improve rendering speed by caching LevelGeometry in database

src/c3nav/mapdata/management/commands/rebuildgeometries.py

@@ -0,0 +1,9 @@
+from django.core.management.base import BaseCommand
+
+
+class Command(BaseCommand):
+    help = 'rebuild level geometries'
+
+    def handle(self, *args, **options):
+        from c3nav.mapdata.render.base import LevelGeometries
+        LevelGeometries.rebuild()

src/c3nav/mapdata/migrations/0037_level_geoms_cache.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.6 on 2017-10-19 11:21
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mapdata', '0036_geometry_bounds'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='level',
+            name='geoms_cache',
+            field=models.BinaryField(default=b''),
+            preserve_default=False,
+        ),
+    ]

src/c3nav/mapdata/models/level.py

@@ -26,6 +26,8 @@ class Level(SpecificLocation, models.Model):
     on_top_of = models.ForeignKey('mapdata.Level', null=True, on_delete=models.CASCADE,
                                   related_name='levels_on_top', verbose_name=_('on top of'))
 
+    geoms_cache = models.BinaryField()
+
     class Meta:
         verbose_name = _('Level')
         verbose_name_plural = _('Levels')

src/c3nav/mapdata/render/base.py

@@ -0,0 +1,50 @@
+import pickle
+
+from django.db import transaction
+from django.db.models import Q
+from shapely.ops import unary_union
+
+from c3nav.mapdata.models import Level
+
+
+class LevelGeometries:
+    def __init__(self):
+        self.altitudeareas = []
+        self.walls = None
+        self.doors = None
+
+    @staticmethod
+    def rebuild():
+        levels = Level.objects.prefetch_related('altitudeareas', 'buildings', 'doors', 'spaces',
+                                                'spaces__holes', 'spaces__columns')
+        for level in levels:
+            geoms = LevelGeometries()
+            buildings_geom = unary_union([b.geometry for b in level.buildings.all()])
+
+            for space in level.spaces.all():
+                if space.outside:
+                    space.geometry = space.geometry.difference(buildings_geom)
+                space.geometry = space.geometry.difference(unary_union([c.geometry for c in space.columns.all()]))
+                space.holes_geom = unary_union([h.geometry for h in space.holes.all()])
+                space.walkable_geom = space.geometry.difference(space.holes_geom)
+
+            spaces_geom = unary_union([s.geometry for s in level.spaces.all()])
+            geoms.doors = unary_union([d.geometry for d in level.doors.all()])
+            walkable_geom = unary_union([s.walkable_geom for s in level.spaces.all()]).union(geoms.doors)
+
+            for altitudearea in level.altitudeareas.all():
+                geoms.altitudeareas.append((altitudearea.geometry.intersection(walkable_geom), altitudearea.altitude))
+
+            geoms.walls = buildings_geom.difference(spaces_geom).difference(geoms.doors)
+            level.geoms_cache = pickle.dumps(geoms)
+            level.save()
+
+        with transaction.atomic():
+            for level in levels:
+                level.save()
+
+
+def get_render_level_data(level):
+    levels = Level.objects.filter(Q(on_top_of=level.pk) | Q(base_altitude__lte=level.base_altitude))
+    levels = levels.values_list('geoms_cache', 'default_height')
+    return levels

src/c3nav/mapdata/render/svg.py

@@ -1,8 +1,8 @@
-from django.db.models import Prefetch, Q
-from shapely.geometry import box
-from shapely.ops import unary_union
+import pickle
 
-from c3nav.mapdata.models import AltitudeArea, Building, Door, Level, Space
+from shapely.geometry import box
+
+from c3nav.mapdata.render.base import get_render_level_data
 from c3nav.mapdata.utils.svg import SVGImage
 
 
@@ -12,41 +12,14 @@ def render_svg(level, miny, minx, maxy, maxx, scale=1):
     within_coords = (minx-2, miny-2, maxx+2, maxy+2)
     bbox = box(*within_coords)
 
-    levels = Level.objects.filter(Q(on_top_of=level.pk) | Q(base_altitude__lte=level.base_altitude))
-    levels = levels.prefetch_related(Prefetch('altitudeareas', AltitudeArea.objects.within(*within_coords)),
-                                     Prefetch('buildings', Building.objects.within(*within_coords)),
-                                     Prefetch('doors', Door.objects.within(*within_coords)),
-                                     Prefetch('spaces', Space.objects.within(*within_coords).prefetch_related(
-                                         'holes', 'columns'
-                                     )))
+    for geoms_cache, default_height in get_render_level_data(level):
+        geoms = pickle.loads(geoms_cache)
+        for altitudearea_geom, altitude in geoms.altitudeareas:
+            svg.add_geometry(bbox.intersection(altitudearea_geom), fill_color='#eeeeee', altitude=altitude)
 
-    for level in levels:
-        buildings_geom = bbox.intersection(unary_union([b.geometry for b in level.buildings.all()]))
-        # svg.add_geometry(buildings_geom, fill_color='#aaaaaa')
+        svg.add_geometry(bbox.intersection(geoms.walls),
+                         fill_color='#aaaaaa', stroke_px=0.5, stroke_color='#aaaaaa', elevation=default_height)
 
-        for space in level.spaces.all():
-            if space.outside:
-                space.geometry = space.geometry.difference(buildings_geom)
-            space.geometry = space.geometry.difference(unary_union([c.geometry for c in space.columns.all()]))
-            space.holes_geom = unary_union([h.geometry for h in space.holes.all()])
-            space.walkable_geom = space.geometry.difference(space.holes_geom)
-
-        spaces_geom = bbox.intersection(unary_union([s.geometry for s in level.spaces.all()]))
-        doors_geom = bbox.intersection(unary_union([d.geometry for d in level.doors.all()]))
-        walkable_geom = unary_union([w.walkable_geom for w in level.spaces.all()]).union(doors_geom)
-
-        for altitudearea in level.altitudeareas.all():
-            svg.add_geometry(bbox.intersection(altitudearea.geometry).intersection(walkable_geom),
-                             fill_color='#eeeeee', altitude=altitudearea.altitude)
-
-        spaces_geom = bbox.intersection(unary_union([s.geometry for s in level.spaces.all()]))
-        doors_geom = bbox.intersection(unary_union([d.geometry for d in level.doors.all()]))
-
-        walls_geom = buildings_geom.difference(spaces_geom).difference(doors_geom)
-
-        svg.add_geometry(walls_geom, fill_color='#aaaaaa', stroke_px=0.5, stroke_color='#aaaaaa',
-                         elevation=level.default_height)
-
-        svg.add_geometry(doors_geom, fill_color='#ffffff', elevation=0)
+        svg.add_geometry(bbox.intersection(geoms.doors), fill_color='#ffffff', elevation=0)
 
     return svg