ABORT_OP doesn't undo epoch registration of payloads

[qtcwt]

For operations adding new payloads in the nonblocking structure, BEGIN_OP takes payloads and register corresponding epoch number in the payloads. However, such registration should be undo, i.e., epoch number in the payloads should be reset to NULL_EPOCH, when ABORT_OP occurs.
ABORT_OP means CAS fail and we should release the epoch we occupied.

[qtcwt]

Or another way, relevant to Issue #5, could be to register epoch in payloads after linearization point succeeds?
No it won't work. We have to tag payload with epoch before it is published.
Adding payload to to-be-persisted list cannot be deferred either, since payload with reset epoch needs to be explicitly persisted after ABORT_OP to overwrite potential writes-back after tagging epoch but before resetting.

[qtcwt]

Addressed in commit c31f37, which is included in PR #3 .