Add pagination to serversockets

src/core/lib/channel/channelz.cc

@@ -204,16 +204,27 @@ ServerNode::ServerNode(grpc_server* server, size_t channel_tracer_max_nodes)
 ServerNode::~ServerNode() {}
 
 char* ServerNode::RenderServerSockets(intptr_t start_socket_id) {
+  const int kPaginationLimit = 100;
   grpc_json* top_level_json = grpc_json_create(GRPC_JSON_OBJECT);
   grpc_json* json = top_level_json;
   grpc_json* json_iterator = nullptr;
   ChildSocketsList socket_refs;
   grpc_server_populate_server_sockets(server_, &socket_refs, start_socket_id);
+  int sockets_added = 0;
+  bool reached_pagination_limit = false;
   if (!socket_refs.empty()) {
     // create list of socket refs
     grpc_json* array_parent = grpc_json_create_child(
         nullptr, json, "socketRef", nullptr, GRPC_JSON_ARRAY, false);
     for (size_t i = 0; i < socket_refs.size(); ++i) {
+      // check if we are over pagination limit to determine if we need to set
+      // the "end" element. If we don't go through this block, we know that
+      // when the loop terminates, we have <= to kPaginationLimit.
+      if (sockets_added == kPaginationLimit) {
+        reached_pagination_limit = true;
+        break;
+      }
+      sockets_added++;
       grpc_json* socket_ref_json =
           grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
                                  GRPC_JSON_OBJECT, false);
@@ -223,11 +234,10 @@ char* ServerNode::RenderServerSockets(intptr_t start_socket_id) {
                              socket_refs[i]->remote(), GRPC_JSON_STRING, false);
     }
   }
-  // For now we do not have any pagination rules. In the future we could
-  // pick a constant for max_channels_sent for a GetServers request.
-  // Tracking: https://github.com/grpc/grpc/issues/16019.
-  json_iterator = grpc_json_create_child(nullptr, json, "end", nullptr,
-                                         GRPC_JSON_TRUE, false);
+  if (!reached_pagination_limit) {
+    json_iterator = grpc_json_create_child(nullptr, json, "end", nullptr,
+                                           GRPC_JSON_TRUE, false);
+  }
   char* json_str = grpc_json_dump_to_string(top_level_json, 0);
   grpc_json_destroy(top_level_json);
   return json_str;