Using requests iter_content() to avoid storing response body in RAM.

docs/latest/.buildinfo

@@ -1,4 +1,4 @@
 # Sphinx build info version 1
 # This file hashes the configuration used when building these files. When it is not found, a full rebuild will be done.
-config: f74829a8d80ac23fb5f1ba14167f300f
+config: 4d96852847ec225f6bda6ce4c0135d77
 tags: 645f666f9bcd5a90fca523b33c5a78b7

docs/latest/google.resumable_media.requests.download.html

@@ -331,6 +331,8 @@
 <dt id="google.resumable_media.requests.download.Download.consume">
 <code class="descname">consume</code><span class="sig-paren">(</span><em>transport</em><span class="sig-paren">)</span><a class="headerlink" href="#google.resumable_media.requests.download.Download.consume" title="Permalink to this definition">¶</a></dt>
 <dd><p>Consume the resource to be downloaded.</p>
+<p>If a <code class="docutils literal"><span class="pre">stream</span></code> is attached to this download, then the downloaded
+resource will be written to the stream.</p>
 <table class="docutils field-list" frame="void" rules="none">
 <col class="field-name" />
 <col class="field-body" />

google/resumable_media/requests/_helpers.py

@@ -73,7 +73,7 @@ def _get_body(response):
 
 
 def http_request(transport, method, url, data=None, headers=None,
-                 retry_strategy=_DEFAULT_RETRY_STRATEGY):
+                 retry_strategy=_DEFAULT_RETRY_STRATEGY, **transport_kwargs):
     """Make an HTTP request.
 
     Args:
@@ -88,11 +88,14 @@ def http_request(transport, method, url, data=None, headers=None,
             may also add additional headers).
         retry_strategy (~google.resumable_media.common.RetryStrategy): The
             strategy to use if the request fails and must be retried.
+        transport_kwargs (Dict[str, str]): Extra keyword arguments to be
+            passed along to ``transport.request``.
 
     Returns:
         ~requests.Response: The return value of ``transport.request()``.
     """
     func = functools.partial(
-        transport.request, method, url, data=data, headers=headers)
+        transport.request, method, url, data=data, headers=headers,
+        **transport_kwargs)
     return _helpers.wait_and_retry(
         func, RequestsMixin._get_status_code, retry_strategy)

google/resumable_media/requests/download.py

@@ -19,6 +19,9 @@
 from google.resumable_media.requests import _helpers
 
 
+_SINGLE_GET_CHUNK_SIZE = 8192
+
+
 class Download(_helpers.RequestsMixin, _download.Download):
     """Helper to manage downloading a resource from a Google API.
 
@@ -45,9 +48,29 @@ class Download(_helpers.RequestsMixin, _download.Download):
         end (Optional[int]): The last byte in a range to be downloaded.
     """
 
+    def _write_to_stream(self, response):
+        """Write response body to a write-able stream.
+
+        .. note:
+
+            This method assumes that the ``_stream`` attribute is set on the
+            current download.
+
+        Args:
+            response (~requests.Response): The HTTP response object.
+        """
+        with response:
+            body_iter = response.iter_content(
+                chunk_size=_SINGLE_GET_CHUNK_SIZE, decode_unicode=False)
+            for chunk in body_iter:
+                self._stream.write(chunk)
+
     def consume(self, transport):
         """Consume the resource to be downloaded.
 
+        If a ``stream`` is attached to this download, then the downloaded
+        resource will be written to the stream.
+
         Args:
             transport (~requests.Session): A ``requests`` object which can
                 make authenticated requests.
@@ -61,9 +84,20 @@ def consume(self, transport):
         """
         method, url, payload, headers = self._prepare_request()
         # NOTE: We assume "payload is None" but pass it along anyway.
+        request_kwargs = {
+            u'data': payload,
+            u'headers': headers,
+            u'retry_strategy': self._retry_strategy,
+        }
+        if self._stream is not None:
+            request_kwargs[u'stream'] = True
+
         result = _helpers.http_request(
-            transport, method, url, data=payload, headers=headers,
-            retry_strategy=self._retry_strategy)
+            transport, method, url, **request_kwargs)
+
+        if self._stream is not None:
+            self._write_to_stream(result)
+
         self._process_response(result)
         return result