feat: use api_compat for stats.json (#7918)

* feat: use api_compat for stats.json

* chore: flag old stats.json keys as api_compat-only

libtransmission/api-compat.cc

@@ -276,9 +276,9 @@ auto constexpr SessionKeys = std::array<ApiKey, 139U>{ {
     { TR_KEY_download_dir, TR_KEY_download_dir_kebab }, // TODO(ckerr) legacy duplicate
     { TR_KEY_download_queue_enabled, TR_KEY_download_queue_enabled_kebab },
     { TR_KEY_download_queue_size, TR_KEY_download_queue_size_kebab },
-    { TR_KEY_downloaded_bytes, TR_KEY_downloaded_bytes_kebab }, // TODO(ckerr) legacy duplicate
+    { TR_KEY_downloaded_bytes, TR_KEY_downloaded_bytes_kebab_APICOMPAT },
     { TR_KEY_downloading_time_seconds, TR_KEY_downloading_time_seconds_kebab },
-    { TR_KEY_files_added, TR_KEY_files_added_kebab }, // TODO(ckerr) legacy duplicate
+    { TR_KEY_files_added, TR_KEY_files_added_kebab_APICOMPAT },
     { TR_KEY_filter_mode, TR_KEY_filter_mode_kebab },
     { TR_KEY_filter_text, TR_KEY_filter_text_kebab },
     { TR_KEY_filter_trackers, TR_KEY_filter_trackers_kebab },
@@ -344,11 +344,11 @@ auto constexpr SessionKeys = std::array<ApiKey, 139U>{ {
     { TR_KEY_script_torrent_done_filename, TR_KEY_script_torrent_done_filename_kebab },
     { TR_KEY_script_torrent_done_seeding_enabled, TR_KEY_script_torrent_done_seeding_enabled_kebab },
     { TR_KEY_script_torrent_done_seeding_filename, TR_KEY_script_torrent_done_seeding_filename_kebab },
-    { TR_KEY_seconds_active, TR_KEY_seconds_active_kebab }, // TODO(ckerr) legacy duplicate
+    { TR_KEY_seconds_active, TR_KEY_seconds_active_kebab_APICOMPAT },
     { TR_KEY_seed_queue_enabled, TR_KEY_seed_queue_enabled_kebab },
     { TR_KEY_seed_queue_size, TR_KEY_seed_queue_size_kebab },
     { TR_KEY_seeding_time_seconds, TR_KEY_seeding_time_seconds_kebab },
-    { TR_KEY_session_count, TR_KEY_session_count_kebab }, // TODO(ckerr) legacy duplicate
+    { TR_KEY_session_count, TR_KEY_session_count_kebab_APICOMPAT },
     { TR_KEY_show_backup_trackers, TR_KEY_show_backup_trackers_kebab },
     { TR_KEY_show_extra_peer_details, TR_KEY_show_extra_peer_details_kebab },
     { TR_KEY_show_filterbar, TR_KEY_show_filterbar_kebab },
@@ -378,7 +378,7 @@ auto constexpr SessionKeys = std::array<ApiKey, 139U>{ {
     { TR_KEY_trash_can_enabled, TR_KEY_trash_can_enabled_kebab },
     { TR_KEY_trash_original_torrent_files, TR_KEY_trash_original_torrent_files_kebab },
     { TR_KEY_upload_slots_per_torrent, TR_KEY_upload_slots_per_torrent_kebab },
-    { TR_KEY_uploaded_bytes, TR_KEY_uploaded_bytes_kebab }, // TODO(ckerr) legacy duplicate
+    { TR_KEY_uploaded_bytes, TR_KEY_uploaded_bytes_kebab_APICOMPAT },
     { TR_KEY_use_global_speed_limit, TR_KEY_use_global_speed_limit_kebab },
     { TR_KEY_use_speed_limit, TR_KEY_use_speed_limit_kebab },
     { TR_KEY_utp_enabled, TR_KEY_utp_enabled_kebab },

libtransmission/quark.h

@@ -9,11 +9,26 @@
 #include <optional>
 #include <string_view>
 
-/* Quarks — a 2-way association between a string and a unique integer identifier */
+/**
+ * Quarks — a 2-way association between a compile-time interned string
+ * and a unique integer identifier. Used to make well-known strings
+ * (e.g. strings in settings files, the JSON-RPC API, and BitTorrent protocol)
+ * cheap to store, cheap to compare, and usable in switch-case statements.
+ */
 using tr_quark = size_t;
 
-/*
+/**
  * Predefined Quarks.
+ *
+ * IMPORTANT:
+ *
+ * * Use snake case for new entries.
+ *
+ * * Entries whose names contain `_camel`, `_kebab`, or `_APICOMPAT` are
+ *   all deprecated. Do not use them in new code except in api_compat.
+ *   - `_camel` means the entry's string is in camelCase.
+ *   - `_kebab` means the entry's string is in kebab-case.
+ *   - `_APICOMPAT` means the entry is only used in api_compat.
  */
 enum // NOLINT(performance-enum-size)
 {
@@ -149,7 +164,7 @@ enum // NOLINT(performance-enum-size)
     TR_KEY_download_queue_size,
     TR_KEY_download_speed,
     TR_KEY_downloaded,
-    TR_KEY_downloaded_bytes_kebab,
+    TR_KEY_downloaded_bytes_kebab_APICOMPAT,
     TR_KEY_downloaded_bytes_camel,
     TR_KEY_downloaded_ever_camel,
     TR_KEY_downloaded_bytes,
@@ -178,7 +193,7 @@ enum // NOLINT(performance-enum-size)
     TR_KEY_file_stats,
     TR_KEY_filename,
     TR_KEY_files,
-    TR_KEY_files_added_kebab,
+    TR_KEY_files_added_kebab_APICOMPAT,
     TR_KEY_files_unwanted_kebab,
     TR_KEY_files_wanted_kebab,
     TR_KEY_files_added_camel,
@@ -526,7 +541,7 @@ enum // NOLINT(performance-enum-size)
     TR_KEY_script_torrent_done_filename,
     TR_KEY_script_torrent_done_seeding_enabled,
     TR_KEY_script_torrent_done_seeding_filename,
-    TR_KEY_seconds_active_kebab,
+    TR_KEY_seconds_active_kebab_APICOMPAT,
     TR_KEY_seconds_active_camel,
     TR_KEY_seconds_downloading_camel,
     TR_KEY_seconds_seeding_camel,
@@ -554,7 +569,7 @@ enum // NOLINT(performance-enum-size)
     TR_KEY_sequential_download,
     TR_KEY_sequential_download_from_piece,
     TR_KEY_session_close_kebab,
-    TR_KEY_session_count_kebab,
+    TR_KEY_session_count_kebab_APICOMPAT,
     TR_KEY_session_get_kebab,
     TR_KEY_session_id_kebab,
     TR_KEY_session_set_kebab,
@@ -701,7 +716,7 @@ enum // NOLINT(performance-enum-size)
     TR_KEY_upload_slots_per_torrent,
     TR_KEY_upload_speed,
     TR_KEY_uploaded,
-    TR_KEY_uploaded_bytes_kebab,
+    TR_KEY_uploaded_bytes_kebab_APICOMPAT,
     TR_KEY_uploaded_bytes_camel,
     TR_KEY_uploaded_ever_camel,
     TR_KEY_uploaded_bytes,

libtransmission/stats.cc

@@ -9,6 +9,7 @@
 
 #include "libtransmission/transmission.h"
 
+#include "libtransmission/api-compat.h"
 #include "libtransmission/file.h"
 #include "libtransmission/quark.h"
 #include "libtransmission/stats.h"
@@ -17,24 +18,29 @@
 #include "libtransmission/variant.h"
 
 using namespace std::literals;
+namespace api_compat = libtransmission::api_compat;
 
 namespace
 {
-std::optional<tr_variant> load_stats(std::string_view config_dir)
+[[nodiscard]] auto load_stats(std::string_view config_dir)
 {
-    if (auto filename = tr_pathbuf{ config_dir, "/stats.json"sv }; tr_sys_path_exists(filename))
+    auto var = std::optional<tr_variant>{};
+
+    if (auto file = tr_pathbuf{ config_dir, "/stats.json"sv }; tr_sys_path_exists(file))
     {
-        return tr_variant_serde::json().parse_file(filename);
+        var = tr_variant_serde::json().parse_file(file);
+    }
+    else if (auto oldfile = tr_pathbuf{ config_dir, "/stats.benc"sv }; tr_sys_path_exists(oldfile))
+    {
+        var = tr_variant_serde::benc().parse_file(oldfile);
     }
 
-    // maybe the user just upgraded from an old version of Transmission
-    // that was still using stats.benc
-    if (auto filename = tr_pathbuf{ config_dir, "/stats.benc"sv }; tr_sys_path_exists(filename))
+    if (var)
     {
-        return tr_variant_serde::benc().parse_file(filename);
+        var = api_compat::convert_incoming_data(*var);
     }
 
-    return {};
+    return var;
 }
 } // namespace
 
@@ -52,21 +58,21 @@ tr_session_stats tr_stats::load_old_stats(std::string_view config_dir)
         return {};
     }
 
-    auto const load = [map](std::initializer_list<tr_quark> keys, uint64_t& dst)
+    auto const load = [map](auto const key, uint64_t& tgt)
     {
-        if (auto const val = map->value_if<int64_t>(keys); val)
+        if (auto const val = map->value_if<int64_t>(key))
         {
-            dst = *val;
+            tgt = *val;
         }
     };
 
     auto ret = tr_session_stats{};
 
-    load({ TR_KEY_downloaded_bytes, TR_KEY_downloaded_bytes_kebab }, ret.downloadedBytes);
-    load({ TR_KEY_files_added, TR_KEY_files_added_kebab }, ret.filesAdded);
-    load({ TR_KEY_seconds_active, TR_KEY_seconds_active_kebab }, ret.secondsActive);
-    load({ TR_KEY_session_count, TR_KEY_session_count_kebab }, ret.sessionCount);
-    load({ TR_KEY_uploaded_bytes, TR_KEY_uploaded_bytes_kebab }, ret.uploadedBytes);
+    load(TR_KEY_downloaded_bytes, ret.downloadedBytes);
+    load(TR_KEY_files_added, ret.filesAdded);
+    load(TR_KEY_seconds_active, ret.secondsActive);
+    load(TR_KEY_session_count, ret.sessionCount);
+    load(TR_KEY_uploaded_bytes, ret.uploadedBytes);
 
     return ret;
 }
@@ -80,7 +86,10 @@ void tr_stats::save() const
     map.try_emplace(TR_KEY_seconds_active, saveme.secondsActive);
     map.try_emplace(TR_KEY_session_count, saveme.sessionCount);
     map.try_emplace(TR_KEY_uploaded_bytes, saveme.uploadedBytes);
-    tr_variant_serde::json().to_file(tr_variant{ std::move(map) }, tr_pathbuf{ config_dir_, "/stats.json"sv });
+
+    auto var = tr_variant{ std::move(map) };
+    var = api_compat::convert_outgoing_data(var);
+    tr_variant_serde::json().to_file(var, tr_pathbuf{ config_dir_, "/stats.json"sv });
 }
 
 void tr_stats::clear()