Smarter set intersection between app image and non boot image strings

If there are fewer non boot image strings in the runtime, iterate
over those strings instead of the set being newly added.

On AOSP, nonBootImageInternStrings is around 500.

Test: test-art-host
Bug: 116059983
Change-Id: I76b49f2090971cf593ba487889b35dfc1fa8cf13

1 files changed, 37 insertions, 11 deletions

diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index e3dfdb3256..6a5e8b6d65 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -1495,18 +1495,44 @@ void AppImageLoadingHelper::HandleAppImageStrings(gc::space::ImageSpace* space)
   intern_table->AddImageStringsToTable(space, [&](InternTable::UnorderedSet& interns)
       REQUIRES_SHARED(Locks::mutator_lock_)
       REQUIRES(Locks::intern_table_lock_) {
+    const size_t non_boot_image_strings = intern_table->CountInterns(
+        /*visit_boot_images=*/false,
+        /*visit_non_boot_images=*/true);
     VLOG(image) << "AppImage:stringsInInternTableSize = " << interns.size();
-    for (auto it = interns.begin(); it != interns.end(); ) {
-      ObjPtr<mirror::String> string = it->Read();
-      ObjPtr<mirror::String> existing = intern_table->LookupWeakLocked(string);
-      if (existing == nullptr) {
-        existing = intern_table->LookupStrongLocked(string);
-      }
-      if (existing != nullptr) {
-        intern_remap.Put(string.Ptr(), existing.Ptr());
-        it = interns.erase(it);
-      } else {
-        ++it;
+    VLOG(image) << "AppImage:nonBootImageInternStrings = " << non_boot_image_strings;
+    // Visit the smaller of the two sets to compute the intersection.
+    if (interns.size() < non_boot_image_strings) {
+      for (auto it = interns.begin(); it != interns.end(); ) {
+        ObjPtr<mirror::String> string = it->Read();
+        ObjPtr<mirror::String> existing = intern_table->LookupWeakLocked(string);
+        if (existing == nullptr) {
+          existing = intern_table->LookupStrongLocked(string);
+        }
+        if (existing != nullptr) {
+          intern_remap.Put(string.Ptr(), existing.Ptr());
+          it = interns.erase(it);
+        } else {
+          ++it;
+        }
+      }
+    } else {
+      intern_table->VisitInterns([&](const GcRoot<mirror::String>& root)
+          REQUIRES_SHARED(Locks::mutator_lock_)
+          REQUIRES(Locks::intern_table_lock_) {
+        auto it = interns.find(root);
+        if (it != interns.end()) {
+          ObjPtr<mirror::String> existing = root.Read();
+          intern_remap.Put(it->Read(), existing.Ptr());
+          it = interns.erase(it);
+        }
+      }, /*visit_boot_images=*/false, /*visit_non_boot_images=*/true);
+    }
+    // Sanity check to ensure correctness.
+    if (kIsDebugBuild) {
+      for (GcRoot<mirror::String>& root : interns) {
+        ObjPtr<mirror::String> string = root.Read();
+        CHECK(intern_table->LookupWeakLocked(string) == nullptr) << string->ToModifiedUtf8();
+        CHECK(intern_table->LookupStrongLocked(string) == nullptr) << string->ToModifiedUtf8();
       }
     }
   });