Fix some, but not all, race conditions at startup. #16

CHANGES.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Fix some race conditions at startup
+
 ## 0.1.9
 
 - Add a `stop` method, so the tool can be programmatically controlled

route-snapper/lib.js

@@ -14,8 +14,11 @@ export class RouteSnapper {
  console.timeEnd("Deserialize and setup JsRouteSnapper");
  console.log("JsRouteSnapper ready, waiting for idle event");
  this.active = false;
+ // Indicates the idle event has been received, and the source/layers are set up
+ this.loaded = false;
 
- // on(load) is a bad trigger, because downloading the RouteSnapper input can race. Just wait for the map to be usable.
+ // on(load) is a bad trigger, because downloading the RouteSnapper input
+ // can race. Just wait for the map to be usable.
  this.map.once("idle", () => {
  console.log("JsRouteSnapper now usable");
  this.map.addSource("route-snapper", {
@@ -65,6 +68,7 @@ export class RouteSnapper {
  },
  filter: ["in", "$type", "LineString"],
  });
+ this.loaded = true;
 
  this.map.on("mousemove", (e) => {
  if (!this.active) {
@@ -149,6 +153,10 @@ export class RouteSnapper {
  // Destroy resources attached to the map. Warning, this doesn't yet handle
  // event listeners!
  tearDown() {
+ if (!this.loaded) {
+ // TODO Can we cancel the map.on(idle) event?
+ return;
+ }
  this.map.removeLayer("route-points");
  this.map.removeLayer("route-lines");
  this.map.removeSource("route-snapper");
@@ -158,13 +166,24 @@ export class RouteSnapper {
  // This takes a GeoJSON feature previously returned from the new-route event.
  // It must have all properties returned originally.
  editExisting(feature) {
+ if (!this.loaded) {
+ // TODO This is an unlikely race condition. What should we do?
+ console.error(
+ "editExisting called before the map idle event received. Not starting tool."
+ );
+ return;
+ }
  this.#activeControl();
  this.inner.editExisting(feature.properties.waypoints);
  this.#redraw();
  }
 
  // Deactivate the tool, clearing all state. No events (`no-new-route`) are fired.
  stop() {
+ if (!this.loaded) {
+ return;
+ }
+
  this.active = false;
 
  this.inner.clearState();
@@ -237,9 +256,11 @@ export class RouteSnapper {
  }
 
  #redraw() {
- this.map
- .getSource("route-snapper")
- .setData(JSON.parse(this.inner.renderGeojson()));
+ if (this.loaded) {
+ this.map
+ .getSource("route-snapper")
+ .setData(JSON.parse(this.inner.renderGeojson()));
+ }
  }
 }