From 1f51c14e7ef4e52b8397abf988343cf95346f243 Mon Sep 17 00:00:00 2001
From: Andreas Hocevar <andreas.hocevar@gmail.com>
Date: Thu, 8 Jun 2017 15:32:36 +0200
Subject: [PATCH] Do not stop the render loop when all wanted tiles are aborted

---
 src/ol/tilequeue.js            | 13 +++++++++++--
 test/spec/ol/tilequeue.test.js | 14 ++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/ol/tilequeue.js b/src/ol/tilequeue.js
index 5750d0086b..14bb075e90 100644
--- a/src/ol/tilequeue.js
+++ b/src/ol/tilequeue.js
@@ -106,16 +106,25 @@ ol.TileQueue.prototype.handleTileChange = function(event) {
  */
 ol.TileQueue.prototype.loadMoreTiles = function(maxTotalLoading, maxNewLoads) {
   var newLoads = 0;
-  var tile, tileKey;
+  var abortedTiles = false;
+  var state, tile, tileKey;
   while (this.tilesLoading_ < maxTotalLoading && newLoads < maxNewLoads &&
          this.getCount() > 0) {
     tile = /** @type {ol.Tile} */ (this.dequeue()[0]);
     tileKey = tile.getKey();
-    if (tile.getState() === ol.TileState.IDLE && !(tileKey in this.tilesLoadingKeys_)) {
+    state = tile.getState();
+    if (state === ol.TileState.ABORT) {
+      abortedTiles = true;
+    } else if (state === ol.TileState.IDLE && !(tileKey in this.tilesLoadingKeys_)) {
       this.tilesLoadingKeys_[tileKey] = true;
       ++this.tilesLoading_;
       ++newLoads;
       tile.load();
     }
   }
+  if (newLoads === 0 && abortedTiles) {
+    // Do not stop the render loop when all wanted tiles were aborted due to
+    // a small, saturated tile cache.
+    this.tileChangeCallback_();
+  }
 };
diff --git a/test/spec/ol/tilequeue.test.js b/test/spec/ol/tilequeue.test.js
index 87c40ed956..802e44cc76 100644
--- a/test/spec/ol/tilequeue.test.js
+++ b/test/spec/ol/tilequeue.test.js
@@ -86,6 +86,20 @@ describe('ol.TileQueue', function() {
 
     });
 
+    it('calls #tileChangeCallback_ when all wanted tiles are aborted', function() {
+      var tileChangeCallback = sinon.spy();
+      var queue = new ol.TileQueue(noop, tileChangeCallback);
+      var numTiles = 20;
+      for (var i = 0; i < numTiles; ++i) {
+        var tile = createImageTile();
+        tile.state = ol.TileState.ABORT;
+        queue.enqueue([tile]);
+      }
+      var maxLoading = numTiles / 2;
+      queue.loadMoreTiles(maxLoading, maxLoading);
+      expect(tileChangeCallback.callCount).to.be(1);
+    });
+
   });
 
   describe('heapify', function() {