MemoryTarget.cs

// 
// Copyright (c) 2004-2020 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without 
// modification, are permitted provided that the following conditions 
// are met:
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// * Redistributions of source code must retain the above copyright notice, 
//   this list of conditions and the following disclaimer. 
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// * Redistributions in binary form must reproduce the above copyright notice,
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// * Neither the name of Jaroslaw Kowalski nor the names of its 
//   contributors may be used to endorse or promote products derived from this
//   software without specific prior written permission. 
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namespace NLog.Targets
{
    using System.Collections.Generic;
    using System.ComponentModel;

    /// <summary>
    /// Writes log messages to <see cref="Logs"/> in memory for programmatic retrieval.
    /// </summary>
    /// <seealso href="https://github.com/nlog/nlog/wiki/Memory-target">Documentation on NLog Wiki</seealso>
    /// <example>
    /// <p>
    /// To set up the target in the <a href="config.html">configuration file</a>, 
    /// use the following syntax:
    /// </p>
    /// <code lang="XML" source="examples/targets/Configuration File/Memory/NLog.config" />
    /// <p>
    /// This assumes just one target and a single rule. More configuration
    /// options are described <a href="config.html">here</a>.
    /// </p>
    /// <p>
    /// To set up the log target programmatically use code like this:
    /// </p>
    /// <code lang="C#" source="examples/targets/Configuration API/Memory/Simple/Example.cs" />
    /// </example>
    [Target("Memory")]
    public sealed class MemoryTarget : TargetWithLayout
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="MemoryTarget" /> class.
        /// </summary>
        /// <remarks>
        /// The default value of the layout is: <code>${longdate}|${level:uppercase=true}|${logger}|${message}</code>
        /// </remarks>
        public MemoryTarget()
        {
            Logs = new List<string>();
            OptimizeBufferReuse = true;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="MemoryTarget" /> class.
        /// </summary>
        /// <remarks>
        /// The default value of the layout is: <code>${longdate}|${level:uppercase=true}|${logger}|${message}</code>
        /// </remarks>
        /// <param name="name">Name of the target.</param>
        public MemoryTarget(string name) : this()
        {
            Name = name;
        }

        /// <summary>
        /// Gets the list of logs gathered in the <see cref="MemoryTarget"/>.
        /// </summary>
        public IList<string> Logs { get; }

        /// <summary>
        /// Gets or sets the max number of items to have in memory
        /// </summary>
        /// <docgen category='Buffering Options' order='10' />
        [DefaultValue(0)]
        public int MaxLogsCount { get; set; }

        /// <summary>
        /// Renders the logging event message and adds to <see cref="Logs"/>
        /// </summary>
        /// <param name="logEvent">The logging event.</param>
        protected override void Write(LogEventInfo logEvent)
        {
            if (MaxLogsCount > 0 && Logs.Count >= MaxLogsCount)
            {
                Logs.RemoveAt(0);
            }
            Logs.Add(RenderLogEvent(Layout, logEvent));
        }
    }
}