rvesse commented on a change in pull request #537: JENA-1676 , JENA-1677: Make
the commit step more robust against external factors
URL: https://github.com/apache/jena/pull/537#discussion_r261641027
##########
File path:
jena-db/jena-dboe-transaction/src/main/java/org/apache/jena/dboe/transaction/txn/TransactionCoordinator.java
##########
@@ -683,28 +687,80 @@ private boolean promotionWaitForWriters() {
// Do here because it needs access to the journal.
notifyPrepareStart(transaction);
transaction.getComponents().forEach(sysTrans -> {
- TransactionalComponent c = sysTrans.getComponent() ;
- ByteBuffer data = c.commitPrepare(transaction) ;
+ ByteBuffer data = sysTrans.commitPrepare() ;
if ( data != null ) {
- PrepareState s = new PrepareState(c.getComponentId(), data) ;
+ PrepareState s = new PrepareState(sysTrans.getComponentId(),
data) ;
journal.write(s) ;
}
}) ;
notifyPrepareFinish(transaction);
}
-
- /*package*/ void executeCommit(Transaction transaction, Runnable commit,
Runnable finish) {
+
+ /*package*/ void executeCommit(Transaction transaction, Runnable commit,
Runnable finish, Runnable sysabort) {
if ( transaction.getMode() == ReadWrite.READ ) {
finish.run();
notifyCommitFinish(transaction);
return;
}
-
- // This is the commit for a write transaction
+ journal.startWrite();
+ try {
+ executeCommitWriter(transaction, commit, finish, sysabort);
+ journal.commitWrite();
+ } catch (TransactionException ex) {
+ throw ex;
+ } catch (Throwable th) {
+ throw th;
+ } finally { journal.endWrite(); }
+ }
+
+ private void executeCommitWriter(Transaction transaction, Runnable commit,
Runnable finish, Runnable sysabort) {
synchronized(coordinatorLock) {
- // *** COMMIT POINT
- journal.sync() ;
- // *** COMMIT POINT
+ try {
+ // Simulate a Thread.interrupt during I/O.
+// if ( true )
+// throw new FileException(new
ClosedByInterruptException());
+
+ // *** COMMIT POINT
+ journal.writeJournal(JournalEntry.COMMIT);
+ journal.sync();
+ // *** COMMIT POINT
+ }
+ // catch (ClosedByInterruptException ex) {}
+ // Some low level system error - probably a sign of something
serious like disk error.
+ catch(FileException ex) {
+ if ( ex.getCause() instanceof ClosedByInterruptException ) {
+ // Thread interrupt during java I/O.
+ // File was closed by java.nio.
+ // Reopen - this truncates to the last write start
position.
+ journal.reopen();
+ // This call should clear up the transaction state.
+ rollback(transaction, sysabort);
+ SysLog.warn("Thread interrupt during I/O in 'commit' :
executed transaction rollback: "+ex.getMessage());
+ throw new TransactionException("Thread interrupt during
I/O in 'commit' : transaction rollback.", ex);
+ }
+ if ( isIOException(ex) )
+ SysErr.warn("IOException during 'commit' : transaction may
have committed. Attempting rollback: "+ex.getMessage());
+ else
+ SysErr.warn("Exception during 'commit' : transaction may
have committed. Attempting rollback. Details:",ex);
+ if ( abandonTxn(transaction, sysabort) ) {
+ SysErr.warn("Transaction rollback");
+ throw new TransactionException("Exception during 'commit'
- transaction rollback.", ex);
+ }
+ // Very bad. (This have been dealt with already and should get
to here.)
+ SysErr.error("Transaction rollback failed. System unstable.");
+ throw new TransactionException("Exception during 'rollback' -
System unstable.", ex);
Review comment:
Perhaps something asking users to report back to us so we get an idea of how
prevalent (or not) this situation is in the wild. If something might be wrong
with the users IO setup (whether transient or not) may be worth making that
clear
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