[callback] add comment describing EnsureCalled
TEST=comment only
Change-Id: Ied1bd6be9b71d19efe39f9c6c34a7f7aaefc89b4
diff --git a/garnet/public/lib/callback/ensure_called.h b/garnet/public/lib/callback/ensure_called.h
index 719f1d0..6eb9290 100644
--- a/garnet/public/lib/callback/ensure_called.h
+++ b/garnet/public/lib/callback/ensure_called.h
@@ -14,6 +14,12 @@
namespace callback {
+// Given a function and a set a default arguments, ensures that the function
+// will always be called exactly once.
+// If the function is not called manually (by operator()) with specified
+// arguments, it will be called with the default arguments on destruction.
+// The function and its default arguments are destructed immediately after the
+// function is called.
template <typename T, typename... ArgType>
class EnsureCalled {
public:
