Initial async support

Add asyncio to the storage backends and most of the codebase. A lot of
it merely uses asyncio APIs, but still doesn't actually run several
things concurrently internally. Further improvements will be added on
top of these changes

Thanks to  Thomas Grainger (@graingert) for a few useful pointers
related to asyncio.

Author: Hugo Osvaldo Barrera

.builds/archlinux.yaml

@@ -19,6 +19,10 @@ packages:
   - python-pytest-cov
   - python-pytest-httpserver
   - python-trustme
+  - python-pytest-asyncio
+  - python-aiohttp
+  - python-aiostream
+  - python-aioresponses
 sources:
   - https://github.com/pimutils/vdirsyncer
 environment:

setup.cfg

@@ -8,6 +8,7 @@ addopts =
   --cov=vdirsyncer
   --cov-report=term-missing
   --no-cov-on-fail
+# filterwarnings=error
 
 [flake8]
 application-import-names = tests,vdirsyncer

setup.py

@@ -13,14 +13,14 @@
     # https://github.com/mitsuhiko/click/issues/200
     "click>=5.0,<9.0",
     "click-log>=0.3.0, <0.4.0",
-    # https://github.com/pimutils/vdirsyncer/issues/478
-    "click-threading>=0.5",
     "requests >=2.20.0",
     # https://github.com/sigmavirus24/requests-toolbelt/pull/28
     # And https://github.com/sigmavirus24/requests-toolbelt/issues/54
     "requests_toolbelt >=0.4.0",
     # https://github.com/untitaker/python-atomicwrites/commit/4d12f23227b6a944ab1d99c507a69fdbc7c9ed6d  # noqa
     "atomicwrites>=0.1.7",
+    "aiohttp>=3.7.1,<4.0.0",
+    "aiostream>=0.4.3,<0.5.0",
 ]
 
 

test-requirements.txt

@@ -3,3 +3,5 @@ pytest
 pytest-cov
 pytest-httpserver
 trustme
+pytest-asyncio
+aioresponses

tests/conftest.py

@@ -4,6 +4,7 @@
 import logging
 import os
 
+import aiohttp
 import click_log
 import pytest
 from hypothesis import HealthCheck
@@ -52,3 +53,18 @@ def benchmark():
     settings.load_profile("ci")
 else:
     settings.load_profile("dev")
+
+
+@pytest.fixture
+async def aio_session(event_loop):
+    async with aiohttp.ClientSession() as session:
+        yield session
+
+
+@pytest.fixture
+async def aio_connector(event_loop):
+    conn = aiohttp.TCPConnector(limit_per_host=16)
+    try:
+        yield conn
+    finally:
+        await conn.close()