using log4net;
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using log4net.Appender;
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using log4net.Core;
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namespace DeviceService.Logging;
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/// <summary>内存缓冲中的一条日志。</summary>
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public sealed class LogEntry
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{
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public DateTime Time { get; set; }
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public string Level { get; set; } = string.Empty;
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public string Logger { get; set; } = string.Empty;
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public string Message { get; set; } = string.Empty;
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public string Display => $"{Time:yyyy-MM-dd HH:mm:ss.fff} [{Level}] {Logger} - {Message}";
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public override string ToString() => Display;
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}
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/// <summary>
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/// 自定义 Appender：只在内存环形缓冲中保留最近 <see cref="Capacity"/> 条日志，
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/// 通过 <see cref="EntryAppended"/> 与 <see cref="Snapshot"/> 供日志窗口查看。
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/// 文件输出由 log4net.config 中的 RollingFileAppender 负责，本 Appender 不写任何文件。
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/// 实例由 log4net 依据 Config/log4net.config 创建（appender name="Memory"）。
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/// </summary>
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public sealed class MemoryAppender : AppenderSkeleton
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{
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/// <summary>内存中最多保留的日志条数，可由 log4net.config 的 capacity 参数覆盖。</summary>
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public int Capacity { get; set; } = 1000;
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/// <summary>log4net.config 中配置的 MemoryAppender 实例。</summary>
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public static MemoryAppender Current =>
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LogManager.GetRepository(typeof(MemoryAppender).Assembly)
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.GetAppenders()
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.OfType<MemoryAppender>()
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.FirstOrDefault()
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?? throw new InvalidOperationException(
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"未找到 MemoryAppender，请检查 Config/log4net.config 中是否配置了 name=\"Memory\" 的 appender，并在 root 中引用。");
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private readonly object _sync = new object();
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private readonly Queue<LogEntry> _entries = new Queue<LogEntry>();
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/// <summary>新日志到达（可能在后台线程触发，UI 订阅方需切换回 UI 线程）。</summary>
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public event Action<LogEntry>? EntryAppended;
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/// <summary>当前内存中日志的快照。</summary>
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public IReadOnlyList<LogEntry> Snapshot
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{
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get
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{
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lock (_sync)
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{
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return _entries.ToList();
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}
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}
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}
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public MemoryAppender()
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{
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Name = "Memory";
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}
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/// <summary>清空内存缓冲（不影响文件）。</summary>
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public void Clear()
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{
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lock (_sync)
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{
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_entries.Clear();
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}
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}
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protected override void Append(LoggingEvent loggingEvent)
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{
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if (loggingEvent == null)
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{
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return;
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}
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string message = loggingEvent.RenderedMessage ?? string.Empty;
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if (loggingEvent.ExceptionObject != null)
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{
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message += Environment.NewLine + loggingEvent.ExceptionObject;
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}
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var entry = new LogEntry
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{
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Time = loggingEvent.TimeStamp,
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Level = loggingEvent.Level?.Name ?? string.Empty,
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Logger = loggingEvent.LoggerName,
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Message = message
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};
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lock (_sync)
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{
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_entries.Enqueue(entry);
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while (_entries.Count > Capacity)
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{
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_entries.Dequeue();
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}
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// Monitor 锁可重入，回调内部若调用 Snapshot/Clear 不会死锁
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EntryAppended?.Invoke(entry);
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}
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}
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}
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