Add CachingHTTPFileSource::clearLoop()

So loop state can be cleaned up in the appropriate thread.
This is a hack; loop needs to be externalized from Map.

Fixes #686

include/mbgl/storage/caching_http_file_source.hpp

@@ -21,6 +21,7 @@ public:
     // Stores and checks the libuv loop for requests
     void setLoop(uv_loop_t*);
     bool hasLoop();
+    void clearLoop();
 
     // Stores and retrieves the base path/URL for relative requests
     void setBase(const std::string &value);

include/mbgl/storage/file_source.hpp

@@ -16,8 +16,11 @@ namespace mbgl {
 class FileSource : public util::noncopyable {
 public:
     virtual ~FileSource() = default;
+
     virtual void setLoop(uv_loop_t*) = 0;
     virtual bool hasLoop() = 0;
+    virtual void clearLoop() = 0;
+
     virtual void setBase(const std::string &value) = 0;
     virtual std::unique_ptr<Request> request(ResourceType type, const std::string &url) = 0;
     virtual void prepare(std::function<void()> fn) = 0;

src/mbgl/map/map.cpp

@@ -151,6 +151,8 @@ void Map::start() {
         workers.reset();
         activeSources.clear();
 
+        fileSource.clearLoop();
+
         // Closes all open handles on the loop. This means that the loop will automatically terminate.
         asyncCleanup.reset();
         asyncRender.reset();
@@ -310,10 +312,7 @@ void Map::setStyleJSON(std::string newStyleJSON, const std::string &base) {
         style = std::make_shared<Style>();
     }
     style->loadJSON((const uint8_t *)styleJSON.c_str());
-    if (!fileSource.hasLoop()) {
-        fileSource.setLoop(**loop);
-        glyphStore = std::make_shared<GlyphStore>(fileSource);
-    }
+    glyphStore = std::make_shared<GlyphStore>(fileSource);
     fileSource.setBase(base);
     glyphStore->setURL(util::mapbox::normalizeGlyphsURL(style->glyph_url, getAccessToken()));
     update();

src/mbgl/storage/caching_http_file_source.cpp

@@ -13,21 +13,6 @@ CachingHTTPFileSource::CachingHTTPFileSource(const std::string &path_)
     : path(path_) {}
 
 CachingHTTPFileSource::~CachingHTTPFileSource() {
-    if (hasLoop()) {
-        assert(thread_id == std::this_thread::get_id());
-        uv_messenger_stop(queue, [](uv_messenger_t *msgr) {
-            delete msgr;
-        });
-
-        util::ptr<BaseRequest> req;
-
-        // Send a cancel() message to all requests that we are still holding.
-        for (const std::pair<std::string, std::weak_ptr<BaseRequest>> &pair : pending) {
-            if ((req = pair.second.lock())) {
-                req->cancel();
-            }
-        }
-    }
 }
 
 void CachingHTTPFileSource::setLoop(uv_loop_t* loop_) {
@@ -47,6 +32,26 @@ bool CachingHTTPFileSource::hasLoop() {
     return loop;
 }
 
+void CachingHTTPFileSource::clearLoop() {
+    assert(thread_id == std::this_thread::get_id());
+    assert(loop);
+
+    uv_messenger_stop(queue, [](uv_messenger_t *msgr) {
+        delete msgr;
+    });
+
+    util::ptr<BaseRequest> req;
+
+    // Send a cancel() message to all requests that we are still holding.
+    for (const std::pair<std::string, std::weak_ptr<BaseRequest>> &pair : pending) {
+        if ((req = pair.second.lock())) {
+            req->cancel();
+        }
+    }
+
+    store.reset();
+}
+
 void CachingHTTPFileSource::setBase(const std::string &value) {
     assert(thread_id == std::this_thread::get_id());
     base = value;