Update logging and check macros. (#1627)

* Update logging and check macros.

* Fix linting.

* Fix RAY_DCHECK and unused variable.

* Fix linting

src/ray/id.cc

@@ -78,4 +78,9 @@ bool UniqueID::operator==(const UniqueID &rhs) const {
   return std::memcmp(data(), rhs.data(), kUniqueIDSize) == 0;
 }
 
+std::ostream &operator<<(std::ostream &os, const UniqueID &id) {
+  os << id.hex();
+  return os;
+}
+
 }  // namespace ray

src/ray/id.h

@@ -44,6 +44,8 @@ struct UniqueIDHasher {
   }
 };
 
+std::ostream &operator<<(std::ostream &os, const UniqueID &id);
+
 typedef UniqueID TaskID;
 typedef UniqueID JobID;
 typedef UniqueID ObjectID;

src/ray/util/logging.h

@@ -34,12 +34,26 @@ namespace ray {
                         << __FILE__ << __LINE__          \
                         << " Check failed: " #condition " "
 
+#ifdef NDEBUG
+
+#define RAY_DCHECK(condition) \
+  RAY_IGNORE_EXPR(condition)  \
+  while (false)               \
+  ::ray::internal::NullLog()
+
+#else
+
+#define RAY_DCHECK(condition) RAY_CHECK(condition)
+
+#endif  // NDEBUG
+
 namespace internal {
 
 class NullLog {
  public:
   template <class T>
   NullLog &operator<<(const T &t) {
+    RAY_IGNORE_EXPR(t);
     return *this;
   }
 };