Roll forward to cl/338482889

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: Ic2bdb234e89f3c5860d1b483dd4bce689f13d057

cpp/platform/impl/g3/scheduled_executor.cc

@@ -0,0 +1,79 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "platform/impl/g3/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 g3 {
+
+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 g3
+}  // namespace nearby
+}  // namespace location