private PagerState.AllocationInfo TryCreateNewFileMappingAtAddress(long allocationSize, byte *baseAddress)
{
var newMemoryMappedFile = MemoryMappedFile.CreateNew(null, allocationSize);
var newFileMappingHandle = newMemoryMappedFile.SafeMemoryMappedFileHandle.DangerousGetHandle();
var newMappingBaseAddress = MemoryMapNativeMethods.MapViewOfFileEx(newFileMappingHandle,
MemoryMapNativeMethods.NativeFileMapAccessType.Read | MemoryMapNativeMethods.NativeFileMapAccessType.Write,
0, 0,
UIntPtr.Zero,
baseAddress);
var hasMappingSucceeded = newMappingBaseAddress != null && newMappingBaseAddress != (byte *)0;
if (!hasMappingSucceeded)
{
newMemoryMappedFile.Dispose();
return(null);
}
return(new PagerState.AllocationInfo
{
BaseAddress = newMappingBaseAddress,
Size = allocationSize,
MappedFile = newMemoryMappedFile
});
}
private PagerState.AllocationInfo RemapViewOfFileAtAddress(long allocationSize, ulong offsetInFile, byte *baseAddress)
{
var offset = new SplitValue {
Value = offsetInFile
};
var mmf = MemoryMappedFile.CreateFromFile(_fileStream, null, _fileStream.Length,
_memoryMappedFileAccess,
null, HandleInheritability.None, true);
var newMappingBaseAddress = MemoryMapNativeMethods.MapViewOfFileEx(mmf.SafeMemoryMappedFileHandle.DangerousGetHandle(),
MemoryMapNativeMethods.NativeFileMapAccessType.Read | MemoryMapNativeMethods.NativeFileMapAccessType.Write,
offset.High, offset.Low,
new UIntPtr((ulong)allocationSize),
baseAddress);
var hasMappingSucceeded = newMappingBaseAddress != null && newMappingBaseAddress != (byte *)0;
if (!hasMappingSucceeded)
{
mmf.Dispose();
return(null);
}
return(new PagerState.AllocationInfo
{
BaseAddress = newMappingBaseAddress,
Size = allocationSize,
MappedFile = mmf
});
}
private static void UndoMappings(IEnumerable <PagerState.AllocationInfo> newAllocationInfos)
{
foreach (var newAllocationInfo in newAllocationInfos)
{
MemoryMapNativeMethods.UnmapViewOfFile(newAllocationInfo.BaseAddress);
}
}
public override void Sync()
{
if (MemoryMapNativeMethods.FlushViewOfFile(PagerState.MapBase, new IntPtr(PagerState.Accessor.Capacity)) == false)
{
throw new Win32Exception();
}
if (MemoryMapNativeMethods.FlushFileBuffers(_handle) == false)
{
throw new Win32Exception();
}
}
public override void Sync()
{
if (PagerState.AllocationInfos.Any(allocationInfo =>
MemoryMapNativeMethods.FlushViewOfFile(allocationInfo.BaseAddress, new IntPtr(allocationInfo.Size)) == false))
{
throw new Win32Exception();
}
if (MemoryMapNativeMethods.FlushFileBuffers(_handle) == false)
{
throw new Win32Exception();
}
}
private PagerState CreatePagerState()
{
var mmf = MemoryMappedFile.CreateFromFile(_fileStream, null, _fileStream.Length,
_memoryMappedFileAccess,
null, HandleInheritability.None, true);
var fileMappingHandle = mmf.SafeMemoryMappedFileHandle.DangerousGetHandle();
var mmFileAccessType = _access == NativeFileAccess.GenericRead
? MemoryMapNativeMethods.NativeFileMapAccessType.Read
: MemoryMapNativeMethods.NativeFileMapAccessType.Read | MemoryMapNativeMethods.NativeFileMapAccessType.Write;
var startingBaseAddressPtr = MemoryMapNativeMethods.MapViewOfFileEx(fileMappingHandle,
mmFileAccessType,
0, 0,
UIntPtr.Zero, //map all what was "reserved" in CreateFileMapping on previous row
null);
if (startingBaseAddressPtr == (byte *)0) //system didn't succeed in mapping the address where we wanted
{
throw new Win32Exception();
}
var allocationInfo = new PagerState.AllocationInfo
{
BaseAddress = startingBaseAddressPtr,
Size = _fileStream.Length,
MappedFile = mmf
};
var newPager = new PagerState(this)
{
Files = new[] { mmf },
Accessor = null, //not available since MapViewOfFileEx is used (instead of MapViewOfFile - which is used in managed wrapper)
MapBase = startingBaseAddressPtr,
AllocationInfos = new[] { allocationInfo }
};
newPager.AddRef(); // one for the pager
return(newPager);
}
private PagerState CreateInitialPagerState(long size, byte *requestedBaseAddress)
{
var allocationSize = NearestSizeToAllocationGranularity(size);
var mmf = MemoryMappedFile.CreateNew(null, allocationSize, MemoryMappedFileAccess.ReadWrite);
var fileMappingHandle = mmf.SafeMemoryMappedFileHandle.DangerousGetHandle();
var startingBaseAddressPtr = MemoryMapNativeMethods.MapViewOfFileEx(fileMappingHandle,
MemoryMapNativeMethods.NativeFileMapAccessType.Read | MemoryMapNativeMethods.NativeFileMapAccessType.Write,
0, 0,
UIntPtr.Zero, //map all what was "reserved" in CreateFileMapping on previous row
requestedBaseAddress);
if (startingBaseAddressPtr == (byte *)0) //system didn't succeed in mapping the address where we wanted
{
throw new Win32Exception();
}
var allocationInfo = new PagerState.AllocationInfo
{
BaseAddress = startingBaseAddressPtr,
Size = allocationSize,
MappedFile = mmf
};
var newPager = new PagerState(this)
{
Files = new[] { mmf },
Accessor = null, //not available since MapViewOfFileEx is used (instead of MapViewOfFile - which is used in managed wrapper)
MapBase = startingBaseAddressPtr,
AllocationInfos = new[] { allocationInfo }
};
newPager.AddRef();
return(newPager);
}
private PagerState AllocateMorePagesAndRemapContinuously(long allocationSize)
{
var retryCount = 0;
while (retryCount++ < MaxAllocationRetries)
{
byte *newBaseAddress;
if (TryFindContinuousMemory((ulong)(_totalAllocationSize + allocationSize), out newBaseAddress) == false)
{
var message =
string.Format(
"Unable to allocate more pages - unsuccessfully tried to allocate continuous block of size = {0} bytes\r\n" +
"It is likely that we are suffering from virtual memory exhaustion or memory fragmentation.\r\n" +
"64 bits process: {1}\r\n" +
"If you are running in 32 bits, this is expected, and you need to run in 64 bits to resume normal operations.\r\n" +
"If you are running in 64 bits, this is likely an error and should be reported."
, (_totalAllocationSize + allocationSize), Environment.Is64BitProcess);
throw new OutOfMemoryException(message);
}
bool failedToAllocate = false;
long offset = 0;
var allocationInfoAfterReallocation = new List <PagerState.AllocationInfo>();
foreach (var allocationInfo in PagerState.AllocationInfos)
{
var newAlloctedBaseAddress = MemoryMapNativeMethods.MapViewOfFileEx(allocationInfo.MappedFile.SafeMemoryMappedFileHandle.DangerousGetHandle(),
MemoryMapNativeMethods.NativeFileMapAccessType.Read | MemoryMapNativeMethods.NativeFileMapAccessType.Write,
0, 0,
UIntPtr.Zero,
newBaseAddress + offset);
if (newAlloctedBaseAddress == null || newAlloctedBaseAddress == (byte *)0)
{
Debug.WriteLine("Failed to remap file continuously. Unmapping already mapped files and re-trying");
UndoMappings(allocationInfoAfterReallocation);
failedToAllocate = true;
break;
}
offset += allocationInfo.Size;
allocationInfoAfterReallocation.Add(new PagerState.AllocationInfo
{
BaseAddress = newAlloctedBaseAddress,
MappedFile = allocationInfo.MappedFile,
Size = allocationInfo.Size
});
}
if (failedToAllocate)
{
continue;
}
var newAllocationInfo = TryCreateNewFileMappingAtAddress(allocationSize, newBaseAddress + _totalAllocationSize);
if (newAllocationInfo == null)
{
UndoMappings(allocationInfoAfterReallocation);
continue;
}
var newPagerState = new PagerState(this)
{
Files = PagerState.Files.Concat(newAllocationInfo.MappedFile),
AllocationInfos = allocationInfoAfterReallocation.Concat(newAllocationInfo),
MapBase = newBaseAddress
};
return(newPagerState);
}
throw new InvalidOperationException(
string.Format(
"Something bad has happened, after {0} tries, could not find any spot in virtual memory to remap continuous virtual memory for {1:##,###;;0} bytes",
MaxAllocationRetries, allocationSize));
}
