> This is somewhat a continuation for
> [JDK-8307160](https://bugs.openjdk.org/browse/JDK-8307160) and
> [JDK-8334509](https://bugs.openjdk.org/browse/JDK-8334509).
>
> The former removed the `doIt` flag in #18584, but it introduced a regression.
>
> The regression is resolved by the latter in #19786, and it added the 'doIt'
> flag again.
>
> I think using a flag makes the code less clear. When reading the code, one
> has to keep track of the current value of the `doIt` flag.
>
> I raised my concern in [comments in PR
> 19786](https://github.com/openjdk/jdk/pull/19786#discussion_r1649191308):
>
>> I'd rather keep `JNI_FALSE` here — it's more explicit and therefore clearer.
>> You don't have to keep track of the value of `doIt` flag while reading the
>> code.
>>
>> In fact, I'd prefer no `doIt` flag at all… yet it makes handling the code
>> below `if (ret)` slightly harder.
>
> I came up with a solution which simplifies handling the clean-up. The
> solution relies on C++ destructors which are called when the declared objects
> go out of scope.
>
> The C++ object wraps a lambda function to clean up and invokes this function
> in its destructor. Such C++ class has to be a templated class because there's
> no defined type to represent a lambda. The class has to be declared at the
> top of the file because it needs C++ linkage.
>
> There are two `Cleaner` objects declared in the code of
> `Java_sun_awt_windows_WPageDialogPeer__1show`:
>
> **`refCleaner`** is declared right after all the references to Java objects
> are initialised. The corresponding `refCleanup` lambda deletes all the
> references and replaces the `CLEANUP_SHOW` macro. Before JDK-8307160, the
> code jumped to a go-to label to perform the clean-up.
>
> **`postCleaner`** is declared after `AwtDialog::CheckInstallModalHook` is
> called. Its lambda `postCleanup` uninstalls the modal hook and handles focus
> transfer as well as saves the updated printer parameters.
>
> It is `postCleaner` that resolves the bug JDK-8334868 by ensuring
> `CheckUninstallModalHook` and `ModalActivateNextWindow` are called if
> `::PageSetupDlg` is called.
>
> As the result of using `refCleaner`, all the `return` statements in the
> function use an explicit value, which makes the code cleaner. There's no need
> to use a `go to` statement or insert a macro to delete references to Java
> objects, about which one had to remember — the destructor of the `refCleaner`
> handles deleting references when `refCleaner` goes out of scope, that is when
> the function returns.
Alexey Ivanov has updated the pull request with a new target base due to a
merge or a rebase. The incremental webrev excludes the unrelated changes
brought in by the merge/rebase. The pull request contains two additional
commits since the last revision:
- Merge master
- 8334868: Ensure CheckUninstallModalHook is called in WPageDialogPeer._show
Use a C++ object to wrap a lambda which performs clean-up actions:
* Deletes references to Java objects,
* Unhooks modal dialog, and
* Saves printer parameters.
The lambda is invoked from the C++ object destructor.
Drop 'doIt' flag and use explicit returns.
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/19867/files
- new: https://git.openjdk.org/jdk/pull/19867/files/6f2b3c11..4505ebc0
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=19867&range=01
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=19867&range=00-01
Stats: 2587324 lines in 25590 files changed: 1530675 ins; 825162 del; 231487
mod
Patch: https://git.openjdk.org/jdk/pull/19867.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/19867/head:pull/19867
PR: https://git.openjdk.org/jdk/pull/19867
