1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_RUNTIME_BASE_DEBUG_STACK_H_
18#define ART_RUNTIME_BASE_DEBUG_STACK_H_
19
20#include "base/logging.h"
21#include "base/macros.h"
22#include "globals.h"
23
24namespace art {
25
26// Helper classes for reference counting to enforce construction/destruction order and
27// usage of the top element of a stack in debug mode with no overhead in release mode.
28
29// Reference counter. No references allowed in destructor or in explicitly called CheckNoRefs().
30template <bool kIsDebug>
31class DebugStackRefCounterImpl;
32// Reference. Allows an explicit check that it's the top reference.
33template <bool kIsDebug>
34class DebugStackReferenceImpl;
35// Indirect top reference. Checks that the reference is the top reference when used.
36template <bool kIsDebug>
37class DebugStackIndirectTopRefImpl;
38
39typedef DebugStackRefCounterImpl<kIsDebugBuild> DebugStackRefCounter;
40typedef DebugStackReferenceImpl<kIsDebugBuild> DebugStackReference;
41typedef DebugStackIndirectTopRefImpl<kIsDebugBuild> DebugStackIndirectTopRef;
42
43// Non-debug mode specializations. This should be optimized away.
44
45template <>
46class DebugStackRefCounterImpl<false> {
47 public:
48  size_t IncrementRefCount() { return 0u; }
49  void DecrementRefCount() { }
50  size_t GetRefCount() const { return 0u; }
51  void CheckNoRefs() const { }
52};
53
54template <>
55class DebugStackReferenceImpl<false> {
56 public:
57  explicit DebugStackReferenceImpl(DebugStackRefCounterImpl<false>* counter) { UNUSED(counter); }
58  DebugStackReferenceImpl(const DebugStackReferenceImpl& other) = default;
59  DebugStackReferenceImpl& operator=(const DebugStackReferenceImpl& other) = default;
60  void CheckTop() { }
61};
62
63template <>
64class DebugStackIndirectTopRefImpl<false> {
65 public:
66  explicit DebugStackIndirectTopRefImpl(DebugStackReferenceImpl<false>* ref) { UNUSED(ref); }
67  DebugStackIndirectTopRefImpl(const DebugStackIndirectTopRefImpl& other) = default;
68  DebugStackIndirectTopRefImpl& operator=(const DebugStackIndirectTopRefImpl& other) = default;
69  void CheckTop() { }
70};
71
72// Debug mode versions.
73
74template <bool kIsDebug>
75class DebugStackRefCounterImpl {
76 public:
77  DebugStackRefCounterImpl() : ref_count_(0u) { }
78  ~DebugStackRefCounterImpl() { CheckNoRefs(); }
79  size_t IncrementRefCount() { return ++ref_count_; }
80  void DecrementRefCount() { --ref_count_; }
81  size_t GetRefCount() const { return ref_count_; }
82  void CheckNoRefs() const { CHECK_EQ(ref_count_, 0u); }
83
84 private:
85  size_t ref_count_;
86};
87
88template <bool kIsDebug>
89class DebugStackReferenceImpl {
90 public:
91  explicit DebugStackReferenceImpl(DebugStackRefCounterImpl<kIsDebug>* counter)
92    : counter_(counter), ref_count_(counter->IncrementRefCount()) {
93  }
94  DebugStackReferenceImpl(const DebugStackReferenceImpl& other)
95    : counter_(other.counter_), ref_count_(counter_->IncrementRefCount()) {
96  }
97  DebugStackReferenceImpl& operator=(const DebugStackReferenceImpl& other) {
98    CHECK(counter_ == other.counter_);
99    return *this;
100  }
101  ~DebugStackReferenceImpl() { counter_->DecrementRefCount(); }
102  void CheckTop() { CHECK_EQ(counter_->GetRefCount(), ref_count_); }
103
104 private:
105  DebugStackRefCounterImpl<true>* counter_;
106  size_t ref_count_;
107};
108
109template <bool kIsDebug>
110class DebugStackIndirectTopRefImpl {
111 public:
112  explicit DebugStackIndirectTopRefImpl(DebugStackReferenceImpl<kIsDebug>* ref)
113      : ref_(ref) {
114    CheckTop();
115  }
116  DebugStackIndirectTopRefImpl(const DebugStackIndirectTopRefImpl& other)
117      : ref_(other.ref_) {
118    CheckTop();
119  }
120  DebugStackIndirectTopRefImpl& operator=(const DebugStackIndirectTopRefImpl& other) {
121    CHECK(ref_ == other.ref_);
122    CheckTop();
123    return *this;
124  }
125  ~DebugStackIndirectTopRefImpl() {
126    CheckTop();
127  }
128  void CheckTop() {
129    ref_->CheckTop();
130  }
131
132 private:
133  DebugStackReferenceImpl<kIsDebug>* ref_;
134};
135
136}  // namespace art
137
138#endif  // ART_RUNTIME_BASE_DEBUG_STACK_H_
139