Logic to reset statistics of the evicted reverse flow

The point where we reset statistics for an evicted flow is when we
trap the first packet to the agent. The trap message carries the
old statistics. However, for the reverse flow, there is no trap.
Hence, the statistics of the evicted reverse flow entry is sent
back to the agent in the sandesh flow message and reset once the
agent tries to add the reverse flow entry.

Change-Id: Ic67318b9632f39560292512be503f90eb6f33068
Closes-BUG: 1362701

dp-core/vr_flow.c

@@ -1789,18 +1789,34 @@ vr_flow_set(struct vrouter *router, vr_flow_req *req)
         fe->fe_drop_reason = (uint8_t)req->fr_drop_reason;
 
     fe->fe_flags = VR_FLOW_FLAG_MASK(req->fr_flags);
-    if (new_flow && (fe->fe_flags & VR_RFLOW_VALID)) {
-        rfe = vr_get_flow_entry(router, fe->fe_rflow);
-        if (rfe) {
-            if (rfe->fe_tcp_flags & VR_FLOW_TCP_SYN) {
-                (void)__sync_fetch_and_or(&fe->fe_tcp_flags,
-                        VR_FLOW_TCP_SYN_R);
+    if (new_flow) {
+
+        req->fr_flow_bytes = fe->fe_stats.flow_bytes;
+        req->fr_flow_packets = fe->fe_stats.flow_packets;
+        req->fr_flow_stats_oflow = (fe->fe_stats.flow_bytes_oflow |
+                (fe->fe_stats.flow_packets_oflow << 16));
+
+        if (fe->fe_flags & VR_FLOW_FLAG_NEW_FLOW) {
+            if (fe->fe_stats.flow_packets || fe->fe_stats.flow_packets_oflow)
+                memset(&fe->fe_stats, 0, sizeof(fe->fe_stats));
+        }
+
+        if (fe->fe_flags & VR_RFLOW_VALID) {
+            rfe = vr_get_flow_entry(router, fe->fe_rflow);
+            if (rfe) {
+                if (rfe->fe_tcp_flags & VR_FLOW_TCP_SYN) {
+                    (void)__sync_fetch_and_or(&fe->fe_tcp_flags,
+                            VR_FLOW_TCP_SYN_R);
+                }
             }
         }
     }
 
     vr_flow_udp_src_port(router, fe);
 
+    if (fe->fe_flags & VR_FLOW_FLAG_NEW_FLOW)
+        fe->fe_flags &= ~VR_FLOW_FLAG_NEW_FLOW;
+
     ret = vr_flow_schedule_transition(router, req, fe);
 
 exit_set:

sandesh/vr.sandesh

@@ -178,6 +178,9 @@ buffer sandesh vr_flow_req {
    30: i32          fr_cpus;
    31: i32          fr_hold_oflows;
    32: list<i32>    fr_hold_stat;
+   33: u32          fr_flow_bytes;
+   34: u32          fr_flow_packets;
+   35: u32          fr_flow_stats_oflow;
 }
 
 buffer sandesh vr_vrf_assign_req {