/// <summary>
/// Internal function called by the plugin to remove old, non-used buffers.
/// </summary>
internal static void Maintain()
{
DateTime now = DateTime.UtcNow;
if (!_isEnabled || lastMaintenance + RunMaintenanceEvery > now)
{
return;
}
lastMaintenance = now;
DateTime olderThan = now - RemoveOlderThan;
rwLock.EnterWriteLock();
try
{
//if (HTTPManager.Logger.Level == Logger.Loglevels.All)
// HTTPManager.Logger.Information("VariableSizedBufferPool", "Before Maintain: " + GetStatistics());
for (int i = 0; i < FreeBuffers.Count; ++i)
{
BufferStore store = FreeBuffers[i];
List <BufferDesc> buffers = store.buffers;
for (int cv = buffers.Count - 1; cv >= 0; cv--)
{
BufferDesc desc = buffers[cv];
if (desc.released < olderThan)
{
// buffers stores available buffers ascending by age. So, when we find an old enough, we can
// delete all entries in the [0..cv] range.
int removeCount = cv + 1;
buffers.RemoveRange(0, removeCount);
PoolSize -= (int)(removeCount * store.Size);
break;
}
}
if (RemoveEmptyLists && buffers.Count == 0)
{
FreeBuffers.RemoveAt(i--);
}
}
//if (HTTPManager.Logger.Level == Logger.Loglevels.All)
// HTTPManager.Logger.Information("VariableSizedBufferPool", "After Maintain: " + GetStatistics());
}
finally
{
rwLock.ExitWriteLock();
}
}
/// <summary>
/// Get byte[] from the pool. If canBeLarge is true, the returned buffer might be larger than the requested size.
/// </summary>
public static byte[] Get(long size, bool canBeLarger)
{
if (!_isEnabled)
{
return(new byte[size]);
}
// Return a fix reference for 0 length requests. Any resize call (even Array.Resize) creates a new reference
// so we are safe to expose it to multiple callers.
if (size == 0)
{
return(VariableSizedBufferPool.NoData);
}
lock (FreeBuffers)
{
if (FreeBuffers.Count == 0)
{
return(new byte[size]);
}
BufferDesc bufferDesc = FindFreeBuffer(size, canBeLarger);
if (bufferDesc.buffer == null)
{
if (canBeLarger)
{
if (size < MinBufferSize)
{
size = MinBufferSize;
}
else if (!IsPowerOfTwo(size))
{
size = NextPowerOf2(size);
}
}
return(new byte[size]);
}
else
{
GetBuffers++;
}
PoolSize -= bufferDesc.buffer.Length;
return(bufferDesc.buffer);
}
}
private static BufferDesc FindFreeBuffer(long size, bool canBeLarger)
{
for (int i = 0; i < FreeBuffers.Count; ++i)
{
BufferStore store = FreeBuffers[i];
if (store.buffers.Count > 0 && (store.Size == size || (canBeLarger && store.Size > size)))
{
// Getting the last one has two desired effect:
// 1.) RemoveAt should be quicker as it don't have to move all the remaining entries
// 2.) Old, non-used buffers will age. Getting a buffer and putting it back will not keep buffers fresh.
BufferDesc lastFree = store.buffers[store.buffers.Count - 1];
store.buffers.RemoveAt(store.buffers.Count - 1);
return(lastFree);
}
}
return(BufferDesc.Empty);
}
