protected override object DoJob()

in AdlsDotNetSDK/FileTransfer/Jobs/CopyFileJob.cs [58:124]
48 lines of code
16 McCabe index (conditional complexity)

        protected override object DoJob()
        {
            long chunkLength = _lengthToRead;
            try
            {
                // If a chunked file was reported to be attempted last transfer and it is resumed, then we have to establish whether we need to transfer any remaining chunks. 
                // Reason is just based on log file we cannot gurantee the state (Please refer FileTransferCommon.AddFileToConsumerQueue for more doc). 
                // We need to verify whether the chunk temp file exists or concat temp file exist (for upload) or the destination exist
                // to establish where we are in resume. If we are anywhere after "chunk temp file/folder does not exist" state then there is no need of transferring chunks
                if (Metadata.IsFileHalfDone)
                {
                    bool notContinue = Metadata.IsUpload ? !Metadata.ResumeUpload(Client) : !Metadata.ResumeDownload();
                    if (notContinue)
                    {
                        // Some irrecoverable problem during resume
                        if (!string.IsNullOrEmpty(Metadata.UnexpectedTransferErrorResume))
                        {
                            return new SingleEntryTransferStatus(Metadata.SrcFile, Metadata.Dest,
                                Metadata.UnexpectedTransferErrorResume, EntryType.Chunk, SingleChunkStatus.Failed);
                        }
                        // Here all the chunks are actually transferred even though it was not reported in logfile
                        // Here we return success for those cases where we have outstanding jobs for chunks so that they get reported as success in log file
                        if (Metadata.StartChunksAlreadyTransfered < Metadata.TotalChunks)
                        {
                            return new SingleEntryTransferStatus(Metadata.SrcFile, Metadata.Dest, "", EntryType.Chunk, SingleChunkStatus.Successful, ChunkIndex, chunkLength);
                        }
                        // This is the case where actually all chunks were already reported to be transferred
                        return new SingleEntryTransferStatus(Metadata.SrcFile, Metadata.Dest,
                            "", EntryType.Chunk, SingleChunkStatus.Skipped);
                        
                    }
                }
                // Determines whether a chunk of a file need to be skipped. This is more effecient for chunked case because other threads
                // do not have to check fileExists again and again. For nonchunked we determine it while creating otherwise there will be two 
                // filesystem calls
                if (ChunkIndex >= 0 && Metadata.ShouldSkipForChunkedFile(Client))
                {
                    return new SingleEntryTransferStatus(Metadata.SrcFile, Metadata.Dest, "", EntryType.File, SingleChunkStatus.Skipped);
                }
                bool uploadDestExists, downloadDestExists;
                // uploadDestExists checks whether the destination exists in remote adl while creating the file
                // downloadDestExists checks whether the destination exists in local disk while creating the file
                //Either uploadDestExists will be true or downloadDestExists can be true. Both can never be true
                // For non chunked job: Determine whether this entry will be skipped while creating the stream, this is why we pass skip flag as output
                using (Stream remoteStream = GetRemoteStream(out uploadDestExists),
                    localStream = GetLocalStream(out downloadDestExists))

                {
                    if (uploadDestExists || downloadDestExists)
                    {
                        return new SingleEntryTransferStatus(Metadata.SrcFile, Metadata.Dest, "", EntryType.File, SingleChunkStatus.Skipped);
                    }
                    TransferChunks(Metadata.IsUpload ? localStream : remoteStream, Metadata.IsUpload ? remoteStream : localStream);
                }
                //No need to update the chunk if it is a job for a non-chunked file
                if (ChunkIndex >= 0)
                {
                    Metadata.UpdateChunk();
                }
                return new SingleEntryTransferStatus(Metadata.SrcFile, Destination, "", ChunkIndex >= 0 ? EntryType.Chunk : EntryType.File, SingleChunkStatus.Successful, ChunkIndex, chunkLength);
            }

            catch (Exception e)
            {
                return new SingleEntryTransferStatus(Metadata.SrcFile, Destination, e.Message, ChunkIndex >= 0 ? EntryType.Chunk : EntryType.File, SingleChunkStatus.Failed, ChunkIndex, chunkLength);
            }
        }