RE: simulating tail -f

[Wayne Bradney]

Many ways to do this – the way I do it doesn’t involve the log _file_ at all, rather by creating a special appender dynamically, that populates a grid control:                      private delegate void AppendDelegate(log4net.Core.LoggingEvent evt, Thread thread, log4net.Layout.ILayout layout);                    private GridAppender gridAppender;                    private AppendDelegate append;   …                      // To implement a visual log, just use a custom log4net appender, suitably configured.                    // This will catch all events logged and append them to a C1FlexGrid                    log4net.Repository.Hierarchy.Hierarchy h = (log4net.Repository.Hierarchy.Hierarchy) LogManager.GetRepository();                    AppendDelegate append = new AppendDelegate(Append);                    gridAppender = new GridAppender(append);                    gridAppender.Layout = new log4net.Layout.PatternLayout("%d{yyyy-MM-dd HH:mm:ss} %m");                    h.Root.AddAppender(gridAppender);   …                      private void Append(log4net.Core.LoggingEvent evt, log4net.Layout.ILayout layout) {                              if (this.IsDisposed)                                       return;                                if (!InvokeRequired) {                                       /*                                        * The appender will append one event at a time to the bottom of a grid control                                        */                                       Grid1.Redraw = false;                                          StringBuilder messageBuilder = new StringBuilder();                                       StringWriter sw = new StringWriter(messageBuilder);                                       layout.Format(sw, evt);                                       messageBuilder.Append(evt.GetExceptionString());                                         // Build the full message and exception report if applicable                                       string message = messageBuilder.ToString();                                         // Split the message into lines                                       string[] lines = message.Split('\n');                                         if (lines.Length > 0) {                                                 // Add the first line                                                 Row newRow = Grid1.AddItem(new object[] { null, lines[0] });                                                   // Enforce the line limit                                                 if (Grid1.Rows.Count > lineLimit) {                                                           // Too many lines -- roll one off                                                           if (Grid1.Rows[0].IsNode) {                                                                    // Roll off the entire node                                                                    Grid1.Rows[0].Node.RemoveNode();                                                           }                                                           else {                                                                    // Roll off the single item                                                                    Grid1.RemoveItem(0);                                                           }                                                 }                                                   // Set the image for the new event according to its Level                                                 Image image = null;                                                 if (evt.Level == log4net.Core.Level.Fatal)                                                           image = logImages.Images[(int) LogLevelEnum.Fatal];                                                 else if (evt.Level == log4net.Core.Level.Error)                                                           image = logImages.Images[(int) LogLevelEnum.Error];                                                 else if (evt.Level == log4net.Core.Level.Warn)                                                           image = logImages.Images[(int) LogLevelEnum.Warning];                                                 else if (evt.Level == log4net.Core.Level.Info)                                                           image = logImages.Images[(int) LogLevelEnum.Info];                                                 else if (evt.Level == log4net.Core.Level.Debug)                                                           image = logImages.Images[(int) LogLevelEnum.Debug];                                                 else                                                           image = null;                                                 Grid1.SetCellImage(newRow.Index, 1, image);                                                   newRow.IsNode = true;                                                   if (lines.Length > 1) {                                                           // There are more lines -- use a tree node to expand the rest                                                           for (int i = 1; i < lines.Length; i++) {                                                                    if (lines[i].Trim().Length > 0) {                                                                              Node newSubNode = newRow.Node.AddNode(NodeTypeEnum.LastChild, lines[i]);                                                                    }                                                           }                                                 }                                       }                                         // Auto-scroll to the end (the newest message)                                       Grid1.Select(c1FlexGrid1.Rows.Count - 1, 1);                                       Grid1.ShowCell(c1FlexGrid1.Rows.Count - 1, 1);                                         Grid1.Redraw = true;                              }                              else {                                       AppendDelegate append = new AppendDelegate(Append);                                       this.BeginInvoke(append, new object[] { evt, layout });                              }                    }     …                    private class GridAppender : log4net.Appender.AppenderSkeleton {                              /*                               * This custom log4net appender will append to a grid                               * It has a limited number of lines (old lines will be rolled off), and holds an                               * ImageList for the different levels of severity.                               */                              private AppendDelegate append;                                public GridAppender(AppendDelegate append) {                                       this.append = append;                              }                                protected override void Append(log4net.Core.LoggingEvent evt) {                                       append(evt, Layout);                              }                    }   Wayne M. Bradney Application Architect, Derivatives & Structured Products Wall Street Systems 30 Broad Street, 24th Floor, New York, NY 10004 USA Tel: +1 (212) 809 7200 Fax: +1 (212) 809 7578 Visit our website at http://www.wallstreetsystems.com This transmission may be a privileged or confidential communication. If you are not the intended recipient, you are hereby notified that you have received this transmission in error; any review, dissemination, distribution or copying of this transmission is strictly prohibited. If you have received this communication in error, please notify us immediately by reply or by telephone (call us at +1-212-809-7200) and immediately delete this message and all its attachments.   From: Saurabh Dani [mailto:[EMAIL PROTECTED] Sent: Wednesday, August 16, 2006 10:23 PM To: log4net-user@logging.apache.org Subject: simulating tail -f   Greetings, I am writing the logs to log files using File appenders (2 different logs, one for info and one for debug). Is it possible to access these logs and show them within my application's Interface upon clicking a "view current logs" button? Basically I would like to simulate "tail -f" from within the application. Thanks Saurabh