+abstract class LeaderFrontendState implements Identifiable<ClientIdentifier> {
+ static final class Disabled extends LeaderFrontendState {
+ Disabled(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree) {
+ super(persistenceId, clientId, tree);
+ }
+
+ @Override
+ LocalHistorySuccess handleLocalHistoryRequest(final LocalHistoryRequest<?> request,
+ final RequestEnvelope envelope, final long now) throws RequestException {
+ throw new UnsupportedRequestException(request);
+ }
+
+ @Override
+ TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request,
+ final RequestEnvelope envelope, final long now) throws RequestException {
+ throw new UnsupportedRequestException(request);
+ }
+ }
+
+ static final class Enabled extends LeaderFrontendState {
+ // Histories which have not been purged
+ private final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories;
+
+ // RangeSet performs automatic merging, hence we keep minimal state tracking information
+ private final UnsignedLongRangeSet purgedHistories;
+
+ // Used for all standalone transactions
+ private final AbstractFrontendHistory standaloneHistory;
+
+ private long expectedTxSequence;
+ private Long lastSeenHistory = null;
+
+ Enabled(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree) {
+ this(persistenceId, clientId, tree, UnsignedLongRangeSet.create(),
+ StandaloneFrontendHistory.create(persistenceId, clientId, tree), new HashMap<>());
+ }
+
+ Enabled(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree,
+ final UnsignedLongRangeSet purgedHistories, final AbstractFrontendHistory standaloneHistory,
+ final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories) {
+ super(persistenceId, clientId, tree);
+ this.purgedHistories = requireNonNull(purgedHistories);
+ this.standaloneHistory = requireNonNull(standaloneHistory);
+ this.localHistories = requireNonNull(localHistories);
+ }
+
+ @Override
+ @Nullable LocalHistorySuccess handleLocalHistoryRequest(final LocalHistoryRequest<?> request,
+ final RequestEnvelope envelope, final long now) throws RequestException {
+ checkRequestSequence(envelope);
+
+ try {
+ if (request instanceof CreateLocalHistoryRequest) {
+ return handleCreateHistory((CreateLocalHistoryRequest) request, envelope, now);
+ } else if (request instanceof DestroyLocalHistoryRequest) {
+ return handleDestroyHistory((DestroyLocalHistoryRequest) request, envelope, now);
+ } else if (request instanceof PurgeLocalHistoryRequest) {
+ return handlePurgeHistory((PurgeLocalHistoryRequest)request, envelope, now);
+ } else {
+ LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
+ throw new UnsupportedRequestException(request);
+ }
+ } finally {
+ expectNextRequest();
+ }
+ }
+
+ @Override
+ @Nullable TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request,
+ final RequestEnvelope envelope, final long now) throws RequestException {
+ checkRequestSequence(envelope);
+
+ try {
+ final LocalHistoryIdentifier lhId = request.getTarget().getHistoryId();
+ final AbstractFrontendHistory history;
+
+ if (lhId.getHistoryId() != 0) {
+ history = localHistories.get(lhId);
+ if (history == null) {
+ if (purgedHistories.contains(lhId.getHistoryId())) {
+ LOG.warn("{}: rejecting request {} to purged history", persistenceId(), request);
+ throw new DeadHistoryException(purgedHistories.toImmutable());
+ }
+
+ LOG.warn("{}: rejecting unknown history request {}", persistenceId(), request);
+ throw new UnknownHistoryException(lastSeenHistory);
+ }
+ } else {
+ history = standaloneHistory;
+ }
+
+ return history.handleTransactionRequest(request, envelope, now);
+ } finally {
+ expectNextRequest();
+ }
+ }
+
+ @Override
+ void reconnect() {
+ expectedTxSequence = 0;
+ super.reconnect();
+ }
+
+ @Override
+ void retire() {
+ super.retire();
+
+ // Clear out all transaction chains
+ localHistories.values().forEach(AbstractFrontendHistory::retire);
+ localHistories.clear();
+ standaloneHistory.retire();
+ }
+
+ @Override
+ ToStringHelper addToStringAttributes(final ToStringHelper helper) {
+ return super.addToStringAttributes(helper).add("purgedHistories", purgedHistories);
+ }
+
+ private LocalHistorySuccess handleCreateHistory(final CreateLocalHistoryRequest request,
+ final RequestEnvelope envelope, final long now) throws RequestException {
+ final LocalHistoryIdentifier historyId = request.getTarget();
+ final AbstractFrontendHistory existing = localHistories.get(historyId);
+ if (existing != null) {
+ // History already exists: report success
+ LOG.debug("{}: history {} already exists", persistenceId(), historyId);
+ return new LocalHistorySuccess(historyId, request.getSequence());
+ }
+
+ // We have not found the history. Before we create it we need to check history ID sequencing so that we do
+ // not end up resurrecting a purged history.
+ if (purgedHistories.contains(historyId.getHistoryId())) {
+ LOG.debug("{}: rejecting purged request {}", persistenceId(), request);
+ throw new DeadHistoryException(purgedHistories.toImmutable());
+ }
+
+ // Update last history we have seen
+ if (lastSeenHistory == null || Long.compareUnsigned(lastSeenHistory, historyId.getHistoryId()) < 0) {
+ lastSeenHistory = historyId.getHistoryId();
+ }
+
+ // We have to send the response only after persistence has completed
+ final ShardDataTreeTransactionChain chain = tree().ensureTransactionChain(historyId, () -> {
+ LOG.debug("{}: persisted history {}", persistenceId(), historyId);
+ envelope.sendSuccess(new LocalHistorySuccess(historyId, request.getSequence()),
+ tree().readTime() - now);
+ });
+
+ localHistories.put(historyId, LocalFrontendHistory.create(persistenceId(), tree(), chain));
+ LOG.debug("{}: created history {}", persistenceId(), historyId);
+ return null;
+ }
+
+ private LocalHistorySuccess handleDestroyHistory(final DestroyLocalHistoryRequest request,
+ final RequestEnvelope envelope, final long now) {
+ final LocalHistoryIdentifier id = request.getTarget();
+ final LocalFrontendHistory existing = localHistories.get(id);
+ if (existing == null) {
+ // History does not exist: report success
+ LOG.debug("{}: history {} does not exist, nothing to destroy", persistenceId(), id);
+ return new LocalHistorySuccess(id, request.getSequence());
+ }
+
+ existing.destroy(request.getSequence(), envelope, now);
+ return null;
+ }
+
+ private LocalHistorySuccess handlePurgeHistory(final PurgeLocalHistoryRequest request,
+ final RequestEnvelope envelope, final long now) {
+ final LocalHistoryIdentifier id = request.getTarget();
+ final LocalFrontendHistory existing = localHistories.remove(id);
+ if (existing == null) {
+ LOG.debug("{}: history {} has already been purged", persistenceId(), id);
+ return new LocalHistorySuccess(id, request.getSequence());
+ }
+
+ LOG.debug("{}: purging history {}", persistenceId(), id);
+ purgedHistories.add(id.getHistoryId());
+ existing.purge(request.getSequence(), envelope, now);
+ return null;
+ }
+
+ private void checkRequestSequence(final RequestEnvelope envelope) throws OutOfSequenceEnvelopeException {
+ if (expectedTxSequence != envelope.getTxSequence()) {
+ throw new OutOfSequenceEnvelopeException(expectedTxSequence);
+ }
+ }