/// <summary> /// Writes an <see cref="IOperation" /> to the log. /// </summary> /// <param name="resource">The parent <see cref="ITransactedResource" /> responsible for serializing the operation.</param> /// <param name="operation">The operation to be written.</param> /// <remarks> /// <note> /// This property can only be called if the operation log is in <see cref="OperationLogMode.Undo" /> /// mode. /// </note> /// </remarks> /// <exception cref="TransactionException">Thrown if the log isn't open or if the mode isn't <see cref="OperationLogMode.Undo" />.</exception> public void Write(ITransactedResource resource, IOperation operation) { long cbPos; long cb; using (TimedLock.Lock(this)) { if (file == null) { throw new TransactionException(ClosedMsg); } if (mode != OperationLogMode.Undo) { throw new TransactionException("Write is available only when the log is in UNDO mode."); } file.WriteInt32(Magic); // Magic number cbPos = file.Position; // Length place holder file.WriteInt32(0); file.WriteString32(operation.Description); // Description resource.WriteOperation(file, operation); // Serialized operation cb = file.Position - cbPos - 4; if (cb < 0 || cb > int.MaxValue) { throw new TransactionException("ITransactedResource.WriteOperation() returned with an unexpected stream position."); } file.Position = cbPos; file.WriteInt32((int)cb); file.Position = file.Length; file.Flush(); } }
private OperationLogMode mode; // The current mode /// <summary> /// Opens or creates a file operation log file. /// </summary> /// <param name="path">The path to the log file.</param> /// <param name="transactionID">The log's transaction <see cref="Guid" />.</param> /// <remarks> /// New logs will be created in <see cref="OperationLogMode.Undo" /> mode. /// </remarks> public FileOperationLog(string path, Guid transactionID) { this.path = Path.GetFullPath(path); this.file = new EnhancedFileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite); if (file.Length == 0) { // Initialize a new file file.WriteInt32(Magic); file.WriteInt32(0); file.WriteInt32(0); file.WriteInt32((int)OperationLogMode.Undo); file.WriteBytesNoLen(transactionID.ToByteArray()); file.Flush(); } else { // Open an existing file. try { if (file.ReadInt32() != Magic || // Magic number file.ReadInt32() != 0) { // Format Versopn throw new Exception(); } file.ReadInt32(); // Reserved switch (file.ReadInt32()) // Mode { case (int)OperationLogMode.Undo: mode = OperationLogMode.Undo; break; case (int)OperationLogMode.Redo: mode = OperationLogMode.Redo; break; default: throw new Exception(); } this.transactionID = new Guid(file.ReadBytes(16)); if (transactionID != this.transactionID) { throw new Exception(); } } catch { throw new TransactionException(CorruptMsg); } } }
/// <summary> /// Loads the message index file. If the index does not exist or is corrupt then /// the index will be rebuilt by performing a full scan of message files under /// the root folder. /// </summary> /// <param name="newIndexFile">Pass as <c>true</c> if a new index file is being created.</param> private void LoadIndex(bool newIndexFile) { string formatErr = string.Format("Invalid or missing index file [{0}].", indexPath); int cMessages; string[] files; Dictionary <Guid, string> msgFiles; TimedLock.AssertLocked(this); messages = new Dictionary <Guid, QueuedMsgInfo>(); // List the message files and build a hash table mapping each message GUID // the fully qualified path to the file. files = Helper.GetFilesByPattern(root + "*.msg", SearchOption.AllDirectories); msgFiles = new Dictionary <Guid, string>(files.Length); foreach (string path in files) { string file = Path.GetFileName(path).ToLowerInvariant(); Guid msgID; if (!file.EndsWith(".msg")) { continue; } try { msgID = new Guid(file.Substring(0, file.Length - 4)); } catch { continue; } msgFiles[msgID] = path; } // Load the index file. try { // Parse the index file header fsIndex.Position = 0; if (fsIndex.ReadInt32() != IndexMagic) // Magic Number { throw new FormatException(formatErr); } if (fsIndex.ReadInt32() != 0) // Format Version { throw new FormatException(formatErr); } fsIndex.ReadInt32(); // Reserved if (fsIndex.ReadInt32() != 0) { throw new FormatException(string.Format("Index file [{0}] was not closed properly. Full message folder scan will be performed.", indexPath)); } cMessages = fsIndex.ReadInt32(); // Message Count // Parse the message metadata for (int i = 0; i < cMessages; i++) { QueuedMsgInfo msgInfo; msgInfo = new QueuedMsgInfo(fsIndex.ReadString16()); msgInfo.PersistID = msgInfo.ID; msgInfo.ProviderData = root + fsIndex.ReadString16(); // Make the paths absolute messages[msgInfo.ID] = msgInfo; } // Perform an extra consistency check by listing all of the message files // under the root folder and comparing the message GUIDs encoded into the // file names with the GUIDs loaded from the index file and then bringing // the index into sync with the actual message files. bool updated = false; int cLoaded = 0; // Delete any metadata for messages that exist in the index // but don't exist on the file system. var delList = new List <Guid>(); foreach (Guid msgID in messages.Keys) { if (!msgFiles.ContainsKey(msgID)) { delList.Add(msgID); } } foreach (Guid msgID in delList) { messages.Remove(msgID); } if (delList.Count > 0) { updated = true; SysLog.LogWarning(string.Format("Message index [{0}] has message metadata for messages that do not exist. [{1}] messages will be removed from the index.", indexPath, delList.Count)); } // Load metadata for messages that exist in the file system // but were not in the index. foreach (Guid msgID in msgFiles.Keys) { if (!messages.ContainsKey(msgID)) { string path = msgFiles[msgID]; try { messages[msgID] = ReadMessageMetadata(msgID, path); cLoaded++; } catch (Exception e) { SysLog.LogException(e); } } } if (cLoaded > 0) { updated = true; SysLog.LogWarning(string.Format("Message index [{0}] is missing metadata for [{1}] messages. Missing entries will be added.", indexPath, cLoaded)); } if (updated) { SaveIndex(true); } // Mark the index as "open" for crash detection. fsIndex.Position = OpenFlagOffset; fsIndex.WriteInt32(1); fsIndex.Flush(); } catch { if (newIndexFile) { SysLog.LogWarning("Rebuilding missing message index file [{0}].", indexPath); } else { SysLog.LogWarning("Rebuilding corrupt message index file [{0}].", indexPath); } // Clear the index file if there was a serious error and then // rebuild it from scratch by scanning the message metadata. fsIndex.SetLength(0); fsIndex.Flush(); messages.Clear(); foreach (Guid msgID in msgFiles.Keys) { try { messages.Add(msgID, ReadMessageMetadata(msgID, msgFiles[msgID])); } catch (Exception e2) { SysLog.LogException(e2); } } // Save the index, marking the file as "open" for crash detection SaveIndex(true); } }