Github user poornachandra commented on a diff in the pull request:
https://github.com/apache/incubator-tephra/pull/22#discussion_r93238207
--- Diff: tephra-core/src/main/java/org/apache/tephra/util/TxUtils.java ---
@@ -163,8 +167,22 @@ public static long getPruneUpperBound(Transaction tx) {
long maxInvalidTx =
tx.getInvalids().length > 0 ?
tx.getInvalids()[tx.getInvalids().length - 1] : Transaction.NO_TX_IN_PROGRESS;
+
+ // An invalid transaction can be used up to its max lifetime for data
writes, hence we cannot prune an invalid
+ // transaction until it exhausts its max lifetime.
+ long elapsedTime = currentTimeMillis -
TxUtils.getTimestamp(maxInvalidTx);
+ long invalidTxBound;
+ if (elapsedTime > txMaxLifetimeMillis) {
+ // maxInvalidTx is past its max lifetime
+ invalidTxBound = maxInvalidTx;
+ } else {
+ // Reduce the lifetime of maxInvalidTx, so that it cannot be used
for any more writes
+ long remainingTime = txMaxLifetimeMillis - elapsedTime;
+ invalidTxBound = maxInvalidTx - remainingTime *
TxConstants.MAX_TX_PER_MS - 1;
--- End diff --
On further thought, we will need to compute inactive transaction bound
separately from prune upper bound.
Inactive transaction bound can be computed using just current time and tx
max lifetime as ` (currentTimeMillis - txMaxLifetimeMillis) *
TxConstants.MAX_TX_PER_MS - 1`.
However, prune upper bound is a record of what invalid data was removed
during a major compaction, and hence will need to use the invalid list and
in-progress list from the transaction snapshot used at the time of the major
compaction.
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