backport py3.7 asyncio.run to support py3.6

hyperglass/cli/util.py

@@ -165,9 +165,9 @@ def build_ui():
         ClickException: Raised on any errors.
     """
     try:
-        import asyncio
-        from hyperglass.configuration import params, frontend_params, CONFIG_PATH
+        from hyperglass.compat import aiorun
         from hyperglass.util import build_frontend
+        from hyperglass.configuration import params, frontend_params, CONFIG_PATH
     except ImportError as e:
         error("Error importing UI builder: {e}", e=e)
 
@@ -179,7 +179,7 @@ def build_ui():
         dev_mode = "development"
 
     try:
-        build_success = asyncio.run(
+        build_success = aiorun(
             build_frontend(
                 dev_mode=params.developer_mode,
                 dev_url=f"http://localhost:{str(params.listen_port)}/",

hyperglass/compat.py

@@ -0,0 +1,116 @@
+"""Functions for maintaining compatability with older Python versions."""
+
+# Standard Library
+import sys
+import asyncio
+import weakref
+
+try:
+    from asyncio import get_running_loop
+except ImportError:
+    from asyncio.events import _get_running_loop as get_running_loop
+
+RUNNING_PYTHON_VERSION = sys.version_info
+
+# _patch_loop, _patched_run, and _cancel_all_tasks are taken directly
+# from github.com/nickdavis:
+# https://gist.github.com/nickdavies/4a37c6cd9dcc7041fddd2d2a81cee383
+
+# These functions are a backport of the functionality added in
+# Python 3.7 to support asyncio.run(), which is used in several areas
+# of hyperglass. Because the LTS version of Ubuntu at this time (18.04)
+# still ships with Python 3.6, compatibility with Python 3.6 is the
+# goal.
+
+
+def _patch_loop(loop):
+    tasks = weakref.WeakSet()
+
+    task_factory = [None]
+
+    def _set_task_factory(factory):
+        task_factory[0] = factory
+
+    def _get_task_factory():
+        return task_factory[0]
+
+    def _safe_task_factory(loop, coro):
+        if task_factory[0] is None:
+            task = asyncio.Task(coro, loop=loop)
+            if task._source_traceback:
+                del task._source_traceback[-1]
+        else:
+            task = task_factory[0](loop, coro)
+        tasks.add(task)
+        return task
+
+    loop.set_task_factory(_safe_task_factory)
+    loop.set_task_factory = _set_task_factory
+    loop.get_task_factory = _get_task_factory
+
+    return tasks
+
+
+def _patched_run(main, *, debug=False):
+    try:
+        loop = get_running_loop()
+    except RuntimeError:
+        loop = None
+
+    if loop is not None:
+        raise RuntimeError("asyncio.run() cannot be called from a running event loop")
+
+    if not asyncio.iscoroutine(main):
+        raise ValueError("a coroutine was expected, got {!r}".format(main))
+
+    loop = asyncio.new_event_loop()
+    tasks = _patch_loop(loop)
+
+    try:
+        asyncio.set_event_loop(loop)
+        loop.set_debug(debug)
+        return loop.run_until_complete(main)
+    finally:
+        try:
+            _cancel_all_tasks(loop, tasks)
+            loop.run_until_complete(loop.shutdown_asyncgens())
+        finally:
+            asyncio.set_event_loop(None)
+            loop.close()
+
+
+def _cancel_all_tasks(loop, tasks):
+    to_cancel = [task for task in tasks if not task.done()]
+
+    if not to_cancel:
+        return
+
+    for task in to_cancel:
+        task.cancel()
+
+    loop.run_until_complete(
+        asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
+    )
+
+    for task in to_cancel:
+        if task.cancelled():
+            continue
+        if task.exception() is not None:
+            loop.call_exception_handler(
+                {
+                    "message": "unhandled exception during asyncio.run() shutdown",
+                    "exception": task.exception(),
+                    "task": task,
+                }
+            )
+
+
+# If local system's python version is at least 3.6, use the backported
+# asyncio runner.
+if RUNNING_PYTHON_VERSION >= (3, 6):
+    aiorun = _patched_run
+
+# If the local system's python version is at least 3.7, use the standard
+# library's asyncio.run()
+elif RUNNING_PYTHON_VERSION >= (3, 7):
+    aiorun = asyncio.run

hyperglass/configuration/__init__.py

@@ -4,7 +4,6 @@
 import os
 import copy
 import math
-import asyncio
 from pathlib import Path
 
 # Third Party
@@ -15,6 +14,7 @@ from pydantic import ValidationError
 
 # Project
 from hyperglass.util import log, check_path, set_app_path
+from hyperglass.compat import aiorun
 from hyperglass.constants import (
     CREDIT,
     LOG_LEVELS,
@@ -80,9 +80,7 @@ async def _check_config_files(directory):
 
 STATIC_PATH = CONFIG_PATH / "static"
 
-CONFIG_MAIN, CONFIG_DEVICES, CONFIG_COMMANDS = asyncio.run(
-    _check_config_files(CONFIG_PATH)
-)
+CONFIG_MAIN, CONFIG_DEVICES, CONFIG_COMMANDS = aiorun(_check_config_files(CONFIG_PATH))
 
 
 def _set_log_level(debug, log_file=None):
@@ -166,7 +164,7 @@ async def _config_devices():
     return config
 
 
-user_config = asyncio.run(_config_main())
+user_config = aiorun(_config_main())
 
 # Logging Config
 try:
@@ -177,8 +175,8 @@ except KeyError:
 # Read raw debug value from config to enable debugging quickly.
 _set_log_level(_debug)
 
-_user_commands = asyncio.run(_config_commands())
-_user_devices = asyncio.run(_config_devices())
+_user_commands = aiorun(_config_commands())
+_user_devices = aiorun(_config_devices())
 
 # Map imported user config files to expected schema:
 try:
@@ -383,7 +381,7 @@ def _build_vrf_help():
                     "title"
                 ] = f"{vrf.display_name}: {command_params.display_name}"
 
-            md = asyncio.run(
+            md = aiorun(
                 get_markdown(
                     config_path=cmd,
                     default=DEFAULT_DETAILS[command],
@@ -404,7 +402,7 @@ content_vrf = _build_vrf_help()
 
 content_help_params = copy.copy(content_params)
 content_help_params["title"] = params.web.help_menu.title
-content_help = asyncio.run(
+content_help = aiorun(
     get_markdown(
         config_path=params.web.help_menu,
         default=DEFAULT_HELP,
@@ -414,7 +412,7 @@ content_help = asyncio.run(
 
 content_terms_params = copy.copy(content_params)
 content_terms_params["title"] = params.web.terms.title
-content_terms = asyncio.run(
+content_terms = aiorun(
     get_markdown(
         config_path=params.web.terms, default=DEFAULT_TERMS, params=content_terms_params
     )

hyperglass/constants.py

@@ -11,7 +11,7 @@ __license__ = "BSD 3-Clause Clear License"
 
 METADATA = (__name__, __version__, __author__, __copyright__, __license__)
 
-MIN_PYTHON_VERSION = (3, 7)
+MIN_PYTHON_VERSION = (3, 6)
 
 protocol_map = {80: "http", 8080: "http", 443: "https", 8443: "https"}