duplicati/Duplicati/Library/Main/ControllerMultiLogTarget.cs

// Copyright (C) 2025, The Duplicati Team
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// 
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// copy of this software and associated documentation files (the "Software"), 
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// 
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#nullable enable

using System;
using System.Collections.Generic;
using System.Linq;
using Duplicati.Library.Logging;

namespace Duplicati.Library.Main
{
    /// <summary>
    /// The log target handler for the controller, which sends to multiple log targets
    /// </summary>
    public class ControllerMultiLogTarget : ILogDestination, IDisposable
    {
        /// <summary>
        /// The target entry for the log target
        /// </summary>
        /// <param name="Target">The log target.</param>
        /// <param name="Level">The minimum log level to consider</param>
        /// <param name="Filter">The log filter.</param>
        private sealed record TargetEntry(ILogDestination Target, LogMessageType Level, Library.Utility.IFilter Filter);

        /// <summary>
        /// The list of log targets to handle
        /// </summary>
        private readonly List<TargetEntry> m_targets = new List<TargetEntry>();

        /// <summary>
        /// The filter used to suppress warnings
        /// </summary>
        private readonly HashSet<string>? m_supressWarningFilter;

        /// <summary>
        /// Initializes a new instance of the <see cref="T:Duplicati.Library.Main.ControllerMultiLogTarget"/> class.
        /// </summary>
        /// <param name="target">The log target.</param>
        /// <param name="loglevel">The minimum log level to consider</param>
        /// <param name="filter">The log filter.</param>
        public ControllerMultiLogTarget(ILogDestination target, Logging.LogMessageType loglevel, Library.Utility.IFilter? filter, HashSet<string>? supressWarningFilter)
        {
            m_supressWarningFilter = supressWarningFilter;
            AddTarget(target, loglevel, filter);
        }

        /// <summary>
        /// Adds the target to the list.
        /// </summary>
        /// <param name="target">The log target.</param>
        /// <param name="loglevel">The minimum log level to consider</param>
        /// <param name="filter">The log filter.</param>
        public void AddTarget(ILogDestination? target, LogMessageType loglevel, Library.Utility.IFilter? filter)
        {
            if (target == null)
                return;

            m_targets.Add(new TargetEntry(target, loglevel, filter ?? new Library.Utility.FilterExpression()));
        }

        /// <summary>
        /// Releases all resource used by the <see cref="T:Duplicati.Library.Main.ControllerMultiLogTarget"/> object.
        /// </summary>
        /// <remarks>Call <see cref="Dispose"/> when you are finished using the
        /// <see cref="T:Duplicati.Library.Main.ControllerMultiLogTarget"/>. The <see cref="Dispose"/> method leaves the
        /// <see cref="T:Duplicati.Library.Main.ControllerMultiLogTarget"/> in an unusable state. After calling
        /// <see cref="Dispose"/>, you must release all references to the
        /// <see cref="T:Duplicati.Library.Main.ControllerMultiLogTarget"/> so the garbage collector can reclaim the
        /// memory that the <see cref="T:Duplicati.Library.Main.ControllerMultiLogTarget"/> was occupying.</remarks>
		public void Dispose()
        {
            foreach (var m in m_targets)
                (m.Target as IDisposable)?.Dispose();
            m_targets.Clear();
        }

        /// <summary>
        /// Gets the minimum log level of all the targets
        /// </summary>
        public LogMessageType MinimumLevel
            => m_targets.Select(x => x.Level).DefaultIfEmpty(LogMessageType.Error).Min();

        /// <summary>
        /// Writes the message to all the destinations.
        /// </summary>
        /// <param name="entry">Entry.</param>
        public void WriteMessage(LogEntry entry)
        {
            // If the message is a warning, check if we should suppress it
            if (m_supressWarningFilter != null && entry.Level == LogMessageType.Warning && m_supressWarningFilter.Contains(entry.Id))
                entry = new LogEntry(entry.Message, entry.Arguments, LogMessageType.Information, entry.Tag, entry.Id, entry.Exception);

            foreach (var e in m_targets)
            {
                var found = e.Filter.Matches(entry.FilterTag, out var result, out var _);

                // If there is a filter match, use that
                if (found)
                {
                    if (!result)
                        continue;
                }
                else
                {
                    // Otherwise, filter by log-level
                    if (entry.Level < e.Level)
                        continue;
                }

                // If we get here, write the message
                e.Target.WriteMessage(entry);
            }
        }
    }
}