MINIFICPP-2760 Input/OutputStreamCallback should return std::expected

[martinzink]

Depends on

• MINIFICPP-2731 Allow cancellation from ProcessSession::write #2120

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[Copilot]

Pull request overview

This PR updates MiNiFi C++ stream callback APIs to return an expected-style result (io::IoResult / io::ReadWriteResult) instead of raw int64_t / std::optional, and propagates that change through core session I/O, utilities (e.g., internal::pipe), processors, extensions, and tests.

Changes:

• Introduce io::IoResult and io::ReadWriteResult and switch InputStreamCallback/OutputStreamCallback/InputOutputStreamCallback to use them.
• Update core session read/write/readWrite plumbing and various utilities/serializers to handle the new result types.
• Update processors, extensions, and unit tests to return IoResult/ReadWriteResult consistently.

Reviewed changes

Copilot reviewed 77 out of 77 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
minifi-api/common/include/minifi-cpp/io/StreamCallback.h	Adds IoResult/ReadWriteResult and changes stream callback typedefs to return them.
libminifi/test/unit/SiteToSiteTests.cpp	Updates session->write callback to return IoResult.
libminifi/test/unit/MetricsTests.cpp	Updates read/write/append callbacks to return IoResult.
libminifi/test/unit/FlowFileSerializationTests.cpp	Updates serializer reader callbacks to return IoResult.
libminifi/test/libtest/unit/ContentRepositoryDependentTests.h	Updates test callbacks to return IoResult and use error/cancel helpers.
libminifi/src/sitetosite/SiteToSiteClient.cpp	Updates session callbacks used for S2S send/receive to return IoResult.
libminifi/src/sitetosite/CompressionOutputStream.cpp	Adjusts use of internal::pipe after it returns IoResult.
libminifi/src/minifi-c.cpp	Bridges C callbacks into IoResult for ProcessSession read/write.
libminifi/src/core/ProcessSessionReadCallback.cpp	Updates file-copy read callback to return IoResult.
libminifi/src/core/ProcessSession.cpp	Updates ProcessSession callbacks handling to IoResult/ReadWriteResult.
libminifi/src/c2/C2Utils.cpp	Updates internal::pipe usage after return type change.
libminifi/include/core/ProcessSessionReadCallback.h	Updates callback signature to IoResult.
extensions/standard-processors/tests/unit/XMLRecordSetWriterTests.cpp	Updates callback return to IoResult.
extensions/standard-processors/processors/TailFile.cpp	Updates file reader callbacks to return IoResult.
extensions/standard-processors/processors/SplitText.cpp	Updates read/write callbacks and return type to IoResult.
extensions/standard-processors/processors/SplitRecord.cpp	Updates record-set read callback to return IoResult.
extensions/standard-processors/processors/SplitJson.cpp	Updates write callback to return IoResult.
extensions/standard-processors/processors/RouteText.cpp	Updates read callback to return IoResult.
extensions/standard-processors/processors/HashContent.cpp	Updates read callback to return IoResult.
extensions/standard-processors/processors/ExtractText.h	Updates read callback signature to IoResult.
extensions/standard-processors/processors/ExtractText.cpp	Updates read callback implementation to return IoResult.
extensions/standard-processors/processors/EvaluateJsonPath.cpp	Updates write callback to return IoResult.
extensions/standard-processors/processors/DefragmentText.cpp	Updates serializer reader and append callback to return IoResult.
extensions/standard-processors/processors/ConvertRecord.cpp	Updates record-set read callback to return IoResult.
extensions/standard-processors/controllers/XMLRecordSetWriter.cpp	Updates write callback to return IoResult.
extensions/standard-processors/controllers/JsonRecordSetWriter.cpp	Updates write callbacks to return IoResult.
extensions/sftp/processors/PutSFTP.cpp	Updates SFTP upload read callback to return IoResult.
extensions/sftp/processors/FetchSFTP.cpp	Updates SFTP download write callback to return IoResult.
extensions/rocksdb-repos/tests/SwapTests.cpp	Updates test write callback to return IoResult.
extensions/python/types/PyRecordSetReader.cpp	Updates read callback return type to IoResult.
extensions/python/types/PyProcessSession.cpp	Updates Python session read/write callbacks to return IoResult.
extensions/opencv/MotionDetector.cpp	Updates read/write callbacks to return IoResult.
extensions/opencv/CaptureRTSPFrame.cpp	Updates write callback to return IoResult.
extensions/mqtt/processors/PublishMQTT.cpp	Updates record-set read callback to return IoResult.
extensions/mqtt/processors/ConsumeMQTT.h	Updates write callback signature to IoResult.
extensions/mqtt/processors/ConsumeMQTT.cpp	Updates write callback implementation to return IoResult.
extensions/lua/LuaProcessSession.cpp	Updates Lua session read/write callbacks to return IoResult.
extensions/libarchive/tests/MergeFileTests.cpp	Updates serializer reader callbacks to return IoResult.
extensions/libarchive/tests/CompressContentTests.cpp	Updates read callback to return IoResult.
extensions/libarchive/UnfocusArchiveEntry.h	Updates write callback signature to IoResult.
extensions/libarchive/UnfocusArchiveEntry.cpp	Updates write callback implementation to return IoResult.
extensions/libarchive/MergeContent.h	Updates merge write callbacks to return IoResult.
extensions/libarchive/MergeContent.cpp	Updates serializer reader wrapper to return IoResult.
extensions/libarchive/FocusArchiveEntry.h	Updates read callback signature to IoResult.
extensions/libarchive/FocusArchiveEntry.cpp	Updates read callback implementation to return IoResult.
extensions/libarchive/CompressContent.h	Updates compress callback and nested read callback to return IoResult.
extensions/libarchive/CompressContent.cpp	Updates transformer/read/write callback wiring to IoResult.
extensions/kafka/PublishKafka.cpp	Updates flowfile read callback to return IoResult.
extensions/gcp/processors/PutGCSObject.cpp	Updates upload read callback to return IoResult.
extensions/gcp/processors/FetchGCSObject.cpp	Updates download write callback to return IoResult.
extensions/couchbase/processors/GetCouchbaseKey.cpp	Updates write callback to return IoResult.
extensions/bustache/ApplyTemplate.cpp	Updates write callback to return IoResult.
extensions/azure/storage/AzureDataLakeStorage.cpp	Adapts internal::pipe return to optional via expected.
extensions/azure/storage/AzureBlobStorage.cpp	Adapts internal::pipe return to optional via expected.
extensions/azure/processors/PutAzureDataLakeStorage.h	Updates read callback signature to IoResult.
extensions/azure/processors/PutAzureDataLakeStorage.cpp	Updates read callback implementation to return IoResult.
extensions/azure/processors/PutAzureBlobStorage.h	Updates inline read callback implementation to return IoResult.
extensions/azure/processors/FetchAzureDataLakeStorage.cpp	Updates write callback to return IoResult.
extensions/azure/processors/FetchAzureBlobStorage.cpp	Updates write callback to return IoResult.
extensions/aws/processors/PutS3Object.cpp	Updates read callback to return IoResult and handles multipart logic.
extensions/aws/processors/FetchS3Object.cpp	Updates write callback to return IoResult.
extension-framework/src/utils/file/FileWriterCallback.cpp	Updates file writer read callback to return IoResult.
extension-framework/src/utils/file/FileReaderCallback.cpp	Updates file reader write callback to return IoResult.
extension-framework/src/serialization/PayloadSerializer.cpp	Updates serializer serialize() return type to IoResult.
extension-framework/src/serialization/FlowFileV3Serializer.cpp	Updates serializer serialize() return type to IoResult.
extension-framework/include/utils/file/FileWriterCallback.h	Updates callback signature to IoResult.
extension-framework/include/utils/file/FileReaderCallback.h	Updates callback signature to IoResult.
extension-framework/include/serialization/PayloadSerializer.h	Updates serializer interface to return IoResult.
extension-framework/include/serialization/FlowFileV3Serializer.h	Updates serializer interface to return IoResult.
extension-framework/include/serialization/FlowFileSerializer.h	Updates serializer interface and reader function type to return IoResult.
extension-framework/cpp-extension-lib/src/core/ProcessSession.cpp	Converts IoResult back to int64_t for the C API bridge.
core-framework/src/utils/LineByLineInputOutputStreamCallback.cpp	Updates read/write callback return type to ReadWriteResult.
core-framework/include/utils/LineByLineInputOutputStreamCallback.h	Updates callback signature to ReadWriteResult.
core-framework/include/utils/JsonCallback.h	Updates JSON callbacks to return IoResult.
core-framework/include/utils/ByteArrayCallback.h	Updates byte-array callback to return IoResult.
core-framework/include/io/StreamPipe.h	Changes internal::pipe and related pipes to return IoResult.
core-framework/include/http/HTTPCallback.h	Updates HTTP streaming callback processing to return IoResult.

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[fgerlits]

Thank you for doing this! I think it improves readability significantly.