/// <summary>
/// Cache block info lately removed.
/// Dequeue one element if the cached count reaches <see cref="CrossChainConstants.ChainCacheEntityCapacity"/>
/// </summary>
/// <param name="blockCacheEntity"></param>
private bool TryDequeue(out IBlockCacheEntity blockCacheEntity)
{
var res = BlockCacheEntities.TryTake(out blockCacheEntity,
CrossChainConstants.WaitingIntervalInMillisecond);
if (res)
{
DequeuedBlockCacheEntities.Add(blockCacheEntity);
}
return(res);
}
public bool TryAdd(IBlockCacheEntity blockCacheEntity)
{
if (BlockCacheEntities.Count >= CrossChainConstants.ChainCacheEntityCapacity)
{
return(false);
}
// thread unsafe in some extreme cases, but it can be covered with caching mechanism.
if (blockCacheEntity.Height != TargetChainHeight())
{
return(false);
}
var res = BlockCacheEntities.TryAdd(blockCacheEntity);
return(res);
}
public long TargetChainHeight()
{
var lastEnqueuedBlockCacheEntity = BlockCacheEntities.LastOrDefault();
if (lastEnqueuedBlockCacheEntity != null)
{
return(lastEnqueuedBlockCacheEntity.Height + 1);
}
var lastDequeuedBlockCacheEntity = DequeuedBlockCacheEntities.LastOrDefault();
if (lastDequeuedBlockCacheEntity != null)
{
return(lastDequeuedBlockCacheEntity.Height + 1);
}
return(_initTargetHeight);
}
/// <summary>
/// Cache outdated data. The block with height lower than <paramref name="height"/> is outdated.
/// </summary>
/// <param name="height"></param>
private bool DequeueBlockCacheEntitiesBeforeHeight(long height)
{
while (true)
{
var blockCacheEntity = BlockCacheEntities.FirstOrDefault();
if (blockCacheEntity == null || blockCacheEntity.Height > height)
{
return(false);
}
if (blockCacheEntity.Height == height)
{
return(true);
}
TryDequeue(out blockCacheEntity);
}
}
public long TargetChainHeight()
{
if (BlockCacheEntities.Count >= CrossChainConstants.ChainCacheEntityCapacity)
{
return(-1);
}
var lastEnqueuedBlockCacheEntity = BlockCacheEntities.LastOrDefault();
if (lastEnqueuedBlockCacheEntity != null)
{
return(lastEnqueuedBlockCacheEntity.Height + 1);
}
var lastDequeuedBlockCacheEntity = DequeuedBlockCacheEntities.LastOrDefault();
if (lastDequeuedBlockCacheEntity != null)
{
return(lastDequeuedBlockCacheEntity.Height + 1);
}
return(_targetHeight);
}
/// <summary>
/// Try take element from cached queue.
/// Make sure that more than <see cref="CrossChainConstants.MinimalBlockCacheEntityCount"/> block cache entities are left in <see cref="BlockCacheEntities"/>.
/// </summary>
/// <param name="height">Height of block info needed</param>
/// <param name="blockCacheEntity"></param>
/// <param name="isCacheSizeLimited">Use <see cref="CrossChainConstants.ChainCacheEntityCapacity"/> as cache count threshold if true.</param>
/// <returns></returns>
public bool TryTake(long height, out IBlockCacheEntity blockCacheEntity, bool isCacheSizeLimited)
{
// clear outdated data
var cachedInQueue = DequeueBlockCacheEntitiesBeforeHeight(height);
// isCacheSizeLimited means minimal caching size limit, so that most nodes have this block.
var lastQueuedHeight = BlockCacheEntities.LastOrDefault()?.Height ?? 0;
if (cachedInQueue && !(isCacheSizeLimited && lastQueuedHeight < height + CrossChainConstants.MinimalBlockCacheEntityCount))
{
return(TryDequeue(out blockCacheEntity));
}
blockCacheEntity = GetLastDequeuedBlockCacheEntity(height);
if (blockCacheEntity != null)
{
return(!isCacheSizeLimited ||
BlockCacheEntities.Count + DequeuedBlockCacheEntities.Count(ci => ci.Height >= height)
>= CrossChainConstants.MinimalBlockCacheEntityCount);
}
return(false);
}
