聊聊claudb的set command

序

本文主要研究一下claudb的set command

SetAddCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetAddCommand.java

@Command("sadd")
@ParamLength(2)
@ParamType(DataType.SET)
public class SetAddCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    List<SafeString> values = request.getParams().stream().skip(1).collect(toList());
    DatabaseValue value = db.merge(safeKey(request.getParam(0)), set(values),
      (oldValue, newValue) -> set(oldValue.getSet().appendAll(newValue.getSet())));
    return integer(value.size());
  }
}

SetAddCommand实现了DBCommand接口，其execute方法先从request参数提取values，然后执行db.merge，使用oldValue.getSet().appendAll(newValue.getSet())

SetMembersCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetMembersCommand.java

@ReadOnly
@Command("smembers")
@ParamLength(1)
@ParamType(DataType.SET)
public class SetMembersCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    DatabaseValue value = db.getOrDefault(safeKey(request.getParam(0)), DatabaseValue.EMPTY_SET);
    return convert(value);
  }
}

SetMembersCommand实现了DBCommand接口，其execute方法通过db.getOrDefault获取DatabaseValue

SetCardinalityCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetCardinalityCommand.java

@ReadOnly
@Command("scard")
@ParamLength(1)
@ParamType(DataType.SET)
public class SetCardinalityCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    ImmutableSet<SafeString> set = db.getSet(request.getParam(0));
    return integer(set.size());
  }
}

SetCardinalityCommand实现了DBCommand接口，其execute方法通过db.getSet(request.getParam(0))获取ImmutableSet，然后返回set.size()

SetIsMemberCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetIsMemberCommand.java

@ReadOnly
@Command("sismember")
@ParamLength(2)
@ParamType(DataType.SET)
public class SetIsMemberCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    ImmutableSet<SafeString> set = db.getSet(request.getParam(0));
    return integer(set.contains(request.getParam(1)));
  }
}

SetIsMemberCommand实现了DBCommand接口，其execute方法通过db.getSet(request.getParam(0))获取ImmutableSet，然后再通过set.contains(request.getParam(1))判断是否存在指定元素

SetRemoveCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetRemoveCommand.java

@Command("srem")
@ParamLength(2)
@ParamType(DataType.SET)
public class SetRemoveCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    ImmutableList<SafeString> items = request.getParams().asList().tail();
    List<SafeString> removed = new LinkedList<>();
    db.merge(safeKey(request.getParam(0)), DatabaseValue.EMPTY_SET,
        (oldValue, newValue) -> {
          ImmutableSet<SafeString> oldSet = oldValue.getSet();
          oldSet.intersection(items.asSet()).stream().forEach(removed::add);
          return set(oldSet.removeAll(items));
        });

    return integer(removed.size());
  }
}

SetRemoveCommand实现了DBCommand接口，其execute方法先从request参数提取items，然后执行db.merge，使用oldSet.intersection取出交集，然后执行oldSet.removeAll(items)

SetUnionCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetUnionCommand.java

@ReadOnly
@Command("sunion")
@ParamLength(2)
@ParamType(DataType.SET)
public class SetUnionCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    ImmutableSet<SafeString> result = db.getSet(request.getParam(0));
    for (SafeString param : request.getParams().asList().tail()) {
      result = result.union(db.getSet(param));
    }
    return convert(result);
  }
}

SetUnionCommand实现了DBCommand接口，其execute方法先获取ImmutableSet，然后遍历参数值挨个执行result.union(db.getSet(param))

SetIntersectionCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetIntersectionCommand.java

@ReadOnly
@Command("sinter")
@ParamLength(2)
@ParamType(DataType.SET)
public class SetIntersectionCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    ImmutableSet<SafeString> result = db.getSet(request.getParam(0));
    for (SafeString param : request.getParams().asList().tail()) {
      result = result.intersection(db.getSet(param));
    }
    return convert(result);
  }
}

SetIntersectionCommand实现了DBCommand接口，其execute方法先获取ImmutableSet，然后遍历参数值挨个执行result.intersection(db.getSet(param))

SetDifferenceCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set/SetDifferenceCommand.java

@ReadOnly
@Command("sdiff")
@ParamLength(2)
@ParamType(DataType.SET)
public class SetDifferenceCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    ImmutableSet<SafeString> result = db.getSet(request.getParam(0));
    for (SafeString param : request.getParams().asList().tail()) {
      result = result.difference(db.getSet(param));
    }
    return convert(result);
  }
}

SetDifferenceCommand实现了DBCommand接口，其execute方法先获取ImmutableSet，然后遍历参数值挨个执行result.difference(db.getSet(param))

小结

claudb set相关的command有SetAddCommand、SetMembersCommand、SetCardinalityCommand、SetIsMemberCommand、SetRemoveCommand、SetUnionCommand、SetIntersectionCommand、SetDifferenceCommand

doc

[command/set(claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/set)