From 37094b6dd59f56978b918e79cadf17c6fd5d36e2 Mon Sep 17 00:00:00 2001 From: John Snow Date: Wed, 30 Mar 2022 13:28:10 -0400 Subject: python: rename qemu.aqmp to qemu.qmp Now that we are fully switched over to the new QMP library, move it back over the old namespace. This is being done primarily so that we may upload this package simply as "qemu.qmp" without introducing confusion over whether or not "aqmp" is a new protocol or not. The trade-off is increased confusion inside the QEMU developer tree. Sorry! Note: the 'private' member "_aqmp" in legacy.py also changes to "_qmp"; not out of necessity, but just to remove any traces of the "aqmp" name. Signed-off-by: John Snow Reviewed-by: Beraldo Leal Acked-by: Hanna Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy Message-id: 20220330172812.3427355-8-jsnow@redhat.com Signed-off-by: John Snow --- python/qemu/qmp/util.py | 217 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 217 insertions(+) create mode 100644 python/qemu/qmp/util.py (limited to 'python/qemu/qmp/util.py') diff --git a/python/qemu/qmp/util.py b/python/qemu/qmp/util.py new file mode 100644 index 0000000000..eaa5fc7d5f --- /dev/null +++ b/python/qemu/qmp/util.py @@ -0,0 +1,217 @@ +""" +Miscellaneous Utilities + +This module provides asyncio utilities and compatibility wrappers for +Python 3.6 to provide some features that otherwise become available in +Python 3.7+. + +Various logging and debugging utilities are also provided, such as +`exception_summary()` and `pretty_traceback()`, used primarily for +adding information into the logging stream. +""" + +import asyncio +import sys +import traceback +from typing import ( + Any, + Coroutine, + Optional, + TypeVar, + cast, +) + + +T = TypeVar('T') + + +# -------------------------- +# Section: Utility Functions +# -------------------------- + + +async def flush(writer: asyncio.StreamWriter) -> None: + """ + Utility function to ensure a StreamWriter is *fully* drained. + + `asyncio.StreamWriter.drain` only promises we will return to below + the "high-water mark". This function ensures we flush the entire + buffer -- by setting the high water mark to 0 and then calling + drain. The flow control limits are restored after the call is + completed. + """ + transport = cast(asyncio.WriteTransport, writer.transport) + + # https://github.com/python/typeshed/issues/5779 + low, high = transport.get_write_buffer_limits() # type: ignore + transport.set_write_buffer_limits(0, 0) + try: + await writer.drain() + finally: + transport.set_write_buffer_limits(high, low) + + +def upper_half(func: T) -> T: + """ + Do-nothing decorator that annotates a method as an "upper-half" method. + + These methods must not call bottom-half functions directly, but can + schedule them to run. + """ + return func + + +def bottom_half(func: T) -> T: + """ + Do-nothing decorator that annotates a method as a "bottom-half" method. + + These methods must take great care to handle their own exceptions whenever + possible. If they go unhandled, they will cause termination of the loop. + + These methods do not, in general, have the ability to directly + report information to a caller’s context and will usually be + collected as a Task result instead. + + They must not call upper-half functions directly. + """ + return func + + +# ------------------------------- +# Section: Compatibility Wrappers +# ------------------------------- + + +def create_task(coro: Coroutine[Any, Any, T], + loop: Optional[asyncio.AbstractEventLoop] = None + ) -> 'asyncio.Future[T]': + """ + Python 3.6-compatible `asyncio.create_task` wrapper. + + :param coro: The coroutine to execute in a task. + :param loop: Optionally, the loop to create the task in. + + :return: An `asyncio.Future` object. + """ + if sys.version_info >= (3, 7): + if loop is not None: + return loop.create_task(coro) + return asyncio.create_task(coro) # pylint: disable=no-member + + # Python 3.6: + return asyncio.ensure_future(coro, loop=loop) + + +def is_closing(writer: asyncio.StreamWriter) -> bool: + """ + Python 3.6-compatible `asyncio.StreamWriter.is_closing` wrapper. + + :param writer: The `asyncio.StreamWriter` object. + :return: `True` if the writer is closing, or closed. + """ + if sys.version_info >= (3, 7): + return writer.is_closing() + + # Python 3.6: + transport = writer.transport + assert isinstance(transport, asyncio.WriteTransport) + return transport.is_closing() + + +async def wait_closed(writer: asyncio.StreamWriter) -> None: + """ + Python 3.6-compatible `asyncio.StreamWriter.wait_closed` wrapper. + + :param writer: The `asyncio.StreamWriter` to wait on. + """ + if sys.version_info >= (3, 7): + await writer.wait_closed() + return + + # Python 3.6 + transport = writer.transport + assert isinstance(transport, asyncio.WriteTransport) + + while not transport.is_closing(): + await asyncio.sleep(0) + + # This is an ugly workaround, but it's the best I can come up with. + sock = transport.get_extra_info('socket') + + if sock is None: + # Our transport doesn't have a socket? ... + # Nothing we can reasonably do. + return + + while sock.fileno() != -1: + await asyncio.sleep(0) + + +def asyncio_run(coro: Coroutine[Any, Any, T], *, debug: bool = False) -> T: + """ + Python 3.6-compatible `asyncio.run` wrapper. + + :param coro: A coroutine to execute now. + :return: The return value from the coroutine. + """ + if sys.version_info >= (3, 7): + return asyncio.run(coro, debug=debug) + + # Python 3.6 + loop = asyncio.get_event_loop() + loop.set_debug(debug) + ret = loop.run_until_complete(coro) + loop.close() + + return ret + + +# ---------------------------- +# Section: Logging & Debugging +# ---------------------------- + + +def exception_summary(exc: BaseException) -> str: + """ + Return a summary string of an arbitrary exception. + + It will be of the form "ExceptionType: Error Message", if the error + string is non-empty, and just "ExceptionType" otherwise. + """ + name = type(exc).__qualname__ + smod = type(exc).__module__ + if smod not in ("__main__", "builtins"): + name = smod + '.' + name + + error = str(exc) + if error: + return f"{name}: {error}" + return name + + +def pretty_traceback(prefix: str = " | ") -> str: + """ + Formats the current traceback, indented to provide visual distinction. + + This is useful for printing a traceback within a traceback for + debugging purposes when encapsulating errors to deliver them up the + stack; when those errors are printed, this helps provide a nice + visual grouping to quickly identify the parts of the error that + belong to the inner exception. + + :param prefix: The prefix to append to each line of the traceback. + :return: A string, formatted something like the following:: + + | Traceback (most recent call last): + | File "foobar.py", line 42, in arbitrary_example + | foo.baz() + | ArbitraryError: [Errno 42] Something bad happened! + """ + output = "".join(traceback.format_exception(*sys.exc_info())) + + exc_lines = [] + for line in output.split('\n'): + exc_lines.append(prefix + line) + + # The last line is always empty, omit it + return "\n".join(exc_lines[:-1]) -- cgit v1.2.3-55-g7522