Avoid string allocations when checking for permissions

Fixes: 334988349
Test: presubmit, pprof
Change-Id: Id960aa7356ac927e57aa92a704de8691a996ab59

2 files changed, 10 insertions, 11 deletions

diff --git a/libs/gui/LayerStatePermissions.cpp b/libs/gui/LayerStatePermissions.cpp
index 28697ca953..c467cfdc68 100644
--- a/libs/gui/LayerStatePermissions.cpp
+++ b/libs/gui/LayerStatePermissions.cpp
@@ -23,31 +23,31 @@
 #include <gui/LayerState.h>
 
 namespace android {
-std::unordered_map<std::string, int> LayerStatePermissions::mPermissionMap = {
+std::vector<std::pair<String16, int>> LayerStatePermissions::mPermissionMap = {
         // If caller has ACCESS_SURFACE_FLINGER, they automatically get ROTATE_SURFACE_FLINGER
         // permission, as well
-        {"android.permission.ACCESS_SURFACE_FLINGER",
+        {String16("android.permission.ACCESS_SURFACE_FLINGER"),
          layer_state_t::Permission::ACCESS_SURFACE_FLINGER |
                  layer_state_t::Permission::ROTATE_SURFACE_FLINGER},
-        {"android.permission.ROTATE_SURFACE_FLINGER",
+        {String16("android.permission.ROTATE_SURFACE_FLINGER"),
          layer_state_t::Permission::ROTATE_SURFACE_FLINGER},
-        {"android.permission.INTERNAL_SYSTEM_WINDOW",
+        {String16("android.permission.INTERNAL_SYSTEM_WINDOW"),
          layer_state_t::Permission::INTERNAL_SYSTEM_WINDOW},
 };
 
-static bool callingThreadHasPermission(const std::string& permission __attribute__((unused)),
+static bool callingThreadHasPermission(const String16& permission __attribute__((unused)),
                                        int pid __attribute__((unused)),
                                        int uid __attribute__((unused))) {
 #ifndef __ANDROID_VNDK__
     return uid == AID_GRAPHICS || uid == AID_SYSTEM ||
-            PermissionCache::checkPermission(String16(permission.c_str()), pid, uid);
+            PermissionCache::checkPermission(permission, pid, uid);
 #endif // __ANDROID_VNDK__
     return false;
 }
 
 uint32_t LayerStatePermissions::getTransactionPermissions(int pid, int uid) {
     uint32_t permissions = 0;
-    for (auto [permissionName, permissionVal] : mPermissionMap) {
+    for (const auto& [permissionName, permissionVal] : mPermissionMap) {
         if (callingThreadHasPermission(permissionName, pid, uid)) {
             permissions |= permissionVal;
         }
diff --git a/libs/gui/include/gui/LayerStatePermissions.h b/libs/gui/include/gui/LayerStatePermissions.h
index a90f30c621..b6588a2a82 100644
--- a/libs/gui/include/gui/LayerStatePermissions.h
+++ b/libs/gui/include/gui/LayerStatePermissions.h
@@ -15,15 +15,14 @@
  */
 
 #include <stdint.h>
-#include <string>
-#include <unordered_map>
-
+#include <utils/String16.h>
+#include <vector>
 namespace android {
 class LayerStatePermissions {
 public:
     static uint32_t getTransactionPermissions(int pid, int uid);
 
 private:
-    static std::unordered_map<std::string, int> mPermissionMap;
+    static std::vector<std::pair<String16, int>> mPermissionMap;
 };
 } // namespace android
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