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Commit 2497a152 authored by Mathias Agopian's avatar Mathias Agopian Committed by Alex Ray
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improve [un]marshalling of non-binder objects 

this change introduces a new class LightFlattenable<> which is
a protocol to flatten simple objects that don't require
binders or file descriptors; the benefit of this protocol is that
it doesn't require the objects to have a virtual table and give us
a consitant way of doing this.

we also introduce an implementation of this protocol for
POD structures, LightFlattenablePod<>.

Parcel has been update to handle this protocol automatically.

Sensor, Rect, Point and Region now use this new protocol.

Change-Id: Icb3ce7fa1d785249eb666f39c2129f2fc143ea4a
parent 6454f461

include/utils/Flattenable.h

+72 −0
Original line number Diff line number Diff line
@@ -24,6 +24,11 @@ 


namespace android {



/*

 * The Flattenable interface allows an object to serialize itself out

 * to a byte-buffer and an array of file descriptors.

 */



class Flattenable

{

public:
@@ -56,6 +61,73 @@ protected: 


};



/*

 * LightFlattenable is a protocol allowing object to serialize themselves out

 * to a byte-buffer.

 *

 * LightFlattenable objects must implement this protocol.

 *

 * LightFlattenable doesn't require the object to be virtual.

 */

template <typename T>

class LightFlattenable {

public:

    // returns whether this object always flatten into the same size.

    // for efficiency, this should always be inline.

    inline bool isFixedSize() const;



    // returns size in bytes of the flattened object. must be a constant.

    inline size_t getSize() const;



    // flattens the object into buffer.

    inline status_t flatten(void* buffer) const;



    // unflattens the object from buffer of given size.

    inline status_t unflatten(void const* buffer, size_t size);

};



template <typename T>

inline bool LightFlattenable<T>::isFixedSize() const {

    return static_cast<T const*>(this)->T::isFixedSize();

}

template <typename T>

inline size_t LightFlattenable<T>::getSize() const {

    return static_cast<T const*>(this)->T::getSize();

}

template <typename T>

inline status_t LightFlattenable<T>::flatten(void* buffer) const {

    return static_cast<T const*>(this)->T::flatten(buffer);

}

template <typename T>

inline status_t LightFlattenable<T>::unflatten(void const* buffer, size_t size) {

    return static_cast<T*>(this)->T::unflatten(buffer, size);

}



/*

 * LightFlattenablePod is an implementation of the LightFlattenable protocol

 * for POD (plain-old-data) objects.

 */

template <typename T>

class LightFlattenablePod : public LightFlattenable<T> {

public:

    inline bool isFixedSize() const {

        return true;

    }



    inline size_t getSize() const {

        return sizeof(T);

    }

    inline status_t flatten(void* buffer) const {

        *reinterpret_cast<T*>(buffer) = *static_cast<T const*>(this);

        return NO_ERROR;

    }

    inline status_t unflatten(void const* buffer, size_t) {

        *static_cast<T*>(this) = *reinterpret_cast<T const*>(buffer);

        return NO_ERROR;

    }

};





}; // namespace android