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/*
* 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_
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