[Pipe] Optimize OPC UA TsFile last-value transfer

[Caideyipi]

Description

Optimize the OPC UA sink's client-server TsFile path by reading each timeseries' last point directly from TsFile metadata instead of materializing every Tablet.

Metadata fast path

• Read last points synchronously with TsFileLastReader; only BLOB/OBJECT-style types without values in statistics need their last chunk read.
• Preserve the original measurement schema alongside each TimeValuePair, so logical types such as TIMESTAMP, STRING, and BLOB are not degraded by TsPrimitiveType.
• Validate the number of values returned against independently read metadata because TsFileLastReader.hasNext() logs and suppresses IOExceptions.
• Reuse the existing OPC UA row-transfer code for both embedded-server and client modes.

Compatibility and event semantics

• Use the fast path only for client-server events without mods, time/path filtering, or privilege filtering.
• Keep the existing Tablet parser as the fallback for filtered events and metadata read failures.
• Retain the Tablet path for pub-sub mode, which must publish the full event stream.
• Preserve TsFile event reference counting and close ownership across both paths.

Tests

• Added real non-aligned tree and aligned table TsFile coverage.
• Covered statistics-backed values, BLOB last-chunk reads, TIMESTAMP schema preservation, DATE conversion, aligned time-column filtering, null values, and null table tags.
• Added an opt-in manual benchmark comparing the legacy Tablet path with the metadata last-value path, including tunable workload and final-value equivalence validation; skipped by default.
• Spotless and Checkstyle pass; the 5 focused unit tests pass.

Manual performance result

Measured locally on 2026-08-11 with Windows 11 64-bit, an ASUS Zenbook UX3404VC (Intel Core i9-13900H, 14 cores/20 threads), JDK 17.0.15, and Maven 3.8.8.

Command:

mvn -Ddevelocity.off=true -q -pl iotdb-core/datanode -Dtest=OpcUaSinkTsFilePerformanceTest -Diotdb.opcua.tsfile.last-value.perf.enabled=true -Diotdb.opcua.tsfile.last-value.perf.iterations=50 -Diotdb.opcua.tsfile.last-value.perf.rounds=5 test

Workload: 2 devices, 32 measurements/device (1 BLOB measurement), 50,000 rows/device, 3,200,000 points, and a 12.32 MiB TsFile; 1 warmup iteration and 50 measured iterations per round across 5 alternating rounds. Three independent JVM runs were completed; the table reports the median across those runs (each run reports its own 5-round median).

Path	CPU time/file	Allocated/file	Peak heap delta/file
Legacy Tablet path	156.250 ms	312.235 MiB	336.709 MiB
Metadata last-value path	0.625 ms	0.639 MiB	19.456 MiB
Change	250.00x speedup	99.8% reduction	94.2% reduction

Observed CPU speedup across the three runs was 166.67x-254.50x; allocation reduction stayed at 99.8%, and peak-heap reduction was 94.0%-94.6%. The benchmark's final-value maps were equal in every run, and each run passed the JUnit correctness check (Tests run: 1, Failures: 0, Errors: 0).

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This PR has:

• been self-reviewed.
• added Javadocs for non-trivial methods.
• added comments explaining non-obvious behavior.
• added unit tests covering the new code paths.

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Key changed/added classes

• OpcUaSink
• IoTDBOpcUaClient
• OpcUaNameSpace
• OpcUaSinkTsFileMetadataTest
• OpcUaNameSpaceMetadataTest

[jt2594838]

Add clearer message. Or return null instead.

[Caideyipi]

Applied in 7eca368 using the suggested null option: device/type/count metadata inconsistencies now return null and immediately trigger the existing Tablet fallback instead of throwing a message-less IOException.