/// <summary>Adds items from <paramref name="headersByJobId"/> to the <see cref="reassignedJobsQueue"/>.</summary>
/// <param name="headersByJobId">Block headers mapped by job IDs.</param>
/// <remarks>Have to be locked by <see cref="queueLock"/>.</remarks>
private void ReassignAssignmentsLocked(Dictionary <int, List <ChainedHeader> > headersByJobId)
{
this.logger.LogTrace("({0}.{1}:{2})", nameof(headersByJobId), nameof(headersByJobId.Count), headersByJobId.Count);
foreach (KeyValuePair <int, List <ChainedHeader> > jobIdToHeaders in headersByJobId)
{
var newJob = new DownloadJob()
{
Id = jobIdToHeaders.Key,
Headers = jobIdToHeaders.Value
};
this.reassignedJobsQueue.Enqueue(newJob);
}
this.logger.LogTrace("(-)");
}
/// <summary>Distributes download job's headers to peers that can provide blocks represented by those headers.</summary>
/// <remarks>
/// If some of the blocks from the job can't be provided by any peer those headers will be added to a <param name="failedHashes">.</param>
/// <para>
/// Have to be locked by <see cref="queueLock"/>.
/// </para>
/// <para>
/// Node's quality score is being considered as a weight during the random distribution of the hashes to download among the nodes.
/// </para>
/// </remarks>
/// <param name="downloadJob">Download job to be partially of fully consumed.</param>
/// <param name="failedHashes">List of failed hashes which will be extended in case there is no peer to claim required hash.</param>
/// <param name="emptySlots">Number of empty slots. This is the maximum number of assignments that can be created.</param>
/// <returns>List of downloads that were distributed between the peers.</returns>
private List <AssignedDownload> DistributeHeadersLocked(DownloadJob downloadJob, List <uint256> failedHashes, int emptySlots)
{
this.logger.LogTrace("({0}.{1}:{2},{3}.{4}:{5},{6}:{7})", nameof(downloadJob.Headers), nameof(downloadJob.Headers.Count), downloadJob.Headers.Count,
nameof(failedHashes), nameof(failedHashes.Count), failedHashes.Count, nameof(emptySlots), emptySlots);
var newAssignments = new List <AssignedDownload>();
HashSet <IBlockPullerBehavior> peerBehaviors;
lock (this.peerLock)
{
peerBehaviors = new HashSet <IBlockPullerBehavior>(this.pullerBehaviorsByPeerId.Values);
}
bool jobFailed = false;
if (peerBehaviors.Count == 0)
{
this.logger.LogDebug("There are no peers that can participate in download job distribution! Job ID {0} failed.", downloadJob.Id);
jobFailed = true;
}
int lastSucceededIndex = -1;
for (int index = 0; (index < downloadJob.Headers.Count) && (index < emptySlots) && !jobFailed; index++)
{
ChainedHeader header = downloadJob.Headers[index];
while (!jobFailed)
{
// Weighted random selection based on the peer's quality score.
double sumOfQualityScores = peerBehaviors.Sum(x => x.QualityScore);
double scoreToReachPeer = this.random.NextDouble() * sumOfQualityScores;
IBlockPullerBehavior selectedBehavior = peerBehaviors.First();
foreach (IBlockPullerBehavior peerBehavior in peerBehaviors)
{
if (peerBehavior.QualityScore >= scoreToReachPeer)
{
selectedBehavior = peerBehavior;
break;
}
scoreToReachPeer -= peerBehavior.QualityScore;
}
INetworkPeer attachedPeer = selectedBehavior.AttachedPeer;
// Behavior's tip can't be null because we only have behaviors inserted in the behaviors structure after the tip is set.
if ((attachedPeer != null) && (selectedBehavior.Tip.FindAncestorOrSelf(header) != null))
{
int peerId = attachedPeer.Connection.Id;
// Assign to this peer.
newAssignments.Add(new AssignedDownload()
{
PeerId = peerId,
JobId = downloadJob.Id,
AssignedTime = this.dateTimeProvider.GetUtcNow(),
Header = header
});
lastSucceededIndex = index;
this.logger.LogTrace("Block '{0}' was assigned to peer ID {1}.", header.HashBlock, peerId);
break;
}
else
{
// Peer doesn't claim this header.
peerBehaviors.Remove(selectedBehavior);
if (peerBehaviors.Count != 0)
{
continue;
}
jobFailed = true;
this.logger.LogDebug("Job {0} failed because there is no peer claiming header '{1}'.", downloadJob.Id, header);
}
}
}
if (!jobFailed)
{
downloadJob.Headers.RemoveRange(0, lastSucceededIndex + 1);
}
else
{
int removeFrom = (lastSucceededIndex == -1) ? 0 : lastSucceededIndex + 1;
IEnumerable <uint256> failed = downloadJob.Headers.GetRange(removeFrom, downloadJob.Headers.Count - removeFrom).Select(x => x.HashBlock);
failedHashes.AddRange(failed);
downloadJob.Headers.Clear();
}
this.logger.LogTrace("(-):*.{0}={1},{2}.{3}={4}", nameof(newAssignments.Count), newAssignments.Count, nameof(failedHashes), nameof(failedHashes.Count), failedHashes.Count);
return(newAssignments);
}