Java DBIterator.hasNext方法代码示例

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
@SuppressWarnings("unchecked")
public static <T extends D_TimeLine> T last(String cluster, Class<T> clazz) throws IOException {
	DB db = getDB(path(cluster, clazz));
	ReadOptions readOptions = new ReadOptions().snapshot(db.getSnapshot());
	DBIterator iterator = db.iterator(readOptions);
	try {
		iterator.seekToLast();
		if(!iterator.hasNext()){
			return null;
		}
		Entry<byte[], byte[]> entry = iterator.next();
		byte[] v = entry.getValue();
		return (T)D_Level.deserialize(clazz, v);
	} finally {
		iterator.close();
	}
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
private int size(final String repositoryName) {
    DBIterator it = levelDBFile.getDb().iterator();

    String prefix = repositoryName + '\0';
    int count = 0;
    try {
        for (it.seek(keyBuilder(repositoryName, "")); it.hasNext(); it.next()) {
            if (!asString(it.peekNext().getKey()).startsWith(prefix)) {
                break;
            }
            count++;
        }
    } finally {
        // Make sure you close the iterator to avoid resource leaks.
        IOHelper.close(it);
    }

    LOG.debug("Size of repository [{}] -> {}", repositoryName, count);
    return count;
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public static int getNumChunks(long obj_id) {
	int num = 0;
	DBIterator iterator = db.iterator();
	// TODO: chunk for obj_id may not start with 0!
	String key = Long.toString(obj_id) + ",0";
	try {
		for (iterator.seek(bytes(key)); iterator.hasNext(); iterator.next()) {
			if (!(asString(iterator.peekNext().getKey()).startsWith(Long
					.toString(obj_id) + ",")))
				break;
			num++;
		}
		iterator.close();
	} catch (IOException e) {
		e.printStackTrace();
	}
	return num;
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public static void setObjectDirty(long obj_id) {
	int chunk_num = 0;
	DBIterator iterator = db.iterator();
	String key = Long.toString(obj_id) + "," + Integer.toString(chunk_num);
	try {
		for (iterator.seek(bytes(key)); iterator.hasNext(); iterator.next()) {
			if (!(asString(iterator.peekNext().getKey()).startsWith(Long
					.toString(obj_id) + ",")))
				break;

			SimbaChunkList.addDirtyChunk(obj_id, chunk_num);
			chunk_num++;
		}
		iterator.close();
	} catch (IOException e) {
		e.printStackTrace();
	}
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public static void deleteObject(long obj_id, int startChunk) {
	String key = Long.toString(obj_id) + "," + Integer.toString(startChunk);
	DBIterator iterator = db.iterator();

	try {
		for (iterator.seek(bytes(key)); iterator.hasNext(); iterator.next()) {
			if (!(asString(iterator.peekNext().getKey()).startsWith(Long
					.toString(obj_id) + ",")))
				break;
			Log.d(TAG, "DELETE <" + asString(iterator.peekNext().getKey())
					+ ">");
			db.delete(iterator.peekNext().getKey());
		}
		iterator.close();
	} catch (IOException e) {
		e.printStackTrace();
	}

	// delete object from dirtyChunkList
	SimbaChunkList.removeDirtyChunks(obj_id);
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
/** {@inheritDoc} */
@SuppressWarnings("resource")
@Override
protected void doScan(byte[] beginKey, byte[] endKey,
		IKeyValueCallback callback, boolean includeValue)
		throws StorageException {

	DBIterator iterator = null;
	try {
		iterator = database.iterator();
		iterator.seek(beginKey);
		while (iterator.hasNext()) {
			Entry<byte[], byte[]> keyValue = iterator.next();
			if (ByteArrayUtils.isLess(endKey, keyValue.getKey(), true)) {
				return;
			}
			callback.callback(keyValue.getKey(), keyValue.getValue());
		}
	} catch (DBException e) {
		throw new StorageException(e);
	} finally {
		FileSystemUtils.close(iterator);
	}
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
private static TimelineDomain getTimelineDomain(DBIterator iterator,
    String domainId, byte[] prefix) throws IOException {
  // Iterate over all the rows whose key starts with prefix to retrieve the
  // domain information.
  TimelineDomain domain = new TimelineDomain();
  domain.setId(domainId);
  boolean noRows = true;
  for (; iterator.hasNext(); iterator.next()) {
    byte[] key = iterator.peekNext().getKey();
    if (!prefixMatches(prefix, prefix.length, key)) {
      break;
    }
    if (noRows) {
      noRows = false;
    }
    byte[] value = iterator.peekNext().getValue();
    if (value != null && value.length > 0) {
      if (key[prefix.length] == DESCRIPTION_COLUMN[0]) {
        domain.setDescription(new String(value, UTF_8));
      } else if (key[prefix.length] == OWNER_COLUMN[0]) {
        domain.setOwner(new String(value, UTF_8));
      } else if (key[prefix.length] == READER_COLUMN[0]) {
        domain.setReaders(new String(value, UTF_8));
      } else if (key[prefix.length] == WRITER_COLUMN[0]) {
        domain.setWriters(new String(value, UTF_8));
      } else if (key[prefix.length] == TIMESTAMP_COLUMN[0]) {
        domain.setCreatedTime(readReverseOrderedLong(value, 0));
        domain.setModifiedTime(readReverseOrderedLong(value, 8));
      } else {
        LOG.error("Unrecognized domain column: " + key[prefix.length]);
      }
    }
  }
  if (noRows) {
    return null;
  } else {
    return domain;
  }
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public Set<String> getKeys() {
    final Set<String> keys = new LinkedHashSet<String>();

    // interval task could potentially be running while we are shutting down so check for that
    if (!isRunAllowed()) {
        return null;
    }

    DBIterator it = levelDBFile.getDb().iterator();

    String keyBuffer;
    try {
        String prefix = repositoryName + '\0';
        for (it.seek(keyBuilder(repositoryName, "")); it.hasNext(); it.next()) {
            if (!isRunAllowed()) {
                break;
            }
            keyBuffer = asString(it.peekNext().getKey());

            if (!keyBuffer.startsWith(prefix)) {
                break;
            }

            String key = keyBuffer.substring(prefix.length());

            LOG.trace("getKey [{}]", key);
            keys.add(key);
        }
    } finally {
        // Make sure you close the iterator to avoid resource leaks.
        IOHelper.close(it);
    }

    return Collections.unmodifiableSet(keys);
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public Set<String> scan(CamelContext camelContext) {
    final Set<String> answer = new LinkedHashSet<String>();

    if (!isRunAllowed()) {
        return null;
    }

    DBIterator it = levelDBFile.getDb().iterator();

    String keyBuffer;
    try {
        String prefix = getRepositoryNameCompleted() + '\0';

        for (it.seek(keyBuilder(getRepositoryNameCompleted(), "")); it.hasNext(); it.next()) {
            keyBuffer = asString(it.peekNext().getKey());

            if (!keyBuffer.startsWith(prefix)) {
                break;
            }
            String exchangeId = keyBuffer.substring(prefix.length());

            LOG.trace("Scan exchangeId [{}]", exchangeId);
            answer.add(exchangeId);
        }
    } finally {
        // Make sure you close the iterator to avoid resource leaks.
        IOHelper.close(it);
    }

    if (answer.size() == 0) {
        LOG.trace("Scanned and found no exchange to recover.");
    } else {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Scanned and found {} exchange(s) to recover (note some of them may already be in progress).", answer.size());
        }
    }
    return answer;

}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
@VisibleForTesting
List<String> getEntityTypes() throws IOException {
  DBIterator iterator = null;
  try {
    iterator = getDbIterator(false);
    List<String> entityTypes = new ArrayList<String>();
    iterator.seek(ENTITY_ENTRY_PREFIX);
    while (iterator.hasNext()) {
      byte[] key = iterator.peekNext().getKey();
      if (key[0] != ENTITY_ENTRY_PREFIX[0]) {
        break;
      }
      KeyParser kp = new KeyParser(key,
          ENTITY_ENTRY_PREFIX.length);
      String entityType = kp.getNextString();
      entityTypes.add(entityType);
      byte[] lookupKey = KeyBuilder.newInstance().add(ENTITY_ENTRY_PREFIX)
          .add(entityType).getBytesForLookup();
      if (lookupKey[lookupKey.length - 1] != 0x0) {
        throw new IOException("Found unexpected end byte in lookup key");
      }
      lookupKey[lookupKey.length - 1] = 0x1;
      iterator.seek(lookupKey);
    }
    return entityTypes;
  } finally {
    IOUtils.cleanup(LOG, iterator);
  }
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
/**
 * Finds all keys in the db that have a given prefix and deletes them on
 * the given write batch.
 */
private void deleteKeysWithPrefix(WriteBatch writeBatch, byte[] prefix,
    DBIterator iterator) {
  for (iterator.seek(prefix); iterator.hasNext(); iterator.next()) {
    byte[] key = iterator.peekNext().getKey();
    if (!prefixMatches(prefix, prefix.length, key)) {
      break;
    }
    writeBatch.delete(key);
  }
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
private static TimelineDomain getTimelineDomain(
    DBIterator iterator, String domainId, byte[] prefix) throws IOException {
  // Iterate over all the rows whose key starts with prefix to retrieve the
  // domain information.
  TimelineDomain domain = new TimelineDomain();
  domain.setId(domainId);
  boolean noRows = true;
  for (; iterator.hasNext(); iterator.next()) {
    byte[] key = iterator.peekNext().getKey();
    if (!prefixMatches(prefix, prefix.length, key)) {
      break;
    }
    if (noRows) {
      noRows = false;
    }
    byte[] value = iterator.peekNext().getValue();
    if (value != null && value.length > 0) {
      if (key[prefix.length] == DESCRIPTION_COLUMN[0]) {
        domain.setDescription(new String(value));
      } else if (key[prefix.length] == OWNER_COLUMN[0]) {
        domain.setOwner(new String(value));
      } else if (key[prefix.length] == READER_COLUMN[0]) {
        domain.setReaders(new String(value));
      } else if (key[prefix.length] == WRITER_COLUMN[0]) {
        domain.setWriters(new String(value));
      } else if (key[prefix.length] == TIMESTAMP_COLUMN[0]) {
        domain.setCreatedTime(readReverseOrderedLong(value, 0));
        domain.setModifiedTime(readReverseOrderedLong(value, 8));
      } else {
        LOG.error("Unrecognized domain column: " + key[prefix.length]);
      }
    }
  }
  if (noRows) {
    return null;
  } else {
    return domain;
  }
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
@Override
public List<Event> loadEventStream(UUID aggregateId) {
    checkNotNull(aggregateId);
    DBIterator iterator = null;

    try {
        iterator = eventDatabase.iterator();
        iterator.seek(new Key(aggregateId).toBytes());

        List<Event> events = new ArrayList<>();

        boolean keepMoving = true;
        while (keepMoving && iterator.hasNext()) {
            Map.Entry<byte[], byte[]> entry = iterator.next();
            Key key = Key.deserialize(entry.getKey());
            if (!aggregateId.equals(key.id)) {
                keepMoving = false;
            }  else {
                events.add(deserializeEvent(entry.getValue(), key.schemaFingerprint));
            }
        }
        return events;
    } finally {
        if (iterator != null) {
            try {
                iterator.close();
            } catch (IOException e) {
                logger.error("Error while closing LevelDB iterator", e);
            }
        }
    }
}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public DatabaseImpl(String name) {
    	// Initialize Database
        this.name = name;
		Options options = new Options();
		options.createIfMissing(true);
		options.compressionType(CompressionType.NONE);
		try {
			logger.debug("Opening database");
            File dbLocation = new File(System.getProperty("user.dir") + "/" +
                                       SystemProperties.CONFIG.databaseDir() + "/");
            File fileLocation = new File(dbLocation, name);

			if(SystemProperties.CONFIG.databaseReset()) {
				destroyDB(fileLocation);
			}

			logger.debug("Initializing new or existing database: '{}'", name);
			db = factory.open(fileLocation, options);
//			logger.debug("Showing database stats");
//			String stats = DATABASE.getProperty("leveldb.stats");
//			logger.debug(stats);

            if (logger.isTraceEnabled()){

                logger.trace("Dump for: {}", fileLocation.toString());
                DBIterator iter =  db.iterator();

                while(iter.hasNext()){
                    byte[] key   = iter.peekNext().getKey();
                    byte[] value = iter.peekNext().getValue();

                    logger.trace("key={}, value={}", Hex.toHexString(key), Hex.toHexString(value));
                    iter.next();
                }
            }
		} catch (IOException ioe) {
			logger.error(ioe.getMessage(), ioe);
			throw new RuntimeException("Can't initialize database");
		}		
	}
 

import org.iq80.leveldb.DBIterator; //导入方法依赖的package包/类
public List<ByteArrayWrapper> dumpKeys() {
	DBIterator iterator = getDb().iterator();
	ArrayList<ByteArrayWrapper> keys = new ArrayList<>();

	while (iterator.hasNext()) {
		ByteArrayWrapper key = new ByteArrayWrapper(iterator.next().getKey());
		keys.add(key);
	}
	Collections.sort((List<ByteArrayWrapper>) keys);
	return keys;
}