Enable automatic result expiration with couchbase backend (#4751)

* utilize time to live option with couchbase backend

* set expires_type int in constructor

* Couchbase now supports result_expires

* default expires_type, unit tests for expires setting

* isort imports

* isort imports order-by-type

celery/backends/couchbase.py

@@ -39,12 +39,15 @@ class CouchbaseBackend(KeyValueStoreBackend):
     username = None
     password = None
     quiet = False
+    supports_autoexpire = True
+
     timeout = 2.5
 
     # Use str as couchbase key not bytes
     key_t = str_t
 
     def __init__(self, url=None, *args, **kwargs):
+        kwargs.setdefault('expires_type', int)
         super(CouchbaseBackend, self).__init__(*args, **kwargs)
         self.url = url
 
@@ -103,7 +106,7 @@ class CouchbaseBackend(KeyValueStoreBackend):
             return None
 
     def set(self, key, value):
-        self.connection.set(key, value)
+        self.connection.set(key, value, ttl=self.expires)
 
     def mget(self, keys):
         return [self.get(key) for key in keys]

docs/userguide/configuration.rst

@@ -661,7 +661,7 @@ on backend specifications).
 
 .. note::
 
-    For the moment this only works with the AMQP, database, cache,
+    For the moment this only works with the AMQP, database, cache, Couchbase,
     and Redis backends.
 
     When using the database backend, ``celery beat`` must be

t/unit/backends/test_couchbase.py

@@ -1,6 +1,8 @@
 """Tests for the CouchbaseBackend."""
 from __future__ import absolute_import, unicode_literals
 
+from datetime import timedelta
+
 import pytest
 from case import MagicMock, Mock, patch, sentinel, skip
 
@@ -59,9 +61,19 @@ class test_CouchbaseBackend:
         assert x.get('1f3fab') == sentinel.retval
         x._connection.get.assert_called_once_with('1f3fab')
 
-    def test_set(self):
+    def test_set_no_expires(self):
         self.app.conf.couchbase_backend_settings = None
         x = CouchbaseBackend(app=self.app)
+        x.expires = None
+        x._connection = MagicMock()
+        x._connection.set = MagicMock()
+        # should return None
+        assert x.set(sentinel.key, sentinel.value) is None
+
+    def test_set_expires(self):
+        self.app.conf.couchbase_backend_settings = None
+        x = CouchbaseBackend(app=self.app, expires=30)
+        assert x.expires == 30
         x._connection = MagicMock()
         x._connection.set = MagicMock()
         # should return None
@@ -107,3 +119,20 @@ class test_CouchbaseBackend:
             assert x.username == 'johndoe'
             assert x.password == 'mysecret'
             assert x.port == 123
+
+    def test_expires_defaults_to_config(self):
+        self.app.conf.result_expires = 10
+        b = CouchbaseBackend(expires=None, app=self.app)
+        assert b.expires == 10
+
+    def test_expires_is_int(self):
+        b = CouchbaseBackend(expires=48, app=self.app)
+        assert b.expires == 48
+
+    def test_expires_is_None(self):
+        b = CouchbaseBackend(expires=None, app=self.app)
+        assert b.expires == self.app.conf.result_expires.total_seconds()
+
+    def test_expires_is_timedelta(self):
+        b = CouchbaseBackend(expires=timedelta(minutes=1), app=self.app)
+        assert b.expires == 60