[res] A bit more efficient locale collection

Don't copy the string unless it's a new locale, and limit
the allocations as well

Test: unit tests
Flag: EXEMPT minor performance improvement
Change-Id: Icfe433ab211a0ca22882bd579415a96dc40db30a

6 files changed, 18 insertions, 14 deletions

diff --git a/libs/androidfw/AssetManager2.cpp b/libs/androidfw/AssetManager2.cpp
index e09ab5fd1643..f169cfa68946 100644
--- a/libs/androidfw/AssetManager2.cpp
+++ b/libs/androidfw/AssetManager2.cpp
@@ -600,12 +600,12 @@ base::expected<std::set<ResTable_config>, IOError> AssetManager2::GetResourceCon
   return configurations;
 }
 
-std::set<std::string> AssetManager2::GetResourceLocales(bool exclude_system,
-                                                        bool merge_equivalent_languages) const {
+LoadedPackage::Locales AssetManager2::GetResourceLocales(
+    bool exclude_system, bool merge_equivalent_languages) const {
   ATRACE_NAME("AssetManager::GetResourceLocales");
   auto op = StartOperation();
 
-  std::set<std::string> locales;
+  LoadedPackage::Locales locales;
   const auto non_system_overlays =
       exclude_system ? GetNonSystemOverlays() : std::set<ApkAssetsPtr>();
 
@@ -619,8 +619,7 @@ std::set<std::string> AssetManager2::GetResourceLocales(bool exclude_system,
         if (!non_system_overlays.empty()) {
           // Exclude overlays that target only system resources.
           const auto& apk_assets = GetApkAssets(package_group.cookies_[i]);
-          if (apk_assets && apk_assets->IsOverlay() &&
-              non_system_overlays.find(apk_assets) == non_system_overlays.end()) {
+          if (apk_assets && apk_assets->IsOverlay() && !non_system_overlays.contains(apk_assets)) {
             continue;
           }
         }
diff --git a/libs/androidfw/LoadedArsc.cpp b/libs/androidfw/LoadedArsc.cpp
index d9166a16cdea..7cebb6d79502 100644
--- a/libs/androidfw/LoadedArsc.cpp
+++ b/libs/androidfw/LoadedArsc.cpp
@@ -361,14 +361,18 @@ base::expected<std::monostate, IOError> LoadedPackage::CollectConfigurations(
   return {};
 }
 
-void LoadedPackage::CollectLocales(bool canonicalize, std::set<std::string>* out_locales) const {
-  char temp_locale[RESTABLE_MAX_LOCALE_LEN];
+void LoadedPackage::CollectLocales(bool canonicalize,
+                                   Locales* out_locales) const {
   for (const auto& type_spec : type_specs_) {
     for (const auto& type_entry : type_spec.second.type_entries) {
       if (type_entry.config.locale != 0) {
+        char temp_locale[RESTABLE_MAX_LOCALE_LEN];
         type_entry.config.getBcp47Locale(temp_locale, canonicalize);
-        std::string locale(temp_locale);
-        out_locales->insert(std::move(locale));
+        auto locale_sv = std::string_view(temp_locale);
+        if (auto it = out_locales->lower_bound(locale_sv);
+            it == out_locales->end() || *it != locale_sv) {
+          out_locales->emplace_hint(it, locale_sv);
+        }
       }
     }
   }
diff --git a/libs/androidfw/include/androidfw/AssetManager2.h b/libs/androidfw/include/androidfw/AssetManager2.h
index b0179524f6cd..69fb3b39b5d2 100644
--- a/libs/androidfw/include/androidfw/AssetManager2.h
+++ b/libs/androidfw/include/androidfw/AssetManager2.h
@@ -189,8 +189,8 @@ class AssetManager2 {
   // ('android' package, other libraries) will be excluded from the list.
   // If `merge_equivalent_languages` is set to true, resource locales will be canonicalized
   // and de-duped in the resulting list.
-  std::set<std::string> GetResourceLocales(bool exclude_system = false,
-                                           bool merge_equivalent_languages = false) const;
+  LoadedPackage::Locales GetResourceLocales(
+      bool exclude_system = false, bool merge_equivalent_languages = false) const;
 
   // Searches the set of APKs loaded by this AssetManager and opens the first one found located
   // in the assets/ directory.
diff --git a/libs/androidfw/include/androidfw/LoadedArsc.h b/libs/androidfw/include/androidfw/LoadedArsc.h
index 413b27829474..eb99dc7b8eff 100644
--- a/libs/androidfw/include/androidfw/LoadedArsc.h
+++ b/libs/androidfw/include/androidfw/LoadedArsc.h
@@ -238,7 +238,8 @@ class LoadedPackage {
   // Populates a set of strings representing locales.
   // If `canonicalize` is set to true, each locale is transformed into its canonical format
   // before being inserted into the set. This may cause some equivalent locales to de-dupe.
-  void CollectLocales(bool canonicalize, std::set<std::string>* out_locales) const;
+  using Locales = std::set<std::string, std::less<>>;
+  void CollectLocales(bool canonicalize, Locales* out_locales) const;
 
   // type_idx is TT - 1 from 0xPPTTEEEE.
   inline const TypeSpec* GetTypeSpecByTypeIndex(uint8_t type_index) const {
diff --git a/libs/androidfw/tests/AssetManager2_bench.cpp b/libs/androidfw/tests/AssetManager2_bench.cpp
index 136f5ea639a1..c469817d3595 100644
--- a/libs/androidfw/tests/AssetManager2_bench.cpp
+++ b/libs/androidfw/tests/AssetManager2_bench.cpp
@@ -191,7 +191,7 @@ static void BM_AssetManagerGetResourceLocales(benchmark::State& state) {
   assets.SetApkAssets({apk});
 
   for (auto&& _ : state) {
-    std::set<std::string> locales =
+    auto locales =
         assets.GetResourceLocales(false /*exclude_system*/, true /*merge_equivalent_languages*/);
     benchmark::DoNotOptimize(locales);
   }
diff --git a/libs/androidfw/tests/AssetManager2_test.cpp b/libs/androidfw/tests/AssetManager2_test.cpp
index 3f228841f6ba..01da902674bb 100644
--- a/libs/androidfw/tests/AssetManager2_test.cpp
+++ b/libs/androidfw/tests/AssetManager2_test.cpp
@@ -621,7 +621,7 @@ TEST_F(AssetManager2Test, GetResourceLocales) {
   AssetManager2 assetmanager;
   assetmanager.SetApkAssets({system_assets_, basic_de_fr_assets_});
 
-  std::set<std::string> locales = assetmanager.GetResourceLocales();
+  auto locales = assetmanager.GetResourceLocales();
 
   // We expect the locale sv from the system assets, and de and fr from basic_de_fr assets.
   EXPECT_EQ(3u, locales.size());