WIP: Cancellable async tasksupstream/alexshalamov_cancellable_async_task

2 files changed, 20 insertions, 4 deletions

diff --git a/include/mbgl/util/async_task.hpp b/include/mbgl/util/async_task.hpp
index 69746c3eb3..1003471332 100644
--- a/include/mbgl/util/async_task.hpp
+++ b/include/mbgl/util/async_task.hpp
@@ -14,6 +14,7 @@ public:
     ~AsyncTask();
 
     void send();
+    void cancel();
 
 private:
     class Impl;
diff --git a/platform/android/src/async_task.cpp b/platform/android/src/async_task.cpp
index 6c14e96fa6..9cb4d62aef 100644
--- a/platform/android/src/async_task.cpp
+++ b/platform/android/src/async_task.cpp
@@ -26,14 +26,23 @@ public:
         }
     }
 
+    void cancel() {
+        if (!queued) {
+            queued = true;
+            loop->removeRunnable(this);
+        }
+    }
+
     TimePoint dueTime() const override {
         return due;
     }
 
     void runTask() override {
-        loop->removeRunnable(this);
-        queued = true;
-        task();
+        if (!queued) {
+            queued = true;
+            loop->removeRunnable(this);
+            task();
+        }
     }
 
 private:
@@ -52,11 +61,17 @@ AsyncTask::AsyncTask(std::function<void()>&& fn)
     : impl(std::make_unique<Impl>(std::move(fn))) {
 }
 
-AsyncTask::~AsyncTask() = default;
+AsyncTask::~AsyncTask() {
+    cancel();
+};
 
 void AsyncTask::send() {
     impl->maySend();
 }
 
+void AsyncTask::cancel() {
+    impl->cancel();
+}
+
 } // namespace util
 } // namespace mbgl