Roll forward to cl/338482889

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I9850950db8bd84f0904ea1a413151887f52098cf

cpp/platform/impl/ios/scheduled_executor.mm

@@ -0,0 +1,65 @@
+#include "platform/impl/ios/scheduled_executor.h"
+
+#include <atomic>
+#include <memory>
+
+#include "platform/api/cancelable.h"
+#include "platform/base/runnable.h"
+#include "absl/time/clock.h"
+
+namespace location {
+namespace nearby {
+namespace ios {
+
+namespace {
+
+class ScheduledCancelable : public api::Cancelable {
+ public:
+  bool Cancel() override {
+    Status expected = kNotRun;
+    while (expected == kNotRun) {
+      if (status_.compare_exchange_strong(expected, kCanceled)) {
+        return true;
+      }
+    }
+    return false;
+  }
+  bool MarkExecuted() {
+    Status expected = kNotRun;
+    while (expected == kNotRun) {
+      if (status_.compare_exchange_strong(expected, kExecuted)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+ private:
+  enum Status {
+    kNotRun,
+    kExecuted,
+    kCanceled,
+  };
+  std::atomic<Status> status_ = kNotRun;
+};
+
+}  // namespace
+
+std::shared_ptr<api::Cancelable> ScheduledExecutor::Schedule(
+    Runnable&& runnable, absl::Duration delay) {
+  auto scheduled_cancelable = std::make_shared<ScheduledCancelable>();
+  if (executor_.InShutdown()) {
+    return scheduled_cancelable;
+  }
+  executor_.ScheduleAfter(
+      delay, [this, scheduled_cancelable, runnable(std::move(runnable))]() {
+        if (!executor_.InShutdown() && scheduled_cancelable->MarkExecuted()) {
+          runnable();
+        }
+      });
+  return scheduled_cancelable;
+}
+
+}  // namespace ios
+}  // namespace nearby
+}  // namespace location