Add Memcache Best Practices Samples

appengine/memcache/best_practices/README.md

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+# Memcache Best Practices
+
+Code snippets for [Memcache Cache Best Practices article](https://cloud.google.com/appengine/articles/best-practices-for-app-engine-memcache)
+
+

appengine/memcache/best_practices/failure/app.yaml

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+runtime: python27
+threadsafe: yes
+api_version: 1
+
+handlers:
+- url: .*
+  script: main.app

appengine/memcache/best_practices/failure/failure.py

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+#!/usr/bin/env python
+
+# Copyright 2016 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from google.appengine.api import memcache
+
+import webapp2
+
+
+def read_from_persistent_store():
+    """Fake method for demonstration purposes. Usually would return
+     a value from a database like Cloud Datastore or MySQL."""
+    return "a persistent value"
+
+
+class ReadPage(webapp2.RequestHandler):
+    def get(self):
+        key = "some-key"
+        # [START memcache-read]
+        v = memcache.get(key)
+        if v is None:
+            v = read_from_persistent_store()
+            memcache.add(key, v)
+        # [END memcache-read]
+
+        self.response.content_type = 'text/html'
+        self.response.write(str(v))
+
+
+class DeletePage(webapp2.RequestHandler):
+    def get(self):
+        key = "some key"
+        seconds = 5
+        memcache.set(key, "some value")
+        # [START memcache-delete]
+        memcache.delete(key, seconds)  # clears cache
+        # write to persistent datastore
+        # Do not attempt to put new value in cache, first reader will do that
+        # [END memcache-delete]
+        self.response.content_type = 'text/html'
+        self.response.write('done')
+
+
+class MainPage(webapp2.RequestHandler):
+    def get(self):
+        value = 3
+        # [START memcache-failure]
+        if not memcache.set('counter', value):
+            logging.error("Memcache set failed")
+            # Other error handling here
+        # [END memcache-failure]
+        self.response.content_type = 'text/html'
+        self.response.write('done')
+
+
+app = webapp2.WSGIApplication([
+    ('/', MainPage),
+    ('/delete', DeletePage),
+    ('/read', ReadPage),
+], debug=True)

appengine/memcache/best_practices/failure/failure_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import failure
+
+import pytest
+import webtest
+
+
+@pytest.fixture
+def app(testbed):
+    return webtest.TestApp(failure.app)
+
+
+def test_get(app):
+    app.get('/')
+
+
+def test_read(app):
+    app.get('/read')
+
+
+def test_delete(app):
+    app.get('/delete')

appengine/memcache/best_practices/migration_step1/app.yaml

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+runtime: python27
+threadsafe: yes
+api_version: 1
+
+handlers:
+- url: .*
+  script: main.app

appengine/memcache/best_practices/migration_step1/migration1.py

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+#!/usr/bin/env python
+
+# Copyright 2016 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from google.appengine.api import memcache
+from google.appengine.ext import ndb
+
+import webapp2
+
+
+# [START best-practice-1]
+class Person(ndb.Model):
+    name = ndb.StringProperty(required=True)
+
+
+def get_or_add_person(name):
+    person = memcache.get(name)
+    if person is None:
+        person = Person(name=name)
+        memcache.add(name, person)
+    else:
+        logging.info('Found in cache: ' + name)
+    return person
+# [END best-practice-1]
+
+
+class MainPage(webapp2.RequestHandler):
+    def get(self):
+        person = get_or_add_person('Stevie Wonder')
+        self.response.content_type = 'text/html'
+        self.response.write(person.name)
+
+
+app = webapp2.WSGIApplication([
+    ('/', MainPage),
+], debug=True)

appengine/memcache/best_practices/migration_step1/migration1_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import migration1
+
+import webtest
+
+
+def test_get(testbed):
+    app = webtest.TestApp(migration1.app)
+    app.get('/')

appengine/memcache/best_practices/migration_step2/app.yaml

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+runtime: python27
+threadsafe: yes
+api_version: 1
+
+handlers:
+- url: .*
+  script: main.app

appengine/memcache/best_practices/migration_step2/migration2.py

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+#!/usr/bin/env python
+
+# Copyright 2016 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+from google.appengine.api import memcache
+from google.appengine.ext import ndb
+
+import webapp2
+
+
+# [START best-practice-2]
+class Person(ndb.Model):
+    name = ndb.StringProperty(required=True)
+    userid = ndb.StringProperty(required=True)
+
+
+def get_or_add_person(name, userid):
+    person = memcache.get(name)
+    if person is None:
+        person = Person(name=name, userid=userid)
+        memcache.add(name, person)
+    else:
+        logging.info('Found in cache: ' + name + ', userid: ' + person.userid)
+    return person
+# [END best-practice-2]
+
+
+class MainPage(webapp2.RequestHandler):
+    def get(self):
+        person = get_or_add_person('Stevie Wonder', 1)
+        self.response.content_type = 'text/html'
+        self.response.write(person.name)
+
+
+app = webapp2.WSGIApplication([
+    ('/', MainPage),
+], debug=True)

appengine/memcache/best_practices/migration_step2/migration2_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import migration2
+
+import webtest
+
+
+def test_get(testbed):
+    app = webtest.TestApp(migration2.app)
+    app.get('/')

appengine/memcache/best_practices/sharing/app.yaml

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+runtime: python27
+threadsafe: yes
+api_version: 1
+
+handlers:
+- url: .*
+  script: main.app

appengine/memcache/best_practices/sharing/sharing.py

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+#!/usr/bin/env python
+
+# Copyright 2016 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from google.appengine.api import memcache
+
+import webapp2
+
+
+class MainPage(webapp2.RequestHandler):
+    def get(self):
+        # [START sharing]
+        self.response.headers['Content-Type'] = 'text/plain'
+
+        who = memcache.get('who')
+        self.response.write('Previously incremented by %s\n' % who)
+        memcache.set('who', 'Python')
+
+        count = memcache.incr('count', 1, initial_value=0)
+        self.response.write('Count incremented by Python = %s\n' % count)
+        # [END sharing]
+
+
+app = webapp2.WSGIApplication([
+    ('/', MainPage),
+], debug=True)

appengine/memcache/best_practices/sharing/sharing_test.py

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+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sharing
+
+import webtest
+
+
+def test_get(testbed):
+    app = webtest.TestApp(sharing.app)
+    response = app.get('/')
+    assert 'Previously incremented by ' in response.body