Don't reload the entire font range when a glyph is missing in a font

src/render/glyph_manager.js

@@ -15,6 +15,7 @@ type Entry = {
     // null means we've requested the range, but the glyph wasn't included in the result.
     glyphs: {[id: number]: StyleGlyph | null},
     requests: {[range: number]: Array<Callback<{[_: number]: StyleGlyph | null}>>},
+    ranges: {[range: number]: boolean | null},
     tinySDF?: TinySDF
 };
 
@@ -52,7 +53,8 @@ class GlyphManager {
             if (!entry) {
                 entry = this.entries[stack] = {
                     glyphs: {},
-                    requests: {}
+                    requests: {},
+                    ranges: {}
                 };
             }
 
@@ -75,6 +77,11 @@ class GlyphManager {
                 return;
             }
 
+            if (entry.ranges[range]) {
+                callback(null, {stack, id, glyph});
+                return;
+            }
+
             let requests = entry.requests[range];
             if (!requests) {
                 requests = entry.requests[range] = [];
@@ -86,6 +93,7 @@ class GlyphManager {
                                     entry.glyphs[+id] = response[+id];
                                 }
                             }
+                            entry.ranges[range] = true;
                         }
                         for (const cb of requests) {
                             cb(err, response);

test/unit/render/glyph_manager.test.js

@@ -28,6 +28,36 @@ test('GlyphManager requests 0-255 PBF', (t) => {
     });
 });
 
+test('GlyphManager doesn\'t request twice 0-255 PBF if a glyph is missing', (t) => {
+    const identityTransform = (url) => ({url});
+    const stub = t.stub(GlyphManager, 'loadGlyphRange').callsFake((stack, range, urlTemplate, transform, callback) => {
+        t.equal(stack, 'Arial Unicode MS');
+        t.equal(range, 0);
+        t.equal(urlTemplate, 'https://localhost/fonts/v1/{fontstack}/{range}.pbf');
+        t.equal(transform, identityTransform);
+        setImmediate(() => callback(null, glyphs));
+    });
+
+    const manager = new GlyphManager(identityTransform);
+    manager.setURL('https://localhost/fonts/v1/{fontstack}/{range}.pbf');
+
+    manager.getGlyphs({'Arial Unicode MS': [0.5]}, (err) => {
+        t.ifError(err);
+        t.equal(manager.entries['Arial Unicode MS'].ranges[0], true);
+        t.equal(stub.calledOnce, true);
+
+        // We remove all requests as in getGlyphs code.
+        delete manager.entries['Arial Unicode MS'].requests[0];
+
+        manager.getGlyphs({'Arial Unicode MS': [0.5]}, (err) => {
+            t.ifError(err);
+            t.equal(manager.entries['Arial Unicode MS'].ranges[0], true);
+            t.equal(stub.calledOnce, true);
+            t.end();
+        });
+    });
+});
+
 test('GlyphManager requests remote CJK PBF', (t) => {
     t.stub(GlyphManager, 'loadGlyphRange').callsFake((stack, range, urlTemplate, transform, callback) => {
         setImmediate(() => callback(null, glyphs));