kevinrr888 commented on code in PR #4524:
URL: https://github.com/apache/accumulo/pull/4524#discussion_r1702220425
##########
core/src/main/java/org/apache/accumulo/core/fate/MetaFateStore.java:
##########
@@ -104,19 +109,108 @@ public FateId create() {
}
@Override
- protected void create(FateId fateId, FateKey key) {
+ public Optional<FateTxStore<T>> createAndReserve(FateKey fateKey) {
+ final var reservation = FateReservation.from(lockID, UUID.randomUUID());
+ final var fateId = fateIdGenerator.fromTypeAndKey(type(), fateKey);
+
try {
- zk.putPersistentData(getTXPath(fateId), new NodeValue(TStatus.NEW,
key).serialize(),
- NodeExistsPolicy.FAIL);
- } catch (KeeperException | InterruptedException e) {
+ byte[] nodeVal = zk.mutateOrCreate(getTXPath(fateId),
+ new NodeValue(TStatus.NEW, reservation, fateKey).serialize(),
currSerNodeVal -> {
+ // We are only returning a non-null value for the following cases:
+ // 1) The existing NodeValue for fateId is exactly the same as the
value set for the
+ // node if it doesn't yet exist:
+ // TStatus = TStatus.NEW, FateReservation = reservation, FateKey =
fateKey
+ // This might occur if there was a ZK server fault and the same
write is running a 2nd
+ // time
+ // 2) The existing NodeValue for fateId has:
+ // TStatus = TStatus.NEW, no FateReservation present, FateKey =
fateKey
+ // The fateId is NEW/unseeded and not reserved, so we can allow it
to be reserved
+ NodeValue currNodeVal = new NodeValue(currSerNodeVal);
+ if (currNodeVal.status == TStatus.NEW &&
currNodeVal.isReservedBy(reservation)) {
+ verifyFateKey(fateId, currNodeVal.fateKey, fateKey);
+ return currSerNodeVal;
+ } else if (currNodeVal.status == TStatus.NEW &&
!currNodeVal.isReserved()) {
+ verifyFateKey(fateId, currNodeVal.fateKey, fateKey);
+ // NEW/unseeded transaction and not reserved, so we can allow it
to be reserved
+ return new NodeValue(TStatus.NEW, reservation,
fateKey).serialize();
+ } else {
+ log.trace(
+ "fate id {} tstatus {} fate key {} is reserved {} is either
currently reserved "
+ + "or has already been seeded with work (non-NEW
status), or both",
+ fateId, currNodeVal.status, currNodeVal.fateKey.orElse(null),
+ currNodeVal.isReserved());
+ // This will not change the value to null but will return null
+ return null;
+ }
+ });
+ if (nodeVal != null) {
+ return Optional.of(new FateTxStoreImpl(fateId, reservation));
+ } else {
+ return Optional.empty();
+ }
+ } catch (InterruptedException | KeeperException |
AcceptableThriftTableOperationException e) {
+ throw new IllegalStateException(e);
+ }
+ }
+
+ @Override
+ public Optional<FateTxStore<T>> tryReserve(FateId fateId) {
+ // uniquely identify this attempt to reserve the fate operation data
+ FateReservation reservation = FateReservation.from(lockID,
UUID.randomUUID());
+
+ try {
+ byte[] newSerNodeVal = zk.mutateExisting(getTXPath(fateId),
currSerNodeVal -> {
Review Comment:
Yeah, I considered adding the check to that test, but chose to add it to
MultipleStoresIT.testReserveUnreserve() since there it also makes sure it
doesn't affect the current active reservations at all.
Are you suggesting I also have the check in testAbsent()? Or that I move the
check?
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