ファイルの排他制御

public static class LogWriter
{
	private class Log
	{
		public DateTime time;
		public string text;

		public Log(DateTime time, string text)
		{
			this.time = time;
			this.text = text;
		}
	}

	private static Queue<Log> queue = new Queue<Log>();

	public static void Enqueue(DateTime time, string text)
	{
		lock (queue) {
			queue.Enqueue(new log(time, text));
		}
	}

	private static Log Dequeue()
	{
		lock (queue) {
			if (queue.Count > 0)
				return queue.Dequeue();
			else
				return null;
		}
	}

	public static void WriteLog(string file)
	{
		Log log = Dequeue();
		if (log != null) {
			using (StreamWriter sw = new StreamWriter(file, true)) {
				do {
					sw.WriteLine(log.time + "," + log.text);
				} while ((log = Dequeue()) != null);
			}
		}
	}
}