third_party/WebKit/Source/wtf/LeakAnnotations.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 * Copyright (C) 2013 Samsung Electronics. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef WTF_LeakAnnotations_h
#define WTF_LeakAnnotations_h

// This file defines macros for working with LeakSanitizer, allowing memory
// and allocations to be registered as exempted from LSan consideration.

#include "wtf/Noncopyable.h"
#if USE(LEAK_SANITIZER)
#include "wtf/AddressSanitizer.h"
#include "wtf/TypeTraits.h"
#endif

namespace WTF {

#if USE(LEAK_SANITIZER)
class LeakSanitizerDisabler {
    WTF_MAKE_NONCOPYABLE(LeakSanitizerDisabler);
public:
    LeakSanitizerDisabler()
    {
        __lsan_disable();
    }

    ~LeakSanitizerDisabler()
    {
        __lsan_enable();
    }
};

// WTF_INTERNAL_LEAK_SANITIZER_DISABLED_SCOPE: all allocations made in the
// current scope will be exempted from LSan consideration. Only to be
// used internal to wtf/, Blink should use LEAK_SANITIZER_DISABLED_SCOPE
// elsewhere.
//
// TODO(sof): once layering rules allow wtf/ to make use of the Oilpan
// infrastructure, remove this macro.
#define WTF_INTERNAL_LEAK_SANITIZER_DISABLED_SCOPE \
        WTF::LeakSanitizerDisabler leakSanitizerDisabler; static_cast<void>(0)

// LEAK_SANITIZER_IGNORE_OBJECT(X): the heap object referenced by pointer X
// will be ignored by LSan.
//
// "Ignorance" means that LSan's reachability traversal is stopped short
// upon encountering an ignored memory chunk. Consequently, LSan will not
// scan an ignored memory chunk for live, reachable pointers. However, should
// those embedded pointers be reachable by some other path, they will be
// reported as leaking.
#define LEAK_SANITIZER_IGNORE_OBJECT(X) __lsan_ignore_object(X)

// If the object pointed to by the static local is on the Oilpan heap, a strong
// Persistent<> is created to keep the pointed-to heap object alive. This makes
// both the Persistent<> and the heap object _reachable_ by LeakSanitizer's leak
// detection pass. We do not want these intentional leaks to be reported by LSan,
// hence the static local is registered with Oilpan
// (see RegisterStaticLocalReference<> below.)
//
// Upon Blink shutdown, all the registered statics are released and a final round
// of GCs are performed to sweep out their now-unreachable object graphs. The end
// result being a tidied heap that the LeakSanitizer can then scan to report real leaks.
//
// The CanRegisterStaticLocalReference<> and RegisterStaticLocalReference<> templates
// arrange for this -- for a class type T, a registerStatic() implementation is
// provided if "T* T::registerAsStaticReference(T*)" is a method on T
// (inherited or otherwise.)
//
// An empty, trivial registerStatic() method is provided for all other class types T.
template<typename T>
class CanRegisterStaticLocalReference {
    typedef char YesType;
    typedef struct NoType {
        char padding[8];
    } NoType;

    // Check if class T has public method "T* registerAsStaticReference()".
    template<typename V> static YesType checkHasRegisterAsStaticReferenceMethod(V* p, typename std::enable_if<IsSubclass<V, typename std::remove_pointer<decltype(p->registerAsStaticReference())>::type>::value>::type* = 0);
    template<typename V> static NoType checkHasRegisterAsStaticReferenceMethod(...);

public:
    static const bool value = sizeof(YesType) + sizeof(T) == sizeof(checkHasRegisterAsStaticReferenceMethod<T>(nullptr)) + sizeof(T);
};

template<typename T, bool = CanRegisterStaticLocalReference<T>::value>
class RegisterStaticLocalReference {
public:
    static T* registerStatic(T* ptr)
    {
        return ptr;
    }
};

template<typename T>
class RegisterStaticLocalReference<T, true> {
public:
    static T* registerStatic(T* ptr)
    {
        return static_cast<T*>(ptr->registerAsStaticReference());
    }
};

#define LEAK_SANITIZER_REGISTER_STATIC_LOCAL(Type, Object) WTF::RegisterStaticLocalReference<Type>::registerStatic(Object)
#else
#define WTF_INTERNAL_LEAK_SANITIZER_DISABLED_SCOPE
#define LEAK_SANITIZER_IGNORE_OBJECT(X) ((void)0)
#define LEAK_SANITIZER_REGISTER_STATIC_LOCAL(Type, Object) Object
#endif // USE(LEAK_SANITIZER)

} // namespace WTF

#endif // WTF_LeakAnnotations_h