commit e7c9a8c2b8481aafbc6af4ce6229bd361ba24742
author Mathieu Chartier <mathieuc@google.com> Thu Nov 06 16:35:45 2014 -0800
committer Mathieu Chartier <mathieuc@google.com> Fri Nov 07 11:45:06 2014 -0800
tree f6d8fe8fd7aeae117a6547dc4f012cd4085cb4e8
parent 00b2da5c02339c36ffa4006f731f55203b09265d

Add hash map, reduce excessive hashing

Changed the class def index to use a HashMap instead of unordered_map
so that we can use FindWithHash to reduce how often we need to compute
hashes.

Fixed a bug in ClassLinker::UpdateClass where we didn't properly
handle classes with the same descriptor but different class loaders.
Introduced by previous CL.

Before (fb launch):
1.74% art::ComputeModifiedUtf8Hash(char const*)

After:
0.95% art::ComputeModifiedUtf8Hash(char const*)

Bug: 18054905
Bug: 16828525

Change-Id: Iba2ee37c9837289e0ea187800ba4af322225a994

(cherry picked from commit 564ff985184737977aa26c485d0c1a413e530705)

runtime/class_linker.h

diff --git a/runtime/class_linker.h b/runtime/class_linker.h
index 7b2ba43..385f135 100644
--- a/runtime/class_linker.h
+++ b/runtime/class_linker.h
@@ -117,9 +117,10 @@
                            Handle<mirror::ClassLoader> class_loader)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
-  // Find a class in the path class loader, loading it if necessary.
+  // Find a class in the path class loader, loading it if necessary. Hash function is supposed to
+  // be ComputeModifiedUtf8Hash(descriptor).
   mirror::Class* FindClassInPathClassLoader(ScopedObjectAccessAlreadyRunnable& soa,
-                                            Thread* self, const char* descriptor,
+                                            Thread* self, const char* descriptor, size_t hash,
                                             Handle<mirror::ClassLoader> class_loader)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
@@ -138,14 +139,14 @@
   }
 
   // Define a new a class based on a ClassDef from a DexFile
-  mirror::Class* DefineClass(Thread* self, const char* descriptor,
+  mirror::Class* DefineClass(Thread* self, const char* descriptor, size_t hash,
                              Handle<mirror::ClassLoader> class_loader,
                              const DexFile& dex_file, const DexFile::ClassDef& dex_class_def)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Finds a class by its descriptor, returning NULL if it isn't wasn't loaded
   // by the given 'class_loader'.
-  mirror::Class* LookupClass(Thread* self, const char* descriptor,
+  mirror::Class* LookupClass(Thread* self, const char* descriptor, size_t hash,
                              mirror::ClassLoader* class_loader)
       LOCKS_EXCLUDED(Locks::classlinker_classes_lock_)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
@@ -499,7 +500,7 @@
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
 
-  mirror::Class* CreateArrayClass(Thread* self, const char* descriptor,
+  mirror::Class* CreateArrayClass(Thread* self, const char* descriptor, size_t hash,
                                   Handle<mirror::ClassLoader> class_loader)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);