关于redis:聊聊claudb的keys-command

序

本文次要钻研一下 claudb 的 keys command

KeysCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/KeysCommand.java

@ReadOnly
@Command("keys")
@ParamLength(1)
public class KeysCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {GlobPattern pattern = createPattern(request.getParam(0));
    ImmutableSet<SafeString> keys = db.entrySet()
        .filter(matchPattern(pattern))
        .filter(filterExpired(Instant.now()).negate())
        .map(Tuple2::get1)
        .map(DatabaseKey::getValue);
    return convert(keys);
  }

  private GlobPattern createPattern(SafeString param) {return new GlobPattern(param.toString());
  }

  private Matcher1<Tuple2<DatabaseKey, DatabaseValue>> filterExpired(Instant now) {return entry -> entry.get2().isExpired(now);
  }

  private Matcher1<Tuple2<DatabaseKey, DatabaseValue>> matchPattern(GlobPattern pattern) {return entry -> pattern.match(entry.get1().toString());
  }
}

• KeysCommand 实现了 DBCommand 接口，其 execute 办法先通过 createPattern 创立 GlobPattern，之后遍历 db.entrySet()，过滤出 matchPattern 的，再过滤出非 expired 的，最初返回

DeleteCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/DeleteCommand.java

@Command("del")
@ParamLength(1)
public class DeleteCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    int removed = 0;
    for (SafeString key : request.getParams()) {DatabaseValue value = db.remove(safeKey(key));
      if (value != null) {removed += 1;}
    }
    return integer(removed);
  }
}

• DeleteCommand 实现了 DBCommand 接口，其 execute 办法遍历 request.getParams() 执行 db.remove(safeKey(key))，最初返回 integer(removed)

ExistsCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/ExistsCommand.java

@ReadOnly
@Command("exists")
@ParamLength(1)
public class ExistsCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {DatabaseValue value = db.get(safeKey(request.getParam(0)));
    return integer(value != null ? !value.isExpired(Instant.now()) : false);
  }
}

• ExistsCommand 实现了 DBCommand 接口，其 execute 办法先通过 db.get(safeKey(request.getParam(0))) 获取 DatabaseValue，之后判断是否 null，非 null 的话再判断是否 expired，非 expired 的返回 true

TypeCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/TypeCommand.java

@ReadOnly
@Command("type")
@ParamLength(1)
public class TypeCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {DatabaseValue value = db.get(safeKey(request.getParam(0)));
    if (value != null) {return status(value.getType().text());
    } else {return status(DataType.NONE.text());
    }
  }
}

• TypeCommand 实现了 DBCommand 接口，其 execute 办法先通过 db.get(safeKey(request.getParam(0))) 获取 DatabaseValue，若不为 null 则返回 status(value.getType().text())，否则返回 status(DataType.NONE.text())

RenameCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/RenameCommand.java

@Command("rename")
@ParamLength(2)
public class RenameCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {if (db.rename(safeKey(request.getParam(0)), safeKey(request.getParam(1)))) {return responseOk();
    } else {return error("ERR no such key");
    }
  }
}

• RenameCommand 实现了 DBCommand 接口，其 execute 办法执行 db.rename

ExpireCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/ExpireCommand.java

@Command("expire")
@ParamLength(2)
public class ExpireCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {
    try {DatabaseValue value = db.get(safeKey(request.getParam(0)));
      if (value != null) {db.put(safeKey(request.getParam(0)), value.expiredAt(parsetTtl(request.getParam(1))));
      }
      return integer(value != null);
    } catch (NumberFormatException e) {return error("ERR value is not an integer or out of range");
    }
  }

  private int parsetTtl(SafeString param) {return Integer.parseInt(param.toString());
  }
}

• ExpireCommand 实现了 DBCommand 接口，其 execute 办法先通过 db.get(safeKey(request.getParam(0))) 获取 DatabaseValue，若不为 null 则执行 value.expiredAt(parsetTtl(request.getParam(1)))，而后 put 进去

PersistCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/PersistCommand.java

@Command("persist")
@ParamLength(1)
public class PersistCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {DatabaseValue value = db.get(safeKey(request.getParam(0)));
    if (value != null) {db.put(safeKey(request.getParam(0)), value.noExpire());
    }
    return integer(value != null);
  }
}

• PersistCommand 办法实现了 DBCommand 接口，其 execute 办法先通过 db.get(safeKey(request.getParam(0))) 获取 DatabaseValue，若不为 null 则执行 db.put(safeKey(request.getParam(0)), value.noExpire())

TimeToLiveCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/TimeToLiveCommand.java

public abstract class TimeToLiveCommand implements DBCommand {

  @Override
  public RedisToken execute(Database db, Request request) {DatabaseValue value = db.get(safeKey(request.getParam(0)));
    if (value != null) {return keyExists(value);
    } else {return notExists();
    }
  }

  protected abstract int timeToLive(DatabaseValue value, Instant now);

  private RedisToken keyExists(DatabaseValue value) {if (value.getExpiredAt() != null) {return hasExpiredAt(value);
    } else {return integer(-1);
    }
  }

  private RedisToken hasExpiredAt(DatabaseValue value) {Instant now = Instant.now();
    if (!value.isExpired(now)) {return integer(timeToLive(value, now));
    } else {return notExists();
    }
  }

  private RedisToken notExists() {return integer(-2);
  }
}

• TimeToLiveCommand 申明实现 DBCommand 接口，其 execute 接口先通过 db.get(safeKey(request.getParam(0))) 获取 DatabaseValue，若为 null 则返回 notExists，若不为 null 则执行 keyExists；keyExists 办法在 value.getExpiredAt() 不为 null 时执行 hasExpiredAt 办法；hasExpiredAt 办法在 value.isExpired(now) 为 false 时返回 integer(timeToLive(value, now))；timeToLive 办法为形象办法，须要子类实现

TimeToLiveMillisCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/TimeToLiveMillisCommand.java

@Command("pttl")
@ParamLength(1)
public class TimeToLiveMillisCommand extends TimeToLiveCommand {

  @Override
  protected int timeToLive(DatabaseValue value, Instant now) {return (int) value.timeToLiveMillis(now);
  }
}

• TimeToLiveMillisCommand 实现了 TimeToLiveCommand 接口，其 timeToLive 办法返回 value.timeToLiveMillis(now)

TimeToLiveSecondsCommand

claudb-1.7.1/src/main/java/com/github/tonivade/claudb/command/key/TimeToLiveSecondsCommand.java

@Command("ttl")
@ParamLength(1)
public class TimeToLiveSecondsCommand extends TimeToLiveCommand {

  @Override
  protected int timeToLive(DatabaseValue value, Instant now) {return value.timeToLiveSeconds(now);
  }
}

• TimeToLiveSecondsCommand 实现了 TimeToLiveCommand 接口，其 timeToLive 办法返回 value.timeToLiveSeconds(now)

小结

claudb keys 相干的 command 有 KeysCommand、DeleteCommand、ExistsCommand、TypeCommand、RenameCommand、ExpireCommand、PersistCommand、TimeToLiveMillisCommand、TimeToLiveSecondsCommand

doc

• KeysCommand