private T GetFreeResource(out long messageId)
{
lock (key1)
{
foreach (long key in messages.Keys)
{
if (!messages[key].InUse)
{
messages[key].InUse = true;
messageId = key;
return(messages[key].Resource);
}
}
//申请新资源
T message = IResourceObject.Request();
//申请资源失败
if (message == null)
{
messageId = GetNullResourceId();
return(null);
}
else
{
ResourceWatcher <T> tag = new ResourceWatcher <T>(message, true);
long id = NewResourceId();
messages.Add(id, tag);
messageId = id;
return(message);
}
}
}
/// <summary>返回资源</summary>
/// <param name="message">ref类型的参数，将在函数内部设为null，意味着返回后不能再用。</param>
/// <param name="messageId">获取资源时得到的那个messageId。如果返回一个不正确的id,将抛出异常。</param>
public void ReturnResource(ref T message, long messageId)
{
if (!messages.ContainsKey(messageId))
{
throw new InvalidOperationException("试图归还一个非法的资源。");
}
T toDispose = null;
lock (key2)
{
ResourceWatcher <T> tag = messages[messageId];
tag.InUse = false;
//当前的id将作废，不能再用
messages.Remove(messageId);
//将当前的message置空，不能再用
message = null;
//达到上限，将释放资源
if (messages.Keys.Count >= maxResource)
{
toDispose = message;
}
else
{
messages.Add(NewResourceId(), tag);
}
}
if (toDispose != null)
{
toDispose.Dispose();
}
}