/// <summary>
/// Resize the heap encreasing the size by the specified value mantaining all data
/// in the same position.
/// </summary>
/// <param name="size">Grow size in bytes (the actual grow size could be bigger than the specified).</param>
/// <param name="noOvergrowth">Force the allocator to grow the heap by the exact specified size.</param>
/// <returns>Returns <see cref="true"/> if the memory allocation has been done.</returns>
public virtual bool Grow(uint size, bool noOvergrowth = false)
{
// - Check if the heap can grow
if (!CanGrow)
{
return(false);
}
// - Check if we reached the memory limit
if (HeapSize + size > MaximumSize)
{
return(false);
}
// - Calculates the actual grow size
uint growSize = noOvergrowth ? size : (uint)(size + GrowFactor * HeapSize);
try
{
// - Realloc the heap memory
RawMemory = Marshal.ReAllocHGlobal(RawMemory, new IntPtr(HeapSize + growSize));
}
catch (OutOfMemoryException)
{
return(false);
}
// - Gets the last avaiable chunk of memory
var lastChunk = FreeSpace.LastOrDefault();
// - Create a new memory pointer pointing to the last block if there's no free block at the end
if (lastChunk == null || lastChunk.Offset + lastChunk.Size < HeapSize)
{
FreeSpace.Add(new MemoryPointer(this, growSize, HeapSize));
}
// - Modify the existing chunk if it's at the end of the heap
if (lastChunk != null || lastChunk.Offset + lastChunk.Size >= HeapSize)
{
lastChunk.ChangeOffsetAndSize(lastChunk.Offset, lastChunk.Size + growSize);
}
// - Update the heap size
HeapSize += growSize;
return(true);
}
/// <summary>
/// Shrinks the heap memory to the smallest memory that contains
/// all the allocated blocks.
/// </summary>
/// <param name="keepBytes">Number of bytes to keep at the heap's tail.</param>
/// <returns>Returns <see cref="true"/> if the shring goes well.</returns>
public virtual bool FreeUnusedMemory(int keepBytes = -1)
{
// - Gets the last avaiable chunk of memory
var lastChunk = FreeSpace.LastOrDefault();
// - Create a new memory pointer pointing to the last block if there's no free block at the end
if (lastChunk != null || lastChunk.Offset + lastChunk.Size >= HeapSize)
{
// - Automatically takes 10% of the whole size free if keepBytes is -1
if (keepBytes < 0)
{
keepBytes = (int)System.Math.Ceiling(HeapSize * 0.1);
}
// - Calculate the amount of memory to free
uint shrinkSize = (uint)System.Math.Max(lastChunk.Size - keepBytes, 0);
if (shrinkSize > 0)
{
try
{
// - Realloc the heap memory
RawMemory = Marshal.ReAllocHGlobal(RawMemory, new IntPtr(HeapSize - shrinkSize));
// - Resize the last chunk
if (lastChunk.Size - shrinkSize > 0)
{
lastChunk.ChangeOffsetAndSize(lastChunk.Offset, lastChunk.Size - shrinkSize);
}
else
{
FreeSpace.Remove(lastChunk);
}
HeapSize -= shrinkSize;
}
catch (OutOfMemoryException)
{
return(false);
}
}
}
return(true);
}
