Refactored ParallelTxReturnVal

[SirTyson]

Description

Resolves #5084

Simplifies ParallelTxReturnVal on failed TXs by returning a std::nullopt instead of a weird, half baked version of the return val.

Checklist

• Reviewed the contributing document
• Rebased on top of master (no merge commits)
• Ran clang-format v8.0.0 (via make format or the Visual Studio extension)
• Compiles
• Ran all tests
• If change impacts performance, include supporting evidence per the performance document

[Copilot]

Pull request overview

Refactors the parallel-apply return type to avoid “sentinel” failure values by returning std::optional and only constructing a success payload on successful parallel apply, addressing #5084.

Changes:

• Replaces ParallelTxReturnVal with ParallelTxSuccessVal and returns it via std::optional from parallel-apply APIs.
• Updates transaction/operation parallel-apply call sites to use if (res) / *res instead of getSuccess().
• Simplifies TxParallelApplyLedgerState result handling by returning std::nullopt on failure.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/transactions/test/TransactionTestFrame.h	Updates test wrapper parallel-apply signature to return optional success value.
src/transactions/test/TransactionTestFrame.cpp	Updates implementation to forward optional success value.
src/transactions/TransactionMeta.h	Updates meta builder API to accept success-only parallel apply value.
src/transactions/TransactionMeta.cpp	Updates implementation to match new success-only type.
src/transactions/TransactionFrameBase.h	Renames return payload type and switches parallelApply to std::optional<ParallelTxSuccessVal>.
src/transactions/TransactionFrame.h	Updates TransactionFrame parallelApply override to optional success value.
src/transactions/TransactionFrame.cpp	Returns std::nullopt on failures and updates success checks/dereferences.
src/transactions/RestoreFootprintOpFrame.h	Updates parallel apply signature to return optional success value.
src/transactions/RestoreFootprintOpFrame.cpp	Simplifies helper result handling to return optional directly.
src/transactions/ParallelApplyUtils.h	Updates thread-state APIs and tx-state result API to use success-only value + optional.
src/transactions/ParallelApplyUtils.cpp	Removes getSuccess() assertions and returns std::nullopt on failure in takeResult.
src/transactions/OperationFrame.h	Updates operation parallel-apply APIs to return optional success value.
src/transactions/OperationFrame.cpp	Updates definitions to match optional success value return type.
src/transactions/InvokeHostFunctionOpFrame.h	Updates parallel apply signature to return optional success value.
src/transactions/InvokeHostFunctionOpFrame.cpp	Simplifies helper result handling to return optional directly.
src/transactions/FeeBumpTransactionFrame.h	Updates fee-bump parallelApply override to return optional success value.
src/transactions/FeeBumpTransactionFrame.cpp	Updates delegation to return optional directly.
src/transactions/ExtendFootprintTTLOpFrame.h	Updates parallel apply signature to return optional success value.
src/transactions/ExtendFootprintTTLOpFrame.cpp	Simplifies helper result handling to return optional directly.
src/ledger/LedgerManagerImpl.cpp	Updates parallel apply thread logic to handle optional success result.

[Copilot]

TransactionMeta.h is not self-contained: it declares setLedgerChangesFromSuccessfulOp(...) using ThreadParallelApplyLedgerState and ParallelTxSuccessVal, but neither type is declared/included in this header. Additionally, this header uses std::optional (e.g. mSorobanReturnValue) without including <optional>. Add the needed forward declarations and include <optional> (or include the headers that define these types) so the header compiles regardless of include order.