move to libuv for the rendering loop

src/map/tile_data.cpp

@@ -10,7 +10,7 @@
 #include <llmr/util/raster.hpp>
 #include <llmr/util/string.hpp>
 
-#include <uv.h>
+#include <llmr/util/uv.hpp>
 
 using namespace llmr;
 
@@ -47,16 +47,14 @@ void TileData::request() {
             // to drop to zero for destruction.
         } else if (res->code == 200) {
             tile->state = State::loaded;
+
             tile->data.swap(res->body);
-            tile->parse();
+
+            // Schedule tile parsing in another thread
+            tile->scheduleParsing();
         } else {
             fprintf(stderr, "[%s] tile loading failed: %d, %s\n", tile->url.c_str(), res->code, res->error_message.c_str());
         }
-    }, [weak_tile]() {
-        std::shared_ptr<TileData> tile = weak_tile.lock();
-        if (tile) {
-            tile->map.redraw();
-        }
     }, map.getLoop());
 }
 
@@ -67,9 +65,19 @@ void TileData::cancel() {
     }
 }
 
-bool TileData::parse() {
+void TileData::scheduleParsing() {
+    // We're creating a new work request. The work request deletes itself after it executed
+    // the after work handler
+    new uv::work<std::shared_ptr<TileData>>(
+        map.getLoop(),
+        [](std::shared_ptr<TileData> &tile) { tile->parse(); },
+        [](std::shared_ptr<TileData> &tile) { tile->map.update(); },
+        shared_from_this());
+}
+
+void TileData::parse() {
     if (state != State::loaded) {
-        return false;
+        return;
     }
 
     try {
@@ -80,14 +88,10 @@ bool TileData::parse() {
     } catch (const std::exception& ex) {
         fprintf(stderr, "[%p] exception [%d/%d/%d]... failed: %s\n", this, id.z, id.x, id.y, ex.what());
         cancel();
-        return false;
+        return;
     }
 
-    if (state == State::obsolete) {
-        return false;
-    } else {
+    if (state != State::obsolete) {
         state = State::parsed;
     }
-
-    return true;
 }