Enrico Olivelli created BOOKKEEPER-1037:
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Summary: BP7 - Explicit LAC on addEntry
Key: BOOKKEEPER-1037
URL: https://issues.apache.org/jira/browse/BOOKKEEPER-1037
Project: Bookkeeper
Issue Type: New Feature
Components: bookkeeper-client, bookkeeper-server
Affects Versions: 4.4.0
Reporter: Enrico Olivelli
Assignee: Enrico Olivelli
see
https://cwiki.apache.org/confluence/display/BOOKKEEPER/BP7+-+Explicit+LAC+on+addEntry
Summary of the problem:
We want to ensure that some "important" entries will be readable for which the
writer has received the acknowledge from a quorum of bookies without being able
to piggyback the LastAddConfirmed or close the LedgerHandle (a writer which
crashes).
This is the simplest failing scenario:
A writer creates a ledger
The writer adds and entry and blocks for the acknowldege of the configured
quorum of Bookies
The writer crashes
LAC has not been sent to Bookies and it has not been written to metadata
A recovery is performed, truncating the ledger to the maximum
LastAddConfirmed entry ID
Now the entry is no more readable and there is no trace of it on metadata
so it cannot be recovered
We can add a new BookKeeper function, addConfirmedEntry which acks like the
addEntry function but sends on the protocol a new flag which tells to the
Bookie to "advance" the LastAddConfirmed flag immediately as we already do with
the ExplicitLAC.
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