using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace LeanCloud.Storage.Internal {
  public class LockSet {
    private static readonly ConditionalWeakTable<object, IComparable> stableIds =
        new ConditionalWeakTable<object, IComparable>();
    private static long nextStableId = 0;

    private readonly IEnumerable<object> mutexes;

    public LockSet(IEnumerable<object> mutexes) {
      this.mutexes = (from mutex in mutexes
                      orderby GetStableId(mutex)
                      select mutex).ToList();
    }

    public void Enter() {
      foreach (var mutex in mutexes) {
        Monitor.Enter(mutex);
      }
    }

    public void Exit() {
      foreach (var mutex in mutexes) {
        Monitor.Exit(mutex);
      }
    }

    private static IComparable GetStableId(object mutex) {
      lock (stableIds) {
        return stableIds.GetValue(mutex, k => nextStableId++);
      }
    }
  }
}