HDDS-13906. Reduce Bootstrap Write lock time on OM during bootstrapping execution.

[sadanand48]

What changes were proposed in this pull request?

Because of fixes in HDDS-13905 an entire BG service task would be blocked because of bootstrap operation running on a leader OM. One possible improvement here would be to just to create a hardlink(which we already do to ensure this file doesn't get deleted by rocksdb operations but we also write the file into the Tarball stream synchronously

ozone/hadoop-hdds/framework/src/main/java/org/apache/hadoop/hdds/utils/Archiver.java

Lines 135 to 155 in 96390ac

	public static long linkAndIncludeFile(File file, String entryName,
	ArchiveOutputStream<TarArchiveEntry> archiveOutput, Path tmpDir) throws IOException {
	File link = tmpDir.resolve(entryName).toFile();
	long bytes = 0;
	try {
	Files.createLink(link.toPath(), file.toPath());
	TarArchiveEntry entry = archiveOutput.createArchiveEntry(link, entryName);
	archiveOutput.putArchiveEntry(entry);
	try (InputStream input = Files.newInputStream(link.toPath())) {
	bytes = IOUtils.copyLarge(input, archiveOutput);
	}
	archiveOutput.closeArchiveEntry();
	} catch (IOException ioe) {
	LOG.error("Couldn't create hardlink for file {} while including it in tarball.",
	file.getAbsolutePath(), ioe);
	throw ioe;
	} finally {
	Files.deleteIfExists(link.toPath());
	}
	return bytes;
	}

) to the file to be copied into tar outputStream into a tmp directory under the bootstrap lock and write all the entries corresponding to the link created outside the lock(The entry should also include the hardLinkFile created in the last batch).

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-13906

How was this patch tested?

Will add tests

[swamirishi]

Thanks for the patch @sadanand48 . Have a few doubts with the implementation

[swamirishi]

We shouldn't be writing the hardLinkFile in all iterations

[swamirishi]

We can have this logic inside recordFileEntry

[swamirishi]

@rnblough Do you wanna take a look at this patch?