对于 Hazelcast python 客户端，我如何在服务器端没有保留_all() 的情况下在多个 Hazelcast 集实体之间设置交集？

Question

I have multiple Hazelcast sets for which I want to find the Intersection, however I want to avoid pulling any data on the client side. My current approach is exactly that with this code. It finds intersection between the 1st set and the list of the rest of set so that set1 is now the intersection of all.

for i in range(1, len(sets)):
    cur = sets[i]
    set1.retain_all(cur.get_all())

Hazelcast's retain_all doesn't work with 2 set entities, only with a set and a collection which is not what I am looking for. For example, it can be done with Redis with this code, so I want its Hazelcast equivalent.

set_result = "set_result"
redisClient.sinterstore(set_result, *list(sets))

Any help would be appreciated!

Answer 1

Since Hazelcast's ISet is a Set which is a Collection the following code should work:

set1.retainAll(cur);

But, it doesn't seem like you'd like set1 to be modified but would rather store the result in a different set much like redis' sinterstore function.

The following is an example of an alternative implementation:

public class RetainAllExample {

public static void main(String[] args) {

    HazelcastInstance h1 = Hazelcast.newHazelcastInstance();
    HazelcastInstance h2 = Hazelcast.newHazelcastInstance();

    Set<String> set1 = h1.getSet("set1");
    Set<String> set2 = h1.getSet("set2");

    set1.add("a");
    set1.add("b");
    set1.add("c");
    set1.add("d");

    set2.add("c");
    set2.add("d");
    set2.add("e");

    String resultName = "result";
    String[] setNames = new String[] { "set1", "set2"};
    RetainAll retainAll = new RetainAll(resultName, setNames;
    IExecutorService exec = h1.getExecutorService("HZ-Executor-1");
    Future<Boolean> task = exec.submit(retainAll);

    try {
        if(task.get(1_000, TimeUnit.MILLISECONDS)) {
            Set<String> result = h1.getSet(resultName);
            result.forEach(str -> System.out.println(str + ", "));
        }
    } catch (Exception e) {
        e.printStackTrace();
        System.exit(-1);
    }
    System.exit(0);
}

static class RetainAll implements Callable<Boolean>, HazelcastInstanceAware, Serializable {
    private HazelcastInstance hazelcastInstance;
    private String resultSetName;
    private String[] setNames;
    public RetainAll(String resultSetName, String[] setNames) {
        this.resultSetName = resultSetName;
        this.setNames = setNames;
    }
    @Override
    public Boolean call() {
        try {
            Set[] sets = new Set[setNames.length];
            IntStream.range(0, setNames.length).forEach(i -> sets[i] = hazelcastInstance.getSet(setNames[i]));

            ISet resultSet = hazelcastInstance.getSet(resultSetName);
            resultSet.addAll(sets[0]);
            IntStream.range(1, sets.length).forEach(i -> resultSet.retainAll(sets[i]));
        }
        catch (Exception e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }
    @Override
    public void setHazelcastInstance(HazelcastInstance hazelcastInstance) {
        this.hazelcastInstance = hazelcastInstance;
    }
}

}