/// <summary>
/// Loads this buffer's content into physical memory.
///
/// <para> This method makes a best effort to ensure that, when it returns,
/// this buffer's content is resident in physical memory. Invoking this
/// method may cause some number of page faults and I/O operations to
/// occur. </para>
/// </summary>
/// <returns> This buffer </returns>
public MappedByteBuffer Load()
{
CheckMapped();
if ((Address == 0) || (Capacity() == 0))
{
return(this);
}
long offset = MappingOffset();
long length = MappingLength(offset);
load0(MappingAddress(offset), length);
// Read a byte from each page to bring it into memory. A checksum
// is computed as we go along to prevent the compiler from otherwise
// considering the loop as dead code.
Unsafe @unsafe = Unsafe.Unsafe;
int ps = Bits.PageSize();
int count = Bits.PageCount(length);
long a = MappingAddress(offset);
sbyte x = 0;
for (int i = 0; i < count; i++)
{
x ^= @unsafe.getByte(a);
a += ps;
}
if (Unused != 0)
{
Unused = x;
}
return(this);
}
// Primary constructor
//
internal DirectByteBuffer(int cap) : base(-1, 0, cap, cap) // package-private
{
bool pa = VM.DirectMemoryPageAligned;
int ps = Bits.PageSize();
long size = System.Math.Max(1L, (long)cap + (pa ? ps : 0));
Bits.ReserveMemory(size, cap);
long @base = 0;
try
{
@base = @unsafe.allocateMemory(size);
}
catch (OutOfMemoryError x)
{
Bits.UnreserveMemory(size, cap);
throw x;
}
@unsafe.setMemory(@base, size, (sbyte)0);
if (pa && (@base % ps != 0))
{
// Round up to page boundary
Address = @base + ps - (@base & (ps - 1));
}
else
{
Address = @base;
}
Cleaner_Renamed = Cleaner.create(this, new Deallocator(@base, size, cap));
Att = null;
}
// Returns the distance (in bytes) of the buffer from the page aligned address
// of the mapping. Computed each time to avoid storing in every direct buffer.
private long MappingOffset()
{
int ps = Bits.PageSize();
long offset = Address % ps;
return((offset >= 0) ? offset : (ps + offset));
}