refactor: Throw exception rather than LOG(FATAL) when encounter IO error

[zhanglei1949]

Fix #514

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR updates LocalWalParser to throw IO exceptions instead of terminating the process on WAL file I/O failures, and adds unit tests to validate these error paths (Fix #514).

Changes:

• Replace LOG(FATAL) behavior with IOException throws for open()/mmap() failures in LocalWalParser.
• Ensure LocalWalParser::open() resets prior state via close() and make close() fully clear internal state.
• Add new LocalWalParser unit tests for valid parsing, unreadable file errors, mmap failures, and empty directories.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
tests/transaction/test_insert_transaction.cc	Adds LocalWalParser tests (success + IO failure cases) and supporting helpers to create WAL files.
src/transaction/wal/local_wal_parser.cc	Switches fatal logging to exceptions for I/O errors; resets parser state on open/close.

Comments suppressed due to low confidence (1)

src/transaction/wal/local_wal_parser.cc:1

• close() is called before throwing on open()/mmap() failure. If THROW_IO_EXCEPTION (or the exception ctor) relies on errno, close()/::close() can overwrite errno, producing incorrect diagnostics. Capture errno immediately after the failing syscall (before any cleanup) and include it in the thrown exception (or pass it into the exception) so the error reason is accurate.

/** Copyright 2020 Alibaba Group Holding Limited.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[liulx20]

can we expose error information using operations like strerror(errno)？

[zhanglei1949]

resolved.