using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace IStation
{
    internal sealed partial class SharedMemoryCache
    {
        /// <summary>
        /// 移除所有缓存项，在移除之前阻止任何操作
        /// Remove all cache entries, blocking any set operations until complete
        /// </summary>
        public void Wipe()
        {
            if (_isWiping) { return; }

            lock (_wipeLock)
            {
                if (_isWiping) { return; }

                _isWiping = true;

                SpinWait.SpinUntil(() => !_isSetting); // wait until all running set operations are complete (new ones are blocked)

                var keys = _memoryCache.Select(x => x.Key);

                Parallel.ForEach(keys, x => ((IMemoryCacheDirect)this).Remove(x));

                try
                {
                    if (keys.Any())
                    {
                        throw new Exception("Unable to remove keys: " + string.Join(", ", keys));
                    }
                }
                finally
                {
                    _isWiping = false;
                }
            }
        }
    }
}