add rtree Index with wrapper and fallback

src/c3nav/mapdata/utils/index.py

@@ -0,0 +1,70 @@
+import operator
+from functools import reduce
+
+from django.core import checks
+from shapely import speedups
+
+if speedups.available:
+    speedups.enable()
+
+
+try:
+    import rtree
+except OSError:
+    rtree_index = False
+
+    class Index:
+        def __init__(self):
+            self.objects = {}
+
+        def insert(self, value, geometry):
+            self.objects[value] = geometry
+
+        def delete(self, value):
+            self.objects.pop(value)
+
+        def intersections(self, geometry):
+            return self.objects.values()
+else:
+    rtree_index = True
+
+    class Index:
+        def __init__(self):
+            self._index = rtree.index.Index()
+            self._bounds = {}
+
+        def insert(self, value, geometry):
+            try:
+                geoms = geometry.geoms
+            except AttributeError:
+                self._bounds.setdefault(value, []).append(geometry.bounds)
+                self._index.insert(value, geometry.bounds)
+            else:
+                for geom in geoms:
+                    self.insert(value, geom)
+
+        def delete(self, value):
+            for bounds in self._bounds.pop(value):
+                self._index.delete(value, bounds)
+
+        def intersections(self, geometry):
+            try:
+                geoms = geometry.geoms
+            except AttributeError:
+                return set(self._index.intersection(geometry.bounds))
+            else:
+                return reduce(operator.__or__, (self.intersections(geom) for geom in geoms), set())
+
+
+@checks.register()
+def check_svg_renderer(app_configs, **kwargs):
+    errors = []
+    if not rtree_index:
+        errors.append(
+            checks.Warning(
+                'The libspatialindex_c library is missing. This will drastically slow down c3nav rendering.',
+                obj='rtree.index.Index',
+                id='c3nav.mapdata.W001',
+            )
+        )
+    return errors

src/c3nav/mapdata/utils/svg.py

@@ -6,7 +6,7 @@ from itertools import chain
 
 import numpy as np
 from django.conf import settings
-from django.core.checks import Error, register
+from django.core import checks
 from PIL import Image
 from shapely.affinity import translate
 from shapely.geometry import LineString, Polygon
@@ -20,12 +20,12 @@ if settings.SVG_RENDERER == 'rsvg':
     from pgi.repository import Rsvg
 
 
-@register()
+@checks.register()
 def check_svg_renderer(app_configs, **kwargs):
     errors = []
     if settings.SVG_RENDERER not in ('rsvg', 'rsvg-convert', 'inkscape'):
         errors.append(
-            Error(
+            checks.Error(
                 'Invalid SVG renderer: '+settings.SVG_RENDERER,
                 obj='settings.SVG_RENDERER',
                 id='c3nav.mapdata.E001',

src/requirements/production.txt

@@ -5,6 +5,7 @@ csscompressor
 djangorestframework>=3.6,<3.7
 django-filter>=1.0,<1.1
 shapely>=1.5,<1.6
+rtree>=0.8,<0.9
 celery>=4.0,<4.1
 requests>=2.17,<2.18
 Pillow>=4.1,<4.2