MINIFICPP-2901 Rust route_to_failure by default, rollback explicit

[martinzink]

I've changed how err routing works in transformer processors
Removed the processerr (complex and source processors now return Result<T, MinifiErr> any error 'bubbled' via ? is rollback error (we cant route the error to failure because there maybe multiple flowfiles in use and if a source has some problems its usually dont want to create flowfiles rather than to route them to fialure.
So for complex and source processors the processor must be explicit what to do in case of errors if they dont want them to cause rollback.

For trasnformer type processors (FlowFileTransform FlowFileStreamTransform) , since they work on a single flow file its simpler so I've introduced an ErrorRelationship which the processor has to explicitly set. Now every 'bubbled' (via ?) error will simply route the flowfile it is working on to this relationship and will WARN log the error in question.

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[Copilot]

🟡 Changes recommended

Existing complex processors and a stream transformer are not fully migrated to the new error semantics.

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Pull request overview

Refactors Rust processor error handling so ordinary errors route to failure while rollback is explicit, and improves Rust test execution.

Changes:

• Introduces ProcessError::Rollback and ProcessErrorExt.
• Updates wrappers and playground processors to use the new semantics.
• Uses cargo-nextest when available.

File summaries

File	Description
minifi_rust/CMakeLists.txt	Adds nextest support and doctests.
minifi_native/src/lib.rs	Re-exports the renamed error extension trait.
minifi_native/src/api/errors.rs	Defines default routing and explicit rollback conversion.
minifi_native/src/c_ffi/c_ffi_processor_definition.rs	Maps rollback errors to native statuses.
minifi_native/src/api/processor_wrappers/complex_processor.rs	Makes unscheduled errors explicit rollbacks.
minifi_native/src/api/processor_wrappers/flow_file_source.rs	Rolls back session failures.
minifi_native/src/api/processor_wrappers/flow_file_stream_transform.rs	Separates routing from rollback behavior.
minifi_native/src/api/processor_wrappers/flow_file_transform.rs	Implements and tests routing versus rollback.
minifi_rs_playground/src/processors/asciify_german.rs	Uses default failure routing.
minifi_rs_playground/src/processors/kamikaze_processor.rs	Returns an explicit rollback error.
minifi_rs_playground/src/processors/kamikaze_processor/tests.rs	Updates rollback expectations.
minifi_rs_playground/src/processors/lorem_ipsum_cs_user.rs	Rolls back controller-service errors.
minifi_rs_playground/src/processors/put_file.rs	Uses default failure routing.

Review details

Suppressed comments (1)

minifi_rust/minifi_native/src/api/errors.rs:89

• Routing every raw I/O error to the literal failure relationship breaks DuplicateStreamText: its read/write calls use ?, but its processor definition declares only success and does not support dynamic relationships. On an I/O error the stream wrapper therefore transfers to an undeclared, non-auto-terminated relationship, causing commit to fail instead of producing the intended failure route. Add a declared failure relationship for that processor or make those I/O errors explicit rollbacks; also audit other consumers before making this the default conversion.

                    ProcessError::Route(RouteError {
                        relationship: "failure",
                        source: Box::new(err),
                        log_level: LogLevel::Warn,
                    })

• Files reviewed: 13/13 changed files
• Comments generated: 1
• Review effort level: Balanced

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[Copilot]

🟡 Changes recommended

Mock cancellation can retain partial output, and generated processor documentation is stale.

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Review details

• Files reviewed: 21/21 changed files
• Comments generated: 2
• Review effort level: Balanced

[Copilot]

🔵 Needs a closer look

The generated processor documentation omits DuplicateStreamText’s newly added failure relationship.

Review details

Suppressed comments (1)

minifi_rust/extensions/minifi_rs_playground/src/processors/duplicate_text.rs:76

• Adding FAILURE changes the processor schema, but the regenerated minifi_rs_playground.md still documents only success for DuplicateStreamText (lines 91–96). Please regenerate and commit the extension documentation so users can discover and connect the new failure relationship.

    const RELATIONSHIPS: &'static [Relationship] = &[SUCCESS, FAILURE];

• Files reviewed: 23/23 changed files
• Comments generated: 0 new
• Review effort level: Balanced