1 files changed, 147 insertions, 0 deletions
diff --git a/libartbase/base/debug_stack.h b/libartbase/base/debug_stack.h
new file mode 100644
index 0000000000..f2d93d462a
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+++ b/libartbase/base/debug_stack.h
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#ifndef ART_LIBARTBASE_BASE_DEBUG_STACK_H_
+#define ART_LIBARTBASE_BASE_DEBUG_STACK_H_
+
+#include <android-base/logging.h>
+#include <android-base/macros.h>
+
+#include "globals.h"
+
+namespace art {
+
+// Helper classes for reference counting to enforce construction/destruction order and
+// usage of the top element of a stack in debug mode with no overhead in release mode.
+
+// Reference counter. No references allowed in destructor or in explicitly called CheckNoRefs().
+template <bool kIsDebug>
+class DebugStackRefCounterImpl;
+// Reference. Allows an explicit check that it's the top reference.
+template <bool kIsDebug>
+class DebugStackReferenceImpl;
+// Indirect top reference. Checks that the reference is the top reference when used.
+template <bool kIsDebug>
+class DebugStackIndirectTopRefImpl;
+
+typedef DebugStackRefCounterImpl<kIsDebugBuild> DebugStackRefCounter;
+typedef DebugStackReferenceImpl<kIsDebugBuild> DebugStackReference;
+typedef DebugStackIndirectTopRefImpl<kIsDebugBuild> DebugStackIndirectTopRef;
+
+// Non-debug mode specializations. This should be optimized away.
+
+template <>
+class DebugStackRefCounterImpl<false> {
+ public:
+  size_t IncrementRefCount() { return 0u; }
+  void DecrementRefCount() { }
+  size_t GetRefCount() const { return 0u; }
+  void CheckNoRefs() const { }
+};
+
+template <>
+class DebugStackReferenceImpl<false> {
+ public:
+  explicit DebugStackReferenceImpl(DebugStackRefCounterImpl<false>* counter ATTRIBUTE_UNUSED) {}
+  DebugStackReferenceImpl(const DebugStackReferenceImpl& other) = default;
+  DebugStackReferenceImpl& operator=(const DebugStackReferenceImpl& other) = default;
+  void CheckTop() { }
+};
+
+template <>
+class DebugStackIndirectTopRefImpl<false> {
+ public:
+  explicit DebugStackIndirectTopRefImpl(DebugStackReferenceImpl<false>* ref ATTRIBUTE_UNUSED) {}
+  DebugStackIndirectTopRefImpl(const DebugStackIndirectTopRefImpl& other) = default;
+  DebugStackIndirectTopRefImpl& operator=(const DebugStackIndirectTopRefImpl& other) = default;
+  void CheckTop() { }
+};
+
+// Debug mode versions.
+
+template <bool kIsDebug>
+class DebugStackRefCounterImpl {
+ public:
+  DebugStackRefCounterImpl() : ref_count_(0u) { }
+  ~DebugStackRefCounterImpl() { CheckNoRefs(); }
+  size_t IncrementRefCount() { return ++ref_count_; }
+  void DecrementRefCount() { --ref_count_; }
+  size_t GetRefCount() const { return ref_count_; }
+  void CheckNoRefs() const { CHECK_EQ(ref_count_, 0u); }
+
+ private:
+  size_t ref_count_;
+};
+
+template <bool kIsDebug>
+class DebugStackReferenceImpl {
+ public:
+  explicit DebugStackReferenceImpl(DebugStackRefCounterImpl<kIsDebug>* counter)
+    : counter_(counter), ref_count_(counter->IncrementRefCount()) {
+  }
+  DebugStackReferenceImpl(const DebugStackReferenceImpl& other)
+    : counter_(other.counter_), ref_count_(counter_->IncrementRefCount()) {
+  }
+  DebugStackReferenceImpl(DebugStackReferenceImpl&& other)
+    : counter_(other.counter_), ref_count_(other.ref_count_) {
+    other.counter_ = nullptr;
+  }
+  DebugStackReferenceImpl& operator=(const DebugStackReferenceImpl& other) {
+    CHECK(counter_ == other.counter_);
+    return *this;
+  }
+  ~DebugStackReferenceImpl() {
+    if (counter_ != nullptr) {
+      counter_->DecrementRefCount();
+    }
+  }
+  void CheckTop() { CHECK_EQ(counter_->GetRefCount(), ref_count_); }
+
+ private:
+  DebugStackRefCounterImpl<true>* counter_;
+  size_t ref_count_;
+};
+
+template <bool kIsDebug>
+class DebugStackIndirectTopRefImpl {
+ public:
+  explicit DebugStackIndirectTopRefImpl(DebugStackReferenceImpl<kIsDebug>* ref)
+      : ref_(ref) {
+    CheckTop();
+  }
+  DebugStackIndirectTopRefImpl(const DebugStackIndirectTopRefImpl& other)
+      : ref_(other.ref_) {
+    CheckTop();
+  }
+  DebugStackIndirectTopRefImpl& operator=(const DebugStackIndirectTopRefImpl& other) {
+    CHECK(ref_ == other.ref_);
+    CheckTop();
+    return *this;
+  }
+  ~DebugStackIndirectTopRefImpl() {
+    CheckTop();
+  }
+  void CheckTop() {
+    ref_->CheckTop();
+  }
+
+ private:
+  DebugStackReferenceImpl<kIsDebug>* ref_;
+};
+
+}  // namespace art
+
+#endif  // ART_LIBARTBASE_BASE_DEBUG_STACK_H_