Skip to content

ISSUE-2770: Code refactor calling ledgerExists two times. #2903

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
jadireddi wants to merge 1 commit into
base: master
Choose a base branch
from
Open

ISSUE-2770: Code refactor calling ledgerExists two times. #2903

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 1 addition & 3 deletions bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/SortedLedgerStorage.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -144,9 +144,7 @@ public boolean ledgerExists(long ledgerId) throws IOException {
// the O(1) for the ledgerCache.
if (!interleavedLedgerStorage.ledgerExists(ledgerId)) {
EntryKeyValue kv = memTable.getLastEntry(ledgerId);
if (null == kv) {
return interleavedLedgerStorage.ledgerExists(ledgerId);
Copy link
Contributor

@eolivelli eolivelli Nov 20, 2021

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I have seen this patch before.
Maybe there is already another open PR

My question is...
Why this code was written the way it is?
In order to deal with some possible race condition ?

@merlimat do you know?

Copy link
Contributor

@hangc0276 hangc0276 Jul 26, 2022

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Is there any case that line 145 returns false, but line 148 returns true?

Copy link
Member

@zymap zymap Jul 29, 2022 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

As the comment said, checking the skip list is an O(logN) operation compared to the O(1) for the ledgerCache.

My thought that means the memTable.getLastEntry(ledgerId) is time consuming operation. After checking that, the ledgerCache may be filled so we check it again.

}
return null != kv;
}
return true;
}
Expand Down