[GitHub] massakam opened a new pull request #2673: Avoid problem that topic becomes unavailable due to failure of cursor…

[GitBox <gi...@apache.org>]

massakam opened a new pull request #2673: Avoid problem that topic becomes unavailable due to failure of cursor…
URL: https://github.com/apache/pulsar/pull/2673
 
 
   … recovery
   
   ### Motivation
   
   This is a change to avoid https://github.com/apache/pulsar/issues/2666.
   
   If a topic is under the following condition and the broker is restarted, that topic becomes unavailable and we can not send or receive messages.
   
   - The managed ledger contains two ledgers and the newer ledger is empty
   ```
   ledgerInfo {
     ledgerId: 65425
     entries: 2
     size: 238
     timestamp: 1506510325426
   }
   ledgerInfo {
     ledgerId: 1952728
     timestamp: 0
   }
   ```
   - `cursorsLedgerId` included in the managed cursor info is -1
   - `markDeleteLedgerId` is between the two ledgers contained in the managed ledger
   ```
   cursorsLedgerId: -1
   markDeleteLedgerId: 1952575
   markDeleteEntryId: -1
   ```
   
   This is because `position` gets ahead of the last position of the managed ledger, and `IllegalArgumentException` occurs in the following line.
   https://github.com/apache/pulsar/blob/d5e88c1ec16df557655e42c9f648a2fd3343d759/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorImpl.java#L358
   
   ### Modifications
   
   If `position` gets ahead of the last position of the managed ledger when recovering the cursor, `position` is adjusted to the last position.
   
   ### Result
   
   Even a topic with metadata as described above, the cursor will be recovered successfully.

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