hollow/src/main/java/com/netflix/hollow/core/read/engine/HollowBlobReader.java
public void applyDelta(InputStream is) throws IOException {
        HollowBlobHeader header = readHeader(is, true);
        notifyBeginUpdate();

        long startTime = System.currentTimeMillis();

        DataInputStream dis = new DataInputStream(is);

        int numStates = VarInt.readVInt(dis);

        Collection<String> typeNames = new TreeSet<String>();
        for(int i=0;i<numStates;i++) {
            String typeName = readTypeStateDelta(dis, header);
            typeNames.add(typeName);
            stateEngine.getMemoryRecycler().swap();
        }

        long endTime = System.currentTimeMillis();

        log.info("DELTA COMPLETED IN " + (endTime - startTime) + "ms");
        log.info("TYPES: " + typeNames);

        notifyEndUpdate();

    }
public void applyDelta(InputStream is) throws IOException {
        HollowBlobHeader header = readHeader(is, true);
        notifyBeginUpdate();

        long startTime = System.currentTimeMillis();

        DataInputStream dis = new DataInputStream(is);

        int numStates = VarInt.readVInt(dis);

        Collection<String> typeNames = new TreeSet<String>();
        for(int i=0;i<numStates;i++) {
            String typeName = readTypeStateDelta(dis, header);
            typeNames.add(typeName);
            stateEngine.getMemoryRecycler().swap();
        }

        long endTime = System.currentTimeMillis();

        log.info("DELTA COMPLETED IN " + (endTime - startTime) + "ms");
        log.info("TYPES: " + typeNames);

        notifyEndUpdate();

    }
Update the state engine using a delta (or reverse delta) blob from the provided InputStream.
<p>
If a {@link HollowFilterConfig} was applied at the time the {@link HollowReadStateEngine} was initialized
with a snapshot, it will continue to be in effect after the state is updated.

@param is the input stream to read the delta from
@throws IOException if the delta could not be applied