/*
* Copyright (C) 2005 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 ANDROID_REF_BASE_H
#define ANDROID_REF_BASE_H
#include <cutils/atomic.h>
#include <stdint.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <utils/StrongPointer.h>
#include <utils/TypeHelpers.h>
// ---------------------------------------------------------------------------
namespace android {
class TextOutput;
TextOutput& printWeakPointer(TextOutput& to, const void* val);
// ---------------------------------------------------------------------------
#define COMPARE_WEAK(_op_) \
inline bool operator _op_ (const sp<T>& o) const { \
return m_ptr _op_ o.m_ptr; \
} \
inline bool operator _op_ (const T* o) const { \
return m_ptr _op_ o; \
} \
template<typename U> \
inline bool operator _op_ (const sp<U>& o) const { \
return m_ptr _op_ o.m_ptr; \
} \
template<typename U> \
inline bool operator _op_ (const U* o) const { \
return m_ptr _op_ o; \
}
// ---------------------------------------------------------------------------
class ReferenceRenamer {
protected:
// destructor is purposedly not virtual so we avoid code overhead from
// subclasses; we have to make it protected to guarantee that it
// cannot be called from this base class (and to make strict compilers
// happy).
~ReferenceRenamer() { }
public:
virtual void operator()(size_t i) const = 0;
};
// ---------------------------------------------------------------------------
class RefBase
{
public:
void incStrong(const void* id) const;
void decStrong(const void* id) const;
void forceIncStrong(const void* id) const;
//! DEBUGGING ONLY: Get current strong ref count.
int32_t getStrongCount() const;
class weakref_type
{
public:
RefBase* refBase() const;
void incWeak(const void* id);
void decWeak(const void* id);
// acquires a strong reference if there is already one.
bool attemptIncStrong(const void* id);
// acquires a weak reference if there is already one.
// This is not always safe. see ProcessState.cpp and BpBinder.cpp
// for proper use.
bool attemptIncWeak(const void* id);
//! DEBUGGING ONLY: Get current weak ref count.
int32_t getWeakCount() const;
//! DEBUGGING ONLY: Print references held on object.
void printRefs() const;
//! DEBUGGING ONLY: Enable tracking for this object.
// enable -- enable/disable tracking
// retain -- when tracking is enable, if true, then we save a stack trace
// for each reference and dereference; when retain == false, we
// match up references and dereferences and keep only the
// outstanding ones.
void trackMe(bool enable, bool retain);
};
weakref_type* createWeak(const void* id) const;
weakref_type* getWeakRefs() const;
//! DEBUGGING ONLY: Print references held on object.
inline void printRefs() const { getWeakRefs()->printRefs(); }
//! DEBUGGING ONLY: Enable tracking of object.
inline void trackMe(bool enable, bool retain)
{
getWeakRefs()->trackMe(enable, retain);
}
typedef RefBase basetype;
protected:
RefBase();
virtual ~RefBase();
//! Flags for extendObjectLifetime()
enum {
OBJECT_LIFETIME_STRONG = 0x0000,
OBJECT_LIFETIME_WEAK = 0x0001,
OBJECT_LIFETIME_MASK = 0x0001
};
void extendObjectLifetime(int32_t mode);
//! Flags for onIncStrongAttempted()
enum {
FIRST_INC_STRONG = 0x0001
};
virtual void onFirstRef();
virtual void onLastStrongRef(const void* id);
virtual bool onIncStrongAttempted(uint32_t flags, const void* id);
virtual void onLastWeakRef(const void* id);
private:
friend class weakref_type;
class weakref_impl;
RefBase(const RefBase& o);
RefBase& operator=(const RefBase& o);
private:
friend class ReferenceMover;
static void renameRefs(size_t n, const ReferenceRenamer& renamer);
static void renameRefId(weakref_type* ref,
const void* old_id, const void* new_id);
static void renameRefId(RefBase* ref,
const void* old_id, const void* new_id);
weakref_impl* const mRefs;
};
// ---------------------------------------------------------------------------
template <class T>
class LightRefBase
{
public:
inline LightRefBase() : mCount(0) { }
inline void incStrong(__attribute__((unused)) const void* id) const {
android_atomic_inc(&mCount);
}
inline void decStrong(__attribute__((unused)) const void* id) const {
if (android_atomic_dec(&mCount) == 1) {
delete static_cast<const T*>(this);
}
}
//! DEBUGGING ONLY: Get current strong ref count.
inline int32_t getStrongCount() const {
return mCount;
}
typedef LightRefBase<T> basetype;
protected:
inline ~LightRefBase() { }
private:
friend class ReferenceMover;
inline static void renameRefs(size_t n, const ReferenceRenamer& renamer) { }
inline static void renameRefId(T* ref,
const void* old_id, const void* new_id) { }
private:
mutable volatile int32_t mCount;
};
// This is a wrapper around LightRefBase that simply enforces a virtual
// destructor to eliminate the template requirement of LightRefBase
class VirtualLightRefBase : public LightRefBase<VirtualLightRefBase> {
public:
virtual ~VirtualLightRefBase() {}
};
// ---------------------------------------------------------------------------
template <typename T>
class wp
{
public:
typedef typename RefBase::weakref_type weakref_type;
inline wp() : m_ptr(0) { }
wp(T* other);
wp(const wp<T>& other);
wp(const sp<T>& other);
template<typename U> wp(U* other);
template<typename U> wp(const sp<U>& other);
template<typename U> wp(const wp<U>& other);
~wp();
// Assignment
wp& operator = (T* other);
wp& operator = (const wp<T>& other);
wp& operator = (const sp<T>& other);
template<typename U> wp& operator = (U* other);
template<typename U> wp& operator = (const wp<U>& other);
template<typename U> wp& operator = (const sp<U>& other);
void set_object_and_refs(T* other, weakref_type* refs);
// promotion to sp
sp<T> promote() const;
// Reset
void clear();
// Accessors
inline weakref_type* get_refs() const { return m_refs; }
inline T* unsafe_get() const { return m_ptr; }
// Operators
COMPARE_WEAK(==)
COMPARE_WEAK(!=)
COMPARE_WEAK(>)
COMPARE_WEAK(<)
COMPARE_WEAK(<=)
COMPARE_WEAK(>=)
inline bool operator == (const wp<T>& o) const {
return (m_ptr == o.m_ptr) && (m_refs == o.m_refs);
}
template<typename U>
inline bool operator == (const wp<U>& o) const {
return m_ptr == o.m_ptr;
}
inline bool operator > (const wp<T>& o) const {
return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
}
template<typename U>
inline bool operator > (const wp<U>& o) const {
return (m_ptr == o.m_ptr) ? (m_refs > o.m_refs) : (m_ptr > o.m_ptr);
}
inline bool operator < (const wp<T>& o) const {
return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
}
template<typename U>
inline bool operator < (const wp<U>& o) const {
return (m_ptr == o.m_ptr) ? (m_refs < o.m_refs) : (m_ptr < o.m_ptr);
}
inline bool operator != (const wp<T>& o) const { return m_refs != o.m_refs; }
template<typename U> inline bool operator != (const wp<U>& o) const { return !operator == (o); }
inline bool operator <= (const wp<T>& o) const { return !operator > (o); }
template<typename U> inline bool operator <= (const wp<U>& o) const { return !operator > (o); }
inline bool operator >= (const wp<T>& o) const { return !operator < (o); }
template<typename U> inline bool operator >= (const wp<U>& o) const { return !operator < (o); }
private:
template<typename Y> friend class sp;
template<typename Y> friend class wp;
T* m_ptr;
weakref_type* m_refs;
};
template <typename T>
TextOutput& operator<<(TextOutput& to, const wp<T>& val);
#undef COMPARE_WEAK
// ---------------------------------------------------------------------------
// No user serviceable parts below here.
template<typename T>
wp<T>::wp(T* other)
: m_ptr(other)
{
if (other) m_refs = other->createWeak(this);
}
template<typename T>
wp<T>::wp(const wp<T>& other)
: m_ptr(other.m_ptr), m_refs(other.m_refs)
{
if (m_ptr) m_refs->incWeak(this);
}
template<typename T>
wp<T>::wp(const sp<T>& other)
: m_ptr(other.m_ptr)
{
if (m_ptr) {
m_refs = m_ptr->createWeak(this);
}
}
template<typename T> template<typename U>
wp<T>::wp(U* other)
: m_ptr(other)
{
if (other) m_refs = other->createWeak(this);
}
template<typename T> template<typename U>
wp<T>::wp(const wp<U>& other)
: m_ptr(other.m_ptr)
{
if (m_ptr) {
m_refs = other.m_refs;
m_refs->incWeak(this);
}
}
template<typename T> template<typename U>
wp<T>::wp(const sp<U>& other)
: m_ptr(other.m_ptr)
{
if (m_ptr) {
m_refs = m_ptr->createWeak(this);
}
}
template<typename T>
wp<T>::~wp()
{
if (m_ptr) m_refs->decWeak(this);
}
template<typename T>
wp<T>& wp<T>::operator = (T* other)
{
weakref_type* newRefs =
other ? other->createWeak(this) : 0;
if (m_ptr) m_refs->decWeak(this);
m_ptr = other;
m_refs = newRefs;
return *this;
}
template<typename T>
wp<T>& wp<T>::operator = (const wp<T>& other)
{
weakref_type* otherRefs(other.m_refs);
T* otherPtr(other.m_ptr);
if (otherPtr) otherRefs->incWeak(this);
if (m_ptr) m_refs->decWeak(this);
m_ptr = otherPtr;
m_refs = otherRefs;
return *this;
}
template<typename T>
wp<T>& wp<T>::operator = (const sp<T>& other)
{
weakref_type* newRefs =
other != NULL ? other->createWeak(this) : 0;
T* otherPtr(other.m_ptr);
if (m_ptr) m_refs->decWeak(this);
m_ptr = otherPtr;
m_refs = newRefs;
return *this;
}
template<typename T> template<typename U>
wp<T>& wp<T>::operator = (U* other)
{
weakref_type* newRefs =
other ? other->createWeak(this) : 0;
if (m_ptr) m_refs->decWeak(this);
m_ptr = other;
m_refs = newRefs;
return *this;
}
template<typename T> template<typename U>
wp<T>& wp<T>::operator = (const wp<U>& other)
{
weakref_type* otherRefs(other.m_refs);
U* otherPtr(other.m_ptr);
if (otherPtr) otherRefs->incWeak(this);
if (m_ptr) m_refs->decWeak(this);
m_ptr = otherPtr;
m_refs = otherRefs;
return *this;
}
template<typename T> template<typename U>
wp<T>& wp<T>::operator = (const sp<U>& other)
{
weakref_type* newRefs =
other != NULL ? other->createWeak(this) : 0;
U* otherPtr(other.m_ptr);
if (m_ptr) m_refs->decWeak(this);
m_ptr = otherPtr;
m_refs = newRefs;
return *this;
}
template<typename T>
void wp<T>::set_object_and_refs(T* other, weakref_type* refs)
{
if (other) refs->incWeak(this);
if (m_ptr) m_refs->decWeak(this);
m_ptr = other;
m_refs = refs;
}
template<typename T>
sp<T> wp<T>::promote() const
{
sp<T> result;
if (m_ptr && m_refs->attemptIncStrong(&result)) {
result.set_pointer(m_ptr);
}
return result;
}
template<typename T>
void wp<T>::clear()
{
if (m_ptr) {
m_refs->decWeak(this);
m_ptr = 0;
}
}
template <typename T>
inline TextOutput& operator<<(TextOutput& to, const wp<T>& val)
{
return printWeakPointer(to, val.unsafe_get());
}
// ---------------------------------------------------------------------------
// this class just serves as a namespace so TYPE::moveReferences can stay
// private.
class ReferenceMover {
public:
// it would be nice if we could make sure no extra code is generated
// for sp<TYPE> or wp<TYPE> when TYPE is a descendant of RefBase:
// Using a sp<RefBase> override doesn't work; it's a bit like we wanted
// a template<typename TYPE inherits RefBase> template...
template<typename TYPE> static inline
void move_references(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
class Renamer : public ReferenceRenamer {
sp<TYPE>* d;
sp<TYPE> const* s;
virtual void operator()(size_t i) const {
// The id are known to be the sp<>'s this pointer
TYPE::renameRefId(d[i].get(), &s[i], &d[i]);
}
public:
Renamer(sp<TYPE>* d, sp<TYPE> const* s) : s(s), d(d) { }
};
memmove(d, s, n*sizeof(sp<TYPE>));
TYPE::renameRefs(n, Renamer(d, s));
}
template<typename TYPE> static inline
void move_references(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
class Renamer : public ReferenceRenamer {
wp<TYPE>* d;
wp<TYPE> const* s;
virtual void operator()(size_t i) const {
// The id are known to be the wp<>'s this pointer
TYPE::renameRefId(d[i].get_refs(), &s[i], &d[i]);
}
public:
Renamer(wp<TYPE>* d, wp<TYPE> const* s) : s(s), d(d) { }
};
memmove(d, s, n*sizeof(wp<TYPE>));
TYPE::renameRefs(n, Renamer(d, s));
}
};
// specialization for moving sp<> and wp<> types.
// these are used by the [Sorted|Keyed]Vector<> implementations
// sp<> and wp<> need to be handled specially, because they do not
// have trivial copy operation in the general case (see RefBase.cpp
// when DEBUG ops are enabled), but can be implemented very
// efficiently in most cases.
template<typename TYPE> inline
void move_forward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
ReferenceMover::move_references(d, s, n);
}
template<typename TYPE> inline
void move_backward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
ReferenceMover::move_references(d, s, n);
}
template<typename TYPE> inline
void move_forward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
ReferenceMover::move_references(d, s, n);
}
template<typename TYPE> inline
void move_backward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
ReferenceMover::move_references(d, s, n);
}
}; // namespace android
// ---------------------------------------------------------------------------
#endif // ANDROID_REF_BASE_H