fallback when tile fallback is missing (#937)

planetiler-core/pom.xml

@@ -188,6 +188,16 @@
       <resource>
         <directory>src/main/resources</directory>
         <filtering>true</filtering>
+        <includes>
+          <include>buildinfo.properties</include>
+        </includes>
+      </resource>
+      <resource>
+        <directory>src/main/resources</directory>
+        <filtering>false</filtering>
+        <excludes>
+          <exclude>buildinfo.properties</exclude>
+        </excludes>
       </resource>
     </resources>
     <testResources>

planetiler-core/src/main/java/com/onthegomap/planetiler/util/TileWeights.java

@@ -15,6 +15,7 @@ import com.onthegomap.planetiler.geo.TileCoord;
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Comparator;
@@ -84,14 +85,33 @@ public class TileWeights {
   /**
    * Load tile weights from a gzipped TSV file with {@code z, x, y, loads} columns.
    * <p>
-   * Duplicate entries will be added together.
+   * Duplicate entries will be added together. If the file is missing, will fall back to embedded file with top 50k OSM
+   * tiles.
    */
   public static TileWeights readFromFile(Path path) {
+    try (var fileStream = new GZIPInputStream(new BufferedInputStream(Files.newInputStream(path)))) {
+      var result = readFrom(fileStream);
+      if (!result.weights.isEmpty()) {
+        return result;
+      }
+    } catch (IOException | RuntimeJsonMappingException e) {
+      LOGGER.info("Unable to load tile weights from {}, falling back to top 100k", path);
+    }
+
+    try (var resourceStream = TileWeights.class.getResourceAsStream("/top_50k_osm_tiles.tsv")) {
+      return readFrom(resourceStream);
+    } catch (IOException e) {
+      LOGGER.warn("Unable to load top 100k tile weights, falling back to unweighted average", e);
+      return new TileWeights();
+    }
+  }
+
+  private static TileWeights readFrom(InputStream input) throws IOException {
+    if (input == null) {
+      throw new IOException("No input provided");
+    }
     TileWeights result = new TileWeights();
-    try (
-      var input = new GZIPInputStream(new BufferedInputStream(Files.newInputStream(path)));
-      var reader = READER.<Row>readValues(input)
-    ) {
+    try (var reader = READER.<Row>readValues(input)) {
       while (reader.hasNext()) {
         var row = reader.next();
         if (row.z >= PlanetilerConfig.MIN_MINZOOM && row.z <= PlanetilerConfig.MAX_MAXZOOM) {
@@ -100,9 +120,6 @@ public class TileWeights {
           result.put(TileCoord.ofXYZ(x, y, row.z()), row.loads());
         }
       }
-    } catch (IOException | RuntimeJsonMappingException e) {
-      LOGGER.warn("Unable to load tile weights from {}, will fall back to unweighted average: {}", path, e);
-      return new TileWeights();
     }
     return result;
   }

planetiler-core/src/test/java/com/onthegomap/planetiler/util/TileWeightsTest.java

@@ -42,7 +42,8 @@ class TileWeightsTest {
     Path file = path.resolve("test.tsv.gz");
     new TileWeights().writeToFile(file);
     var read = TileWeights.readFromFile(file);
-    assertEquals(0, read.getWeight(TileCoord.ofXYZ(0, 0, 0)));
+    // when read is empty, fall back to embedded
+    assertEquals(376201934, read.getWeight(TileCoord.ofXYZ(0, 0, 0)));
   }
 
   @Test
@@ -67,18 +68,19 @@ class TileWeightsTest {
   void testReadCorruptFile(@TempDir Path path) throws IOException {
     Path file = path.resolve("test.tsv.gz");
     var result = TileWeights.readFromFile(file);
-    assertEquals(0, result.getWeight(TileCoord.ofXYZ(0, 0, 0)));
+    int expected = 376201934;
+    assertEquals(expected, result.getWeight(TileCoord.ofXYZ(0, 0, 0)));
 
     Files.write(file, Gzip.gzip("""
       garbage
       """.getBytes(StandardCharsets.UTF_8)));
-    assertEquals(0, TileWeights.readFromFile(file).getWeight(TileCoord.ofXYZ(0, 0, 0)));
+    assertEquals(expected, TileWeights.readFromFile(file).getWeight(TileCoord.ofXYZ(0, 0, 0)));
 
     Files.write(file, Gzip.gzip("""
       z	x	y	loads
       a	b	c	d
       """.getBytes(StandardCharsets.UTF_8)));
-    assertEquals(0, TileWeights.readFromFile(file).getWeight(TileCoord.ofXYZ(0, 0, 0)));
+    assertEquals(expected, TileWeights.readFromFile(file).getWeight(TileCoord.ofXYZ(0, 0, 0)));
 
     Files.write(file, Gzip.gzip("""
       z	x	d	loads