/// <summary>
/// Coalesces/Merges all the adjacent FREE arenas into one arena.
/// </summary>
internal static MemArena CoalesceAdjacent(MemArena arena)
{
// Only free arenas can be coalesced.
if (!arena.IsFree)
{
return(arena);
}
// Check if there is an arena next to this one.
MemArena curr = arena;
MemArena next = arena.NextArena();
int nHeaderCount = 0;//need to know how many headers are being freed while merging free arenas.
if (next != null)
{
uint freedSpace = 0;
// Find the first USED arena below this arena in the view.
// Skip/Merge all the free arenas along the way.
while (next != null && next.IsFree)
{
nHeaderCount++;
freedSpace += next.TotalLength;
curr = next;
next = next.NextArena();
}
// Fix up links!
if (freedSpace > 0)
{
arena.Capacity += freedSpace;
uint nCapacity = arena.Capacity;
arena = SetNextArena(arena, GetActualArena(next)); //update only the actual arena
arena.Capacity = nCapacity;
}
}
if (arena.HasPrevious)
{
uint freedSpace = 0;
// Find the first USED arena above this arena in the view.
// Skip/Merge all the free arenas along the way.
MemArena cur = arena;
MemArena prev = null;
do
{
prev = cur.PreviousArena();
if (prev == null || !prev.IsFree)
{
break;
}
freedSpace += prev.TotalLength;
cur = prev;
nHeaderCount++;
}while (true);
// Fix up links! For even if we find previous arena free.. The last from previous is now our Pivot.Its call to adjust its Next then.
if (freedSpace > 0)
{
arena.Capacity += freedSpace;
uint nCapacity = arena.Capacity;
MemArena tempNext = arena.NextArena();
arena = SetNextArena(cur, GetActualArena(next)); //update only the actual arena
arena.Capacity = nCapacity;
}
}
if (nHeaderCount > 0) //update memory freed, while merging arenas.
{
arena.View.MyFreeSpace += (uint)(nHeaderCount * Header.Size);
}
return(arena);
}
