Amit and all,
I noticed today that TwoPhaseGetOldestXidInCommit has a header comment
where the same function is called TwoPhaseGetXidByLockingProc:
/*
 * TwoPhaseGetXidByLockingProc
 *              Return the oldest transaction ID from prepared
transactions that are
 *              currently in the commit critical section.
 *
 * This function only considers transactions in the currently connected
 * database. If no matching transactions are found, it returns
 * InvalidTransactionId.
 */
TransactionId
TwoPhaseGetOldestXidInCommit(void)
This inconsistency should be corrected.
Thanks,
-- 
Robert Haas
EDB: http://www.enterprisedb.com