StatsValue - define operator+=

while this is a little bit more code,
it seems much better for the accumulation operation
to be next to the struct definition itself
(in case we ever add more fields)

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I26022db4566e69c964298d7b3f2cc4fa4a9a5152

bpf_progs/netd.h

@@ -55,6 +55,16 @@ typedef struct {
 } StatsValue;
 STRUCT_SIZE(StatsValue, 4 * 8);  // 32
 
+#ifdef __cplusplus
+static inline StatsValue& operator+=(StatsValue& lhs, const StatsValue& rhs) {
+    lhs.rxPackets += rhs.rxPackets;
+    lhs.rxBytes += rhs.rxBytes;
+    lhs.txPackets += rhs.txPackets;
+    lhs.txBytes += rhs.txBytes;
+    return lhs;
+}
+#endif
+
 typedef struct {
     char name[IFNAMSIZ];
 } IfaceValue;

service-t/native/libs/libnetworkstats/BpfNetworkStats.cpp

@@ -75,10 +75,7 @@ int bpfGetIfaceStatsInternal(const char* iface, StatsValue* stats,
             if (!statsEntry.ok()) {
                 return statsEntry.error();
             }
-            stats->rxPackets += statsEntry.value().rxPackets;
-            stats->txPackets += statsEntry.value().txPackets;
-            stats->rxBytes += statsEntry.value().rxBytes;
-            stats->txBytes += statsEntry.value().txBytes;
+            *stats += statsEntry.value();
         }
         return Result<void>();
     };