Examples with IteratorState io.pravega.segmentstore.contracts.tables.IteratorState used on opensource projects

Example 1 with IteratorState

use of io.pravega.segmentstore.contracts.tables.IteratorState in project pravega by pravega.

the class HashTableSegmentLayout method newIterator.

private <T> CompletableFuture<AsyncIterator<IteratorItem<T>>> newIterator(@NonNull DirectSegmentAccess segment, @NonNull IteratorArgs args, @NonNull GetBucketReader<T> createBucketReader) {
    Preconditions.checkArgument(args.getFrom() == null && args.getTo() == null, "Range Iterators not supported for HashTableSegments.");
    UUID fromHash;
    BufferView serializedState = args.getContinuationToken();
    try {
        fromHash = KeyHasher.getNextHash(serializedState == null ? null : IteratorStateImpl.deserialize(serializedState).getKeyHash());
    } catch (IOException ex) {
        // Bad IteratorState serialization.
        throw new IllegalDataFormatException("Unable to deserialize `serializedState`.", ex);
    }
    if (fromHash == null) {
        // Nothing to iterate on.
        return CompletableFuture.completedFuture(TableIterator.empty());
    }
    // Create a converter that will use a TableBucketReader to fetch all requested items in the iterated Buckets.
    val bucketReader = createBucketReader.apply(segment, this.keyIndex::getBackpointerOffset, this.executor);
    TableIterator.ConvertResult<IteratorItem<T>> converter = bucket -> bucketReader.findAllExisting(bucket.getSegmentOffset(), new TimeoutTimer(args.getFetchTimeout())).thenApply(result -> new IteratorItemImpl<>(new IteratorStateImpl(bucket.getHash()).serialize(), result));
    // Fetch the Tail (Unindexed) Hashes, then create the TableIterator.
    return this.keyIndex.getUnindexedKeyHashes(segment).thenComposeAsync(cacheHashes -> TableIterator.<IteratorItem<T>>builder().segment(segment).cacheHashes(cacheHashes).firstHash(fromHash).executor(executor).resultConverter(converter).fetchTimeout(args.getFetchTimeout()).build(), this.executor);
}