internal StreamWriter AcquireStatusFileLock()

in src/WebJobs.Extensions/Extensions/Files/Listener/FileProcessor.cs [337:386]
39 lines of code
8 McCabe index (conditional complexity)

        internal StreamWriter AcquireStatusFileLock(string filePath, WatcherChangeTypes changeType, out StatusFileEntry statusEntry)
        {
            Stream stream = null;
            statusEntry = null;
            try
            {
                // Attempt to create (or update) the companion status file and lock it. The status
                // file is the mechanism for handling multi-instance concurrency.
                string statusFilePath = GetStatusFile(filePath);
                stream = File.Open(statusFilePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);

                // Once we've established the lock, we need to check to ensure that another instance
                // hasn't already processed the file in the time between our getting the event and
                // acquiring the lock.
                statusEntry = GetLastStatus(stream);
                if (statusEntry != null && statusEntry.State == ProcessingState.Processed)
                {
                    // For file Create, we have no additional checks to perform. However for
                    // file Change, we need to also check the LastWrite value for the entry
                    // since there can be multiple Processed entries in the file over time.
                    if (changeType == WatcherChangeTypes.Created)
                    {
                        return null;
                    }
                    else if (changeType == WatcherChangeTypes.Changed &&
                        File.GetLastWriteTimeUtc(filePath) == statusEntry.LastWrite)
                    {
                        return null;
                    }
                }

                stream.Seek(0, SeekOrigin.End);
                StreamWriter streamReader = new StreamWriter(stream);
                streamReader.AutoFlush = true;
                stream = null;

                return streamReader;
            }
            catch
            {
                return null;
            }
            finally
            {
                if (stream != null)
                {
                    stream.Dispose();
                }
            }
        }