Method allocate

src/memory/PoolAllocator.cpp:101–192

Allocate memory of a given size (in bytes) and return a pointer to the allocated memory.

// Allocate memory of a given size (in bytes) and return a pointer to the
// allocated memory.
void* PoolAllocator::allocate(size_t size) {

    // Lock the method with a mutex
    std::lock_guard<std::mutex> lock(mMutex);

    assert(size > 0);

    // We cannot allocate zero bytes
    if (size == 0) return nullptr;

#ifndef NDEBUG
        mNbTimesAllocateMethodCalled++;
#endif

    // If we need to allocate more than the maximum memory unit size
    if (size > MAX_UNIT_SIZE) {

        // Allocate memory using default allocation
        void* allocatedMemory = mBaseAllocator.allocate(size);

        // Check that allocated memory is 16-bytes aligned
        assert(reinterpret_cast<uintptr_t>(allocatedMemory) % GLOBAL_ALIGNMENT == 0);

        return allocatedMemory;
    }

    // Get the index of the heap that will take care of the allocation request
    int indexHeap = mMapSizeToHeapIndex[size];
    assert(indexHeap >= 0 && indexHeap < NB_HEAPS);

    // If there still are free memory units in the corresponding heap
    if (mFreeMemoryUnits[indexHeap] != nullptr) {

        // Return a pointer to the memory unit
        MemoryUnit* unit = mFreeMemoryUnits[indexHeap];
        mFreeMemoryUnits[indexHeap] = unit->nextUnit;

        void* allocatedMemory = static_cast<void*>(unit);

        // Check that allocated memory is 16-bytes aligned
        assert(reinterpret_cast<uintptr_t>(allocatedMemory) % GLOBAL_ALIGNMENT == 0);

        return allocatedMemory;
    }
    else {  // If there is no more free memory units in the corresponding heap

        // If we need to allocate more memory to contains the blocks
        if (mNbCurrentMemoryBlocks == mNbAllocatedMemoryBlocks) {

            // Allocate more memory to contain the blocks
            MemoryBlock* currentMemoryBlocks = mMemoryBlocks;
            mNbAllocatedMemoryBlocks += 64;
            mMemoryBlocks = static_cast<MemoryBlock*>(mBaseAllocator.allocate(mNbAllocatedMemoryBlocks * sizeof(MemoryBlock)));
            memcpy(mMemoryBlocks, currentMemoryBlocks, mNbCurrentMemoryBlocks * sizeof(MemoryBlock));
            memset(mMemoryBlocks + mNbCurrentMemoryBlocks, 0, 64 * sizeof(MemoryBlock));
            mBaseAllocator.release(currentMemoryBlocks, mNbCurrentMemoryBlocks * sizeof(MemoryBlock));
        }