[GitHub] sijie opened a new issue #281: make ledger metadata immutable

[gi...@git.apache.org]

sijie opened a new issue #281: make ledger metadata immutable
URL: https://github.com/apache/bookkeeper/issues/281
 
 
   **FEATURE REQUEST**
   
   1. Please describe the feature you are requesting.
   
   Address the TODO item in *LedgerHandle*
   
                   if (isClosed()) {
                       // TODO: make ledger metadata immutable
                       // Although the metadata is already closed, we don't need to proceed zookeeper metadata update, but
                       // we still need to error out the pending add ops.
                       //
                       // There is a race condition a pending add op is enqueued, after a close op reset ledger metadata state
                       // to unclosed to resolve metadata conflicts. If we don't error out these pending add ops, they would be
                       // leak and never callback.
                       //
                       // The race condition happen in following sequence:
                       // a) ledger L is fenced
                       // b) write entry E encountered LedgerFencedException, trigger ledger close procedure
                       // c) ledger close encountered metadata version exception and set ledger metadata back to open
                       // d) writer tries to write entry E+1, since ledger metadata is still open (reset by c))
                       // e) the close procedure in c) resolved the metadata conflicts and set ledger metadata to closed
                       // f) writing entry E+1 encountered LedgerFencedException which will enter ledger close procedure
                       // g) it would find that ledger metadata is closed, then it callbacks immediately without erroring out any pendings
                       synchronized (LedgerHandle.this) {
                           pendingAdds = drainPendingAddsToErrorOut();
                       }
                       errorOutPendingAdds(rc, pendingAdds);
                       cb.closeComplete(BKException.Code.OK, LedgerHandle.this, ctx);
                       return;
                   }
   
   2. Indicate the importance of this issue to you (blocker, must-have, should-have, nice-to-have). Are you currently using any workarounds to address this issue?
   
   *nice-to-have*
   
   3. Provide any additional detail on your proposed use case for this feature.
   
   
 
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