// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using Libuv.Internal;

namespace Libuv
{
  public class WriteReqPool
  {
    private const int _maxPooledWriteReqs = 1024;

    private readonly LibuvThread _thread;
    private readonly Queue<UvWriteReq> _pool = new Queue<UvWriteReq>(_maxPooledWriteReqs);
    private readonly ILibuvTrace _log;
    private bool _disposed;

    public WriteReqPool(LibuvThread thread, ILibuvTrace log)
    {
      _thread = thread;
      _log = log;
    }

    public UvWriteReq Allocate()
    {
      if (_disposed) throw new ObjectDisposedException(GetType().Name);

      UvWriteReq req;
      if (_pool.Count > 0)
      {
        req = _pool.Dequeue();
      }
      else
      {
        req = new UvWriteReq(_log);
        req.Init(_thread);
      }

      return req;
    }

    public void Return(UvWriteReq req)
    {
      if (_disposed) throw new ObjectDisposedException(GetType().Name);

      if (_pool.Count < _maxPooledWriteReqs)
        _pool.Enqueue(req);
      else
        req.Dispose();
    }

    public void Dispose()
    {
      if (!_disposed)
      {
        _disposed = true;

        while (_pool.Count > 0) _pool.Dequeue().Dispose();
      }
    }
  }
}