TextWriterEventSink.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
 
namespace Waher.Events.Files
{
    public class TextWriterEventSink : EventSink, IDisposable
    {
        protected TextWriter output;
        
        private readonly object synchObject = new object();
        private bool disposed = false;
 
        public TextWriterEventSink(string ObjectID, TextWriter Output)
            : base(ObjectID)
        {
            this.output = Output;
        }
 
        protected virtual void BeforeWrite()
        {
            // Do nothing by default.
        }
 
        protected virtual void AfterWrite()
        {
            // Do nothing by default.
        }
 
        public override void Dispose()
        {
            this.disposed = true;
 
            this.DisposeOutput();
            base.Dispose();
        }
 
        public override Task Queue(Event Event)
        {
            if (this.disposed)
                return Task.CompletedTask;
 
            lock (this.synchObject)
            {
                this.BeforeWrite();
                try
                {
                    if (!(this.output is null))
                    {
                        this.output.Write(Event.Timestamp.ToString("d"));
                        this.output.Write(", ");
                        this.output.Write(Event.Timestamp.ToString("T"));
                        this.output.Write('\t');
                        this.output.Write(Event.Type.ToString());
                        this.output.Write('\t');
                        this.output.Write(Event.Level.ToString());
 
                        if (!string.IsNullOrEmpty(Event.EventId))
                        {
                            this.output.Write('\t');
                            this.output.Write(Event.EventId);
                        }
 
                        if (!string.IsNullOrEmpty(Event.Object))
                        {
                            this.output.Write('\t');
                            this.output.Write(Event.Object);
                        }
 
                        if (!string.IsNullOrEmpty(Event.Actor))
                        {
                            this.output.Write('\t');
                            this.output.Write(Event.Actor);
                        }
 
                        this.output.WriteLine("\r\n");
 
                        if (!string.IsNullOrEmpty(Event.Module))
                        {
                            this.output.Write('\t');
                            this.output.Write(Event.Module);
                        }
 
                        if (!string.IsNullOrEmpty(Event.Facility))
                        {
                            this.output.Write('\t');
                            this.output.Write(Event.Facility);
                        }
 
                        if (!(Event.Tags is null) && Event.Tags.Length > 0)
                        {
                            this.output.WriteLine("\r\n");
 
                            foreach (KeyValuePair<string, object> Tag in Event.Tags)
                            {
                                this.output.Write('\t');
                                this.output.Write(Tag.Key);
                                this.output.Write('=');
 
                                if (!(Tag.Value is null))
                                    this.output.Write(Tag.Value.ToString());
                            }
                        }
 
                        this.output.WriteLine("\r\n");
                        this.output.WriteLine(Event.Message);
 
                        if (Event.Type >= EventType.Critical && !string.IsNullOrEmpty(Event.StackTrace))
                        {
                            this.output.WriteLine("\r\n");
                            this.output.WriteLine(Event.StackTrace);
                        }
 
                        this.output.Flush();
                    }
                }
                catch (Exception)
                {
                    try
                    {
                        this.DisposeOutput();
                    }
                    catch (Exception)
                    {
                        // Ignore
                    }
                }
                finally
                {
                    this.AfterWrite();
                }
            }
 
            return Task.CompletedTask;
        }
            
        public virtual bool CanDisposeOutput => true;
 
        public virtual void DisposeOutput()
        {
            if (this.CanDisposeOutput)
            {
                this.output?.Flush();
                this.output?.Dispose();
            }
 
            this.output = null;
        }
    }
}