Examples with Sequence com.palantir.atlasdb.keyvalue.api.watch.Sequence used on opensource projects

Example 1 with Sequence

use of com.palantir.atlasdb.keyvalue.api.watch.Sequence in project atlasdb by palantir.

the class LockWatchValueScopingCacheImpl method updateStores.

/**
 * In order to maintain the necessary invariants, we need to do the following:
 *
 *  1. For each new event, we apply it to the cache. The effects of this application is described in
 *     {@link LockWatchValueScopingCache}.
 *  2. For each transaction, we must ensure that we store a snapshot of the cache at the sequence corresponding
 *     to the transaction's start timestamp. Note that not every sequence will have a corresponding timestamp, so we
 *     don't bother storing a snapshot for those sequences. Also note that we know that each call here will only
 *     ever have new events, and that consecutive calls to this method will *always* have increasing sequences
 *     (without this last guarantee, we'd need to store snapshots for all sequences).
 *  3. For each transaction, we must create a transaction scoped cache. We do this now as we have tighter guarantees
 *     around when the cache is created, and thus deleted.
 */
private synchronized void updateStores(TransactionsLockWatchUpdate updateForTransactions) {
    Multimap<Sequence, StartTimestamp> reversedMap = createSequenceTimestampMultimap(updateForTransactions);
    // Without this block, updates with no events would not store a snapshot.
    currentVersion.map(LockWatchVersion::version).map(Sequence::of).ifPresent(sequence -> snapshotStore.storeSnapshot(sequence, reversedMap.get(sequence), valueStore.getSnapshot()));
    updateForTransactions.events().stream().filter(this::isNewEvent).forEach(event -> {
        valueStore.applyEvent(event);
        Sequence sequence = Sequence.of(event.sequence());
        snapshotStore.storeSnapshot(sequence, reversedMap.get(sequence), valueStore.getSnapshot());
    });
    updateForTransactions.startTsToSequence().keySet().forEach(timestamp -> cacheStore.createCache(StartTimestamp.of(timestamp)));
    if (valueStore.getSnapshot().hasAnyTablesWatched()) {
        assertNoSnapshotsMissing(reversedMap);
    }
}