runtime/reference_table_test.cc - platform/art - Gitiles

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "reference_table.h"

 #include <regex>  // NOLINT [build/c++11] [5]

 #include "android-base/stringprintf.h"

 #include "art_method-inl.h"
 #include "class_linker.h"
 #include "common_runtime_test.h"
 #include "handle_scope-inl.h"
 #include "mirror/array-inl.h"
 #include "mirror/class-inl.h"
 #include "mirror/class_loader.h"
 #include "mirror/string.h"
 #include "primitive.h"
 #include "runtime.h"
 #include "scoped_thread_state_change-inl.h"
 #include "thread-current-inl.h"
 #include "well_known_classes.h"

 namespace art {

 using android::base::StringPrintf;

 class ReferenceTableTest : public CommonRuntimeTest {};

 static mirror::Object* CreateWeakReference(mirror::Object* referent)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   Thread* self = Thread::Current();
   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();

   StackHandleScope<3> scope(self);
   Handle<mirror::Object> h_referent(scope.NewHandle<mirror::Object>(referent));

   Handle<mirror::Class> h_ref_class(scope.NewHandle<mirror::Class>(
       class_linker->FindClass(self,
                               "Ljava/lang/ref/WeakReference;",
                               ScopedNullHandle<mirror::ClassLoader>())));
   CHECK(h_ref_class != nullptr);
   CHECK(class_linker->EnsureInitialized(self, h_ref_class, true, true));

   Handle<mirror::Object> h_ref_instance(scope.NewHandle<mirror::Object>(
       h_ref_class->AllocObject(self)));
   CHECK(h_ref_instance != nullptr);

   ArtMethod* constructor = h_ref_class->FindConstructor(
       "(Ljava/lang/Object;)V", class_linker->GetImagePointerSize());
   CHECK(constructor != nullptr);

   uint32_t args[2];
   args[0] = PointerToLowMemUInt32(h_ref_instance.Get());
   args[1] = PointerToLowMemUInt32(h_referent.Get());
   JValue result;
   constructor->Invoke(self, args, sizeof(uint32_t), &result, constructor->GetShorty());
   CHECK(!self->IsExceptionPending());

   return h_ref_instance.Get();
 }

 TEST_F(ReferenceTableTest, Basics) {
   ScopedObjectAccess soa(Thread::Current());
   mirror::Object* o1 = mirror::String::AllocFromModifiedUtf8(soa.Self(), "hello");

   ReferenceTable rt("test", 0, 11);

   // Check dumping the empty table.
   {
     std::ostringstream oss;
     rt.Dump(oss);
     EXPECT_NE(oss.str().find("(empty)"), std::string::npos) << oss.str();
     EXPECT_EQ(0U, rt.Size());
   }

   // Check removal of all nullss in a empty table is a no-op.
   rt.Remove(nullptr);
   EXPECT_EQ(0U, rt.Size());

   // Check removal of all o1 in a empty table is a no-op.
   rt.Remove(o1);
   EXPECT_EQ(0U, rt.Size());

   // Add o1 and check we have 1 element and can dump.
   {
     rt.Add(o1);
     EXPECT_EQ(1U, rt.Size());
     std::ostringstream oss;
     rt.Dump(oss);
     EXPECT_NE(oss.str().find("1 of java.lang.String"), std::string::npos) << oss.str();
     EXPECT_EQ(oss.str().find("short[]"), std::string::npos) << oss.str();
   }

   // Add a second object 10 times and check dumping is sane.
   mirror::Object* o2 = mirror::ShortArray::Alloc(soa.Self(), 0);
   for (size_t i = 0; i < 10; ++i) {
     rt.Add(o2);
     EXPECT_EQ(i + 2, rt.Size());
     std::ostringstream oss;
     rt.Dump(oss);
     EXPECT_NE(oss.str().find(StringPrintf("Last %zd entries (of %zd):",
                                           i + 2 > 10 ? 10 : i + 2,
                                           i + 2)),
               std::string::npos) << oss.str();
     EXPECT_NE(oss.str().find("1 of java.lang.String"), std::string::npos) << oss.str();
     if (i == 0) {
       EXPECT_NE(oss.str().find("1 of short[]"), std::string::npos) << oss.str();
     } else {
       EXPECT_NE(oss.str().find(StringPrintf("%zd of short[] (1 unique instances)", i + 1)),
                 std::string::npos) << oss.str();
     }
   }

   // Remove o1 (first element).
   {
     rt.Remove(o1);
     EXPECT_EQ(10U, rt.Size());
     std::ostringstream oss;
     rt.Dump(oss);
     EXPECT_EQ(oss.str().find("java.lang.String"), std::string::npos) << oss.str();
   }

   // Remove o2 ten times.
   for (size_t i = 0; i < 10; ++i) {
     rt.Remove(o2);
     EXPECT_EQ(9 - i, rt.Size());
     std::ostringstream oss;
     rt.Dump(oss);
     if (i == 9) {
       EXPECT_EQ(oss.str().find("short[]"), std::string::npos) << oss.str();
     } else if (i == 8) {
       EXPECT_NE(oss.str().find("1 of short[]"), std::string::npos) << oss.str();
     } else {
       EXPECT_NE(oss.str().find(StringPrintf("%zd of short[] (1 unique instances)", 10 - i - 1)),
                 std::string::npos) << oss.str();
     }
   }

   // Add a reference and check that the type of the referent is dumped.
   {
     mirror::Object* empty_reference = CreateWeakReference(nullptr);
     ASSERT_TRUE(empty_reference->IsReferenceInstance());
     rt.Add(empty_reference);
     std::ostringstream oss;
     rt.Dump(oss);
     EXPECT_NE(oss.str().find("java.lang.ref.WeakReference (referent is null)"), std::string::npos)
         << oss.str();
     rt.Remove(empty_reference);
   }

   {
     mirror::Object* string_referent = mirror::String::AllocFromModifiedUtf8(Thread::Current(), "A");
     mirror::Object* non_empty_reference = CreateWeakReference(string_referent);
     ASSERT_TRUE(non_empty_reference->IsReferenceInstance());
     rt.Add(non_empty_reference);
     std::ostringstream oss;
     rt.Dump(oss);
     EXPECT_NE(oss.str().find("java.lang.ref.WeakReference (referent is a java.lang.String)"),
               std::string::npos)
         << oss.str();
     rt.Remove(non_empty_reference);
   }

   // Add two objects. Enable allocation tracking for the latter.
   {
     StackHandleScope<3> hs(soa.Self());
     Handle<mirror::String> h_without_trace(hs.NewHandle(
         mirror::String::AllocFromModifiedUtf8(soa.Self(), "Without")));

     {
       ScopedThreadSuspension sts(soa.Self(), ThreadState::kSuspended);
       gc::AllocRecordObjectMap::SetAllocTrackingEnabled(true);
     }

     // To get a stack, actually make a call. Use substring, that's simple. Calling through JNI
     // avoids having to create the low-level args array ourselves.
     Handle<mirror::Object> h_with_trace;
     {
       jmethodID substr = soa.Env()->GetMethodID(WellKnownClasses::java_lang_String,
                                                 "substring",
                                                 "(II)Ljava/lang/String;");
       ASSERT_TRUE(substr != nullptr);
       jobject jobj = soa.Env()->AddLocalReference<jobject>(h_without_trace.Get());
       ASSERT_TRUE(jobj != nullptr);
       jobject result = soa.Env()->CallObjectMethod(jobj,
                                                    substr,
                                                    static_cast<jint>(0),
                                                    static_cast<jint>(4));
       ASSERT_TRUE(result != nullptr);
       h_with_trace = hs.NewHandle(soa.Self()->DecodeJObject(result));
     }

     Handle<mirror::Object> h_ref;
     {
       jclass weak_ref_class = soa.Env()->FindClass("java/lang/ref/WeakReference");
       ASSERT_TRUE(weak_ref_class != nullptr);
       jmethodID init = soa.Env()->GetMethodID(weak_ref_class,
                                               "<init>",
                                               "(Ljava/lang/Object;)V");
       ASSERT_TRUE(init != nullptr);
       jobject referent = soa.Env()->AddLocalReference<jobject>(h_with_trace.Get());
       jobject result = soa.Env()->NewObject(weak_ref_class, init, referent);
       ASSERT_TRUE(result != nullptr);
       h_ref = hs.NewHandle(soa.Self()->DecodeJObject(result));
     }

     rt.Add(h_without_trace.Get());
     rt.Add(h_with_trace.Get());
     rt.Add(h_ref.Get());

     std::ostringstream oss;
     rt.Dump(oss);

     constexpr const char* kStackTracePattern =
         R"(test reference table dump:\n)"
         R"(  Last 3 entries \(of 3\):\n)"  // NOLINT
         R"(        2: 0x[0-9a-f]* java.lang.ref.WeakReference \(referent is a java.lang.String\)\n)"  // NOLINT
         R"(          Allocated at:\n)"
         R"(            \(No managed frames\)\n)"  // NOLINT
         R"(          Referent allocated at:\n)"
         R"(            java.lang.String java.lang.String.fastSubstring\(int, int\):-2\n)"  // NOLINT
         R"(            java.lang.String java.lang.String.substring\(int, int\):[0-9]*\n)"  // NOLINT
         R"(        1: 0x[0-9a-f]* java.lang.String "With"\n)"
         R"(          Allocated at:\n)"
         R"(            java.lang.String java.lang.String.fastSubstring\(int, int\):-2\n)"  // NOLINT
         R"(            java.lang.String java.lang.String.substring\(int, int\):[0-9]*\n)"  // NOLINT
         R"(        0: 0x[0-9a-f]* java.lang.String "Without"\n)"
         R"(  Summary:\n)"
         R"(        2 of java.lang.String \(2 unique instances\)\n)"  // NOLINT
         R"(        1 of java.lang.ref.WeakReference\n)";
     std::regex stack_trace_regex(kStackTracePattern);
     std::smatch stack_trace_match;
     std::string str = oss.str();
     bool found = std::regex_search(str, stack_trace_match, stack_trace_regex);
     EXPECT_TRUE(found) << str;

     {
       ScopedThreadSuspension sts(soa.Self(), ThreadState::kSuspended);
       gc::AllocRecordObjectMap::SetAllocTrackingEnabled(false);
     }
   }
 }

 static std::vector<size_t> FindAll(const std::string& haystack, const char* needle) {
   std::vector<size_t> res;
   size_t start = 0;
   do {
     size_t pos = haystack.find(needle, start);
     if (pos == std::string::npos) {
       break;
     }
     res.push_back(pos);
     start = pos + 1;
   } while (start < haystack.size());
   return res;
 }

 TEST_F(ReferenceTableTest, SummaryOrder) {
   // Check that the summary statistics are sorted.
   ScopedObjectAccess soa(Thread::Current());

   ReferenceTable rt("test", 0, 20);

   {
     mirror::Object* s1 = mirror::String::AllocFromModifiedUtf8(soa.Self(), "hello");
     mirror::Object* s2 = mirror::String::AllocFromModifiedUtf8(soa.Self(), "world");

     // 3 copies of s1, 2 copies of s2, interleaved.
     for (size_t i = 0; i != 2; ++i) {
       rt.Add(s1);
       rt.Add(s2);
     }
     rt.Add(s1);
   }

   {
     // Differently sized byte arrays. Should be sorted by identical (non-unique cound).
     mirror::Object* b1_1 = mirror::ByteArray::Alloc(soa.Self(), 1);
     rt.Add(b1_1);
     rt.Add(mirror::ByteArray::Alloc(soa.Self(), 2));
     rt.Add(b1_1);
     rt.Add(mirror::ByteArray::Alloc(soa.Self(), 2));
     rt.Add(mirror::ByteArray::Alloc(soa.Self(), 1));
     rt.Add(mirror::ByteArray::Alloc(soa.Self(), 2));
   }

   rt.Add(mirror::CharArray::Alloc(soa.Self(), 0));

   // Now dump, and ensure order.
   std::ostringstream oss;
   rt.Dump(oss);

   // Only do this on the part after Summary.
   std::string base = oss.str();
   size_t summary_pos = base.find("Summary:");
   ASSERT_NE(summary_pos, std::string::npos);

   std::string haystack = base.substr(summary_pos);

   std::vector<size_t> strCounts = FindAll(haystack, "java.lang.String");
   std::vector<size_t> b1Counts = FindAll(haystack, "byte[] (1 elements)");
   std::vector<size_t> b2Counts = FindAll(haystack, "byte[] (2 elements)");
   std::vector<size_t> cCounts = FindAll(haystack, "char[]");

   // Only one each.
   EXPECT_EQ(1u, strCounts.size());
   EXPECT_EQ(1u, b1Counts.size());
   EXPECT_EQ(1u, b2Counts.size());
   EXPECT_EQ(1u, cCounts.size());

   // Expect them to be in order.
   EXPECT_LT(strCounts[0], b1Counts[0]);
   EXPECT_LT(b1Counts[0], b2Counts[0]);
   EXPECT_LT(b2Counts[0], cCounts[0]);
 }

 }  // namespace art
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "reference_table.h"

	#include <regex> // NOLINT [build/c++11] [5]

	#include "android-base/stringprintf.h"

	#include "art_method-inl.h"
	#include "class_linker.h"
	#include "common_runtime_test.h"
	#include "handle_scope-inl.h"
	#include "mirror/array-inl.h"
	#include "mirror/class-inl.h"
	#include "mirror/class_loader.h"
	#include "mirror/string.h"
	#include "primitive.h"
	#include "runtime.h"
	#include "scoped_thread_state_change-inl.h"
	#include "thread-current-inl.h"
	#include "well_known_classes.h"

	namespace art {

	using android::base::StringPrintf;

	class ReferenceTableTest : public CommonRuntimeTest {};

	static mirror::Object* CreateWeakReference(mirror::Object* referent)
	REQUIRES_SHARED(Locks::mutator_lock_) {
	Thread* self = Thread::Current();
	ClassLinker* class_linker = Runtime::Current()->GetClassLinker();

	StackHandleScope<3> scope(self);
	Handle<mirror::Object> h_referent(scope.NewHandle<mirror::Object>(referent));

	Handle<mirror::Class> h_ref_class(scope.NewHandle<mirror::Class>(
	class_linker->FindClass(self,
	"Ljava/lang/ref/WeakReference;",
	ScopedNullHandle<mirror::ClassLoader>())));
	CHECK(h_ref_class != nullptr);
	CHECK(class_linker->EnsureInitialized(self, h_ref_class, true, true));

	Handle<mirror::Object> h_ref_instance(scope.NewHandle<mirror::Object>(
	h_ref_class->AllocObject(self)));
	CHECK(h_ref_instance != nullptr);

	ArtMethod* constructor = h_ref_class->FindConstructor(
	"(Ljava/lang/Object;)V", class_linker->GetImagePointerSize());
	CHECK(constructor != nullptr);

	uint32_t args[2];
	args[0] = PointerToLowMemUInt32(h_ref_instance.Get());
	args[1] = PointerToLowMemUInt32(h_referent.Get());
	JValue result;
	constructor->Invoke(self, args, sizeof(uint32_t), &result, constructor->GetShorty());
	CHECK(!self->IsExceptionPending());

	return h_ref_instance.Get();
	}

	TEST_F(ReferenceTableTest, Basics) {
	ScopedObjectAccess soa(Thread::Current());
	mirror::Object* o1 = mirror::String::AllocFromModifiedUtf8(soa.Self(), "hello");

	ReferenceTable rt("test", 0, 11);

	// Check dumping the empty table.
	{
	std::ostringstream oss;
	rt.Dump(oss);
	EXPECT_NE(oss.str().find("(empty)"), std::string::npos) << oss.str();
	EXPECT_EQ(0U, rt.Size());
	}

	// Check removal of all nullss in a empty table is a no-op.
	rt.Remove(nullptr);
	EXPECT_EQ(0U, rt.Size());

	// Check removal of all o1 in a empty table is a no-op.
	rt.Remove(o1);
	EXPECT_EQ(0U, rt.Size());

	// Add o1 and check we have 1 element and can dump.
	{
	rt.Add(o1);
	EXPECT_EQ(1U, rt.Size());
	std::ostringstream oss;
	rt.Dump(oss);
	EXPECT_NE(oss.str().find("1 of java.lang.String"), std::string::npos) << oss.str();
	EXPECT_EQ(oss.str().find("short[]"), std::string::npos) << oss.str();
	}

	// Add a second object 10 times and check dumping is sane.
	mirror::Object* o2 = mirror::ShortArray::Alloc(soa.Self(), 0);
	for (size_t i = 0; i < 10; ++i) {
	rt.Add(o2);
	EXPECT_EQ(i + 2, rt.Size());
	std::ostringstream oss;
	rt.Dump(oss);
	EXPECT_NE(oss.str().find(StringPrintf("Last %zd entries (of %zd):",
	i + 2 > 10 ? 10 : i + 2,
	i + 2)),
	std::string::npos) << oss.str();
	EXPECT_NE(oss.str().find("1 of java.lang.String"), std::string::npos) << oss.str();
	if (i == 0) {
	EXPECT_NE(oss.str().find("1 of short[]"), std::string::npos) << oss.str();
	} else {
	EXPECT_NE(oss.str().find(StringPrintf("%zd of short[] (1 unique instances)", i + 1)),
	std::string::npos) << oss.str();
	}
	}

	// Remove o1 (first element).
	{
	rt.Remove(o1);
	EXPECT_EQ(10U, rt.Size());
	std::ostringstream oss;
	rt.Dump(oss);
	EXPECT_EQ(oss.str().find("java.lang.String"), std::string::npos) << oss.str();
	}

	// Remove o2 ten times.
	for (size_t i = 0; i < 10; ++i) {
	rt.Remove(o2);
	EXPECT_EQ(9 - i, rt.Size());
	std::ostringstream oss;
	rt.Dump(oss);
	if (i == 9) {
	EXPECT_EQ(oss.str().find("short[]"), std::string::npos) << oss.str();
	} else if (i == 8) {
	EXPECT_NE(oss.str().find("1 of short[]"), std::string::npos) << oss.str();
	} else {
	EXPECT_NE(oss.str().find(StringPrintf("%zd of short[] (1 unique instances)", 10 - i - 1)),
	std::string::npos) << oss.str();
	}
	}

	// Add a reference and check that the type of the referent is dumped.
	{
	mirror::Object* empty_reference = CreateWeakReference(nullptr);
	ASSERT_TRUE(empty_reference->IsReferenceInstance());
	rt.Add(empty_reference);
	std::ostringstream oss;
	rt.Dump(oss);
	EXPECT_NE(oss.str().find("java.lang.ref.WeakReference (referent is null)"), std::string::npos)
	<< oss.str();
	rt.Remove(empty_reference);
	}

	{
	mirror::Object* string_referent = mirror::String::AllocFromModifiedUtf8(Thread::Current(), "A");
	mirror::Object* non_empty_reference = CreateWeakReference(string_referent);
	ASSERT_TRUE(non_empty_reference->IsReferenceInstance());
	rt.Add(non_empty_reference);
	std::ostringstream oss;
	rt.Dump(oss);
	EXPECT_NE(oss.str().find("java.lang.ref.WeakReference (referent is a java.lang.String)"),
	std::string::npos)
	<< oss.str();
	rt.Remove(non_empty_reference);
	}

	// Add two objects. Enable allocation tracking for the latter.
	{
	StackHandleScope<3> hs(soa.Self());
	Handle<mirror::String> h_without_trace(hs.NewHandle(
	mirror::String::AllocFromModifiedUtf8(soa.Self(), "Without")));

	{
	ScopedThreadSuspension sts(soa.Self(), ThreadState::kSuspended);
	gc::AllocRecordObjectMap::SetAllocTrackingEnabled(true);
	}

	// To get a stack, actually make a call. Use substring, that's simple. Calling through JNI
	// avoids having to create the low-level args array ourselves.
	Handle<mirror::Object> h_with_trace;
	{
	jmethodID substr = soa.Env()->GetMethodID(WellKnownClasses::java_lang_String,
	"substring",
	"(II)Ljava/lang/String;");
	ASSERT_TRUE(substr != nullptr);
	jobject jobj = soa.Env()->AddLocalReference<jobject>(h_without_trace.Get());
	ASSERT_TRUE(jobj != nullptr);
	jobject result = soa.Env()->CallObjectMethod(jobj,
	substr,
	static_cast<jint>(0),
	static_cast<jint>(4));
	ASSERT_TRUE(result != nullptr);
	h_with_trace = hs.NewHandle(soa.Self()->DecodeJObject(result));
	}

	Handle<mirror::Object> h_ref;
	{
	jclass weak_ref_class = soa.Env()->FindClass("java/lang/ref/WeakReference");
	ASSERT_TRUE(weak_ref_class != nullptr);
	jmethodID init = soa.Env()->GetMethodID(weak_ref_class,
	"<init>",
	"(Ljava/lang/Object;)V");
	ASSERT_TRUE(init != nullptr);
	jobject referent = soa.Env()->AddLocalReference<jobject>(h_with_trace.Get());
	jobject result = soa.Env()->NewObject(weak_ref_class, init, referent);
	ASSERT_TRUE(result != nullptr);
	h_ref = hs.NewHandle(soa.Self()->DecodeJObject(result));
	}

	rt.Add(h_without_trace.Get());
	rt.Add(h_with_trace.Get());
	rt.Add(h_ref.Get());

	std::ostringstream oss;
	rt.Dump(oss);

	constexpr const char* kStackTracePattern =
	R"(test reference table dump:\n)"
	R"( Last 3 entries \(of 3\):\n)" // NOLINT
	R"( 2: 0x[0-9a-f]* java.lang.ref.WeakReference \(referent is a java.lang.String\)\n)" // NOLINT
	R"( Allocated at:\n)"
	R"( \(No managed frames\)\n)" // NOLINT
	R"( Referent allocated at:\n)"
	R"( java.lang.String java.lang.String.fastSubstring\(int, int\):-2\n)" // NOLINT
	R"( java.lang.String java.lang.String.substring\(int, int\):[0-9]*\n)" // NOLINT
	R"( 1: 0x[0-9a-f]* java.lang.String "With"\n)"
	R"( Allocated at:\n)"
	R"( java.lang.String java.lang.String.fastSubstring\(int, int\):-2\n)" // NOLINT
	R"( java.lang.String java.lang.String.substring\(int, int\):[0-9]*\n)" // NOLINT
	R"( 0: 0x[0-9a-f]* java.lang.String "Without"\n)"
	R"( Summary:\n)"
	R"( 2 of java.lang.String \(2 unique instances\)\n)" // NOLINT
	R"( 1 of java.lang.ref.WeakReference\n)";
	std::regex stack_trace_regex(kStackTracePattern);
	std::smatch stack_trace_match;
	std::string str = oss.str();
	bool found = std::regex_search(str, stack_trace_match, stack_trace_regex);
	EXPECT_TRUE(found) << str;

	{
	ScopedThreadSuspension sts(soa.Self(), ThreadState::kSuspended);
	gc::AllocRecordObjectMap::SetAllocTrackingEnabled(false);
	}
	}
	}

	static std::vector<size_t> FindAll(const std::string& haystack, const char* needle) {
	std::vector<size_t> res;
	size_t start = 0;
	do {
	size_t pos = haystack.find(needle, start);
	if (pos == std::string::npos) {
	break;
	}
	res.push_back(pos);
	start = pos + 1;
	} while (start < haystack.size());
	return res;
	}

	TEST_F(ReferenceTableTest, SummaryOrder) {
	// Check that the summary statistics are sorted.
	ScopedObjectAccess soa(Thread::Current());

	ReferenceTable rt("test", 0, 20);

	{
	mirror::Object* s1 = mirror::String::AllocFromModifiedUtf8(soa.Self(), "hello");
	mirror::Object* s2 = mirror::String::AllocFromModifiedUtf8(soa.Self(), "world");

	// 3 copies of s1, 2 copies of s2, interleaved.
	for (size_t i = 0; i != 2; ++i) {
	rt.Add(s1);
	rt.Add(s2);
	}
	rt.Add(s1);
	}

	{
	// Differently sized byte arrays. Should be sorted by identical (non-unique cound).
	mirror::Object* b1_1 = mirror::ByteArray::Alloc(soa.Self(), 1);
	rt.Add(b1_1);
	rt.Add(mirror::ByteArray::Alloc(soa.Self(), 2));
	rt.Add(b1_1);
	rt.Add(mirror::ByteArray::Alloc(soa.Self(), 2));
	rt.Add(mirror::ByteArray::Alloc(soa.Self(), 1));
	rt.Add(mirror::ByteArray::Alloc(soa.Self(), 2));
	}

	rt.Add(mirror::CharArray::Alloc(soa.Self(), 0));

	// Now dump, and ensure order.
	std::ostringstream oss;
	rt.Dump(oss);

	// Only do this on the part after Summary.
	std::string base = oss.str();
	size_t summary_pos = base.find("Summary:");
	ASSERT_NE(summary_pos, std::string::npos);

	std::string haystack = base.substr(summary_pos);

	std::vector<size_t> strCounts = FindAll(haystack, "java.lang.String");
	std::vector<size_t> b1Counts = FindAll(haystack, "byte[] (1 elements)");
	std::vector<size_t> b2Counts = FindAll(haystack, "byte[] (2 elements)");
	std::vector<size_t> cCounts = FindAll(haystack, "char[]");

	// Only one each.
	EXPECT_EQ(1u, strCounts.size());
	EXPECT_EQ(1u, b1Counts.size());
	EXPECT_EQ(1u, b2Counts.size());
	EXPECT_EQ(1u, cCounts.size());

	// Expect them to be in order.
	EXPECT_LT(strCounts[0], b1Counts[0]);
	EXPECT_LT(b1Counts[0], b2Counts[0]);
	EXPECT_LT(b2Counts[0], cCounts[0]);
	}

	} // namespace art