From 6e8c6039254716dca878e84567d3a4e480d47a22 Mon Sep 17 00:00:00 2001
From: Yurii Zubrytskyi <zyy@google.com>
Date: Mon, 14 Nov 2022 23:45:58 -0800
Subject: [PATCH] [res] Change staged alias container to vector

Sorted vector is more efficient than a map for all cases but
if it gets modified a lot. Here we never modify it after loading

Bug: 237583012
Test: build + boot
Change-Id: I7d9f1fe38bd8a6d722b9cacaa7034abcdb02d743
---
 libs/androidfw/LoadedArsc.cpp                 | 29 ++++++++++++-------
 libs/androidfw/include/androidfw/LoadedArsc.h |  6 ++--
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/libs/androidfw/LoadedArsc.cpp b/libs/androidfw/LoadedArsc.cpp
index 386f718208b39..193c8650b2bef 100644
--- a/libs/androidfw/LoadedArsc.cpp
+++ b/libs/androidfw/LoadedArsc.cpp
@@ -645,16 +645,15 @@ std::unique_ptr<const LoadedPackage> LoadedPackage::Load(const Chunk& chunk,
         }
 
         std::string name;
-        util::ReadUtf16StringFromDevice(overlayable->name, arraysize(overlayable->name), &name);
+        util::ReadUtf16StringFromDevice(overlayable->name, std::size(overlayable->name), &name);
         std::string actor;
-        util::ReadUtf16StringFromDevice(overlayable->actor, arraysize(overlayable->actor), &actor);
-
-        if (loaded_package->overlayable_map_.find(name) !=
-            loaded_package->overlayable_map_.end()) {
-          LOG(ERROR) << "Multiple <overlayable> blocks with the same name '" << name << "'.";
+        util::ReadUtf16StringFromDevice(overlayable->actor, std::size(overlayable->actor), &actor);
+        auto [it, inserted] =
+            loaded_package->overlayable_map_.emplace(name, actor);
+        if (!inserted) {
+          LOG(ERROR) << "Multiple <overlayable> blocks with the same name '" << it->first << "'.";
           return {};
         }
-        loaded_package->overlayable_map_.emplace(name, actor);
 
         // Iterate over the overlayable policy chunks contained within the overlayable chunk data
         ChunkIterator overlayable_iter(child_chunk.data_ptr(), child_chunk.data_size());
@@ -736,6 +735,7 @@ std::unique_ptr<const LoadedPackage> LoadedPackage::Load(const Chunk& chunk,
         const auto entry_end = entry_begin + dtohl(lib_alias->count);
         std::unordered_set<uint32_t> finalized_ids;
         finalized_ids.reserve(entry_end - entry_begin);
+        loaded_package->alias_id_map_.reserve(entry_end - entry_begin);
         for (auto entry_iter = entry_begin; entry_iter != entry_end; ++entry_iter) {
           if (!entry_iter) {
             LOG(ERROR) << "NULL ResTable_staged_alias_entry record??";
@@ -749,13 +749,20 @@ std::unique_ptr<const LoadedPackage> LoadedPackage::Load(const Chunk& chunk,
           }
 
           auto staged_id = dtohl(entry_iter->stagedResId);
-          auto [_, success] = loaded_package->alias_id_map_.emplace(staged_id, finalized_id);
-          if (!success) {
+          loaded_package->alias_id_map_.emplace_back(staged_id, finalized_id);
+        }
+
+        std::sort(loaded_package->alias_id_map_.begin(), loaded_package->alias_id_map_.end(),
+            [](auto&& l, auto&& r) { return l.first < r.first; });
+        const auto duplicate_it =
+            std::adjacent_find(loaded_package->alias_id_map_.begin(),
+                               loaded_package->alias_id_map_.end(),
+                               [](auto&& l, auto&& r) { return l.first == r.first; });
+          if (duplicate_it != loaded_package->alias_id_map_.end()) {
             LOG(ERROR) << StringPrintf("Repeated staged resource id '%08x' in staged aliases.",
-                                       staged_id);
+                                       duplicate_it->first);
             return {};
           }
-        }
       } break;
 
       default:
diff --git a/libs/androidfw/include/androidfw/LoadedArsc.h b/libs/androidfw/include/androidfw/LoadedArsc.h
index 79d962829046c..4ab004299500e 100644
--- a/libs/androidfw/include/androidfw/LoadedArsc.h
+++ b/libs/androidfw/include/androidfw/LoadedArsc.h
@@ -275,7 +275,7 @@ class LoadedPackage {
     return overlayable_map_;
   }
 
-  const std::map<uint32_t, uint32_t>& GetAliasResourceIdMap() const {
+  const std::vector<std::pair<uint32_t, uint32_t>>& GetAliasResourceIdMap() const {
     return alias_id_map_;
   }
 
@@ -295,8 +295,8 @@ class LoadedPackage {
   std::unordered_map<uint8_t, TypeSpec> type_specs_;
   ByteBucketArray<uint32_t> resource_ids_;
   std::vector<DynamicPackageEntry> dynamic_package_map_;
-  std::vector<const std::pair<OverlayableInfo, std::unordered_set<uint32_t>>> overlayable_infos_;
-  std::map<uint32_t, uint32_t> alias_id_map_;
+  std::vector<std::pair<OverlayableInfo, std::unordered_set<uint32_t>>> overlayable_infos_;
+  std::vector<std::pair<uint32_t, uint32_t>> alias_id_map_;
 
   // A map of overlayable name to actor
   std::unordered_map<std::string, std::string> overlayable_map_;