/// <summary>
/// Unmaps mapped memory at a given range.
/// </summary>
/// <param name="location">Address of the range</param>
/// <param name="size">Size of the range in bytes</param>
public void UnmapRange(IntPtr location, IntPtr size)
{
ulong startAddress = (ulong)location;
ulong unmapSize = (ulong)size;
ulong endAddress = startAddress + unmapSize;
var overlaps = Array.Empty <IntervalTreeNode <ulong, byte> >();
int count = 0;
lock (_mappings)
{
count = _mappings.Get(startAddress, endAddress, ref overlaps);
}
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
// Tree operations might modify the node start/end values, so save a copy before we modify the tree.
ulong unmapStart = Math.Max(overlap.Start, startAddress);
ulong unmapEnd = Math.Min(overlap.End, endAddress);
_mappings.Remove(overlap);
ulong currentAddress = unmapStart;
while (currentAddress < unmapEnd)
{
WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)currentAddress, 2);
currentAddress += PageSize;
}
}
}
/// <summary>
/// Unreserves a range of memory that has been previously reserved with <see cref="ReserveRange"/>.
/// </summary>
/// <param name="address">Start address of the region to unreserve</param>
/// <param name="size">Size in bytes of the region to unreserve</param>
/// <exception cref="WindowsApiException">Thrown when the Windows API returns an error unreserving the memory</exception>
public void UnreserveRange(ulong address, ulong size)
{
ulong endAddress = address + size;
var overlaps = Array.Empty <IntervalTreeNode <ulong, ulong> >();
int count;
lock (_mappings)
{
count = _mappings.Get(address, endAddress, ref overlaps);
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
if (IsMapped(overlap.Value))
{
if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlap.Start, 2))
{
throw new WindowsApiException("UnmapViewOfFile2");
}
}
_mappings.Remove(overlap);
}
}
if (count > 1)
{
CheckFreeResult(WindowsApi.VirtualFree(
(IntPtr)address,
(IntPtr)size,
AllocationType.Release | AllocationType.CoalescePlaceholders));
}
RemoveProtection(address, size);
}
/// <summary>
/// Unmaps a view that has been previously mapped with <see cref="MapView"/>.
/// </summary>
/// <remarks>
/// For "partial unmaps" (when not the entire mapped range is being unmapped), it might be
/// necessary to unmap the whole range and then remap the sub-ranges that should remain mapped.
/// </remarks>
/// <param name="sharedMemory">Shared memory that the view being unmapped belongs to</param>
/// <param name="location">Address to unmap</param>
/// <param name="size">Size of the region to unmap in bytes</param>
/// <param name="owner">Memory block that owns the mapping</param>
/// <exception cref="WindowsApiException">Thrown when the Windows API returns an error unmapping or remapping the memory</exception>
private void UnmapViewInternal(IntPtr sharedMemory, IntPtr location, IntPtr size, MemoryBlock owner)
{
ulong startAddress = (ulong)location;
ulong unmapSize = (ulong)size;
ulong endAddress = startAddress + unmapSize;
var overlaps = Array.Empty <IntervalTreeNode <ulong, ulong> >();
int count;
lock (_mappings)
{
count = _mappings.Get(startAddress, endAddress, ref overlaps);
}
for (int index = 0; index < count; index++)
{
var overlap = overlaps[index];
if (IsMapped(overlap.Value))
{
if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlap.Start, 2))
{
throw new WindowsApiException("UnmapViewOfFile2");
}
// Tree operations might modify the node start/end values, so save a copy before we modify the tree.
ulong overlapStart = overlap.Start;
ulong overlapEnd = overlap.End;
ulong overlapValue = overlap.Value;
lock (_mappings)
{
_mappings.Remove(overlap);
_mappings.Add(overlapStart, overlapEnd, ulong.MaxValue);
}
bool overlapStartsBefore = overlapStart < startAddress;
bool overlapEndsAfter = overlapEnd > endAddress;
if (overlapStartsBefore || overlapEndsAfter)
{
// If the overlap extends beyond the region we are unmapping,
// then we need to re-map the regions that are supposed to remain mapped.
// This is necessary because Windows does not support partial view unmaps.
// That is, you can only fully unmap a view that was previously mapped, you can't just unmap a chunck of it.
LockCookie lockCookie = _partialUnmapLock.UpgradeToWriterLock(Timeout.Infinite);
_partialUnmapsCount++;
if (overlapStartsBefore)
{
ulong remapSize = startAddress - overlapStart;
MapViewInternal(sharedMemory, overlapValue, (IntPtr)overlapStart, (IntPtr)remapSize);
RestoreRangeProtection(overlapStart, remapSize);
}
if (overlapEndsAfter)
{
ulong overlappedSize = endAddress - overlapStart;
ulong remapBackingOffset = overlapValue + overlappedSize;
ulong remapAddress = overlapStart + overlappedSize;
ulong remapSize = overlapEnd - endAddress;
MapViewInternal(sharedMemory, remapBackingOffset, (IntPtr)remapAddress, (IntPtr)remapSize);
RestoreRangeProtection(remapAddress, remapSize);
}
_partialUnmapLock.DowngradeFromWriterLock(ref lockCookie);
}
}
}
CoalesceForUnmap(startAddress, unmapSize, owner);
RemoveProtection(startAddress, unmapSize);
}
