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/*
* Copyright 2015, The Android Open Source Project
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``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
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ANDROID_FAT_VECTOR_H
#define ANDROID_FAT_VECTOR_H
#include "utils/Macros.h"
#include <stddef.h>
#include <stdlib.h>
#include <utils/Log.h>
#include <type_traits>
#include <vector>
namespace android {
namespace uirenderer {
template <typename T, size_t SIZE>
class InlineStdAllocator {
public:
struct Allocation {
PREVENT_COPY_AND_ASSIGN(Allocation);
public:
Allocation(){};
// char array instead of T array, so memory is uninitialized, with no destructors run
char array[sizeof(T) * SIZE];
bool inUse = false;
};
typedef T value_type; // needed to implement std::allocator
typedef T* pointer; // needed to implement std::allocator
explicit InlineStdAllocator(Allocation& allocation) : mAllocation(allocation) {}
InlineStdAllocator(const InlineStdAllocator& other) : mAllocation(other.mAllocation) {}
~InlineStdAllocator() {}
T* allocate(size_t num, const void* = 0) {
if (!mAllocation.inUse && num <= SIZE) {
mAllocation.inUse = true;
return (T*)mAllocation.array;
} else {
return (T*)malloc(num * sizeof(T));
}
}
void deallocate(pointer p, size_t num) {
if (p == (T*)mAllocation.array) {
mAllocation.inUse = false;
} else {
// 'free' instead of delete here - destruction handled separately
free(p);
}
}
Allocation& mAllocation;
};
/**
* std::vector with SIZE elements preallocated into an internal buffer.
*
* Useful for avoiding the cost of malloc in cases where only SIZE or
* fewer elements are needed in the common case.
*/
template <typename T, size_t SIZE>
class FatVector : public std::vector<T, InlineStdAllocator<T, SIZE>> {
public:
FatVector()
: std::vector<T, InlineStdAllocator<T, SIZE>>(
InlineStdAllocator<T, SIZE>(mAllocation)) {
this->reserve(SIZE);
}
explicit FatVector(size_t capacity) : FatVector() { this->resize(capacity); }
private:
typename InlineStdAllocator<T, SIZE>::Allocation mAllocation;
};
} // namespace uirenderer
} // namespace android
#endif // ANDROID_FAT_VECTOR_H