+    # async
+    def readexactly(self, n):
+        r = b""
+        while n:
+            yield core._io_queue.queue_read(self.s)
+            r2 = self.s.read(n)
+            if r2 is not None:
+                if not len(r2):
+                    raise EOFError
+                r += r2
+                n -= len(r2)
+        return r
+
+    # async
+    def readline(self):
+        l = b""
+        while True:
+            yield core._io_queue.queue_read(self.s)
+            l2 = self.s.readline()  # may do multiple reads but won't block
+            l += l2
+            if not l2 or l[-1] == 10:  # \n (check l in case l2 is str)
+                return l
+
+    def write(self, buf):
+        if not self.out_buf:
+            # Try to write immediately to the underlying stream.
+            ret = self.s.write(buf)
+            if ret == len(buf):
+                return
+            if ret is not None:
+                buf = buf[ret:]
+        self.out_buf += buf
+
+    # async
+    def drain(self):
+        if not self.out_buf:
+            # Drain must always yield, so a tight loop of write+drain can't block the scheduler.
+            return (yield from core.sleep_ms(0))
+        mv = memoryview(self.out_buf)
+        off = 0
+        while off < len(mv):
+            yield core._io_queue.queue_write(self.s)
+            ret = self.s.write(mv[off:])
+            if ret is not None:
+                off += ret
+        self.out_buf = b""
+
+
+# Stream can be used for both reading and writing to save code size
+StreamReader = Stream
+StreamWriter = Stream
+
+
+# Create a TCP stream connection to a remote host
+#
+# async
+def open_connection(host, port):
+    from errno import EINPROGRESS
+    import socket
+
+    ai = socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM)[0]  # TODO this is blocking!
+    s = socket.socket(ai[0], ai[1], ai[2])
+    s.setblocking(False)
+    ss = Stream(s)
+    try:
+        s.connect(ai[-1])
+    except OSError as er:
+        if er.errno != EINPROGRESS:
+            raise er
+    yield core._io_queue.queue_write(s)
+    return ss, ss
+
+
+# Class representing a TCP stream server, can be closed and used in "async with"
+class Server:
+    async def __aenter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, exc, tb):
+        self.close()
+        await self.wait_closed()
+
+    def close(self):
+        self.task.cancel()
+
+    async def wait_closed(self):
+        await self.task
+
+    async def _serve(self, s, cb):
+        # Accept incoming connections
+        while True:
+            try:
+                yield core._io_queue.queue_read(s)
+            except core.CancelledError:
+                # Shutdown server
+                s.close()
+                return
+            try:
+                s2, addr = s.accept()
+            except:
+                # Ignore a failed accept
+                continue
+            s2.setblocking(False)
+            s2s = Stream(s2, {"peername": addr})
+            core.create_task(cb(s2s, s2s))
+
+
+# Helper function to start a TCP stream server, running as a new task
+# TODO could use an accept-callback on socket read activity instead of creating a task
+async def start_server(cb, host, port, backlog=5):
+    import socket
+
+    # Create and bind server socket.
+    host = socket.getaddrinfo(host, port)[0]  # TODO this is blocking!
+    s = socket.socket()
+    s.setblocking(False)
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    s.bind(host[-1])
+    s.listen(backlog)
+
+    # Create and return server object and task.
+    srv = Server()
+    srv.task = core.create_task(srv._serve(s, cb))
+    return srv
+
+
+################################################################################
+# Legacy uasyncio compatibility
+
+
+async def stream_awrite(self, buf, off=0, sz=-1):
+    if off != 0 or sz != -1:
+        buf = memoryview(buf)
+        if sz == -1:
+            sz = len(buf)
+        buf = buf[off : off + sz]
+    self.write(buf)
+    await self.drain()
+
+
+Stream.aclose = Stream.wait_closed
+Stream.awrite = stream_awrite
+Stream.awritestr = stream_awrite  # TODO explicitly convert to bytes?