聊聊claudb的keys command

序

本文主要研究一下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方法先通过createPattern创建GlobPattern，之后遍历db.entrySet()，过滤出matchPattern的，再过滤出非expired的，最后返回

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方法遍历request.getParams()执行db.remove(safeKey(key))，最后返回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方法先通过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方法先通过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方法执行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方法先通过db.get(safeKey(request.getParam(0)))获取DatabaseValue，若不为null则执行value.expiredAt(parsetTtl(request.getParam(1)))，然后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方法实现了DBCommand接口，其execute方法先通过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声明实现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方法在value.getExpiredAt()不为null时执行hasExpiredAt方法；hasExpiredAt方法在value.isExpired(now)为false时返回integer(timeToLive(value, now))；timeToLive方法为抽象方法，需要子类实现

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方法返回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方法返回value.timeToLiveSeconds(now)

小结

claudb keys相关的command有KeysCommand、DeleteCommand、ExistsCommand、TypeCommand、RenameCommand、ExpireCommand、PersistCommand、TimeToLiveMillisCommand、TimeToLiveSecondsCommand

doc

• KeysCommand