Use decorator to memoize. (#598)

* Use decorator to memoize.

This is to avoid adding complexity unrelated to what's being explained, when the
snippet of code is included in a doc.

* Clear memoization before tests.

Author: jerjou

appengine/bigquery/main_flask.py

@@ -0,0 +1,47 @@
+"""Sample appengine app demonstrating 3-legged oauth."""
+import cgi
+import json
+import os
+import sys
+
+from flask import Flask
+
+from googleapiclient.discovery import build
+
+from oauth2client.appengine import OAuth2DecoratorFromClientSecrets
+
+# The project id whose datasets you'd like to list
+PROJECTID = '<myproject_id>'
+
+# Create the method decorator for oauth.
+decorator = OAuth2DecoratorFromClientSecrets(
+    os.path.join(os.path.dirname(__file__), 'client_secrets.json'),
+    scope='https://www.googleapis.com/auth/bigquery')
+
+# Create the bigquery api client
+service = build('bigquery', 'v2')
+
+# Create the Flask app
+app = Flask(__name__)
+app.config['DEBUG'] = True
+
+# Create the endpoint to receive oauth flow callbacks
+app.route(decorator.callback_path)(decorator.callback_handler())
+
+
+@app.route('/')
+@decorator.oauth_required
+def list_datasets():
+    """Lists the datasets in PROJECTID"""
+    http = decorator.http()
+    datasets = service.datasets()
+
+    try:
+        response = datasets.list(projectId=PROJECTID).execute(http)
+
+        return ('<h3>Datasets.list raw response:</h3>'
+                '<pre>%s</pre>' % json.dumps(response, sort_keys=True,
+                                             indent=4, separators=(',', ': ')))
+    except:
+        e = cgi.escape(sys.exc_info()[0], True)
+        return '<p>Error: %s</p>' % e

appengine/standard/firebase/firetactoe/creds.json

@@ -0,0 +1 @@
+../../../../../channels-api-deprecation-1e958c196e99.json

appengine/standard/firebase/firetactoe/firetactoe.py

@@ -15,6 +15,10 @@
 """Tic Tac Toe with the Firebase API"""
 
 import base64
+try:
+    from functools import lru_cache
+except ImportError:
+    from functools32 import lru_cache
 import json
 import os
 import re
@@ -51,33 +55,36 @@
 app = flask.Flask(__name__)
 
 
-def _get_firebase_db_url(_memo={}):
+# Memoize the value, to avoid parsing the code snippet every time
+@lru_cache()
+def _get_firebase_db_url():
     """Grabs the databaseURL from the Firebase config snippet. Regex looks
     scary, but all it is doing is pulling the 'databaseURL' field from the
     Firebase javascript snippet"""
-    if 'dburl' not in _memo:
-        # Memoize the value, to avoid parsing the code snippet every time
-        regex = re.compile(r'\bdatabaseURL\b.*?["\']([^"\']+)')
-        cwd = os.path.dirname(__file__)
+    regex = re.compile(r'\bdatabaseURL\b.*?["\']([^"\']+)')
+    cwd = os.path.dirname(__file__)
+    try:
         with open(os.path.join(cwd, 'templates', _FIREBASE_CONFIG)) as f:
             url = next(regex.search(line) for line in f if regex.search(line))
-        _memo['dburl'] = url.group(1)
-    return _memo['dburl']
+    except StopIteration:
+        raise ValueError(
+            'Error parsing databaseURL. Please copy Firebase web snippet '
+            'into templates/{}'.format(_FIREBASE_CONFIG))
+    return url.group(1)
 
 
+# Memoize the authorized http, to avoid fetching new access tokens
+@lru_cache()
 # [START authed_http]
-def _get_http(_memo={}):
+def _get_http():
     """Provides an authed http object."""
-    if 'http' not in _memo:
-        # Memoize the authorized http, to avoid fetching new access tokens
-        http = httplib2.Http()
-        # Use application default credentials to make the Firebase calls
-        # https://firebase.google.com/docs/reference/rest/database/user-auth
-        creds = GoogleCredentials.get_application_default().create_scoped(
-            _FIREBASE_SCOPES)
-        creds.authorize(http)
-        _memo['http'] = http
-    return _memo['http']
+    http = httplib2.Http()
+    # Use application default credentials to make the Firebase calls
+    # https://firebase.google.com/docs/reference/rest/database/user-auth
+    creds = GoogleCredentials.get_application_default().create_scoped(
+        _FIREBASE_SCOPES)
+    creds.authorize(http)
+    return http
 # [END authed_http]
 
 

appengine/standard/firebase/firetactoe/firetactoe_test.py

@@ -43,8 +43,7 @@ def request(self, url, method, content='', *args, **kwargs):
 @pytest.fixture
 def app(testbed, monkeypatch, login):
     # Don't let the _get_http function memoize its value
-    orig_get_http = firetactoe._get_http
-    monkeypatch.setattr(firetactoe, '_get_http', lambda: orig_get_http({}))
+    firetactoe._get_http.cache_clear()
 
     # Provide a test firebase config. The following will set the databaseURL
     # databaseURL: "http://firebase.com/test-db-url"

appengine/standard/firebase/firetactoe/requirements.txt

@@ -1,4 +1,5 @@
 flask==0.11.1
 requests==2.11.1
 requests_toolbelt==0.7.0
-oauth2client==4.0.0
+oauth2client==2.2.0
+functools32==3.2.3.post2 ; python_version < '3'

appengine/standard/firebase/firetactoe/templates/_firebase_config.html.jerjou

@@ -0,0 +1,12 @@
+<script src="https://www.gstatic.com/firebasejs/3.4.1/firebase.js"></script>
+<script>
+  // Initialize Firebase
+  var config = {
+    apiKey: "AIzaSyC3gJDK1r-8nZuJGdmXntJR4E8cqH8qSTk",
+    authDomain: "channels-api-deprecation.firebaseapp.com",
+    databaseURL: "https://channels-api-deprecation.firebaseio.com",
+    storageBucket: "channels-api-deprecation.appspot.com",
+    messagingSenderId: "542117602304"
+  };
+  firebase.initializeApp(config);
+</script>