Allow setting the label cache size

src/ol/render/canvas.js

@@ -93,7 +93,10 @@ export const defaultLineWidth = 1;
 
 
 /**
+ * The label cache for text rendering. To change the default cache size of 2048
+ * entries, use {@link ol.structs.LRUCache#setSize}.
  * @type {ol.structs.LRUCache.<HTMLCanvasElement>}
+ * @api
  */
 export const labelCache = new LRUCache();
 

src/ol/structs/LRUCache.js

@@ -267,6 +267,16 @@ LRUCache.prototype.set = function(key, value) {
 };
 
 
+/**
+ * Set a maximum number of entries for the cache.
+ * @param {number} size Cache size.
+ * @api
+ */
+LRUCache.prototype.setSize = function(size) {
+  this.highWaterMark = size;
+};
+
+
 /**
  * Prune the cache.
  */

test/spec/ol/structs/lrucache.test.js

@@ -280,4 +280,14 @@ describe('ol.structs.LRUCache', function() {
     });
   });
 
+  describe('setting the cache size', function() {
+    it('sets the cache size', function() {
+      lruCache.setSize(2);
+      expect(lruCache.highWaterMark).to.be(2);
+      fillLRUCache(lruCache);
+      lruCache.prune();
+      expect(lruCache.getKeys().length).to.be(2);
+    });
+  });
+
 });