From e6d77c593d1a25b45c23bf9292ec7ee09fc14b6e Mon Sep 17 00:00:00 2001
From: Jeff Brown <jeffbrown@google.com>
Date: Fri, 16 Mar 2012 14:45:49 -0700
Subject: [PATCH] Add traits to common utils data structures.

Many of our basic data structures are trivially movable using
memcpy() even if they are not trivially constructable, destructable
or copyable.  It's worth taking advantage of this *ahem* trait.

Adding trivial_move_trait to String16 reduces appt running
time on frameworks/base/core/res by 40%!

Change-Id: I630a1a027e2d0ded96856e4ca042ea82906289fe
---
 include/utils/BitSet.h       |  3 +++
 include/utils/KeyedVector.h  |  7 +++++++
 include/utils/RefBase.h      |  1 +
 include/utils/SortedVector.h |  3 +++
 include/utils/String16.h     |  5 +++++
 include/utils/String8.h      |  5 +++++
 include/utils/TypeHelpers.h  | 20 ++++++++++++++++----
 include/utils/Vector.h       |  3 +++
 8 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/include/utils/BitSet.h b/include/utils/BitSet.h
index 9452e86d6..e189d0c73 100644
--- a/include/utils/BitSet.h
+++ b/include/utils/BitSet.h
@@ -18,6 +18,7 @@
 #define UTILS_BITSET_H
 
 #include <stdint.h>
+#include <utils/TypeHelpers.h>
 
 /*
  * Contains some bit manipulation helpers.
@@ -102,6 +103,8 @@ struct BitSet32 {
     inline bool operator!= (const BitSet32& other) const { return value != other.value; }
 };
 
+ANDROID_BASIC_TYPES_TRAITS(BitSet32)
+
 } // namespace android
 
 #endif // UTILS_BITSET_H
diff --git a/include/utils/KeyedVector.h b/include/utils/KeyedVector.h
index 85535bd61..20575ee3e 100644
--- a/include/utils/KeyedVector.h
+++ b/include/utils/KeyedVector.h
@@ -91,6 +91,13 @@ private:
             SortedVector< key_value_pair_t<KEY, VALUE> >    mVector;
 };
 
+// KeyedVector<KEY, VALUE> can be trivially moved using memcpy() because its
+// underlying SortedVector can be trivially moved.
+template<typename KEY, typename VALUE> struct trait_trivial_move<KeyedVector<KEY, VALUE> > {
+    enum { value = trait_trivial_move<SortedVector< key_value_pair_t<KEY, VALUE> > >::value };
+};
+
+
 // ---------------------------------------------------------------------------
 
 /**
diff --git a/include/utils/RefBase.h b/include/utils/RefBase.h
index c7a9b7895..99f51820a 100644
--- a/include/utils/RefBase.h
+++ b/include/utils/RefBase.h
@@ -25,6 +25,7 @@
 #include <string.h>
 
 #include <utils/StrongPointer.h>
+#include <utils/TypeHelpers.h>
 
 // ---------------------------------------------------------------------------
 namespace android {
diff --git a/include/utils/SortedVector.h b/include/utils/SortedVector.h
index 0e98aeb05..24455253c 100644
--- a/include/utils/SortedVector.h
+++ b/include/utils/SortedVector.h
@@ -133,6 +133,9 @@ protected:
     virtual int     do_compare(const void* lhs, const void* rhs) const;
 };
 
+// SortedVector<T> can be trivially moved using memcpy() because moving does not
+// require any change to the underlying SharedBuffer contents or reference count.
+template<typename T> struct trait_trivial_move<SortedVector<T> > { enum { value = true }; };
 
 // ---------------------------------------------------------------------------
 // No user serviceable parts from here...
diff --git a/include/utils/String16.h b/include/utils/String16.h
index 360f407c3..fe06c576f 100644
--- a/include/utils/String16.h
+++ b/include/utils/String16.h
@@ -20,6 +20,7 @@
 #include <utils/Errors.h>
 #include <utils/SharedBuffer.h>
 #include <utils/Unicode.h>
+#include <utils/TypeHelpers.h>
 
 // ---------------------------------------------------------------------------
 
@@ -112,6 +113,10 @@ private:
             const char16_t*     mString;
 };
 
+// String16 can be trivially moved using memcpy() because moving does not
+// require any change to the underlying SharedBuffer contents or reference count.
+ANDROID_TRIVIAL_MOVE_TRAIT(String16)
+
 TextOutput& operator<<(TextOutput& to, const String16& val);
 
 // ---------------------------------------------------------------------------
diff --git a/include/utils/String8.h b/include/utils/String8.h
index 4163697d2..335e7f1bf 100644
--- a/include/utils/String8.h
+++ b/include/utils/String8.h
@@ -20,6 +20,7 @@
 #include <utils/Errors.h>
 #include <utils/SharedBuffer.h>
 #include <utils/Unicode.h>
+#include <utils/TypeHelpers.h>
 
 #include <string.h> // for strcmp
 #include <stdarg.h>
@@ -219,6 +220,10 @@ private:
             const char* mString;
 };
 
+// String8 can be trivially moved using memcpy() because moving does not
+// require any change to the underlying SharedBuffer contents or reference count.
+ANDROID_TRIVIAL_MOVE_TRAIT(String8)
+
 TextOutput& operator<<(TextOutput& to, const String16& val);
 
 // ---------------------------------------------------------------------------
diff --git a/include/utils/TypeHelpers.h b/include/utils/TypeHelpers.h
index 1f2c2d5fd..2bf33c332 100644
--- a/include/utils/TypeHelpers.h
+++ b/include/utils/TypeHelpers.h
@@ -68,12 +68,24 @@ struct aggregate_traits {
     };
 };
 
-#define ANDROID_BASIC_TYPES_TRAITS( T )                                     \
-    template<> struct trait_trivial_ctor< T >   { enum { value = true }; }; \
-    template<> struct trait_trivial_dtor< T >   { enum { value = true }; }; \
-    template<> struct trait_trivial_copy< T >   { enum { value = true }; }; \
+#define ANDROID_TRIVIAL_CTOR_TRAIT( T ) \
+    template<> struct trait_trivial_ctor< T >   { enum { value = true }; };
+
+#define ANDROID_TRIVIAL_DTOR_TRAIT( T ) \
+    template<> struct trait_trivial_dtor< T >   { enum { value = true }; };
+
+#define ANDROID_TRIVIAL_COPY_TRAIT( T ) \
+    template<> struct trait_trivial_copy< T >   { enum { value = true }; };
+
+#define ANDROID_TRIVIAL_MOVE_TRAIT( T ) \
     template<> struct trait_trivial_move< T >   { enum { value = true }; };
 
+#define ANDROID_BASIC_TYPES_TRAITS( T ) \
+    ANDROID_TRIVIAL_CTOR_TRAIT( T ) \
+    ANDROID_TRIVIAL_DTOR_TRAIT( T ) \
+    ANDROID_TRIVIAL_COPY_TRAIT( T ) \
+    ANDROID_TRIVIAL_MOVE_TRAIT( T )
+
 // ---------------------------------------------------------------------------
 
 /*
diff --git a/include/utils/Vector.h b/include/utils/Vector.h
index 5b5296bdb..e39a5b759 100644
--- a/include/utils/Vector.h
+++ b/include/utils/Vector.h
@@ -201,6 +201,9 @@ protected:
     virtual void    do_move_backward(void* dest, const void* from, size_t num) const;
 };
 
+// Vector<T> can be trivially moved using memcpy() because moving does not
+// require any change to the underlying SharedBuffer contents or reference count.
+template<typename T> struct trait_trivial_move<Vector<T> > { enum { value = true }; };
 
 // ---------------------------------------------------------------------------
 // No user serviceable parts from here...