MINIFICPP-2731 Allow cancellation from ProcessSession::write

[martinzink]

This is required to support fluid streaming api.

Currently if we opened the OutputStream it will always replace the old content, but lets say a processor wants to process flowfile content as a stream (read current content and write the new content at the same time), but if something comes up it might want to drop all changes and route the FlowFile to failure.

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[Copilot]

Pull request overview

Enables a processor to cancel an in-progress ProcessSession::write operation (e.g., while streaming) without committing the newly written content, by signaling cancellation from the write callback and discarding the temporary ResourceClaim.

Changes:

• Added ContentSession::remove(...) to allow abandoning newly created/managed ResourceClaims.
• Introduced a C API status enum (MinifiIoStatus) with a cancellation code.
• Updated ProcessSessionImpl::write to detect cancellation from the callback and discard the new claim instead of overwriting the FlowFile’s content.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
minifi-api/include/minifi-cpp/core/ContentSession.h	Adds remove(...) to the content session interface.
minifi-api/include/minifi-c/minifi-c.h	Adds MinifiIoStatus with a cancel status value.
libminifi/src/core/ProcessSession.cpp	Implements cancellation handling in write(...) based on callback return value.
libminifi/src/core/ForwardingContentSession.cpp	Implements remove(...) by dropping claim/session bookkeeping.
libminifi/include/core/ForwardingContentSession.h	Declares the new remove(...) override.
core-framework/src/core/BufferedContentSession.cpp	Implements remove(...) to discard buffered state for a claim.
core-framework/include/core/BufferedContentSession.h	Declares the new remove(...) override.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

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