Allow two-way setting of job data properties.

As a side-effect, this also enables us to lazily load the data.

rq/job.py

@@ -19,6 +19,10 @@ Status = enum('Status',
               QUEUED='queued', FINISHED='finished', FAILED='failed',
               STARTED='started')
 
+# Sentinel value to mark that some of our lazily evaluated properties have not
+# yet been evaluated.
+UNEVALUATED = object()
+
 
 def unpickle(pickled_string):
     """Unpickles a string, but raises a unified UnpickleError in case anything
@@ -66,8 +70,6 @@ class Job(object):
     """A Job is just a convenient datastructure to pass around job (meta) data.
     """
 
-    data = None
-
     # Job construction
     @classmethod
     def create(cls, func, args=None, kwargs=None, connection=None,
@@ -86,6 +88,9 @@ class Job(object):
             raise TypeError('{0!r} is not a valid kwargs dict.'.format(kwargs))
 
         job = cls(connection=connection)
+
+        # Set the core job tuple properties
+        job._instance = None
         if inspect.ismethod(func):
             job._instance = func.__self__
             job._func_name = func.__name__
@@ -95,10 +100,13 @@ class Job(object):
             job._func_name = func
         job._args = args
         job._kwargs = kwargs
+
+        # Extra meta data
         job.description = description or job.get_call_string()
         job.result_ttl = result_ttl
         job.timeout = timeout
         job._status = status
+
         # dependency could be job instance or id
         if depends_on is not None:
             job._dependency_id = depends_on.id if isinstance(depends_on, Job) else depends_on
@@ -155,30 +163,79 @@ class Job(object):
 
         return import_attribute(self.func_name)
 
-    def _get_lazy(self, name):
-        if self.data is not None:
-            self._func_name, self._instance, self._args, self._kwargs = \
-                unpickle(self.data)
+    def _unpickle_data(self):
+        self._func_name, self._instance, self._args, self._kwargs = unpickle(self.data)
+
+    @property
+    def data(self):
+        if self._data is UNEVALUATED:
+            if self._func_name is UNEVALUATED:
+                raise ValueError('Cannot build the job data.')
+
+            if self._instance is UNEVALUATED:
+                self._instance = None
+
+            if self._args is UNEVALUATED:
+                self._args = ()
+
+            if self._kwargs is UNEVALUATED:
+                self._kwargs = {}
 
-            del self.data
+            job_tuple = self._func_name, self._instance, self._args, self._kwargs
+            self._data = dumps(job_tuple)
+        return self._data
 
-        return getattr(self, "_" + name)
+    @data.setter
+    def data(self, value):
+        self._data = value
+        self._func_name = UNEVALUATED
+        self._instance = UNEVALUATED
+        self._args = UNEVALUATED
+        self._kwargs = UNEVALUATED
 
     @property
     def func_name(self):
-        return self._get_lazy('func_name')
+        if self._func_name is UNEVALUATED:
+            self._unpickle_data()
+        return self._func_name
+
+    @func_name.setter
+    def func_name(self, value):
+        self._func_name = value
+        self._data = UNEVALUATED
 
     @property
     def instance(self):
-        return self._get_lazy('instance')
+        if self._instance is UNEVALUATED:
+            self._unpickle_data()
+        return self._instance
+
+    @instance.setter
+    def instance(self, value):
+        self._instance = value
+        self._data = UNEVALUATED
 
     @property
     def args(self):
-        return self._get_lazy('args')
+        if self._args is UNEVALUATED:
+            self._unpickle_data()
+        return self._args
+
+    @args.setter
+    def args(self, value):
+        self._args = value
+        self._data = UNEVALUATED
 
     @property
     def kwargs(self):
-        return self._get_lazy('kwargs')
+        if self._kwargs is UNEVALUATED:
+            self._unpickle_data()
+        return self._kwargs
+
+    @kwargs.setter
+    def kwargs(self, value):
+        self._kwargs = value
+        self._data = UNEVALUATED
 
     @classmethod
     def exists(cls, job_id, connection=None):
@@ -199,10 +256,11 @@ class Job(object):
         self.connection = resolve_connection(connection)
         self._id = id
         self.created_at = utcnow()
-        self._func_name = None
-        self._instance = None
-        self._args = None
-        self._kwargs = None
+        self._data = UNEVALUATED
+        self._func_name = UNEVALUATED
+        self._instance = UNEVALUATED
+        self._args = UNEVALUATED
+        self._kwargs = UNEVALUATED
         self.description = None
         self.origin = None
         self.enqueued_at = None
@@ -215,7 +273,6 @@ class Job(object):
         self._dependency_id = None
         self.meta = {}
 
-
     # Data access
     def get_id(self):  # noqa
         """The job ID for this job instance. Generates an ID lazily the
@@ -251,12 +308,6 @@ class Job(object):
         """The Redis key that is used to store job hash under."""
         return self.dependents_key_for(self.id)
 
-    @property  # noqa
-    def job_tuple(self):
-        """Returns the job tuple that encodes the actual function call that
-        this job represents."""
-        return (self.func_name, self.instance, self.args, self.kwargs)
-
     @property
     def result(self):
         """Returns the return value of the job.
@@ -284,7 +335,6 @@ class Job(object):
     """Backwards-compatibility accessor property `return_value`."""
     return_value = result
 
-
     # Persistence
     def refresh(self):  # noqa
         """Overwrite the current instance's properties with the values in the
@@ -325,11 +375,7 @@ class Job(object):
         """Returns a serialization of the current job instance"""
         obj = {}
         obj['created_at'] = utcformat(self.created_at or utcnow())
-
-        if self.data is not None:
         obj['data'] = self.data
-        elif self.func_name is not None:
-            obj['data'] = dumps(self.job_tuple)
 
         if self.origin is not None:
             obj['origin'] = self.origin
@@ -443,7 +489,6 @@ class Job(object):
     def __str__(self):
         return '<Job %s: %s>' % (self.id, self.description)
 
-
     # Job equality
     def __eq__(self, other):  # noqa
         return self.id == other.id

tests/test_job.py

@@ -3,9 +3,9 @@ from tests import RQTestCase
 from tests.fixtures import Number, some_calculation, say_hello, access_self
 from tests.helpers import strip_microseconds
 try:
-    from cPickle import loads
+    from cPickle import loads, dumps
 except ImportError:
-    from pickle import loads
+    from pickle import loads, dumps
 from rq.compat import as_text
 from rq.job import Job, get_current_job
 from rq.exceptions import NoSuchJobError, UnpickleError
@@ -23,16 +23,21 @@ class TestJob(RQTestCase):
         self.assertIsNotNone(job.created_at)
 
         # ...and nothing else
-        self.assertIsNone(job.func)
-        self.assertIsNone(job.instance)
-        self.assertIsNone(job.args)
-        self.assertIsNone(job.kwargs)
         self.assertIsNone(job.origin)
         self.assertIsNone(job.enqueued_at)
         self.assertIsNone(job.ended_at)
         self.assertIsNone(job.result)
         self.assertIsNone(job.exc_info)
 
+        with self.assertRaises(ValueError):
+            self.assertIsNone(job.func)
+        with self.assertRaises(ValueError):
+            self.assertIsNone(job.instance)
+        with self.assertRaises(ValueError):
+            self.assertIsNone(job.args)
+        with self.assertRaises(ValueError):
+            self.assertIsNone(job.kwargs)
+
     def test_create_typical_job(self):
         """Creation of jobs for function calls."""
         job = Job.create(func=some_calculation, args=(3, 4), kwargs=dict(z=2))
@@ -72,6 +77,27 @@ class TestJob(RQTestCase):
         self.assertIsNone(job.instance)
         self.assertEquals(job.args, ('World',))
 
+    def test_job_properties_set_data_property(self):
+        """Data property gets derived from the job tuple."""
+        job = Job()
+        job.func_name = 'foo'
+        fname, instance, args, kwargs = loads(job.data)
+
+        self.assertEquals(fname, job.func_name)
+        self.assertEquals(instance, None)
+        self.assertEquals(args, ())
+        self.assertEquals(kwargs, {})
+
+    def test_data_property(self):
+        """Job tuple gets derived lazily from data property."""
+        job = Job()
+        job.data = dumps(('foo', None, (1, 2, 3), {'bar': 'qux'}))
+
+        self.assertEquals(job.func_name, 'foo')
+        self.assertEquals(job.instance, None)
+        self.assertEquals(job.args, (1, 2, 3))
+        self.assertEquals(job.kwargs, {'bar': 'qux'})
+
     def test_save(self):  # noqa
         """Storing jobs."""
         job = Job.create(func=some_calculation, args=(3, 4), kwargs=dict(z=2))
@@ -102,23 +128,12 @@ class TestJob(RQTestCase):
         self.assertEquals(job.kwargs, dict(z=2))
         self.assertEquals(job.created_at, datetime(2012, 2, 7, 22, 13, 24))
 
-
     def test_persistence_of_empty_jobs(self):  # noqa
         """Storing empty jobs."""
         job = Job()
+        with self.assertRaises(ValueError):
             job.save()
 
-        expected_date = strip_microseconds(job.created_at)
-        stored_date = self.testconn.hget(job.key, 'created_at').decode('utf-8')
-        self.assertEquals(
-            stored_date,
-            utcformat(expected_date))
-
-        # ... and no other keys are stored
-        self.assertEqual(
-            self.testconn.hkeys(job.key),
-            [b'created_at'])
-
     def test_persistence_of_typical_jobs(self):
         """Storing typical jobs."""
         job = Job.create(func=some_calculation, args=(3, 4), kwargs=dict(z=2))