skia2/include/core/SkRefCnt.h

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/*
Automatic update of all copyright notices to reflect new license terms. I have manually examined all of these diffs and restored a few files that seem to require manual adjustment. The following files still need to be modified manually, in a separate CL: android_sample/SampleApp/AndroidManifest.xml android_sample/SampleApp/res/layout/layout.xml android_sample/SampleApp/res/menu/sample.xml android_sample/SampleApp/res/values/strings.xml android_sample/SampleApp/src/com/skia/sampleapp/SampleApp.java android_sample/SampleApp/src/com/skia/sampleapp/SampleView.java experimental/CiCarbonSampleMain.c experimental/CocoaDebugger/main.m experimental/FileReaderApp/main.m experimental/SimpleCocoaApp/main.m experimental/iOSSampleApp/Shared/SkAlertPrompt.h experimental/iOSSampleApp/Shared/SkAlertPrompt.m experimental/iOSSampleApp/SkiOSSampleApp-Base.xcconfig experimental/iOSSampleApp/SkiOSSampleApp-Debug.xcconfig experimental/iOSSampleApp/SkiOSSampleApp-Release.xcconfig gpu/src/android/GrGLDefaultInterface_android.cpp gyp/common.gypi gyp_skia include/ports/SkHarfBuzzFont.h include/views/SkOSWindow_wxwidgets.h make.bat make.py src/opts/memset.arm.S src/opts/memset16_neon.S src/opts/memset32_neon.S src/opts/opts_check_arm.cpp src/ports/SkDebug_brew.cpp src/ports/SkMemory_brew.cpp src/ports/SkOSFile_brew.cpp src/ports/SkXMLParser_empty.cpp src/utils/ios/SkImageDecoder_iOS.mm src/utils/ios/SkOSFile_iOS.mm src/utils/ios/SkStream_NSData.mm tests/FillPathTest.cpp Review URL: http://codereview.appspot.com/4816058 git-svn-id: http://skia.googlecode.com/svn/trunk@1982 2bbb7eff-a529-9590-31e7-b0007b416f81
2011-07-28 14:26:00 +00:00
* Copyright 2006 The Android Open Source Project
*
Automatic update of all copyright notices to reflect new license terms. I have manually examined all of these diffs and restored a few files that seem to require manual adjustment. The following files still need to be modified manually, in a separate CL: android_sample/SampleApp/AndroidManifest.xml android_sample/SampleApp/res/layout/layout.xml android_sample/SampleApp/res/menu/sample.xml android_sample/SampleApp/res/values/strings.xml android_sample/SampleApp/src/com/skia/sampleapp/SampleApp.java android_sample/SampleApp/src/com/skia/sampleapp/SampleView.java experimental/CiCarbonSampleMain.c experimental/CocoaDebugger/main.m experimental/FileReaderApp/main.m experimental/SimpleCocoaApp/main.m experimental/iOSSampleApp/Shared/SkAlertPrompt.h experimental/iOSSampleApp/Shared/SkAlertPrompt.m experimental/iOSSampleApp/SkiOSSampleApp-Base.xcconfig experimental/iOSSampleApp/SkiOSSampleApp-Debug.xcconfig experimental/iOSSampleApp/SkiOSSampleApp-Release.xcconfig gpu/src/android/GrGLDefaultInterface_android.cpp gyp/common.gypi gyp_skia include/ports/SkHarfBuzzFont.h include/views/SkOSWindow_wxwidgets.h make.bat make.py src/opts/memset.arm.S src/opts/memset16_neon.S src/opts/memset32_neon.S src/opts/opts_check_arm.cpp src/ports/SkDebug_brew.cpp src/ports/SkMemory_brew.cpp src/ports/SkOSFile_brew.cpp src/ports/SkXMLParser_empty.cpp src/utils/ios/SkImageDecoder_iOS.mm src/utils/ios/SkOSFile_iOS.mm src/utils/ios/SkStream_NSData.mm tests/FillPathTest.cpp Review URL: http://codereview.appspot.com/4816058 git-svn-id: http://skia.googlecode.com/svn/trunk@1982 2bbb7eff-a529-9590-31e7-b0007b416f81
2011-07-28 14:26:00 +00:00
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkRefCnt_DEFINED
#define SkRefCnt_DEFINED
#include "../private/SkTLogic.h"
#include "SkTypes.h"
#include <atomic>
#include <functional>
#include <memory>
#include <type_traits>
#include <utility>
/** \class SkRefCntBase
SkRefCntBase is the base class for objects that may be shared by multiple
objects. When an existing owner wants to share a reference, it calls ref().
When an owner wants to release its reference, it calls unref(). When the
shared object's reference count goes to zero as the result of an unref()
call, its (virtual) destructor is called. It is an error for the
destructor to be called explicitly (or via the object going out of scope on
the stack or calling delete) if getRefCnt() > 1.
*/
class SK_API SkRefCntBase : SkNoncopyable {
public:
/** Default construct, initializing the reference count to 1.
*/
SkRefCntBase() : fRefCnt(1) {}
/** Destruct, asserting that the reference count is 1.
*/
virtual ~SkRefCntBase() {
#ifdef SK_DEBUG
SkASSERTF(getRefCnt() == 1, "fRefCnt was %d", getRefCnt());
// illegal value, to catch us if we reuse after delete
fRefCnt.store(0, std::memory_order_relaxed);
#endif
}
#ifdef SK_DEBUG
/** Return the reference count. Use only for debugging. */
int32_t getRefCnt() const {
return fRefCnt.load(std::memory_order_relaxed);
}
void validate() const {
SkASSERT(getRefCnt() > 0);
}
#endif
/** May return true if the caller is the only owner.
* Ensures that all previous owner's actions are complete.
*/
bool unique() const {
if (1 == fRefCnt.load(std::memory_order_acquire)) {
// The acquire barrier is only really needed if we return true. It
// prevents code conditioned on the result of unique() from running
// until previous owners are all totally done calling unref().
return true;
}
return false;
}
/** Increment the reference count. Must be balanced by a call to unref().
*/
void ref() const {
SkASSERT(getRefCnt() > 0);
// No barrier required.
(void)fRefCnt.fetch_add(+1, std::memory_order_relaxed);
}
/** Decrement the reference count. If the reference count is 1 before the
decrement, then delete the object. Note that if this is the case, then
the object needs to have been allocated via new, and not on the stack.
*/
void unref() const {
SkASSERT(getRefCnt() > 0);
// A release here acts in place of all releases we "should" have been doing in ref().
if (1 == fRefCnt.fetch_add(-1, std::memory_order_acq_rel)) {
// Like unique(), the acquire is only needed on success, to make sure
// code in internal_dispose() doesn't happen before the decrement.
this->internal_dispose();
}
}
protected:
/**
* Allow subclasses to call this if they've overridden internal_dispose
SkLite* SkLiteRecorder, a new SkCanvas, fills out SkLiteDL, a new SkDrawable. This SkDrawable is a display list similar to SkRecord and SkBigPicture / SkRecordedDrawable, but with a few new design points inspired by Android and slimming paint: 1) SkLiteDL is structured as one big contiguous array rather than the two layer structure of SkRecord. This trades away flexibility and large-op-count performance for better data locality for small to medium size pictures. 2) We keep a global freelist of SkLiteDLs, both reusing the SkLiteDL struct itself and its contiguous byte array. This keeps the expected number of mallocs per display list allocation <1 (really, ~0) for cyclical use cases. These two together mean recording is faster. Measuring against the code we use at head, SkLiteRecorder trends about ~3x faster across various size pictures, matching speed at 0 draws and beating the special-case 1-draw pictures we have today. (I.e. we won't need those special case implementations anymore, because they're slower than this new generic code.) This new strategy records 10 drawRects() in about the same time the old strategy took for 2. This strategy stays the winner until at least 500 drawRect()s on my laptop, where I stopped checking. A simpler alternative to freelisting is also possible (but not implemented here), where we allow the client to manually reset() an SkLiteDL for reuse when its refcnt is 1. That's essentially what we're doing with the freelist, except tracking what's available for reuse globally instead of making the client do it. This code is not fully capable yet, but most of the key design points are there. The internal structure of SkLiteDL is the area I expect to be most volatile (anything involving Op), but its interface and the whole of SkLiteRecorder ought to be just about done. You can run nanobench --match picture_overhead as a demo. Everything it exercises is fully fleshed out, so what it tests is an apples-to-apples comparison as far as recording costs go. I have not yet compared playback performance. It should be simple to wrap this into an SkPicture subclass if we want. I won't start proposing we replace anything old with anything new quite yet until I have more ducks in a row, but this does look pretty promising (similar to the SkRecord over old SkPicture change a couple years ago) and I'd like to land, experiment, iterate, especially with an eye toward Android. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2213333002 Review-Url: https://codereview.chromium.org/2213333002
2016-08-06 19:51:51 +00:00
* so they can reset fRefCnt before the destructor is called or if they
* choose not to call the destructor (e.g. using a free list).
*/
void internal_dispose_restore_refcnt_to_1() const {
SkASSERT(0 == getRefCnt());
fRefCnt.store(1, std::memory_order_relaxed);
}
private:
/**
* Called when the ref count goes to 0.
*/
virtual void internal_dispose() const {
this->internal_dispose_restore_refcnt_to_1();
delete this;
}
// The following friends are those which override internal_dispose()
// and conditionally call SkRefCnt::internal_dispose().
friend class SkWeakRefCnt;
mutable std::atomic<int32_t> fRefCnt;
typedef SkNoncopyable INHERITED;
};
#ifdef SK_REF_CNT_MIXIN_INCLUDE
// It is the responsibility of the following include to define the type SkRefCnt.
// This SkRefCnt should normally derive from SkRefCntBase.
#include SK_REF_CNT_MIXIN_INCLUDE
#else
class SK_API SkRefCnt : public SkRefCntBase {
// "#include SK_REF_CNT_MIXIN_INCLUDE" doesn't work with this build system.
#if defined(SK_BUILD_FOR_GOOGLE3)
public:
void deref() const { this->unref(); }
#endif
};
#endif
///////////////////////////////////////////////////////////////////////////////
/** Helper macro to safely assign one SkRefCnt[TS]* to another, checking for
null in on each side of the assignment, and ensuring that ref() is called
before unref(), in case the two pointers point to the same object.
*/
#if defined(SK_BUILD_FOR_ANDROID_FRAMEWORK)
// This version heuristically detects data races, since those otherwise result
// in redundant reference count decrements, which are exceedingly
// difficult to debug.
#define SkRefCnt_SafeAssign(dst, src) \
do { \
typedef typename std::remove_reference<decltype(dst)>::type \
SkRefCntPtrT; \
SkRefCntPtrT old_dst = *const_cast<SkRefCntPtrT volatile *>(&dst); \
if (src) src->ref(); \
if (old_dst) old_dst->unref(); \
if (old_dst != *const_cast<SkRefCntPtrT volatile *>(&dst)) { \
SkDebugf("Detected racing Skia calls at %s:%d\n", \
__FILE__, __LINE__); \
} \
dst = src; \
} while (0)
#else /* !SK_BUILD_FOR_ANDROID_FRAMEWORK */
#define SkRefCnt_SafeAssign(dst, src) \
do { \
if (src) src->ref(); \
if (dst) dst->unref(); \
dst = src; \
} while (0)
#endif
/** Call obj->ref() and return obj. The obj must not be nullptr.
*/
template <typename T> static inline T* SkRef(T* obj) {
SkASSERT(obj);
obj->ref();
return obj;
}
/** Check if the argument is non-null, and if so, call obj->ref() and return obj.
*/
template <typename T> static inline T* SkSafeRef(T* obj) {
if (obj) {
obj->ref();
}
return obj;
}
/** Check if the argument is non-null, and if so, call obj->unref()
*/
template <typename T> static inline void SkSafeUnref(T* obj) {
if (obj) {
obj->unref();
}
}
template<typename T> static inline void SkSafeSetNull(T*& obj) {
if (obj) {
obj->unref();
obj = nullptr;
}
}
///////////////////////////////////////////////////////////////////////////////
// This is a variant of SkRefCnt that's Not Virtual, so weighs 4 bytes instead of 8 or 16.
// There's only benefit to using this if the deriving class does not otherwise need a vtable.
template <typename Derived>
class SkNVRefCnt : SkNoncopyable {
public:
SkNVRefCnt() : fRefCnt(1) {}
~SkNVRefCnt() { SkASSERTF(1 == getRefCnt(), "NVRefCnt was %d", getRefCnt()); }
// Implementation is pretty much the same as SkRefCntBase. All required barriers are the same:
// - unique() needs acquire when it returns true, and no barrier if it returns false;
// - ref() doesn't need any barrier;
// - unref() needs a release barrier, and an acquire if it's going to call delete.
bool unique() const { return 1 == fRefCnt.load(std::memory_order_acquire); }
void ref() const { (void)fRefCnt.fetch_add(+1, std::memory_order_relaxed); }
void unref() const {
if (1 == fRefCnt.fetch_add(-1, std::memory_order_acq_rel)) {
// restore the 1 for our destructor's assert
SkDEBUGCODE(fRefCnt.store(1, std::memory_order_relaxed));
delete (const Derived*)this;
}
}
void deref() const { this->unref(); }
private:
mutable std::atomic<int32_t> fRefCnt;
int32_t getRefCnt() const {
return fRefCnt.load(std::memory_order_relaxed);
}
};
///////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Shared pointer class to wrap classes that support a ref()/unref() interface.
*
* This can be used for classes inheriting from SkRefCnt, but it also works for other
* classes that match the interface, but have different internal choices: e.g. the hosted class
* may have its ref/unref be thread-safe, but that is not assumed/imposed by sk_sp.
*/
template <typename T> class sk_sp {
/** Supports safe bool idiom. Obsolete with explicit operator bool. */
using unspecified_bool_type = T* sk_sp::*;
public:
using element_type = T;
constexpr sk_sp() : fPtr(nullptr) {}
constexpr sk_sp(std::nullptr_t) : fPtr(nullptr) {}
/**
* Shares the underlying object by calling ref(), so that both the argument and the newly
* created sk_sp both have a reference to it.
*/
sk_sp(const sk_sp<T>& that) : fPtr(SkSafeRef(that.get())) {}
template <typename U, typename = skstd::enable_if_t<std::is_convertible<U*, T*>::value>>
sk_sp(const sk_sp<U>& that) : fPtr(SkSafeRef(that.get())) {}
/**
* Move the underlying object from the argument to the newly created sk_sp. Afterwards only
* the new sk_sp will have a reference to the object, and the argument will point to null.
* No call to ref() or unref() will be made.
*/
sk_sp(sk_sp<T>&& that) : fPtr(that.release()) {}
template <typename U, typename = skstd::enable_if_t<std::is_convertible<U*, T*>::value>>
sk_sp(sk_sp<U>&& that) : fPtr(that.release()) {}
/**
* Adopt the bare pointer into the newly created sk_sp.
* No call to ref() or unref() will be made.
*/
explicit sk_sp(T* obj) : fPtr(obj) {}
/**
* Calls unref() on the underlying object pointer.
*/
~sk_sp() {
SkSafeUnref(fPtr);
SkDEBUGCODE(fPtr = nullptr);
}
sk_sp<T>& operator=(std::nullptr_t) { this->reset(); return *this; }
/**
* Shares the underlying object referenced by the argument by calling ref() on it. If this
* sk_sp previously had a reference to an object (i.e. not null) it will call unref() on that
* object.
*/
sk_sp<T>& operator=(const sk_sp<T>& that) {
this->reset(SkSafeRef(that.get()));
return *this;
}
template <typename U, typename = skstd::enable_if_t<std::is_convertible<U*, T*>::value>>
sk_sp<T>& operator=(const sk_sp<U>& that) {
this->reset(SkSafeRef(that.get()));
return *this;
}
/**
* Move the underlying object from the argument to the sk_sp. If the sk_sp previously held
* a reference to another object, unref() will be called on that object. No call to ref()
* will be made.
*/
sk_sp<T>& operator=(sk_sp<T>&& that) {
this->reset(that.release());
return *this;
}
template <typename U, typename = skstd::enable_if_t<std::is_convertible<U*, T*>::value>>
sk_sp<T>& operator=(sk_sp<U>&& that) {
this->reset(that.release());
return *this;
}
T& operator*() const {
SkASSERT(this->get() != nullptr);
return *this->get();
}
// MSVC 2013 does not work correctly with explicit operator bool.
// https://chromium-cpp.appspot.com/#core-blacklist
// When explicit operator bool can be used, remove operator! and operator unspecified_bool_type.
//explicit operator bool() const { return this->get() != nullptr; }
operator unspecified_bool_type() const { return this->get() ? &sk_sp::fPtr : nullptr; }
bool operator!() const { return this->get() == nullptr; }
T* get() const { return fPtr; }
T* operator->() const { return fPtr; }
/**
* Adopt the new bare pointer, and call unref() on any previously held object (if not null).
* No call to ref() will be made.
*/
void reset(T* ptr = nullptr) {
// Calling fPtr->unref() may call this->~() or this->reset(T*).
// http://wg21.cmeerw.net/lwg/issue998
// http://wg21.cmeerw.net/lwg/issue2262
T* oldPtr = fPtr;
fPtr = ptr;
SkSafeUnref(oldPtr);
}
/**
* Return the bare pointer, and set the internal object pointer to nullptr.
* The caller must assume ownership of the object, and manage its reference count directly.
* No call to unref() will be made.
*/
T* SK_WARN_UNUSED_RESULT release() {
T* ptr = fPtr;
fPtr = nullptr;
return ptr;
}
void swap(sk_sp<T>& that) /*noexcept*/ {
using std::swap;
swap(fPtr, that.fPtr);
}
private:
T* fPtr;
};
template <typename T> inline void swap(sk_sp<T>& a, sk_sp<T>& b) /*noexcept*/ {
a.swap(b);
}
template <typename T, typename U> inline bool operator==(const sk_sp<T>& a, const sk_sp<U>& b) {
return a.get() == b.get();
}
template <typename T> inline bool operator==(const sk_sp<T>& a, std::nullptr_t) /*noexcept*/ {
return !a;
}
template <typename T> inline bool operator==(std::nullptr_t, const sk_sp<T>& b) /*noexcept*/ {
return !b;
}
template <typename T, typename U> inline bool operator!=(const sk_sp<T>& a, const sk_sp<U>& b) {
return a.get() != b.get();
}
template <typename T> inline bool operator!=(const sk_sp<T>& a, std::nullptr_t) /*noexcept*/ {
return static_cast<bool>(a);
}
template <typename T> inline bool operator!=(std::nullptr_t, const sk_sp<T>& b) /*noexcept*/ {
return static_cast<bool>(b);
}
template <typename T, typename U> inline bool operator<(const sk_sp<T>& a, const sk_sp<U>& b) {
// Provide defined total order on sk_sp.
// http://wg21.cmeerw.net/lwg/issue1297
// http://wg21.cmeerw.net/lwg/issue1401 .
return std::less<skstd::common_type_t<T*, U*>>()(a.get(), b.get());
}
template <typename T> inline bool operator<(const sk_sp<T>& a, std::nullptr_t) {
return std::less<T*>()(a.get(), nullptr);
}
template <typename T> inline bool operator<(std::nullptr_t, const sk_sp<T>& b) {
return std::less<T*>()(nullptr, b.get());
}
template <typename T, typename U> inline bool operator<=(const sk_sp<T>& a, const sk_sp<U>& b) {
return !(b < a);
}
template <typename T> inline bool operator<=(const sk_sp<T>& a, std::nullptr_t) {
return !(nullptr < a);
}
template <typename T> inline bool operator<=(std::nullptr_t, const sk_sp<T>& b) {
return !(b < nullptr);
}
template <typename T, typename U> inline bool operator>(const sk_sp<T>& a, const sk_sp<U>& b) {
return b < a;
}
template <typename T> inline bool operator>(const sk_sp<T>& a, std::nullptr_t) {
return nullptr < a;
}
template <typename T> inline bool operator>(std::nullptr_t, const sk_sp<T>& b) {
return b < nullptr;
}
template <typename T, typename U> inline bool operator>=(const sk_sp<T>& a, const sk_sp<U>& b) {
return !(a < b);
}
template <typename T> inline bool operator>=(const sk_sp<T>& a, std::nullptr_t) {
return !(a < nullptr);
}
template <typename T> inline bool operator>=(std::nullptr_t, const sk_sp<T>& b) {
return !(nullptr < b);
}
template <typename T, typename... Args>
sk_sp<T> sk_make_sp(Args&&... args) {
return sk_sp<T>(new T(std::forward<Args>(args)...));
}
/*
* Returns a sk_sp wrapping the provided ptr AND calls ref on it (if not null).
*
* This is different than the semantics of the constructor for sk_sp, which just wraps the ptr,
* effectively "adopting" it.
*/
template <typename T> sk_sp<T> sk_ref_sp(T* obj) {
return sk_sp<T>(SkSafeRef(obj));
}
template <typename T> sk_sp<T> sk_ref_sp(const T* obj) {
return sk_sp<T>(const_cast<T*>(SkSafeRef(obj)));
}
#endif