[CurveBS] Add chunkserver-level statistics and allocation limits for the curvebs capacity statistics and allocation module

[xu-chaojie]

The current curvebs capacity statistics only consider the overall capacity of the cluster. When the capacity of a single chunkserver is insufficient, the cluster may still be unavailable. Therefore, it is necessary to add the management of the capacity of a single chunkserver and limit the space allocation when the capacity of a single chunkserver is insufficient.

[luooofan]

请问有更详细的说明嘛？
我现在注意到

curve/src/mds/topology/topology.cpp

Lines 553 to 554 in 9d48ce9

	int TopologyImpl::UpdateChunkServerDiskStatus(const ChunkServerState &state,
	ChunkServerIdType id) {

以及

curve/src/mds/topology/topology_stat.cpp

Lines 39 to 40 in 9d48ce9

	void TopologyStatImpl::UpdateChunkServerStat(ChunkServerIdType csId,
	const ChunkServerStat &stat) {

里面都有记录 chunkserver 级别的信息，在收到心跳消息的时候会进行更新

[wuhongsong]

@xu-chaojie

[xu-chaojie]

需要修改的是空间分配模块，空间分配需要考虑单个chunkserver的空间是否足够

[mikechengwei]

/assign