Add renderer/exporter names to cached files

 * Allow for more targeted cache cleaning by indicating the renderer
   or exporter that generated the cache file.

 [SVCS-159]

Author: AddisonSchiller

mfr/core/utils.py

@@ -1,3 +1,4 @@
+import pkg_resources
 from stevedore import driver
 
 from mfr.core import exceptions
@@ -97,6 +98,46 @@ def make_renderer(name, metadata, file_path, url, assets_url, export_url):
             }
         )
 
+def get_renderer_name(name):
+    """ Return the name of the renderer used for a certain file extension.
+
+    :param str name: The name of the extension to get the renderer name for. (.jpg, .docx, etc)
+
+    :rtype : `str`
+    """
+
+    # This can give back empty tuples
+    try:
+        entry_attrs = pkg_resources.iter_entry_points(group='mfr.renderers', name=name)
+
+        # ep.attrs is a tuple of attributes. There should only ever be one or `None`.
+        # None case occurs when trying to render an unsupported file type
+        # entry_attrs is an iterable object, so we turn into a list to index it
+        return list(entry_attrs)[0].attrs[0]
+
+    # This means the file type is not supported. Just return the blank string so `make_renderers`
+    # can log a real exception with all the variables and names it has
+    except IndexError:
+        return ''
+
+def get_exporter_name(name):
+    """ Return the name of the exporter used for a certain file extension.
+
+    :param str name: The name of the extension to get the exporter name for. (.jpg, .docx, etc)
+
+    :rtype : `str`
+    """
+
+    # `make_renderer` should have already caught if an extension doesn't exist.
+
+    # should be a list of length one, since we don't have multiple entrypoints per group
+    entry_attrs = pkg_resources.iter_entry_points(group='mfr.exporters', name=name)
+
+    # ep.attrs is a tuple of attributes. There should only ever be one or `None`.
+    # For our case however there shouldn't be `None`
+    return list(entry_attrs)[0].attrs[0]
+
+
 def sizeof_fmt(num, suffix='B'):
     if abs(num) < 1000:
         return '%3.0f%s' % (num, suffix)

mfr/server/handlers/export.py

@@ -29,11 +29,12 @@ async def prepare(self):
                                     " appropriate extension")
         # TODO: do we need to catch exceptions for decoding?
         self.format = format[0].decode('utf-8')
+        self.exporter_name = utils.get_exporter_name(self.metadata.ext)
 
         self.cache_file_id = '{}.{}'.format(self.metadata.unique_key, self.format)
 
         self.cache_file_path = await self.cache_provider.validate_path(
-            '/export/{}'.format(self.cache_file_id)
+            '/export/{}.{}'.format(self.cache_file_id, self.exporter_name)
         )
         self.source_file_path = await self.local_cache_provider.validate_path(
             '/export/{}'.format(self.source_file_id)

mfr/server/handlers/render.py

@@ -24,9 +24,11 @@ async def prepare(self):
 
         await super().prepare()
 
+        self.renderer_name = utils.get_renderer_name(self.metadata.ext)
+
         self.cache_file_id = self.metadata.unique_key
         self.cache_file_path = await self.cache_provider.validate_path(
-            '/render/{}'.format(self.cache_file_id)
+            '/render/{}.{}'.format(self.cache_file_id, self.renderer_name)
         )
         self.source_file_path = await self.local_cache_provider.validate_path(
             '/render/{}'.format(self.source_file_id)

tests/core/test_utils.py

@@ -0,0 +1,39 @@
+import pytest
+import pkg_resources
+
+from mfr.core import utils as mfr_utils
+
+
+class TestGetRendererName:
+
+    def test_get_renderer_name_explicit_assertions(self):
+        assert mfr_utils.get_renderer_name('.jpg') == 'ImageRenderer'
+        assert mfr_utils.get_renderer_name('.txt') == 'CodePygmentsRenderer'
+        assert mfr_utils.get_renderer_name('.xlsx') == 'TabularRenderer'
+        assert mfr_utils.get_renderer_name('.odt') == 'UnoconvRenderer'
+        assert mfr_utils.get_renderer_name('.pdf') == 'PdfRenderer'
+
+    def test_get_renderer_name(self):
+        entry_points = pkg_resources.iter_entry_points(group='mfr.renderers')
+        for ep in entry_points:
+            expected = ep.attrs[0]
+            assert mfr_utils.get_renderer_name(ep.name) == expected
+
+    def test_get_renderer_name_no_entry_point(self):
+            assert mfr_utils.get_renderer_name('jpg') == ''
+
+class TestGetExporterName:
+
+    def test_get_exporter_name_explicit_assertions(self):
+        assert mfr_utils.get_exporter_name('.jpg') == 'ImageExporter'
+        assert mfr_utils.get_exporter_name('.odt') == 'UnoconvExporter'
+
+    def test_get_exporter_name(self):
+        entry_points = pkg_resources.iter_entry_points(group='mfr.exporters')
+        for ep in entry_points:
+            expected = ep.attrs[0]
+            assert mfr_utils.get_exporter_name(ep.name) == expected
+
+    def test_get_exporter_name_no_entry_point(self):
+        with pytest.raises(IndexError):
+            mfr_utils.get_exporter_name('jpg')