RFR: 8345286: Remove use of SecurityManager API from misc areas [v2]

[Severin Gehwolf]

On Mon, 2 Dec 2024 13:39:57 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Can I please get a review of this change which removes usages of SecurityManager related APIs and some leftover related to SecurityManager changes?
>> 
>> This addresses https://bugs.openjdk.org/browse/JDK-8345286. Most of these changes are trivial. The `src/java.base/linux/classes/jdk/internal/platform/CgroupUtil.java` used to expose utility methods for dealing with SecurityManager permissions and it was called from a few places. That class is no longer needed with the clean up done in this PR.
>> 
>> No new tests have been introduced and tier testing is currently in progress.
>
> Jaikiran Pai has updated the pull request incrementally with four additional commits since the last revision:
> 
>  - remove unnecessary space
>  - Path.of() instead of Paths.get()
>  - fix formatting of try-with-resources in CgroupSubsystemController.java
>  - leave out MethodUtil from the clean up

I've reviewed only the cgroups parts.

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemController.java line 70:

> 68:             String line = bufferedReader.readLine();
> 69:             return line;
> 70:         } catch (IOException e) {

We can use `Files.lines` here right away:

Suggestion:

        try (Stream<String> lines = Files.lines(filePath)) {
            Optional<String> firstLine = lines.findFirst();
            return firstLine.orElse(null);
        } catch (UncheckedIOException | IOException e) {

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemController.java line 71:

> 69:             String line = bufferedReader.readLine();
> 70:             return line;
> 71:         } catch (IOException e) {

I think we can do this refactoring now:

Suggestion:

        try (Stream<String> lines =
                         Files.lines(Paths.of(controller.path(), param))) {
            Optional<String> firstLine = lines.findFirst();
            return firstLine.orElse(null);
        } catch (IOException e) {

src/java.base/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2Subsystem.java line 332:

> 330: 
> 331:     private long sumTokensIOStat(Function<String, Long> mapFunc) {
> 332:         try (Stream<String> lines = Files.lines(Paths.get(unified.path(), "io.stat"))) {

Suggestion:

        try (Stream<String> lines = Files.lines(Paths.of(unified.path(), "io.stat"))) {

src/java.base/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2Subsystem.java line 334:

> 332:         try (Stream<String> lines = Files.lines(Paths.get(unified.path(), "io.stat"))) {
> 333:             return lines.map(mapFunc)
> 334:                     .collect(Collectors.summingLong(e -> e));

Suggestion:

            return lines.map(mapFunc)
                        .collect(Collectors.summingLong(e -> e));

-------------

PR Review: https://git.openjdk.org/jdk/pull/22478#pullrequestreview-2472643767
PR Review Comment: https://git.openjdk.org/jdk/pull/22478#discussion_r1865876078
PR Review Comment: https://git.openjdk.org/jdk/pull/22478#discussion_r1865860841
PR Review Comment: https://git.openjdk.org/jdk/pull/22478#discussion_r1865815063
PR Review Comment: https://git.openjdk.org/jdk/pull/22478#discussion_r1865865085