关于redis:聊聊claudb的zset-command

序

本文次要钻研一下 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 办法先获取 initial，而后执行 db.merge 办法，它先增加 oldValue.getSortedSet()、再增加 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 办法先通过 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 办法先从 request 参数提取 items，而后执行 db.merge，该办法遍历 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 办法执行 db.getOrDefault 获取 value，而后通过 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 办法执行 db.getOrDefault 获取 value，而后通过 set.subSet(score(from, SafeString.EMPTY_STRING), inclusive(request.getParam(1)),score(to, SafeString.EMPTY_STRING), inclusive(request.getParam(2))) 获取 range，最初从 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 办法执行 db.getOrDefault 获取 value，而后通过 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 办法执行 db.getOrDefault 获取 value，而后通过 merge 获取 newValue

小结

claudb sorted set 相干的 command 有 SortedSetAddCommand、SortedSetCardinalityCommand、SortedSetRemoveCommand、SortedSetRangeCommand、SortedSetRangeByScoreCommand、SortedSetReverseRangeCommand、SortedSetIncrementByCommand

doc

• command/zset