org.rocksdb.RocksDB.newIterator()方法的使用及代码示例

x33g5p2x  于2022-01-28 转载在 其他  
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本文整理了Java中org.rocksdb.RocksDB.newIterator方法的一些代码示例，展示了RocksDB.newIterator的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。RocksDB.newIterator方法的具体详情如下：
包路径：org.rocksdb.RocksDB
类名称：RocksDB
方法名：newIterator

RocksDB.newIterator介绍

[英]Return a heap-allocated iterator over the contents of the database. The result of newIterator() is initially invalid (caller must call one of the Seek methods on the iterator before using it).

Caller should close the iterator when it is no longer needed. The returned iterator should be closed before this db is closed.
[中]在数据库内容上返回一个堆分配的迭代器。newIterator（）的结果最初无效（调用方必须在使用迭代器之前调用迭代器上的一个Seek方法）。
当不再需要迭代器时，调用方应该关闭迭代器。在关闭此数据库之前，应该关闭返回的迭代器。

代码示例

代码示例来源：origin: apache/kylin

private RocksIterator getRocksIterator() {
  return rocksDB.newIterator();
}

代码示例来源：origin: apache/flink

static RocksIteratorWrapper getRocksIterator(
  RocksDB db,
  ColumnFamilyHandle columnFamilyHandle) {
  return new RocksIteratorWrapper(db.newIterator(columnFamilyHandle));
}

代码示例来源：origin: apache/flink

public static RocksIteratorWrapper getRocksIterator(RocksDB db) {
  return new RocksIteratorWrapper(db.newIterator());
}

代码示例来源：origin: voldemort/voldemort

protected RocksIterator getRocksDbIterator() {
  return this.getRocksDB().newIterator(storeHandle);
}

代码示例来源：origin: apache/flink

@SuppressWarnings("unchecked")
private static RocksIteratorWrapper getRocksIterator(
  RocksDB db,
  ColumnFamilyHandle columnFamilyHandle,
  StateSnapshotTransformer<byte[]> stateSnapshotTransformer,
  ReadOptions readOptions) {
  RocksIterator rocksIterator = db.newIterator(columnFamilyHandle, readOptions);
  return stateSnapshotTransformer == null ?
    new RocksIteratorWrapper(rocksIterator) :
    new RocksTransformingIteratorWrapper(rocksIterator, stateSnapshotTransformer);
}

代码示例来源：origin: alibaba/jstorm

private static int getStartValue(RocksDB db, ColumnFamilyHandle handler) {
  int startValue = 0;
  SortedMap<Integer, Integer> values = new TreeMap<Integer, Integer>();
  RocksIterator itr = db.newIterator(handler);
  itr.seekToFirst();
  while(itr.isValid()) {
    Integer key = Integer.valueOf(new String(itr.key()));
    Integer value = Integer.valueOf(new String(itr.value()));
    values.put(key, value);
    itr.next();
  }
  LOG.info("Load previous db: size={}, values={}", values.size(), values);
  if (!values.isEmpty()) {
    Integer key = values.lastKey();
    startValue = values.get(key);
    startValue++;
  }
  LOG.info("Start value={}", startValue);
  return startValue;
}

代码示例来源：origin: apache/flink

@Nonnull
private RocksBytesIterator orderedBytesIterator() {
  flushWriteBatch();
  return new RocksBytesIterator(
    new RocksIteratorWrapper(
      db.newIterator(columnFamilyHandle)));
}

代码示例来源：origin: ethereum/ethereumj

@Override
public Set<byte[]> keys() throws RuntimeException {
  resetDbLock.readLock().lock();
  try {
    if (logger.isTraceEnabled()) logger.trace("~> RocksDbDataSource.keys(): " + name);
    try (RocksIterator iterator = db.newIterator()) {
      Set<byte[]> result = new HashSet<>();
      for (iterator.seekToFirst(); iterator.isValid(); iterator.next()) {
        result.add(iterator.key());
      }
      if (logger.isTraceEnabled()) logger.trace("<~ RocksDbDataSource.keys(): " + name + ", " + result.size());
      return result;
    } catch (Exception e) {
      logger.error("Error iterating db '{}'", name, e);
      hintOnTooManyOpenFiles(e);
      throw new RuntimeException(e);
    }
  } finally {
    resetDbLock.readLock().unlock();
  }
}

代码示例来源：origin: Alluxio/alluxio

@Override
public Iterable<Long> getChildIds(Long inodeId) {
 RocksIterator iter = mDb.newIterator(mEdgesColumn, mReadPrefixSameAsStart);
 iter.seek(Longs.toByteArray(inodeId));
 return () -> new Iterator<Long>() {
  @Override
  public boolean hasNext() {
   return iter.isValid();
  }
  @Override
  public Long next() {
   try {
    return Longs.fromByteArray(iter.value());
   } catch (Exception e) {
    throw new RuntimeException(e);
   } finally {
    iter.next();
   }
  }
 };
}

代码示例来源：origin: Alluxio/alluxio

@Override
public Set<MutableInode<?>> allInodes() {
 Set<MutableInode<?>> inodes = new HashSet<>();
 RocksIterator iter = mDb.newIterator(mInodesColumn);
 iter.seekToFirst();
 while (iter.isValid()) {
  inodes.add(getMutable(Longs.fromByteArray(iter.key())).get());
  iter.next();
 }
 return inodes;
}

代码示例来源：origin: alibaba/jstorm

@Override
public Collection<K> listKeys() {
  Collection<K> keys = new ArrayList<>();
  RocksIterator itr = rocksDb.newIterator(columnFamily);
  itr.seekToFirst();
  while (itr.isValid()) {
    keys.add((K) serializer.deserialize(itr.key()));
    itr.next();
  }
  return keys;
}

代码示例来源：origin: Alluxio/alluxio

@Override
public boolean hasChildren(InodeDirectoryView inode) {
 RocksIterator iter = mDb.newIterator(mEdgesColumn, mReadPrefixSameAsStart);
 iter.seek(Longs.toByteArray(inode.getId()));
 return iter.isValid();
}

代码示例来源：origin: Alluxio/alluxio

@Override
public Iterator<Block> iterator() {
 RocksIterator iter =
   mDb.newIterator(mBlockMetaColumn, new ReadOptions().setPrefixSameAsStart(true));
 iter.seekToFirst();
 return new Iterator<Block>() {
  @Override
  public boolean hasNext() {
   return iter.isValid();
  }
  @Override
  public Block next() {
   try {
    return new Block(Longs.fromByteArray(iter.key()), BlockMeta.parseFrom(iter.value()));
   } catch (Exception e) {
    throw new RuntimeException(e);
   } finally {
    iter.next();
   }
  }
 };
}

代码示例来源：origin: Alluxio/alluxio

@Override
public List<BlockLocation> getLocations(long id) {
 RocksIterator iter =
   mDb.newIterator(mBlockLocationsColumn, new ReadOptions().setPrefixSameAsStart(true));
 iter.seek(Longs.toByteArray(id));
 List<BlockLocation> locations = new ArrayList<>();
 for (; iter.isValid(); iter.next()) {
  try {
   locations.add(BlockLocation.parseFrom(iter.value()));
  } catch (Exception e) {
   throw new RuntimeException(e);
  }
 }
 return locations;
}

代码示例来源：origin: brianfrankcooper/YCSB

@Override
public Status scan(final String table, final String startkey, final int recordcount, final Set<String> fields,
   final Vector<HashMap<String, ByteIterator>> result) {
 try {
  if (!COLUMN_FAMILIES.containsKey(table)) {
   createColumnFamily(table);
  }
  final ColumnFamilyHandle cf = COLUMN_FAMILIES.get(table).getHandle();
  try(final RocksIterator iterator = rocksDb.newIterator(cf)) {
   int iterations = 0;
   for (iterator.seek(startkey.getBytes(UTF_8)); iterator.isValid() && iterations < recordcount;
      iterator.next()) {
    final HashMap<String, ByteIterator> values = new HashMap<>();
    deserializeValues(iterator.value(), fields, values);
    result.add(values);
    iterations++;
   }
  }
  return Status.OK;
 } catch(final RocksDBException e) {
  LOGGER.error(e.getMessage(), e);
  return Status.ERROR;
 }
}

代码示例来源：origin: Alluxio/alluxio

@Override
public Set<EdgeEntry> allEdges() {
 Set<EdgeEntry> edges = new HashSet<>();
 RocksIterator iter = mDb.newIterator(mEdgesColumn);
 iter.seekToFirst();
 while (iter.isValid()) {
  long parentId = RocksUtils.readLong(iter.key(), 0);
  String childName = new String(iter.key(), Longs.BYTES, iter.key().length - Longs.BYTES);
  long childId = Longs.fromByteArray(iter.value());
  edges.add(new EdgeEntry(parentId, childName, childId));
  iter.next();
 }
 return edges;
}

代码示例来源：origin: Alluxio/alluxio

RocksIterator inodeIter = mDb.newIterator(mInodesColumn);
inodeIter.seekToFirst();
while (inodeIter.isValid()) {
RocksIterator edgeIter = mDb.newIterator(mEdgesColumn);
edgeIter.seekToFirst();
while (edgeIter.isValid()) {

代码示例来源：origin: ltsopensource/light-task-scheduler

@Override
public <T> List<Pair<String, T>> fetchTop(int size, Type type) throws FailStoreException {
  RocksIterator iterator = null;
  try {
    List<Pair<String, T>> list = new ArrayList<Pair<String, T>>(size);
    iterator = db.newIterator();
    for (iterator.seekToFirst(); iterator.isValid(); iterator.next()) {
      iterator.status();
      String key = new String(iterator.key(), "UTF-8");
      T value = JSON.parse(new String(iterator.value(), "UTF-8"), type);
      Pair<String, T> pair = new Pair<String, T>(key, value);
      list.add(pair);
      if (list.size() >= size) {
        break;
      }
    }
    return list;
  } catch (Exception e) {
    throw new FailStoreException(e);
  } finally {
    if (iterator != null) {
      iterator.dispose();
    }
  }
}

代码示例来源：origin: ltsopensource/light-task-scheduler

@Override
public <T> List<Pair<String, T>> fetchTop(int size, Type type) throws FailStoreException {
  RocksIterator iterator = null;
  try {
    List<Pair<String, T>> list = new ArrayList<Pair<String, T>>(size);
    iterator = db.newIterator();
    for (iterator.seekToFirst(); iterator.isValid(); iterator.next()) {
      iterator.status();
      String key = new String(iterator.key(), "UTF-8");
      T value = JSON.parse(new String(iterator.value(), "UTF-8"), type);
      Pair<String, T> pair = new Pair<String, T>(key, value);
      list.add(pair);
      if (list.size() >= size) {
        break;
      }
    }
    return list;
  } catch (Exception e) {
    throw new FailStoreException(e);
  } finally {
    if (iterator != null) {
      iterator.dispose();
    }
  }
}

代码示例来源：origin: apache/storm

void scanRange(RocksDbKey start, RocksDbKey end, RocksDbScanCallback fn) {
  try (ReadOptions ro = new ReadOptions()) {
    ro.setTotalOrderSeek(true);
    RocksIterator iterator = db.newIterator(ro);
    for (iterator.seek(start.getRaw()); iterator.isValid(); iterator.next()) {
      RocksDbKey key = new RocksDbKey(iterator.key());
      if (key.compareTo(end) >= 0) { // past limit, quit
        return;
      }
      RocksDbValue val = new RocksDbValue(iterator.value());
      if (!fn.cb(key, val)) {
        // if cb returns false, we are done with this section of rows
        return;
      }
    }
  }
}

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