internal override void Delete(StorageTransmission item)
{
try
{
if (StorageFolder == null)
{
return;
}
// Initial storage size calculation.
CalculateSize();
long fileSize = GetSize(item.FileName);
File.Delete(Path.Combine(StorageFolder, item.FileName));
_deletedFilesQueue.Enqueue(item.FileName);
// calculate size
Interlocked.Add(ref _storageSize, -fileSize);
Interlocked.Decrement(ref _storageCountFiles);
}
catch (IOException e)
{
PersistenceChannelDebugLog.WriteException(e, "Failed to delete a file. file: {0}", item == null ? "null" : item.FullFilePath);
}
}
protected void OnPeekedItemDisposed(string fileName)
{
try
{
if (PeekedTransmissions.ContainsKey(fileName))
{
PeekedTransmissions.Remove(fileName);
}
}
catch (Exception e)
{
PersistenceChannelDebugLog.WriteException(e, "Failed to remove the item from storage items.");
}
}
internal override async Task EnqueueAsync(Transmission transmission)
{
try
{
if (transmission == null || StorageFolder == null)
{
return;
}
// Initial storage size calculation.
CalculateSize();
if ((ulong)_storageSize >= CapacityInBytes || _storageCountFiles >= MaxFiles)
{
// if max storage capacity has reached, drop the transmission (but log every 100 lost transmissions).
if (_transmissionsDropped++ % 100 == 0)
{
PersistenceChannelDebugLog.WriteLine("Total transmissions dropped: " + _transmissionsDropped);
}
return;
}
// Writes content to a temporary file and only then rename to avoid the Peek from reading the file before it is being written.
// Creates the temp file name
string tempFileName = Guid.NewGuid().ToString("N");
// Now that the file got created we can increase the files count
Interlocked.Increment(ref _storageCountFiles);
// Saves transmission to the temp file
await SaveTransmissionToFileAsync(transmission, tempFileName).ConfigureAwait(false);
// Now that the file is written increase storage size.
long temporaryFileSize = GetSize(tempFileName);
Interlocked.Add(ref _storageSize, temporaryFileSize);
// Creates a new file name
string now = DateTime.UtcNow.ToString("yyyyMMddHHmmss");
string newFileName = string.Format(CultureInfo.InvariantCulture, "{0}_{1}.trn", now, tempFileName);
// Renames the file
File.Move(Path.Combine(StorageFolder, tempFileName), Path.Combine(StorageFolder, newFileName));
}
catch (Exception e)
{
PersistenceChannelDebugLog.WriteException(e, "EnqueueAsync");
}
}
/// <summary>
/// Get files from <see cref="storageFolder" />.
/// </summary>
/// <param name="fileQuery">Define the logic for sorting the files.</param>
/// <param name="filterByExtension">Defines a file extension. This method will return only files with this extension.</param>
/// <param name="top">
/// Define how many files to return. This can be useful when the directory has a lot of files, in that case
/// GetFilesAsync will have a performance hit.
/// </param>
private IEnumerable <string> GetFiles(string filterByExtension, int top)
{
try
{
if (StorageFolder != null)
{
return(Directory.GetFiles(StorageFolder, filterByExtension).Take(top));
}
}
catch (Exception e)
{
PersistenceChannelDebugLog.WriteException(e, "Peek failed while get files from storage.");
}
return(Enumerable.Empty <string>());
}
internal override void Init(string storageDirectoryPath)
{
PeekedTransmissions = new SnapshottingDictionary <string, string>();
VerifyOrSetDefaultStorageDirectoryPath(storageDirectoryPath);
CapacityInBytes = 10 * 1024 * 1024; // 10 MB
MaxFiles = 100;
Task.Run(DeleteObsoleteFiles)
.ContinueWith(
task =>
{
PersistenceChannelDebugLog.WriteException(
task.Exception,
"Storage: Unhandled exception in DeleteObsoleteFiles");
},
TaskContinuationOptions.OnlyOnFaulted);
}
/// <summary>
/// Enqueue is saving a transmission to a <c>tmp</c> file and after a successful write operation it renames it to a
/// <c>trn</c> file.
/// A file without a <c>trn</c> extension is ignored by Storage.Peek(), so if a process is taken down before rename
/// happens
/// it will stay on the disk forever.
/// This thread deletes files with the <c>tmp</c> extension that exists on disk for more than 5 minutes.
/// </summary>
private void DeleteObsoleteFiles()
{
try
{
IEnumerable <string> files = GetFiles("*.tmp", 50);
foreach (string file in files)
{
DateTime creationTime = File.GetCreationTimeUtc(Path.Combine(StorageFolder, file));
// if the file is older then 5 minutes - delete it.
if (DateTime.UtcNow - creationTime >= TimeSpan.FromMinutes(5))
{
File.Delete(Path.Combine(StorageFolder, file));
}
}
}
catch (Exception e)
{
PersistenceChannelDebugLog.WriteException(e, "Failed to delete tmp files.");
}
}
/// <summary>
/// Reads an item from the storage. Order is Last-In-First-Out.
/// When the Transmission is no longer needed (it was either sent or failed with a non-retryable error) it should be
/// disposed.
/// </summary>
internal override StorageTransmission Peek()
{
IEnumerable <string> files = GetFiles("*.trn", 50);
lock (_peekLockObj)
{
foreach (string file in files)
{
try
{
// if a file was peeked before, skip it (wait until it is disposed).
if (PeekedTransmissions.ContainsKey(file) == false &&
_deletedFilesQueue.Contains(file) == false)
{
// Load the transmission from disk.
StorageTransmission storageTransmissionItem = LoadTransmissionFromFileAsync(file)
.ConfigureAwait(false).GetAwaiter().GetResult();
// when item is disposed it should be removed from the peeked list.
storageTransmissionItem.Disposing = item => OnPeekedItemDisposed(file);
// add the transmission to the list.
PeekedTransmissions.Add(file, storageTransmissionItem.FullFilePath);
return(storageTransmissionItem);
}
}
catch (Exception e)
{
PersistenceChannelDebugLog.WriteException(
e,
"Failed to load an item from the storage. file: {0}",
file);
}
}
}
return(null);
}
/// <summary>
/// Initializes a new instance of the <see cref="Sender" /> class.
/// </summary>
/// <param name="storage">The storage that holds the transmissions to send.</param>
/// <param name="transmitter">
/// The persistence transmitter that manages this Sender.
/// The transmitter will be used as a configuration class, it exposes properties like SendingInterval that will be read
/// by Sender.
/// </param>
/// <param name="startSending">
/// A boolean value that determines if Sender should start sending immediately. This is only
/// used for unit tests.
/// </param>
internal Sender(BaseStorageService storage, PersistenceTransmitter transmitter, bool startSending = true)
{
_stopped = false;
DelayHandler = new AutoResetEvent(false);
_stoppedHandler = new AutoResetEvent(false);
_drainingTimeout = TimeSpan.FromSeconds(100);
_defaultSendingInterval = TimeSpan.FromSeconds(5);
_transmitter = transmitter;
_storage = storage;
if (startSending)
{
// It is currently possible for the long - running task to be executed(and thereby block during WaitOne) on the UI thread when
// called by a task scheduled on the UI thread. Explicitly specifying TaskScheduler.Default
// when calling StartNew guarantees that Sender never blocks the main thread.
Task.Factory.StartNew(SendLoop, CancellationToken.None, TaskCreationOptions.LongRunning,
TaskScheduler.Default)
.ContinueWith(
t => PersistenceChannelDebugLog.WriteException(t.Exception, "Sender: Failure in SendLoop"),
TaskContinuationOptions.OnlyOnFaulted);
}
}
/// <summary>
/// Sends a transmission and handle errors.
/// </summary>
/// <param name="transmission">The transmission to send.</param>
/// <param name="nextSendInterval">
/// When this value returns it will hold a recommendation for when to start the next sending
/// iteration.
/// </param>
/// <returns>True, if there was sent error and we need to retry sending, otherwise false.</returns>
protected virtual bool Send(StorageTransmission transmission, ref TimeSpan nextSendInterval)
{
try
{
if (transmission != null)
{
bool isConnected = NetworkInterface.GetIsNetworkAvailable();
// there is no internet connection available, return than.
if (!isConnected)
{
PersistenceChannelDebugLog.WriteLine(
"Cannot send data to the server. Internet connection is not available");
return(true);
}
transmission.SendAsync().ConfigureAwait(false).GetAwaiter().GetResult();
// After a successful sending, try immediately to send another transmission.
nextSendInterval = SendingInterval;
}
}
catch (WebException e)
{
int?statusCode = GetStatusCode(e);
nextSendInterval = CalculateNextInterval(statusCode, nextSendInterval, _maxIntervalBetweenRetries);
return(IsRetryable(statusCode, e.Status));
}
catch (Exception e)
{
nextSendInterval = CalculateNextInterval(null, nextSendInterval, _maxIntervalBetweenRetries);
PersistenceChannelDebugLog.WriteException(e, "Unknown exception during sending");
}
return(false);
}