关于redis:聊聊claudb的set-command

序

本文次要钻研一下 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 办法先从 request 参数提取 values，而后执行 db.merge，应用 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 办法通过 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 办法通过 db.getSet(request.getParam(0)) 获取 ImmutableSet，而后返回 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 办法通过 db.getSet(request.getParam(0)) 获取 ImmutableSet，而后再通过 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 办法先从 request 参数提取 items，而后执行 db.merge，应用 oldSet.intersection 取出交加，而后执行 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 办法先获取 ImmutableSet，而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 办法先获取 ImmutableSet，而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 办法先获取 ImmutableSet，而后遍历参数值挨个执行 result.difference(db.getSet(param))

小结

claudb set 相干的 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)