Merge pull request #13655 from yang-g/ping

Bug fix, use the last_sent ping time for next send

src/core/ext/transport/chttp2/transport/writing.cc

@@ -69,14 +69,15 @@ static void maybe_initiate_ping(grpc_exec_ctx* exec_ctx,
     return;
   }
   grpc_millis now = grpc_exec_ctx_now(exec_ctx);
+
+  grpc_millis next_allowed_ping_interval =
+      (t->keepalive_permit_without_calls == 0 &&
+       grpc_chttp2_stream_map_size(&t->stream_map) == 0)
+          ? 7200 * GPR_MS_PER_SEC
+          : t->ping_policy.min_sent_ping_interval_without_data;
   grpc_millis next_allowed_ping =
-      t->ping_state.last_ping_sent_time +
-      t->ping_policy.min_sent_ping_interval_without_data;
-  if (t->keepalive_permit_without_calls == 0 &&
-      grpc_chttp2_stream_map_size(&t->stream_map) == 0) {
-    next_allowed_ping =
-        t->ping_recv_state.last_ping_recv_time + 7200 * GPR_MS_PER_SEC;
-  }
+      t->ping_state.last_ping_sent_time + next_allowed_ping_interval;
+
   if (next_allowed_ping > now) {
     /* not enough elapsed time between successive pings */
     if (grpc_http_trace.enabled() || grpc_bdp_estimator_trace.enabled()) {