/// <summary>
/// 根据百分比创建缓存存根
/// </summary>
/// <param name="offset">内存段的偏移量</param>
/// <param name="size">片段大小</param>
/// <param name="percent">百分比</param>
private ConcurrentStack <ISegmentCacheStub> CreateStub(ref int offset, int size, float percent)
{
int percentSize = (int)(Capacity * percent) + _lastSize;
int cacheCount = percentSize / size;
_lastSize = percentSize - (size * cacheCount);
ConcurrentStack <ISegmentCacheStub> stack = new ConcurrentStack <ISegmentCacheStub>();
for (int i = 0; i < cacheCount; i++)
{
ISegmentCacheStub stub = new SegmentCacheStub(new CacheIndexer
{
CacheBuffer = _data,
BeginOffset = offset,
SegmentSize = size
});
stack.Push(stub);
offset += size;
}
return(stack);
}
/// <summary>
/// 获取指定大小缓存所需要的内存片段数量
/// </summary>
/// <param name="size">缓存大小</param>
/// <returns>返回所需要的缓存数量</returns>
private List <ISegmentCacheStub> GetStubs(int size)
{
int count;
int lastSize;
int currentLevel;
List <ISegmentCacheStub> result = new List <ISegmentCacheStub>();
try
{
int subSize;
for (int i = 0; i < _levels.Length; i++)
{
currentLevel = _levels[i];
//优先选择靠近当前等级的分块
if ((subSize = currentLevel - size) >= 0 && subSize <= _lastLevelSize)
{
ISegmentCacheStub segmentCacheStub;
if (!_pools[currentLevel].TryPop(out segmentCacheStub))
{
continue;
}
result.Add(segmentCacheStub);
return(result);
}
if (size > currentLevel)
{
count = size / currentLevel;
lastSize = size - (currentLevel * count);
ISegmentCacheStub[] stubs;
ConcurrentStack <ISegmentCacheStub> stubStack = _pools[currentLevel];
//条件满足
if (stubStack.IsEmpty && i == _levels.Length - 1)
{
return(null);
}
stubs = new SegmentCacheStub[count];
if (stubStack.TryPopRange(stubs, 0, count) != count)
{
//giveback now.
Giveback(stubs);
continue;
}
result.AddRange(stubs);
List <ISegmentCacheStub> temp = GetStubs(lastSize);
if (temp == null)
{
GivebackRang(result.ToArray());
return(null);
}
result.AddRange(temp);
return(result);
}
}
ISegmentCacheStub stub;
if (!_pools[_levels[_levels.Length - 1]].TryPop(out stub))
{
return(null);
}
//小于所有的
result.Add(stub);
return(result);
}
catch (OutOfMemoryException ex)
{
GivebackRang(result.ToArray());
_tracing.Error(ex, null);
return(null);
}
catch (Exception ex)
{
_tracing.Error(ex, null);
throw;
}
}
