聊聊claudb的zset command

序

本文主要研究一下zset command

SortedSetAddCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetAddCommand.java

@Command("zadd")
@ParamLength(3)
@ParamType(DataType.ZSET)
public class SortedSetAddCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    try {
      DatabaseValue initial = db.getOrDefault(safeKey(request.getParam(0)), DatabaseValue.EMPTY_ZSET);
      DatabaseValue result = db.merge(safeKey(request.getParam(0)), parseInput(request),
          (oldValue, newValue) -> {
            Set<Entry<Double, SafeString>> merge = new SortedSet();
            merge.addAll(oldValue.getSortedSet());
            merge.addAll(newValue.getSortedSet());
            return zset(merge);
          });
      return integer(changed(initial.getSortedSet(), result.getSortedSet()));
    } catch (NumberFormatException e) {
      return error("ERR value is not a valid float");
    }
  }

  private int changed(Set<Entry<Double, SafeString>> input, Set<Entry<Double, SafeString>> result) {
    return result.size() - input.size();
  }

  private DatabaseValue parseInput(Request request) {
    Set<Entry<Double, SafeString>> set = new SortedSet();
    SafeString score = null;
    for (SafeString string : request.getParams().stream().skip(1).collect(toList())) {
      if (score != null) {
        set.add(score(parseFloat(score.toString()), string));
        score =  null;
      } else {
        score = string;
      }
    }
    return zset(set);
  }
}

• SortedSetAddCommand实现了DBCommand接口，其execute方法先获取initial，然后执行db.merge方法，它先添加oldValue.getSortedSet()、再添加newValue.getSortedSet()

SortedSetCardinalityCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetCardinalityCommand.java

@ReadOnly
@Command("zcard")
@ParamLength(1)
@ParamType(DataType.ZSET)
public class SortedSetCardinalityCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    DatabaseValue value = db.getOrDefault(safeKey(request.getParam(0)), DatabaseValue.EMPTY_ZSET);
    Set<Entry<Double, SafeString>> set = value.getSortedSet();
    return integer(set.size());
  }
}

• SortedSetCardinalityCommand实现了DBCommand接口，其execute方法先通过db.getOrDefault获取value，在获取value.getSortedSet()

SortedSetRemoveCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetRemoveCommand.java

@Command("zrem")
@ParamLength(2)
@ParamType(DataType.ZSET)
public class SortedSetRemoveCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    List<SafeString> items =  request.getParams().stream().skip(1).collect(toList());
    List<SafeString> removed = new LinkedList<>();
    db.merge(safeKey(request.getParam(0)), DatabaseValue.EMPTY_ZSET,
             (oldValue, newValue) -> {
               Set<Entry<Double, SafeString>> merge = new SortedSet();
               merge.addAll(oldValue.getSortedSet());
               for (SafeString item : items) {
                 if (merge.remove(score(0, item))) {
                   removed.add(item);
                 }
               }
               return zset(merge);
             });

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

• SortedSetRemoveCommand实现了DBCommand接口，其execute方法先从request参数提取items，然后执行db.merge，该方法遍历items挨个执行merge.remove(score(0, item))

SortedSetRangeCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetRangeCommand.java

@ReadOnly
@Command("zrange")
@ParamLength(3)
@ParamType(DataType.ZSET)
public class SortedSetRangeCommand implements DBCommand {

  private static final String PARAM_WITHSCORES = "WITHSCORES";

  @Override
  public RedisToken execute(Database db, Request request) {
    try {
      DatabaseValue value = db.getOrDefault(safeKey(request.getParam(0)), DatabaseValue.EMPTY_ZSET);
      NavigableSet<Entry<Double, SafeString>> set = value.getSortedSet();

      int from = Integer.parseInt(request.getParam(1).toString());
      if (from < 0) {
        from = set.size() + from;
      }
      int to = Integer.parseInt(request.getParam(2).toString());
      if (to < 0) {
        to = set.size() + to;
      }

      List<Object> result = emptyList();
      if (from <= to) {
        Option<SafeString> withScores = request.getOptionalParam(3);
        if (withScores.isPresent() && withScores.get().toString().equalsIgnoreCase(PARAM_WITHSCORES)) {
          result = set.stream().skip(from).limit((to - from) + 1l)
              .flatMap(entry -> Stream.of(entry.getValue(), entry.getKey())).collect(toList());
        } else {
          result = set.stream().skip(from).limit((to - from) + 1l)
              .map(Entry::getValue).collect(toList());
        }
      }

      return convert(result);
    } catch (NumberFormatException e) {
      return error("ERR value is not an integer or out of range");
    }
  }
}

• SortedSetRangeCommand实现了DBCommand接口，其execute方法执行db.getOrDefault获取value，然后通过set.stream().skip(from).limit((to - from) + 1l)获取result

SortedSetRangeByScoreCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetRangeByScoreCommand.java

@ReadOnly
@Command("zrangebyscore")
@ParamLength(3)
@ParamType(DataType.ZSET)
public class SortedSetRangeByScoreCommand implements DBCommand {

  private static final String EXCLUSIVE = "(";
  private static final String MINUS_INFINITY = "-inf";
  private static final String INIFITY = "+inf";
  private static final String PARAM_WITHSCORES = "WITHSCORES";
  private static final String PARAM_LIMIT = "LIMIT";

  @Override
  public RedisToken execute(Database db, Request request) {
    try {
      DatabaseValue value = db.getOrDefault(safeKey(request.getParam(0)), DatabaseValue.EMPTY_ZSET);
      NavigableSet<Entry<Double, SafeString>> set = value.getSortedSet();

      float from = parseRange(request.getParam(1).toString());
      float to = parseRange(request.getParam(2).toString());

      Options options = parseOptions(request);

      Set<Entry<Double, SafeString>> range = set.subSet(
          score(from, SafeString.EMPTY_STRING), inclusive(request.getParam(1)),
          score(to, SafeString.EMPTY_STRING), inclusive(request.getParam(2)));

      List<Object> result = emptyList();
      if (from <= to) {
        if (options.withScores) {
          result = range.stream().flatMap(
              entry -> Stream.of(entry.getValue(), entry.getKey())).collect(toList());
        } else {
          result = range.stream().map(Entry::getValue).collect(toList());
        }

        if (options.withLimit) {
          result = result.stream().skip(options.offset).limit(options.count).collect(toList());
        }
      }

      return convert(result);
    } catch (NumberFormatException e) {
      return error("ERR value is not an float or out of range");
    }
  }

  private Options parseOptions(Request request) {
    Options options = new Options();
    for (int i = 3; i < request.getLength(); i++) {
      String param = request.getParam(i).toString();
      if (param.equalsIgnoreCase(PARAM_LIMIT)) {
        options.withLimit = true;
        options.offset = parseInt(request.getParam(++i).toString());
        options.count = parseInt(request.getParam(++i).toString());
      } else if (param.equalsIgnoreCase(PARAM_WITHSCORES)) {
        options.withScores = true;
      }
    }
    return options;
  }

  private boolean inclusive(SafeString param) {
    return !param.toString().startsWith(EXCLUSIVE);
  }

  private float parseRange(String param) {
    switch (param) {
    case INIFITY:
      return Float.MAX_VALUE;
    case MINUS_INFINITY:
      return Float.MIN_VALUE;
    default:
      if (param.startsWith(EXCLUSIVE)) {
        return Float.parseFloat(param.substring(1));
      }
      return Float.parseFloat(param);
    }
  }

  private static class Options {
    private boolean withScores;
    private boolean withLimit;
    private int offset;
    private int count;
  }
}

• SortedSetRangeByScoreCommand实现了DBCommand接口，其execute方法执行db.getOrDefault获取value，然后通过set.subSet(score(from, SafeString.EMPTY_STRING), inclusive(request.getParam(1)),score(to, SafeString.EMPTY_STRING), inclusive(request.getParam(2)))获取range，最后从range提取result

SortedSetReverseRangeCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetReverseRangeCommand.java

@ReadOnly
@Command("zrevrange")
@ParamLength(3)
@ParamType(DataType.ZSET)
public class SortedSetReverseRangeCommand implements DBCommand {

  private static final String PARAM_WITHSCORES = "WITHSCORES";

  @Override
  public RedisToken execute(Database db, Request request) {
    try {
      DatabaseValue value = db.getOrDefault(safeKey(request.getParam(0)), DatabaseValue.EMPTY_ZSET);
      NavigableSet<Entry<Double, SafeString>> set = value.getSortedSet();

      int from = Integer.parseInt(request.getParam(2).toString());
      if (from < 0) {
        from = set.size() + from;
      }
      int to = Integer.parseInt(request.getParam(1).toString());
      if (to < 0) {
        to = set.size() + to;
      }

      List<Object> result = emptyList();
      if (from <= to) {
        Option<SafeString> withScores = request.getOptionalParam(3);
        if (withScores.isPresent() && withScores.get().toString().equalsIgnoreCase(PARAM_WITHSCORES)) {
          result = set.stream().skip(from).limit((to - from) + 1l)
              .flatMap(item -> Stream.of(item.getValue(), item.getKey())).collect(toList());
        } else {
          result = set.stream().skip(from).limit((to - from) + 1l)
              .map(Entry::getValue).collect(toList());
        }
      }
      reverse(result);

      return convert(result);
    } catch (NumberFormatException e) {
      return error("ERR value is not an integer or out of range");
    }
  }
}

• SortedSetReverseRangeCommand实现了DBCommand接口，其execute方法执行db.getOrDefault获取value，然后通过set.stream().skip(from).limit((to - from) + 1l)获取result

SortedSetIncrementByCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/zset/SortedSetIncrementByCommand.java

@Command("zincrby")
@ParamLength(3)
@ParamType(DataType.ZSET)
public class SortedSetIncrementByCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    try {
      DatabaseKey zkey = safeKey(request.getParam(0));
      DatabaseValue value = db.getOrDefault(zkey, DatabaseValue.EMPTY_ZSET);
      NavigableSet<Entry<Double, SafeString>> set = value.getSortedSet();

      SafeString key = request.getParam(2);
      Double increment = Double.parseDouble(request.getParam(1).toString());

      Entry<Double, SafeString> newValue = merge(set, key, increment);

      SortedSet result = new SortedSet();
      result.addAll(set);
      result.remove(newValue);
      result.add(newValue);
      db.put(zkey, zset(result));

      return string(newValue.getKey().toString());
    } catch (NumberFormatException e) {
      return error("ERR value is not an integer or out of range");
    }
  }

  private Entry<Double, SafeString>
          merge(NavigableSet<Entry<Double, SafeString>> set, SafeString key, Double increment) {
    return score(findByKey(set, key).getKey() + increment, key);
  }

  private Entry<Double, SafeString> findByKey(NavigableSet<Entry<Double, SafeString>> set, SafeString key) {
    // TODO: O(n) search, to fix forget the NavigableSet and use directly the SortedSet to get by key
    return set.stream().filter(entry -> entry.getValue().equals(key)).findFirst().orElse(score(0, key));
  }
}

• SortedSetIncrementByCommand实现了DBCommand接口，其execute方法执行db.getOrDefault获取value，然后通过merge获取newValue

小结

claudb sorted set相关的command有SortedSetAddCommand、SortedSetCardinalityCommand、SortedSetRemoveCommand、SortedSetRangeCommand、SortedSetRangeByScoreCommand、SortedSetReverseRangeCommand、SortedSetIncrementByCommand

doc

• command/zset