@Override public void appendDelta(WaveletDeltaRecord deltaRecord) throws OperationException { HashedVersion currentVersion = getCurrentVersion(); Preconditions.checkArgument(currentVersion.equals(deltaRecord.getAppliedAtVersion()), "Applied version %s doesn't match current version %s", deltaRecord.getAppliedAtVersion(), currentVersion); if (deltaRecord.getAppliedAtVersion().getVersion() == 0) { Preconditions.checkState(lastPersistedVersion.get() == null); snapshot = WaveletDataUtil.buildWaveletFromFirstDelta(getWaveletName(), deltaRecord.getTransformedDelta()); } else { WaveletDataUtil.applyWaveletDelta(deltaRecord.getTransformedDelta(), snapshot); } // Now that we built the snapshot without any exceptions, we record the delta. cachedDeltas.put(deltaRecord.getAppliedAtVersion(), deltaRecord); }