protected override long GetWritePositionLocked(OperationHint hint, int length)
{
var contentHint = hint as OptimizedOperation ?? throw new ArgumentException(nameof(hint));
var retv = -1L;
lock (_blocksLockObject)
{
if (!TryGetAvailableBlock(length, out var block))
{
retv = CurrentPosition;
}
else
{
contentHint.IsExistingBlockUsed = true;
retv = block.Position;
if (block.Length <= length)
{
return(retv);
}
var generatedBlock = new DriveBlock
{
Length = block.Length - length,
Position = block.Position + length
};
AddAvailableBlock(generatedBlock);
contentHint.GeneratedAvailableBlock = generatedBlock;
}
}
return(retv);
}
public IEnumerable <DriveBlock> AllocateSpace(int dataLength)
{
lock (_allocateLock)
{
var dataLeft = dataLength;
while (dataLeft > 0)
{
if (!TryGetAvailableBlock(dataLength, out var block))
{
CurrentPosition = InitialPosition + Length;
block = new DriveBlock
{
Length = dataLength,
Position = CurrentPosition
};
CurrentPosition += block.Length;
Length += block.Length;
}
yield return(block);
dataLeft -= block.Length;
}
}
}
public void RemoveAvailableBlock(DriveBlock block)
{
lock (_blocksLockObject)
{
var queue = _availableBlocks[block.Length];
var list = queue.ToList();
list.Remove(block);
if (!list.Any())
{
_availableBlocks.Remove(block.Length);
return;
}
_availableBlocks[block.Length] = new Queue <DriveBlock>(list);
}
}
protected override bool HandleAddedAvailableBlock(DriveBlock block)
{
//min entry length = 42
if (block.Length < 42)
{
return(false);
}
var blockLengthBytes = BitConverter.GetBytes(block.Length);
var bytesList = new List <byte>(blockLengthBytes)
{
(byte)ServiceMarks.Proceed
};
var operation = new FileTableOperation(drive => drive.Write(block.Position, bytesList.ToArray()), block.Position);
Synchronizer.EnqueueOperation(operation);
return(true);
}
public void AddAvailableBlock(DriveBlock block)
{
if (block == null)
{
throw new ArgumentNullException(nameof(block));
}
if (!HandleAddedAvailableBlock(block))
{
return;
}
lock (_blocksLockObject)
{
if (!_availableBlocks.ContainsKey(block.Length))
{
_availableBlocks[block.Length] = new Queue <DriveBlock>();
}
_availableBlocks[block.Length].Enqueue(block);
}
}
protected virtual bool TryGetAvailableBlock(int length, out DriveBlock block)
{
lock (_blocksLockObject)
{
block = null;
if (!_availableBlocks.TryGetValue(length, out var queue) ||
_availableBlocks.Keys.All(x => x < length))
{
return(false);
}
if (queue == null)
{
var key = _availableBlocks.Keys.FirstOrDefault(x => x > length);
queue = _availableBlocks[key];
}
block = queue.Dequeue();
if (block.Length > length)
{
var generatedBlock = new DriveBlock
{
Length = block.Length - length,
Position = block.Position + length
};
AddAvailableBlock(generatedBlock);
}
if (!queue.Any())
{
_availableBlocks.Remove(length);
}
return(true);
}
}
protected virtual bool HandleAddedAvailableBlock(DriveBlock block)
{
return(true);
}
protected override bool TryGetAvailableBlock(int length, out DriveBlock block)
{
return(base.TryGetAvailableBlock(length, out block) && block.Length >= 42);
}
public DriveBlock(DriveBlock block)
{
Position = block.Position;
Length = block.Length;
}
