[channelz-v2] Introduce start of zviz

I'm building out a new framework for consuming channelz-v2 data and producing visualizations in various formats.

This commit adds some string utilities that'll be needed in a few places.

PiperOrigin-RevId: 775678939

Author: ctiller

src/core/BUILD

@@ -10193,6 +10193,17 @@ grpc_cc_library(
     ],
 )
 
+grpc_cc_library(
+    name = "zviz_strings",
+    srcs = [
+        "channelz/zviz/strings.cc",
+    ],
+    hdrs = ["channelz/zviz/strings.h"],
+    external_deps = [
+        "absl/strings",
+    ],
+)
+
 ### UPB Targets
 
 grpc_upb_proto_library(

src/core/channelz/zviz/strings.cc

@@ -0,0 +1,29 @@
+// Copyright 2025 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/core/channelz/zviz/strings.h"
+
+#include "absl/strings/str_cat.h"
+
+namespace grpc_zviz {
+
+std::string DisplayKind(absl::string_view kind) {
+  if (kind.empty()) return "Entity";
+  if (kind == "channel") return "Channel";
+  if (kind == "subchannel") return "Subchannel";
+  if (kind == "socket") return "Socket";
+  return absl::StrCat("Entity kind '", kind, "'");
+}
+
+}  // namespace grpc_zviz

src/core/channelz/zviz/strings.h

@@ -0,0 +1,28 @@
+// Copyright 2025 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef GRPC_SRC_CORE_CHANNELZ_ZVIZ_STRINGS_H
+#define GRPC_SRC_CORE_CHANNELZ_ZVIZ_STRINGS_H
+
+#include <string>
+
+#include "absl/strings/string_view.h"
+
+namespace grpc_zviz {
+
+std::string DisplayKind(absl::string_view kind);
+
+}  // namespace grpc_zviz
+
+#endif  // GRPC_SRC_CORE_CHANNELZ_ZVIZ_STRINGS_H

test/core/channelz/zviz/BUILD

@@ -0,0 +1,33 @@
+# Copyright 2016 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load("//bazel:grpc_build_system.bzl", "grpc_package")
+load("//test/core/test_util:grpc_fuzzer.bzl", "grpc_fuzz_test")
+
+grpc_package(name = "test/core/channelz/zviz")
+
+licenses(["notice"])
+
+grpc_fuzz_test(
+    name = "strings_test",
+    srcs = ["strings_test.cc"],
+    external_deps = [
+        "absl/log:check",
+        "fuzztest",
+        "fuzztest_main",
+    ],
+    deps = [
+        "//src/core:zviz_strings",
+    ],
+)

test/core/channelz/zviz/strings_test.cc

@@ -0,0 +1,39 @@
+//
+//
+// Copyright 2017 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+//
+
+#include "src/core/channelz/zviz/strings.h"
+
+#include "fuzztest/fuzztest.h"
+#include "gtest/gtest.h"
+
+namespace grpc_zviz {
+
+TEST(StringsTest, DisplayKind) {
+  EXPECT_EQ(DisplayKind("channel"), "Channel");
+  EXPECT_EQ(DisplayKind("subchannel"), "Subchannel");
+  EXPECT_EQ(DisplayKind("socket"), "Socket");
+  EXPECT_EQ(DisplayKind("foo"), "Entity kind 'foo'");
+  EXPECT_EQ(DisplayKind(""), "Entity");
+}
+
+void DisplayKindNeverEmpty(absl::string_view kind) {
+  EXPECT_NE(DisplayKind(kind), "");
+}
+FUZZ_TEST(StringsTest, DisplayKindNeverEmpty);
+
+}  // namespace grpc_zviz