[adwetojha]

What changes were proposed in this pull request?

During Datanode restart and re-registration, SCM may wait for an ALLOCATED pipeline that is removed before becoming OPEN. If no replacement container is available, block allocation fails.

Previously, WritableRatisContainerProvider wrapped this specific failure in a generic IOException. OM consequently returned INTERNAL_ERROR, which was not retried by the Ozone client, causing intermittent key creation failures.

This patch adds a narrowly scoped client-side retry for this transient allocation failure:

• Preserves the missing-pipeline failure as SCMException.ResultCodes.PIPELINE_NOT_FOUND after the provider's final container lookup.
• Maps this SCM result to the new OM status KEY_ALLOCATION_PIPELINE_NOT_FOUND.
• Extends the existing bounded retry helper for CreateKey, CreateFile, and AllocateBlock, while preserving SCM safe-mode retries.
• Does not retry unrelated INTERNAL_ERROR or KEY_ALLOCATION_ERROR responses.
• Adds a client version check to return INTERNAL_ERROR to older clients that do not recognize the new status.
• Adds regression tests covering SCM error propagation, OM error mapping, client retries, retry exhaustion, and backward compatibility.

The CreateKey regression test also verifies that this failure occurs during pre-execution, before OM Ratis submission, without creating successful open-key state.

The retry reuses the existing limit of 90 retries after the initial attempt (up to 91 submissions), with a one-second delay between attempts.

What is the link to the Apache JIRA?

https://issues.apache.org/jira/browse/HDDS-16712

How was this patch tested?

The following checks passed in local JDK 21 runs:

• 264 tests passed: SCM provider, SCM RPC translator, client protocol translator, OM block allocation, CreateKey, client versioning, and result-code tests.
• 225 tests passed: TestRpcClient, TestOMFileCreateRequest, and TestOMFileCreateRequestWithFSO.
• 19 client protocol translator tests passed in a final rerun after the logging change. These tests were already included in the 264-test suite above.
• Protobuf backward-compatibility check passed.
• Checkstyle passed with zero violations.
• git diff --check passed.

Live Kubernetes Datanode restart and rolling-upgrade tests have not been performed.

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