/// <summary>
/// Processes items in the <see cref="toDownloadQueue"/> and ask the block puller for blocks to download.
/// If the tree has too many unconsumed blocks we will not ask block puller for more until some blocks are consumed.
/// </summary>
/// <remarks>
/// Requests that have too many blocks will be split in batches.
/// The amount of blocks in 1 batch to downloaded depends on the average value in <see cref="IBlockPuller.AverageBlockSize"/>.
/// </remarks>
private void ProcessDownloadQueueLocked()
{
this.logger.LogTrace("()");
while (this.toDownloadQueue.Count > 0)
{
BlockDownloadRequest request = this.toDownloadQueue.Peek();
long freeBytes = MaxUnconsumedBlocksDataBytes - this.chainedHeaderTree.UnconsumedBlocksDataBytes - this.expectedBlockDataBytes;
this.logger.LogTrace("{0} bytes worth of blocks is available for download.", freeBytes);
if (freeBytes <= ConsumptionThresholdBytes)
{
this.logger.LogTrace("(-)[THRESHOLD_NOT_MET]");
return;
}
long avgSize = (long)this.blockPuller.GetAverageBlockSizeBytes();
int blocksToAsk = avgSize != 0 ? (int)(freeBytes / avgSize) : DefaultNumberOfBlocksToAsk;
this.logger.LogTrace("With {0} average block size, we have {1} download slots available.", avgSize, blocksToAsk);
if (request.BlocksToDownload.Count <= blocksToAsk)
{
this.toDownloadQueue.Dequeue();
}
else
{
this.logger.LogTrace("Splitting enqueued job of size {0} into 2 pieces of sizes {1} and {2}.", request.BlocksToDownload.Count, blocksToAsk, request.BlocksToDownload.Count - blocksToAsk);
// Split queue item in 2 pieces: one of size blocksToAsk and second is the rest. Ask BP for first part, leave 2nd part in the queue.
var blockPullerRequest = new BlockDownloadRequest()
{
BlocksToDownload = new List <ChainedHeader>(request.BlocksToDownload.GetRange(0, blocksToAsk))
};
request.BlocksToDownload.RemoveRange(0, blocksToAsk);
request = blockPullerRequest;
}
this.blockPuller.RequestBlocksDownload(request.BlocksToDownload);
foreach (ChainedHeader chainedHeader in request.BlocksToDownload)
{
this.expectedBlockSizes.Add(chainedHeader.HashBlock, avgSize);
}
this.expectedBlockDataBytes += request.BlocksToDownload.Count * avgSize;
this.logger.LogTrace("Expected block data bytes was set to {0} and we are expecting {1} blocks to be delivered.", this.expectedBlockDataBytes, this.expectedBlockSizes.Count);
}
this.logger.LogTrace("(-)");
}
/// <summary>
/// Request a list of block headers to download their respective blocks.
/// If <paramref name="chainedHeaders"/> is not an array of consecutive headers it will be split to batches of consecutive header requests.
/// Callbacks of all entries are added to <see cref="callbacksByBlocksRequestedHash"/>. If a block header was already requested
/// to download and not delivered yet, it will not be requested again, instead just it's callback will be called when the block arrives.
/// </summary>
/// <param name="chainedHeaders">Array of chained headers to download.</param>
/// <param name="onBlockDownloadedCallback">A callback to call when the block was downloaded.</param>
private void DownloadBlocks(ChainedHeader[] chainedHeaders, OnBlockDownloadedCallback onBlockDownloadedCallback)
{
this.logger.LogTrace("({0}.{1}:{2})", nameof(chainedHeaders), nameof(chainedHeaders.Length), chainedHeaders.Length);
var downloadRequests = new List <BlockDownloadRequest>();
BlockDownloadRequest request = null;
ChainedHeader previousHeader = null;
lock (this.blockRequestedLock)
{
foreach (ChainedHeader chainedHeader in chainedHeaders)
{
bool blockAlreadyAsked = this.callbacksByBlocksRequestedHash.TryGetValue(chainedHeader.HashBlock, out List <OnBlockDownloadedCallback> callbacks);
if (!blockAlreadyAsked)
{
callbacks = new List <OnBlockDownloadedCallback>();
this.callbacksByBlocksRequestedHash.Add(chainedHeader.HashBlock, callbacks);
}
else
{
this.logger.LogTrace("Registered additional callback for the block '{0}'.", chainedHeader);
}
callbacks.Add(onBlockDownloadedCallback);
bool blockIsNotConsecutive = (previousHeader != null) && (chainedHeader.Previous.HashBlock != previousHeader.HashBlock);
if (blockIsNotConsecutive || blockAlreadyAsked)
{
if (request != null)
{
downloadRequests.Add(request);
request = null;
}
if (blockAlreadyAsked)
{
previousHeader = null;
continue;
}
}
if (request == null)
{
request = new BlockDownloadRequest {
BlocksToDownload = new List <ChainedHeader>()
}
}
;
request.BlocksToDownload.Add(chainedHeader);
previousHeader = chainedHeader;
}
if (request != null)
{
downloadRequests.Add(request);
}
lock (this.peerLock)
{
foreach (BlockDownloadRequest downloadRequest in downloadRequests)
{
this.toDownloadQueue.Enqueue(downloadRequest);
}
this.ProcessDownloadQueueLocked();
}
}
this.logger.LogTrace("(-)");
}
