migrate to fmt::format in fb303/

Reviewed By: Gownta

Differential Revision: D67565140

fbshipit-source-id: c5492707706290d2c9db192f6b8f2c35932adc85

fb303/BUCK

@@ -235,6 +235,7 @@ cpp_library(
         "//folly:singleton",
     ],
     exported_deps = [
+        "fbsource//third-party/fmt:fmt",
         ":export_type",
         ":simple_lru_map",
         ":thread_local_stats_map",

fb303/ThreadCachedServiceData.h

@@ -27,6 +27,8 @@
 #include <utility>
 #include <variant>
 
+#include <fmt/format.h>
+
 #include <fb303/ExportType.h>
 #include <fb303/SimpleLRUMap.h>
 #include <fb303/ThreadLocalStatsMap.h>
@@ -770,7 +772,8 @@ class FormattedKeyHolder {
           [](int64_t v) { return std::to_string(v); },
           [](std::string const& v) { return v; });
     }
-    auto formattedKey = folly::svformat(keyFormat_, subkeyStrings);
+    auto formattedKey = doFormatKeyGlobal(
+        keyFormat_, subkeyStrings, std::make_index_sequence<N>{});
     if (prepareKey_) {
       prepareKey_(formattedKey);
     }
@@ -780,6 +783,14 @@ class FormattedKeyHolder {
     return ReturnType(iter->first, iter->second);
   }
 
+  template <size_t... Idx>
+  static std::string doFormatKeyGlobal(
+      std::string_view keyFormat,
+      std::array<std::string, N> subkeyStrings,
+      std::index_sequence<Idx...>) {
+    return fmt::format(fmt::runtime(keyFormat), subkeyStrings[Idx]...);
+  }
+
  private:
   std::string keyFormat_;
   std::function<void(const std::string& key)> prepareKey_;