Merge pull request #1205 from Anohkka/cancelable-callbacks

Make cpr::async and HTTP (Get, Post, Put, etc.) callbacks cancelable

Author: COM8

include/cpr/api.h

@@ -131,7 +131,7 @@ AsyncResponse GetAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto GetCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Get(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Get(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Post methods
@@ -152,7 +152,7 @@ AsyncResponse PostAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto PostCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Post(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Post(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Put methods
@@ -173,7 +173,7 @@ AsyncResponse PutAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto PutCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Put(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Put(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Head methods
@@ -194,7 +194,7 @@ AsyncResponse HeadAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto HeadCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Head(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Head(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Delete methods
@@ -215,7 +215,7 @@ AsyncResponse DeleteAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto DeleteCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Delete(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Delete(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Options methods
@@ -236,7 +236,7 @@ AsyncResponse OptionsAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto OptionsCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Options(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Options(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Patch methods
@@ -257,7 +257,7 @@ AsyncResponse PatchAsync(Ts... ts) {
 template <typename Then, typename... Ts>
 // NOLINTNEXTLINE(fuchsia-trailing-return)
 auto PatchCallback(Then then, Ts... ts) {
-    return cpr::async([](Then then_inner, Ts... ts_inner) { return then_inner(Patch(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
+    return cpr::async<true>([](Then then_inner, Ts... ts_inner) { return then_inner(Patch(std::move(ts_inner)...)); }, std::move(then), std::move(ts)...);
 }
 
 // Download methods

include/cpr/async.h

@@ -22,9 +22,15 @@ class GlobalThreadPool : public ThreadPool {
  * async(std::bind(&Class::mem_fn, &obj))
  * async(std::mem_fn(&Class::mem_fn, &obj))
  **/
-template <class Fn, class... Args>
+template <bool isCancellable = false, class Fn, class... Args>
 auto async(Fn&& fn, Args&&... args) {
-    return AsyncWrapper{GlobalThreadPool::GetInstance()->Submit(std::forward<Fn>(fn), std::forward<Args>(args)...)};
+  std::future future = GlobalThreadPool::GetInstance()->Submit(std::forward<Fn>(fn), std::forward<Args>(args)...);
+  using async_wrapper_t = AsyncWrapper<decltype(future.get()), isCancellable>;
+  if constexpr (isCancellable) {
+    return async_wrapper_t{std::move(future), std::make_shared<std::atomic_bool>(false)};
+  } else {
+    return async_wrapper_t{std::move(future)};
+  }
 }
 
 class async {