Destroy snapshotter on the thread it was created

platform/android/src/snapshotter/map_snapshotter.cpp

@@ -33,6 +33,8 @@ MapSnapshotter::MapSnapshotter(jni::JNIEnv& _env,
         return;
     }
 
+    weakScheduler = mbgl::Scheduler::GetCurrent()->makeWeakPtr();
+
     jFileSource = FileSource::getNativePeer(_env, _jFileSource);
     auto size = mbgl::Size { static_cast<uint32_t>(width), static_cast<uint32_t>(height) };
 
@@ -61,7 +63,19 @@ MapSnapshotter::MapSnapshotter(jni::JNIEnv& _env,
     activateFilesource(_env);
 }
 
-MapSnapshotter::~MapSnapshotter() = default;
+MapSnapshotter::~MapSnapshotter() {
+    auto guard = weakScheduler.lock();
+    if (weakScheduler && weakScheduler.get() != mbgl::Scheduler::GetCurrent()) {
+        snapshotter->cancel();
+        std::shared_ptr<mbgl::MapSnapshotter> shared = std::move(snapshotter);
+        weakScheduler->schedule([s = std::move(shared)] {
+            (void)s;
+        });
+    } else {
+        snapshotter.reset();
+    }
+    vm = nullptr;
+}
 
 void MapSnapshotter::start(JNIEnv& env) {
     MBGL_VERIFY_THREAD(tid);

platform/android/src/snapshotter/map_snapshotter.hpp

@@ -3,7 +3,9 @@
 #include <jni/jni.hpp>
 #include <mbgl/map/map_snapshotter.hpp>
 #include <mbgl/util/util.hpp>
+
 #include <memory>
+#include <mapbox/weak.hpp>
 
 #include "../file_source.hpp"
 #include "../geometry/lat_lng_bounds.hpp"
@@ -35,7 +37,7 @@ class MapSnapshotter final : public mbgl::MapSnapshotterObserver {
                    jni::jboolean showLogo,
                    const jni::String& localIdeographFontFamily);
 
-    ~MapSnapshotter();
+    virtual ~MapSnapshotter();
 
     void setStyleUrl(JNIEnv&, const jni::String& styleURL);
 
@@ -71,11 +73,12 @@ class MapSnapshotter final : public mbgl::MapSnapshotterObserver {
     float pixelRatio;
     bool showLogo;
 
-    std::unique_ptr<mbgl::MapSnapshotter> snapshotter;
     FileSource *jFileSource;
     void activateFilesource(JNIEnv&);
     void deactivateFilesource(JNIEnv&);
     bool activatedFilesource = false;
+    std::unique_ptr<mbgl::MapSnapshotter> snapshotter;
+    mapbox::base::WeakPtr<mbgl::Scheduler> weakScheduler;
 };
 
 } // namespace android