@Override
  public FindInfo findEntriesSince(FindToken token, long maxSizeOfEntries, String hostname, String remoteReplicaPath)
      throws StoreException {
    // unused function
    MockFindToken mockToken = (MockFindToken) token;
    List<MessageInfo> entriesToReturn = new ArrayList<>();
    long currentSizeOfEntriesInBytes = 0;
    int index = mockToken.getIndex();
    Set<StoreKey> processedKeys = new HashSet<>();
    while (currentSizeOfEntriesInBytes < maxSizeOfEntries && index < messageInfos.size()) {
      StoreKey key = messageInfos.get(index).getStoreKey();
      if (processedKeys.add(key)) {
        entriesToReturn.add(getMergedMessageInfo(key, messageInfos));
      }
      // still use the size of the put (if the original picked up is the put.
      currentSizeOfEntriesInBytes += messageInfos.get(index).getSize();
      index++;
    }

    int startIndex = mockToken.getIndex();
    int totalSizeRead = 0;
    for (int i = 0; i < startIndex; i++) {
      totalSizeRead += messageInfos.get(i).getSize();
    }
    totalSizeRead += currentSizeOfEntriesInBytes;
    return new FindInfo(entriesToReturn,
        new MockFindToken(mockToken.getIndex() + entriesToReturn.size(), totalSizeRead));
  }
Log that stores all data in memory.
ambry-replication/src/test/java/com/github/ambry/replication/InMemoryStore.java