utils: Make UUID ostream-printable

utils/UUID.hh

@@ -9,6 +9,7 @@
 #include <stdint.h>
 #include <cassert>
 #include <array>
+#include <iostream>
 
 #include "core/sstring.hh"
 #include "core/print.hh"
@@ -60,6 +61,8 @@ public:
                 ((uint64_t)least_sig_bits & 0xffffffffffffLL));
     }
 
+    friend std::ostream& operator<<(std::ostream& out, const UUID& uuid);
+
     bool operator==(const UUID& v) const {
         return most_sig_bits == v.most_sig_bits
                 && least_sig_bits == v.least_sig_bits

utils/uuid.cc

@@ -31,4 +31,8 @@ make_random_uuid() {
     return UUID(net::hton(v.w.msb), net::hton(v.w.lsb));
 }
 
+std::ostream& operator<<(std::ostream& out, const UUID& uuid) {
+    return out << uuid.to_sstring();
+}
+
 }