public void begin() throws IllegalStateException {
if (state == ACTIVE) {
throw new IllegalStateException("Transaction is already active");
}
if (THREAD_FLAG.get() != null) {
throw new IllegalStateException("Nested transactions are not allowed!");
}
// init caller thread
if (threadId == null) {
threadId = Thread.currentThread().getId();
setThreadFlag(Boolean.TRUE);
}
startTime = Clock.currentTimeMillis();
backupAddresses = transactionManagerService.pickBackupAddresses(durability);
if (durability > 0 && backupAddresses != null && transactionType == TransactionType.TWO_PHASE) {
List<Future> futures = startTxBackup();
awaitTxBackupCompletion(futures);
}
state = ACTIVE;
}