diff --git a/swh/core/api.py b/swh/core/api.py
--- a/swh/core/api.py
+++ b/swh/core/api.py
@@ -4,6 +4,8 @@
# See top-level LICENSE file for more information
import collections
+import functools
+import inspect
import json
import logging
import pickle
@@ -19,11 +21,66 @@
pass
-class SWHRemoteAPI:
+def remote_api_endpoint(path):
+ def dec(f):
+ f._endpoint_path = path
+ return f
+ return dec
+
+
+class MetaSWHRemoteApi(type):
+ """Metaclass for SWHRemoteAPI, which adds a method for each endpoint
+ of the database it is designed to access.
+
+ See for example :class:`swh.indexer.storage.api.client.RemoteStorage`"""
+ def __new__(cls, name, bases, attributes):
+ # For each method wrapped with @remote_api_endpoint in an API backend
+ # (eg. :class:`swh.indexer.storage.IndexerStorage`), add a new
+ # method in RemoteStorage, with the same documentation.
+ #
+ # Note that, despite the usage of decorator magic (eg. functools.wrap),
+ # this never actually calls an IndexerStorage method.
+ backend_class = attributes['backend_class']
+ if backend_class:
+ for (meth_name, meth) in backend_class.__dict__.items():
+ if hasattr(meth, '_endpoint_path'):
+ cls.__add_endpoint(meth_name, meth, attributes)
+ return super().__new__(cls, name, bases, attributes)
+
+ @staticmethod
+ def __add_endpoint(meth_name, meth, attributes):
+ wrapped_meth = inspect.unwrap(meth)
+
+ @functools.wraps(meth) # Copy signature and doc
+ def meth_(*args, **kwargs):
+ # Match arguments and parameters
+ post_data = inspect.getcallargs(
+ wrapped_meth, *args, **kwargs)
+
+ # Remove arguments that should not be passed
+ self = post_data.pop('self')
+ post_data.pop('cur', None)
+ post_data.pop('db', None)
+
+ # Send the request.
+ return self.post(meth._endpoint_path, post_data)
+ attributes[meth_name] = meth_
+
+
+class SWHRemoteAPI(metaclass=MetaSWHRemoteApi):
"""Proxy to an internal SWH API
"""
+ backend_class = None
+ """For each method of `backend_class` decorated with
+ :func:`remote_api_endpoint`, a method with the same prototype and
+ docstring will be added to this class. Calls to this new method will
+ be translated into HTTP requests to a remote server.
+
+ This backend class will never be instantiated, it only serves as
+ a template."""
+
def __init__(self, api_exception, url, timeout=None):
super().__init__()
self.api_exception = api_exception
@@ -142,4 +199,35 @@
class SWHServerAPIApp(Flask):
+ """For each endpoint of the given `backend_class`, tells app.route to call
+ a function that decodes the request and sends it to the backend object
+ provided by the factory.
+
+ :param Any backend_class: The class of the backend, which will be
+ analyzed to look for API endpoints.
+ :param Callable[[], backend_class] backend_factory: A function with no
+ argument that returns
+ an instance of
+ `backend_class`."""
request_class = BytesRequest
+
+ def __init__(self, *args, backend_class=None, backend_factory=None,
+ **kwargs):
+ super().__init__(*args, **kwargs)
+
+ if backend_class is not None:
+ if backend_factory is None:
+ raise TypeError('Missing argument backend_factory')
+ for (meth_name, meth) in backend_class.__dict__.items():
+ if hasattr(meth, '_endpoint_path'):
+ self.__add_endpoint(meth_name, meth, backend_factory)
+
+ def __add_endpoint(self, meth_name, meth, backend_factory):
+ from flask import request
+
+ @self.route('/'+meth._endpoint_path, methods=['POST'])
+ @functools.wraps(meth) # Copy signature and doc
+ def _f():
+ # Call the actual code
+ obj_meth = getattr(backend_factory(), meth_name)
+ return encode_data_server(obj_meth(**decode_request(request)))
diff --git a/swh/core/tests/test_api.py b/swh/core/tests/test_api.py
new file mode 100644
--- /dev/null
+++ b/swh/core/tests/test_api.py
@@ -0,0 +1,84 @@
+# Copyright (C) 2018 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import unittest
+from nose.tools import istest
+
+import requests_mock
+from werkzeug.wrappers import BaseResponse
+from werkzeug.test import Client as WerkzeugTestClient
+
+from swh.core.api import (
+ error_handler, encode_data_server,
+ remote_api_endpoint, SWHRemoteAPI, SWHServerAPIApp)
+
+
+class ApiTest(unittest.TestCase):
+ @istest
+ def test_server(self):
+ testcase = self
+ nb_endpoint_calls = 0
+
+ class TestStorage:
+ @remote_api_endpoint('test_endpoint_url')
+ def test_endpoint(self, test_data, db=None, cur=None):
+ nonlocal nb_endpoint_calls
+ nb_endpoint_calls += 1
+
+ testcase.assertEqual(test_data, 'spam')
+ return 'egg'
+
+ app = SWHServerAPIApp('testapp',
+ backend_class=TestStorage,
+ backend_factory=lambda: TestStorage())
+
+ @app.errorhandler(Exception)
+ def my_error_handler(exception):
+ return error_handler(exception, encode_data_server)
+
+ client = WerkzeugTestClient(app, BaseResponse)
+ res = client.post('/test_endpoint_url',
+ headers={'Content-Type': 'application/x-msgpack'},
+ data=b'\x81\xa9test_data\xa4spam')
+
+ self.assertEqual(nb_endpoint_calls, 1)
+ self.assertEqual(b''.join(res.response), b'\xa3egg')
+
+ @istest
+ def test_client(self):
+ class TestStorage:
+ @remote_api_endpoint('test_endpoint_url')
+ def test_endpoint(self, test_data, db=None, cur=None):
+ pass
+
+ nb_http_calls = 0
+
+ def callback(request, context):
+ nonlocal nb_http_calls
+ nb_http_calls += 1
+ self.assertEqual(request.headers['Content-Type'],
+ 'application/x-msgpack')
+ self.assertEqual(request.body, b'\x81\xa9test_data\xa4spam')
+ context.headers['Content-Type'] = 'application/x-msgpack'
+ context.content = b'\xa3egg'
+ return b'\xa3egg'
+
+ adapter = requests_mock.Adapter()
+ adapter.register_uri('POST',
+ 'mock://example.com/test_endpoint_url',
+ content=callback)
+
+ class Testclient(SWHRemoteAPI):
+ backend_class = TestStorage
+
+ def __init__(self, *args, **kwargs):
+ super().__init__(*args, **kwargs)
+ self.session.mount('mock', adapter)
+
+ c = Testclient('foo', 'mock://example.com/')
+ res = c.test_endpoint('spam')
+
+ self.assertEqual(nb_http_calls, 1)
+ self.assertEqual(res, 'egg')