Merge pull request #1495 from dhermes/bigtable-read-rows

Adding Bigtable Table.read_row().

Author: dhermes

gcloud/bigtable/table.py

@@ -15,13 +15,16 @@
 """User friendly container for Google Cloud Bigtable Table."""
 
 
+from gcloud._helpers import _to_bytes
+from gcloud.bigtable._generated import bigtable_data_pb2 as data_pb2
 from gcloud.bigtable._generated import (
     bigtable_table_service_messages_pb2 as messages_pb2)
 from gcloud.bigtable._generated import (
     bigtable_service_messages_pb2 as data_messages_pb2)
 from gcloud.bigtable.column_family import _gc_rule_from_pb
 from gcloud.bigtable.column_family import ColumnFamily
 from gcloud.bigtable.row import Row
+from gcloud.bigtable.row_data import PartialRowData
 
 
 class Table(object):
@@ -218,6 +221,40 @@ def list_column_families(self):
             result[column_family_id] = column_family
         return result
 
+    def read_row(self, row_key, filter_=None):
+        """Read a single row from this table.
+
+        :type row_key: bytes
+        :param row_key: The key of the row to read from.
+
+        :type filter_: :class:`.row.RowFilter`
+        :param filter_: (Optional) The filter to apply to the contents of the
+                        row. If unset, returns the entire row.
+
+        :rtype: :class:`.PartialRowData`, :data:`NoneType <types.NoneType>`
+        :returns: The contents of the row if any chunks were returned in
+                  the response, otherwise :data:`None`.
+        :raises: :class:`ValueError <exceptions.ValueError>` if a commit row
+                 chunk is never encountered.
+        """
+        request_pb = _create_row_request(self.name, row_key=row_key,
+                                         filter_=filter_)
+        client = self._cluster._client
+        response_iterator = client._data_stub.ReadRows(request_pb,
+                                                       client.timeout_seconds)
+        # We expect an iterator of `data_messages_pb2.ReadRowsResponse`
+        result = PartialRowData(row_key)
+        for read_rows_response in response_iterator:
+            result.update_from_read_rows(read_rows_response)
+
+        # Make sure the result actually contains data.
+        if not result._chunks_encountered:
+            return None
+        # Make sure the result was committed by the back-end.
+        if not result.committed:
+            raise ValueError('The row remains partial / is not committed.')
+        return result
+
     def sample_row_keys(self):
         """Read a sample of row keys in the table.
 
@@ -255,3 +292,80 @@ def sample_row_keys(self):
         response_iterator = client._data_stub.SampleRowKeys(
             request_pb, client.timeout_seconds)
         return response_iterator
+
+
+def _create_row_request(table_name, row_key=None, start_key=None, end_key=None,
+                        filter_=None, allow_row_interleaving=None, limit=None):
+    """Creates a request to read rows in a table.
+
+    :type table_name: str
+    :param table_name: The name of the table to read from.
+
+    :type row_key: bytes
+    :param row_key: (Optional) The key of a specific row to read from.
+
+    :type start_key: bytes
+    :param start_key: (Optional) The beginning of a range of row keys to
+                      read from. The range will include ``start_key``. If
+                      left empty, will be interpreted as the empty string.
+
+    :type end_key: bytes
+    :param end_key: (Optional) The end of a range of row keys to read from.
+                    The range will not include ``end_key``. If left empty,
+                    will be interpreted as an infinite string.
+
+    :type filter_: :class:`.row.RowFilter`, :class:`.row.RowFilterChain`,
+                   :class:`.row.RowFilterUnion` or
+                   :class:`.row.ConditionalRowFilter`
+    :param filter_: (Optional) The filter to apply to the contents of the
+                    specified row(s). If unset, reads the entire table.
+
+    :type allow_row_interleaving: bool
+    :param allow_row_interleaving: (Optional) By default, rows are read
+                                   sequentially, producing results which are
+                                   guaranteed to arrive in increasing row
+                                   order. Setting
+                                   ``allow_row_interleaving`` to
+                                   :data:`True` allows multiple rows to be
+                                   interleaved in the response stream,
+                                   which increases throughput but breaks
+                                   this guarantee, and may force the
+                                   client to use more memory to buffer
+                                   partially-received rows.
+
+    :type limit: int
+    :param limit: (Optional) The read will terminate after committing to N
+                  rows' worth of results. The default (zero) is to return
+                  all results. Note that if ``allow_row_interleaving`` is
+                  set to :data:`True`, partial results may be returned for
+                  more than N rows. However, only N ``commit_row`` chunks
+                  will be sent.
+
+    :rtype: :class:`data_messages_pb2.ReadRowsRequest`
+    :returns: The ``ReadRowsRequest`` protobuf corresponding to the inputs.
+    :raises: :class:`ValueError <exceptions.ValueError>` if both
+             ``row_key`` and one of ``start_key`` and ``end_key`` are set
+    """
+    request_kwargs = {'table_name': table_name}
+    if (row_key is not None and
+            (start_key is not None or end_key is not None)):
+        raise ValueError('Row key and row range cannot be '
+                         'set simultaneously')
+    if row_key is not None:
+        request_kwargs['row_key'] = _to_bytes(row_key)
+    if start_key is not None or end_key is not None:
+        range_kwargs = {}
+        if start_key is not None:
+            range_kwargs['start_key'] = _to_bytes(start_key)
+        if end_key is not None:
+            range_kwargs['end_key'] = _to_bytes(end_key)
+        row_range = data_pb2.RowRange(**range_kwargs)
+        request_kwargs['row_range'] = row_range
+    if filter_ is not None:
+        request_kwargs['filter'] = filter_.to_pb()
+    if allow_row_interleaving is not None:
+        request_kwargs['allow_row_interleaving'] = allow_row_interleaving
+    if limit is not None:
+        request_kwargs['num_rows_limit'] = limit
+
+    return data_messages_pb2.ReadRowsRequest(**request_kwargs)

gcloud/bigtable/test_table.py

@@ -291,6 +291,85 @@ def test_delete(self):
             {},
         )])
 
+    def _read_row_helper(self, chunks):
+        from gcloud._testing import _Monkey
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+        from gcloud.bigtable._testing import _FakeStub
+        from gcloud.bigtable.row_data import PartialRowData
+        from gcloud.bigtable import table as MUT
+
+        project_id = 'project-id'
+        zone = 'zone'
+        cluster_id = 'cluster-id'
+        table_id = 'table-id'
+        timeout_seconds = 596
+        client = _Client(timeout_seconds=timeout_seconds)
+        cluster_name = ('projects/' + project_id + '/zones/' + zone +
+                        '/clusters/' + cluster_id)
+        cluster = _Cluster(cluster_name, client=client)
+        table = self._makeOne(table_id, cluster)
+
+        # Create request_pb
+        request_pb = object()  # Returned by our mock.
+        mock_created = []
+
+        def mock_create_row_request(table_name, row_key, filter_):
+            mock_created.append((table_name, row_key, filter_))
+            return request_pb
+
+        # Create response_iterator
+        row_key = b'row-key'
+        response_pb = messages_pb2.ReadRowsResponse(row_key=row_key,
+                                                    chunks=chunks)
+        response_iterator = [response_pb]
+
+        # Patch the stub used by the API method.
+        client._data_stub = stub = _FakeStub(response_iterator)
+
+        # Create expected_result.
+        if chunks:
+            expected_result = PartialRowData(row_key)
+            expected_result._committed = True
+            expected_result._chunks_encountered = True
+        else:
+            expected_result = None
+
+        # Perform the method and check the result.
+        filter_obj = object()
+        with _Monkey(MUT, _create_row_request=mock_create_row_request):
+            result = table.read_row(row_key, filter_=filter_obj)
+
+        self.assertEqual(result, expected_result)
+        self.assertEqual(stub.method_calls, [(
+            'ReadRows',
+            (request_pb, timeout_seconds),
+            {},
+        )])
+        self.assertEqual(mock_created, [(table.name, row_key, filter_obj)])
+
+    def test_read_row(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        chunk = messages_pb2.ReadRowsResponse.Chunk(commit_row=True)
+        chunks = [chunk]
+        self._read_row_helper(chunks)
+
+    def test_read_empty_row(self):
+        chunks = []
+        self._read_row_helper(chunks)
+
+    def test_read_row_still_partial(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        # There is never a "commit row".
+        chunk = messages_pb2.ReadRowsResponse.Chunk(reset_row=True)
+        chunks = [chunk]
+        with self.assertRaises(ValueError):
+            self._read_row_helper(chunks)
+
     def test_sample_row_keys(self):
         from gcloud.bigtable._generated import (
             bigtable_service_messages_pb2 as messages_pb2)
@@ -331,6 +410,128 @@ def test_sample_row_keys(self):
         )])
 
 
+class Test__create_row_request(unittest2.TestCase):
+
+    def _callFUT(self, table_name, row_key=None, start_key=None, end_key=None,
+                 filter_=None, allow_row_interleaving=None, limit=None):
+        from gcloud.bigtable.table import _create_row_request
+        return _create_row_request(
+            table_name, row_key=row_key, start_key=start_key, end_key=end_key,
+            filter_=filter_, allow_row_interleaving=allow_row_interleaving,
+            limit=limit)
+
+    def test_table_name_only(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        result = self._callFUT(table_name)
+        expected_result = messages_pb2.ReadRowsRequest(table_name=table_name)
+        self.assertEqual(result, expected_result)
+
+    def test_row_key_row_range_conflict(self):
+        with self.assertRaises(ValueError):
+            self._callFUT(None, row_key=object(), end_key=object())
+
+    def test_row_key(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        row_key = b'row_key'
+        result = self._callFUT(table_name, row_key=row_key)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            row_key=row_key,
+        )
+        self.assertEqual(result, expected_result)
+
+    def test_row_range_start_key(self):
+        from gcloud.bigtable._generated import bigtable_data_pb2 as data_pb2
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        start_key = b'start_key'
+        result = self._callFUT(table_name, start_key=start_key)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            row_range=data_pb2.RowRange(start_key=start_key),
+        )
+        self.assertEqual(result, expected_result)
+
+    def test_row_range_end_key(self):
+        from gcloud.bigtable._generated import bigtable_data_pb2 as data_pb2
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        end_key = b'end_key'
+        result = self._callFUT(table_name, end_key=end_key)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            row_range=data_pb2.RowRange(end_key=end_key),
+        )
+        self.assertEqual(result, expected_result)
+
+    def test_row_range_both_keys(self):
+        from gcloud.bigtable._generated import bigtable_data_pb2 as data_pb2
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        start_key = b'start_key'
+        end_key = b'end_key'
+        result = self._callFUT(table_name, start_key=start_key,
+                               end_key=end_key)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            row_range=data_pb2.RowRange(start_key=start_key, end_key=end_key),
+        )
+        self.assertEqual(result, expected_result)
+
+    def test_with_filter(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+        from gcloud.bigtable.row import RowSampleFilter
+
+        table_name = 'table_name'
+        row_filter = RowSampleFilter(0.33)
+        result = self._callFUT(table_name, filter_=row_filter)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            filter=row_filter.to_pb(),
+        )
+        self.assertEqual(result, expected_result)
+
+    def test_with_allow_row_interleaving(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        allow_row_interleaving = True
+        result = self._callFUT(table_name,
+                               allow_row_interleaving=allow_row_interleaving)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            allow_row_interleaving=allow_row_interleaving,
+        )
+        self.assertEqual(result, expected_result)
+
+    def test_with_limit(self):
+        from gcloud.bigtable._generated import (
+            bigtable_service_messages_pb2 as messages_pb2)
+
+        table_name = 'table_name'
+        limit = 1337
+        result = self._callFUT(table_name, limit=limit)
+        expected_result = messages_pb2.ReadRowsRequest(
+            table_name=table_name,
+            num_rows_limit=limit,
+        )
+        self.assertEqual(result, expected_result)
+
+
 class _Client(object):
 
     data_stub = None