Add Future interface to BigQuery jobs

bigquery/google/cloud/bigquery/job.py

@@ -14,8 +14,12 @@
 
 """Define API Jobs."""
 
+import threading
+import warnings
+
 import six
 
+from google.cloud import exceptions
 from google.cloud.exceptions import NotFound
 from google.cloud._helpers import _datetime_from_microseconds
 from google.cloud.bigquery.dataset import Dataset
@@ -27,6 +31,7 @@
 from google.cloud.bigquery._helpers import UDFResourcesProperty
 from google.cloud.bigquery._helpers import _EnumProperty
 from google.cloud.bigquery._helpers import _TypedProperty
+import google.cloud.future.base
 
 
 class Compression(_EnumProperty):
@@ -82,16 +87,23 @@ class WriteDisposition(_EnumProperty):
     ALLOWED = (WRITE_APPEND, WRITE_TRUNCATE, WRITE_EMPTY)
 
 
-class _BaseJob(object):
-    """Base class for jobs.
+class _AsyncJob(google.cloud.future.base.PollingFuture):
+    """Base class for asynchronous jobs.
+
+    :type name: str
+    :param name: the name of the job
 
     :type client: :class:`google.cloud.bigquery.client.Client`
     :param client: A client which holds credentials and project configuration
                    for the dataset (which requires a project).
     """
-    def __init__(self, client):
+    def __init__(self, name, client):
+        super(_AsyncJob, self).__init__()
+        self.name = name
         self._client = client
         self._properties = {}
+        self._result_set = False
+        self._completion_lock = threading.Lock()
 
     @property
     def project(self):
@@ -117,21 +129,6 @@ def _require_client(self, client):
             client = self._client
         return client
 
-
-class _AsyncJob(_BaseJob):
-    """Base class for asynchronous jobs.
-
-    :type name: str
-    :param name: the name of the job
-
-    :type client: :class:`google.cloud.bigquery.client.Client`
-    :param client: A client which holds credentials and project configuration
-                   for the dataset (which requires a project).
-    """
-    def __init__(self, name, client):
-        super(_AsyncJob, self).__init__(client)
-        self.name = name
-
     @property
     def job_type(self):
         """Type of job
@@ -273,6 +270,9 @@ def _set_properties(self, api_response):
         self._properties.clear()
         self._properties.update(cleaned)
 
+        # For Future interface
+        self._set_future_result()
+
     @classmethod
     def _get_resource_config(cls, resource):
         """Helper for :meth:`from_api_repr`
@@ -345,7 +345,7 @@ def exists(self, client=None):
             return True
 
     def reload(self, client=None):
-        """API call:  refresh job properties via a GET request
+        """API call:  refresh job properties via a GET request.
 
         See
         https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs/get
@@ -371,12 +371,83 @@ def cancel(self, client=None):
                       ``NoneType``
         :param client: the client to use.  If not passed, falls back to the
                        ``client`` stored on the current dataset.
+
+        :rtype: bool
+        :returns: Boolean indicating that the cancel request was sent.
         """
         client = self._require_client(client)
 
         api_response = client._connection.api_request(
             method='POST', path='%s/cancel' % (self.path,))
         self._set_properties(api_response['job'])
+        return True
+
+    # The following methods implement the PollingFuture interface. Note that
+    # the methods above are from the pre-Future interface and are left for
+    # compatibility. The only "overloaded" method is :meth:`cancel`, which
+    # satisfies both interfaces.
+
+    def _set_future_result(self):
+        """Set the result or exception from the job if it is complete."""
+        # This must be done in a lock to prevent the polling thread
+        # and main thread from both executing the completion logic
+        # at the same time.
+        with self._completion_lock:
+            # If the operation isn't complete or if the result has already been
+            # set, do not call set_result/set_exception again.
+            # Note: self._result_set is set to True in set_result and
+            # set_exception, in case those methods are invoked directly.
+            if self.state != 'DONE' or self._result_set:
+                return
+
+            if self.error_result is not None:
+                exception = exceptions.GoogleCloudError(
+                    self.error_result, errors=self.errors)
+                self.set_exception(exception)
+            else:
+                self.set_result(self)
+
+    def done(self):
+        """Refresh the job and checks if it is complete.
+
+        :rtype: bool
+        :returns: True if the job is complete, False otherwise.
+        """
+        # Do not refresh is the state is already done, as the job will not
+        # change once complete.
+        if self.state != 'DONE':
+            self.reload()
+        return self.state == 'DONE'
+
+    def result(self, timeout=None):
+        """Start the job and wait for it to complete and get the result.
+
+        :type timeout: int
+        :param timeout: How long to wait for job to complete before raising
+            a :class:`TimeoutError`.
+
+        :rtype: _AsyncJob
+        :returns: This instance.
+
+        :raises: :class:`~google.cloud.exceptions.GoogleCloudError` if the job
+            failed or  :class:`TimeoutError` if the job did not complete in the
+            given timeout.
+        """
+        if self.state is None:
+            self.begin()
+        return super(_AsyncJob, self).result(timeout=timeout)
+
+    def cancelled(self):
+        """Check if the job has been cancelled.
+
+        This always returns False. It's not possible to check if a job was
+        cancelled in the API. This method is here to satisfy the interface
+        for :class:`google.cloud.future.Future`.
+
+        :rtype: bool
+        :returns: False
+        """
+        return False
 
 
 class _LoadConfiguration(object):
@@ -1127,11 +1198,44 @@ def from_api_repr(cls, resource, client):
         job._set_properties(resource)
         return job
 
-    def results(self):
+    def query_results(self):
         """Construct a QueryResults instance, bound to this job.
 
         :rtype: :class:`~google.cloud.bigquery.query.QueryResults`
         :returns: results instance
         """
         from google.cloud.bigquery.query import QueryResults
         return QueryResults.from_query_job(self)
+
+    def results(self):
+        """DEPRECATED.
+
+        This method is deprecated. Use :meth:`query_results` or :meth:`result`.
+
+        Construct a QueryResults instance, bound to this job.
+
+        :rtype: :class:`~google.cloud.bigquery.query.QueryResults`
+        :returns: The query results.
+        """
+        warnings.warn(
+            'QueryJob.results() is deprecated. Please use query_results() or '
+            'result().', DeprecationWarning)
+        return self.query_results()
+
+    def result(self, timeout=None):
+        """Start the job and wait for it to complete and get the result.
+
+        :type timeout: int
+        :param timeout: How long to wait for job to complete before raising
+            a :class:`TimeoutError`.
+
+        :rtype: :class:`~google.cloud.bigquery.query.QueryResults`
+        :returns: The query results.
+
+        :raises: :class:`~google.cloud.exceptions.GoogleCloudError` if the job
+            failed or  :class:`TimeoutError` if the job did not complete in the
+            given timeout.
+        """
+        super(QueryJob, self).result(timeout=timeout)
+        # Return a QueryResults instance instead of returning the job.
+        return self.query_results()

bigquery/tests/unit/test_job.py

@@ -12,6 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import copy
+import warnings
+
 import unittest
 
 
@@ -1514,15 +1517,76 @@ def test_from_api_repr_w_properties(self):
         self.assertIs(dataset._client, client)
         self._verifyResourceProperties(dataset, RESOURCE)
 
-    def test_results(self):
+    def test_query_results(self):
         from google.cloud.bigquery.query import QueryResults
 
         client = _Client(self.PROJECT)
         job = self._make_one(self.JOB_NAME, self.QUERY, client)
-        results = job.results()
+        results = job.query_results()
         self.assertIsInstance(results, QueryResults)
         self.assertIs(results._job, job)
 
+    def test_results_is_deprecated(self):
+        client = _Client(self.PROJECT)
+        job = self._make_one(self.JOB_NAME, self.QUERY, client)
+
+        with warnings.catch_warnings(record=True) as warned:
+            warnings.simplefilter('always')
+            job.results()
+            self.assertEqual(len(warned), 1)
+            self.assertIn('deprecated', str(warned[0]))
+
+    def test_result(self):
+        from google.cloud.bigquery.query import QueryResults
+
+        client = _Client(self.PROJECT)
+        job = self._make_one(self.JOB_NAME, self.QUERY, client)
+        job._properties['status'] = {'state': 'DONE'}
+
+        result = job.result()
+
+        self.assertIsInstance(result, QueryResults)
+        self.assertIs(result._job, job)
+
+    def test_result_invokes_begins(self):
+        begun_resource = self._makeResource()
+        done_resource = copy.deepcopy(begun_resource)
+        done_resource['status'] = {'state': 'DONE'}
+        connection = _Connection(begun_resource, done_resource)
+        client = _Client(self.PROJECT, connection=connection)
+        job = self._make_one(self.JOB_NAME, self.QUERY, client)
+
+        job.result()
+
+        self.assertEqual(len(connection._requested), 2)
+        begin_request, reload_request = connection._requested
+        self.assertEqual(begin_request['method'], 'POST')
+        self.assertEqual(reload_request['method'], 'GET')
+
+    def test_result_error(self):
+        from google.cloud import exceptions
+
+        client = _Client(self.PROJECT)
+        job = self._make_one(self.JOB_NAME, self.QUERY, client)
+        error_result = {
+            'debugInfo': 'DEBUG',
+            'location': 'LOCATION',
+            'message': 'MESSAGE',
+            'reason': 'REASON'
+        }
+        job._properties['status'] = {
+            'errorResult': error_result,
+            'errors': [error_result],
+            'state': 'DONE'
+        }
+        job._set_future_result()
+
+        with self.assertRaises(exceptions.GoogleCloudError) as exc_info:
+            job.result()
+
+        self.assertIsInstance(exc_info.exception, exceptions.GoogleCloudError)
+        self.assertEqual(exc_info.exception.errors, [error_result])
+
     def test_begin_w_bound_client(self):
         PATH = '/projects/%s/jobs' % (self.PROJECT,)
         RESOURCE = self._makeResource()