Description

This PR implements disk-usage statistics collection in table level and device level for tree model. It adds the necessary data structures, background tasks, and read APIs to compute and expose disk usage metrics used by monitoring, admission control and operational tooling.

Tree Model (No Cache)

IoTDB> show disk_usage from root.test.**
+---------+----------+--------+-------------+-----------+
| Database|DataNodeId|RegionId|TimePartition|SizeInBytes|
+---------+----------+--------+-------------+-----------+
|root.test|         1|       3|            0|         70|
+---------+----------+--------+-------------+-----------+
Total line number = 1
It costs 0.959s

Implements ShowDiskUsageNode and ShowDiskUsageOperator.
• Disk usage is calculated by scanning relevant TsFiles at query time.
• Supports:
• Path pattern matching
• Time partition filtering
• Existing SQL semantics (SHOW DISK_USAGE)

Table Model (With Cache)

IoTDB:information_schema> select * from table_disk_usage
+--------+----------+-------+---------+--------------+-------------+
|database|table_name|datanode_id|region_id|time_partition|size_in_bytes|
+--------+----------+-------+---------+--------------+-------------+
|   test1|        t1|          1|        5|             0|          142|
|   test1|        t2|          1|        5|             0|            0|
|   test1|        t1|          1|        6|             0|            0|
|   test1|        t2|          1|        6|             0|           82|
+--------+----------+-------+---------+--------------+-------------+
Total line number = 4
It costs 2.821s

Table Model introduces a dedicated disk usage cache:
• TableDiskUsageCache manages all cache operations.
• A single-threaded background worker processes write, read, and maintenance tasks via an operation queue.
• Cache state is persistent across restarts.

Cached Data
• TsFile-level table size statistics
• Object file size deltas, recorded incrementally
• Periodic snapshot + delta compaction

Query Integration
• Exposes statistics via information_schema.table_disk_usage.
• Supports:
• Predicate pushdown (except on aggregated size columns)
• Limit / offset
• Parallel region-level scanning