fix: concurrent Lazy::Get should get correct result

[HuaHuaY]

No description provided.

[zhjwpku]

LGTM

[Copilot]

Pull request overview

Fixes Lazy::Get() so that callers always observe the correct cached initialization outcome (success or failure) across repeated/concurrent calls by caching the full Result<T> instead of only caching the value on success.

Changes:

• Update Lazy to store mutable Result<T> and cache initialization errors as well as values via std::call_once.
• Add unit tests covering non-default-constructible lazy values and error reuse behavior.
• Register the new test file in the CMake util_test target.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/iceberg/util/lazy.h	Cache the entire Result<T> in the Lazy instance to ensure correct behavior after failed initialization and to avoid requiring T to be default-constructible.
src/iceberg/test/lazy_test.cc	Adds tests validating successful caching for non-default-constructible types and reuse of initialization errors.
src/iceberg/test/CMakeLists.txt	Adds lazy_test.cc to the util_test target sources.

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[Copilot]

Pull request overview

Fixes iceberg::Lazy::Get() so that initialization failures are correctly persisted and returned on subsequent calls (including across threads), instead of potentially returning an unintended “success” result.

Changes:

• Store the initialized state as mutable Result<T> value_ so both success and error outcomes are cached.
• Simplify Get() to call_once-initialize value_ and then return either the cached error or a reference to the cached value.
• Add unit tests for non-default-constructible values and for reusing initialization errors; register the new test in the util test target.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/iceberg/util/lazy.h	Cache initialization result (Result<T>) and return the correct cached error/value after std::call_once.
src/iceberg/test/lazy_test.cc	Adds coverage for non-default-constructible cached values and for error reuse across calls.
src/iceberg/test/CMakeLists.txt	Adds lazy_test.cc to the util_test target.

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[zhjwpku]

@wgtmac and I have talked about the Windows CI failure yesterday. You can try the following or just wait Gang to trigger the action manually.

 is_windows() {
-    [[ "${OSTYPE}" == "msys" || "${OSTYPE}" == "win32" ]]
+    [[ "${OSTYPE}" == "msys" || "${OSTYPE}" == "win32" || "${OSTYPE}" == "cygwin" ]]
 }

[wgtmac]

Thanks @HuaHuaY for the fix and @zhjwpku @kamcheungting-db for the review!

BTW, glad to see you here, @kamcheungting-db :)