Merge pull request #17456 from ncteisen/socket-pagination

Channelz: Add Pagination to ServerSockets

3 files changed, 18 insertions, 13 deletions

diff --git a/src/core/lib/channel/channelz.cc b/src/core/lib/channel/channelz.cc
index 0cb2890518..8a596ad460 100644
--- a/src/core/lib/channel/channelz.cc
+++ b/src/core/lib/channel/channelz.cc
@@ -203,31 +203,34 @@ ServerNode::ServerNode(grpc_server* server, size_t channel_tracer_max_nodes)
 
 ServerNode::~ServerNode() {}
 
-char* ServerNode::RenderServerSockets(intptr_t start_socket_id) {
+char* ServerNode::RenderServerSockets(intptr_t start_socket_id,
+                                      intptr_t max_results) {
+  // if user does not set max_results, we choose 500.
+  size_t pagination_limit = max_results == 0 ? 500 : max_results;
   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);
+  // declared early so it can be used outside of the loop.
+  size_t i = 0;
   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) {
-      grpc_json* socket_ref_json =
-          grpc_json_create_child(json_iterator, array_parent, nullptr, nullptr,
-                                 GRPC_JSON_OBJECT, false);
+    for (i = 0; i < GPR_MIN(socket_refs.size(), pagination_limit); ++i) {
+      grpc_json* socket_ref_json = grpc_json_create_child(
+          nullptr, array_parent, nullptr, nullptr, GRPC_JSON_OBJECT, false);
       json_iterator = grpc_json_add_number_string_child(
           socket_ref_json, nullptr, "socketId", socket_refs[i]->uuid());
       grpc_json_create_child(json_iterator, socket_ref_json, "name",
                              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 (i == socket_refs.size()) {
+    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;
diff --git a/src/core/lib/channel/channelz.h b/src/core/lib/channel/channelz.h
index 96a4333083..e43792126f 100644
--- a/src/core/lib/channel/channelz.h
+++ b/src/core/lib/channel/channelz.h
@@ -210,7 +210,8 @@ class ServerNode : public BaseNode {
 
   grpc_json* RenderJson() override;
 
-  char* RenderServerSockets(intptr_t start_socket_id);
+  char* RenderServerSockets(intptr_t start_socket_id,
+                            intptr_t pagination_limit);
 
   // proxy methods to composed classes.
   void AddTraceEvent(ChannelTrace::Severity severity, grpc_slice data) {
diff --git a/src/core/lib/channel/channelz_registry.cc b/src/core/lib/channel/channelz_registry.cc
index bc23b90a66..7cca247d64 100644
--- a/src/core/lib/channel/channelz_registry.cc
+++ b/src/core/lib/channel/channelz_registry.cc
@@ -252,7 +252,8 @@ char* grpc_channelz_get_server(intptr_t server_id) {
 }
 
 char* grpc_channelz_get_server_sockets(intptr_t server_id,
-                                       intptr_t start_socket_id) {
+                                       intptr_t start_socket_id,
+                                       intptr_t max_results) {
   grpc_core::channelz::BaseNode* base_node =
       grpc_core::channelz::ChannelzRegistry::Get(server_id);
   if (base_node == nullptr ||
@@ -263,7 +264,7 @@ char* grpc_channelz_get_server_sockets(intptr_t server_id,
   // actually a server node
   grpc_core::channelz::ServerNode* server_node =
       static_cast<grpc_core::channelz::ServerNode*>(base_node);
-  return server_node->RenderServerSockets(start_socket_id);
+  return server_node->RenderServerSockets(start_socket_id, max_results);
 }
 
 char* grpc_channelz_get_channel(intptr_t channel_id) {