nearby: snapshot of cl/304428753

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I0023ac6e40456fc4a8169c3173bcbff3b5ccc476

cpp/platform/api2/count_down_latch.h

@@ -0,0 +1,29 @@
+#ifndef PLATFORM_API2_COUNT_DOWN_LATCH_H_
+#define PLATFORM_API2_COUNT_DOWN_LATCH_H_
+
+#include <cstdint>
+
+#include "platform/exception.h"
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+
+// A synchronization aid that allows one or more threads to wait until a set of
+// operations being performed in other threads completes.
+//
+// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CountDownLatch.html
+class CountDownLatch {
+ public:
+  virtual ~CountDownLatch() {}
+
+  virtual Exception Await() = 0;  // throws Exception::kInterrupted
+  virtual ExceptionOr<bool> Await(
+      absl::Duration timeout) = 0;  // throws Exception::kInterrupted
+  virtual void CountDown() = 0;
+};
+
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_API2_COUNT_DOWN_LATCH_H_