HFileReaderImpl.HFileScannerImpl (Apache HBase

java.lang.Object
- org.apache.hadoop.hbase.io.hfile.HFileReaderImpl.HFileScannerImpl

所有已实现的接口:

Closeable, AutoCloseable, HFileScanner, Shipper

直接已知子类:

HFileReaderImpl.EncodedScanner

封闭类:

HFileReaderImpl
```
protected static class HFileReaderImpl.HFileScannerImpl
extends Object
implements HFileScanner
```

字段概要

字段
限定符和类型	字段和说明
`protected AtomicInteger`	`blockFetches`
`protected boolean`	`cacheBlocks`
`protected HFileBlock`	`curBlock`
`protected boolean`	`isCompaction`
`protected Cell`	`nextIndexedKey` The next indexed key is to keep track of the indexed key of the next data block.
`protected boolean`	`pread`
`protected ArrayList<HFileBlock>`	`prevBlocks`
`protected HFile.Reader`	`reader`

构造器概要

构造器
构造器和说明

HFileScannerImpl(HFile.Reader reader, boolean cacheBlocks, boolean pread, boolean isCompaction)

构造器
构造器和说明
`HFileScannerImpl(HFile.Reader reader, boolean cacheBlocks, boolean pread, boolean isCompaction)`

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`protected void`	`assertSeeked()`
`protected int`	`blockSeek(Cell key, boolean seekBefore)` Within a loaded block, seek looking for the last key that is smaller than (or equal to?)
`protected boolean`	`checkKeyLen(int v)`
`protected void`	`checkKeyValueLen()` Check key and value lengths are wholesome.
`protected boolean`	`checkLen(int v)`
`void`	`close()` Close this HFile scanner and do necessary cleanup.
`int`	`compareKey(CellComparator comparator, Cell key)`
`Cell`	`getCell()`
`DataBlockEncoding`	`getEffectiveDataBlockEncoding()`
`protected Cell`	`getFirstKeyCellInBlock(HFileBlock curBlock)`
`Cell`	`getKey()` Gets the current key in the form of a cell.
`String`	`getKeyString()` Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8.
`Cell`	`getNextIndexedKey()`
`HFile.Reader`	`getReader()`
`ByteBuffer`	`getValue()` Gets a buffer view to the current value.
`String`	`getValueString()` Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8.
`boolean`	`isSeeked()`
`protected int`	`loadBlockAndSeekToKey(HFileBlock seekToBlock, Cell nextIndexedKey, boolean rewind, Cell key, boolean seekBefore)`
`boolean`	`next()` Go to the next key/value in the block section.
`protected boolean`	`processFirstDataBlock()`
`protected void`	`readAndUpdateNewBlock(long firstDataBlockOffset)`
`protected void`	`readKeyValueLen()`
`protected void`	`readMvccVersion(int offsetFromPos)` Read mvcc.
`protected HFileBlock`	`readNextDataBlock()` Scans blocks in the "scanned" section of the `HFile` until the next data block is found.
`int`	`reseekTo(Cell key)` Reseek to or just before the passed `cell`.
`boolean`	`seekBefore(Cell key)` Consider the cell stream of all the cells in the file, `c[0] .. c[n]`, where there are n cells in the file.
`boolean`	`seekTo()` Positions this scanner at the start of the file.
`int`	`seekTo(Cell key)` SeekTo or just before the passed `cell`.
`int`	`seekTo(Cell key, boolean rewind)` An internal API function.
`protected void`	`setNonSeekedState()`
`void`	`shipped()` Called after a batch of rows scanned and set to be returned to client.
`String`	`toString()`
`protected void`	`updateCurrentBlock(HFileBlock newBlock)` Updates the current block to be the given `HFileBlock`.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- 字段详细资料
  - cacheBlocks
```
protected final boolean cacheBlocks
```
  - pread
```
protected final boolean pread
```
  - isCompaction
```
protected final boolean isCompaction
```
  - blockFetches
```
protected AtomicInteger blockFetches
```
  - reader
```
protected final HFile.Reader reader
```
  - nextIndexedKey
```
protected Cell nextIndexedKey
```
    The next indexed key is to keep track of the indexed key of the next data block. If the nextIndexedKey is HConstants.NO_NEXT_INDEXED_KEY, it means that the current data block is the last data block. If the nextIndexedKey is null, it means the nextIndexedKey has not been loaded yet.
  - curBlock
```
protected HFileBlock curBlock
```
  - prevBlocks
```
protected final ArrayList<HFileBlock> prevBlocks
```
- 构造器详细资料
  - HFileScannerImpl
```
public HFileScannerImpl(HFile.Reader reader,
                        boolean cacheBlocks,
                        boolean pread,
                        boolean isCompaction)
```
- 方法详细资料
  - isSeeked
```
public boolean isSeeked()
```
    指定者:
    
    isSeeked 在接口中 HFileScanner
    
    返回:
    
    True is scanner has had one of the seek calls invoked; i.e. HFileScanner.seekBefore(Cell) or HFileScanner.seekTo() or HFileScanner.seekTo(Cell). Otherwise returns false.
  - toString
```
public String toString()
```
    覆盖:
    
    toString 在类中 Object
  - assertSeeked
```
protected void assertSeeked()
```
  - getReader
```
public HFile.Reader getReader()
```
    指定者:
    
    getReader 在接口中 HFileScanner
    
    返回:
    
    Reader that underlies this Scanner instance.
  - close
```
public void close()
```
    从接口复制的说明: HFileScanner
    
    Close this HFile scanner and do necessary cleanup.
    
    指定者:
    
    close 在接口中 Closeable
    
    指定者:
    
    close 在接口中 AutoCloseable
    
    指定者:
    
    close 在接口中 HFileScanner
  - readKeyValueLen
```
protected void readKeyValueLen()
```
  - readMvccVersion
```
protected void readMvccVersion(int offsetFromPos)
```
    Read mvcc. Does checks to see if we even need to read the mvcc at all.
    
    参数:
    
    offsetFromPos -
  - blockSeek
```
protected int blockSeek(Cell key,
                        boolean seekBefore)
```
    Within a loaded block, seek looking for the last key that is smaller than (or equal to?) the key we are interested in. A note on the seekBefore: if you have seekBefore = true, AND the first key in the block = key, then you'll get thrown exceptions. The caller has to check for that case and load the previous block as appropriate.
    
    参数:
    
    key - the key to find
    
    seekBefore - find the key before the given key in case of exact match.
    
    返回:
    
    0 in case of an exact key match, 1 in case of an inexact match, -2 in case of an inexact match and furthermore, the input key less than the first key of current block(e.g. using a faked index key)
  - getNextIndexedKey
```
public Cell getNextIndexedKey()
```
    指定者:
    
    getNextIndexedKey 在接口中 HFileScanner
    
    返回:
    
    the next key in the index (the key to seek to the next block)
  - seekTo
```
public int seekTo(Cell key)
           throws IOException
```
    从接口复制的说明: HFileScanner
    
    SeekTo or just before the passed cell. Examine the return code to figure whether we found the cell or not. Consider the cell stream of all the cells in the file, c[0] .. c[n], where there are n cells in the file.
    
    指定者:
    
    seekTo 在接口中 HFileScanner
    
    返回:
    
    -1, if cell < c[0], no position; 0, such that c[i] = cell and scanner is left in position i; and 1, such that c[i] < cell, and scanner is left in position i. The scanner will position itself between c[i] and c[i+1] where c[i] < cell <= c[i+1]. If there is no cell c[i+1] greater than or equal to the input cell, then the scanner will position itself at the end of the file and next() will return false when it is called.
    
    抛出:
    
    IOException
  - reseekTo
```
public int reseekTo(Cell key)
             throws IOException
```
    从接口复制的说明: HFileScanner
    
    Reseek to or just before the passed cell. Similar to seekTo except that this can be called even if the scanner is not at the beginning of a file. This can be used to seek only to cells which come after the current position of the scanner. Consider the cell stream of all the cells in the file, c[0] .. c[n], where there are n cellc in the file after current position of HFileScanner. The scanner will position itself between c[i] and c[i+1] where c[i] < cell <= c[i+1]. If there is no cell c[i+1] greater than or equal to the input cell, then the scanner will position itself at the end of the file and next() will return false when it is called.
    
    指定者:
    
    reseekTo 在接口中 HFileScanner
    
    参数:
    
    key - Cell to find (should be non-null)
    
    返回:
    
    -1, if cell < c[0], no position; 0, such that c[i] = cell and scanner is left in position i; and 1, such that c[i] < cell, and scanner is left in position i.
    
    抛出:
    
    IOException
  - seekTo
```
public int seekTo(Cell key,
                  boolean rewind)
           throws IOException
```
    An internal API function. Seek to the given key, optionally rewinding to the first key of the block before doing the seek.
    
    参数:
    
    key - - a cell representing the key that we need to fetch
    
    rewind - whether to rewind to the first key of the block before doing the seek. If this is false, we are assuming we never go back, otherwise the result is undefined.
    
    返回:
    
    -1 if the key is earlier than the first key of the file, 0 if we are at the given key, 1 if we are past the given key -2 if the key is earlier than the first key of the file while using a faked index key
    
    抛出:
    
    IOException
  - seekBefore
```
public boolean seekBefore(Cell key)
                   throws IOException
```
    从接口复制的说明: HFileScanner
    
    Consider the cell stream of all the cells in the file, c[0] .. c[n], where there are n cells in the file.
    
    指定者:
    
    seekBefore 在接口中 HFileScanner
    
    参数:
    
    key - Cell to find
    
    返回:
    
    false if cell <= c[0] or true with scanner in position 'i' such that: c[i] < cell. Furthermore: there may be a c[i+1], such that c[i] < cell <= c[i+1] but there may also NOT be a c[i+1], and next() will return false (EOF).
    
    抛出:
    
    IOException
  - readNextDataBlock
```
protected HFileBlock readNextDataBlock()
                                throws IOException
```
    Scans blocks in the "scanned" section of the HFile until the next data block is found.
    
    返回:
    
    the next block, or null if there are no more data blocks
    
    抛出:
    
    IOException
  - getEffectiveDataBlockEncoding
```
public DataBlockEncoding getEffectiveDataBlockEncoding()
```
  - getCell
```
public Cell getCell()
```
    指定者:
    
    getCell 在接口中 HFileScanner
    
    返回:
    
    Instance of Cell.
  - getKey
```
public Cell getKey()
```
    从接口复制的说明: HFileScanner
    
    Gets the current key in the form of a cell. You must call HFileScanner.seekTo(Cell) before this method.
    
    指定者:
    
    getKey 在接口中 HFileScanner
    
    返回:
    
    gets the current key as a Cell.
  - getValue
```
public ByteBuffer getValue()
```
    从接口复制的说明: HFileScanner
    
    Gets a buffer view to the current value. You must call HFileScanner.seekTo(Cell) before this method.
    
    指定者:
    
    getValue 在接口中 HFileScanner
    
    返回:
    
    byte buffer for the value. The limit is set to the value size, and the position is 0, the start of the buffer view.
  - setNonSeekedState
```
protected void setNonSeekedState()
```
  - next
```
public boolean next()
             throws IOException
```
    Go to the next key/value in the block section. Loads the next block if necessary. If successful, getKey() and getValue() can be called.
    
    指定者:
    
    next 在接口中 HFileScanner
    
    返回:
    
    true if successfully navigated to the next key/value
    
    抛出:
    
    IOException
  - seekTo
```
public boolean seekTo()
               throws IOException
```
    Positions this scanner at the start of the file.
    
    指定者:
    
    seekTo 在接口中 HFileScanner
    
    返回:
    
    false if empty file; i.e. a call to next would return false and the current key and value are undefined.
    
    抛出:
    
    IOException
  - processFirstDataBlock
```
protected boolean processFirstDataBlock()
                                 throws IOException
```
    抛出:
    
    IOException
  - readAndUpdateNewBlock
```
protected void readAndUpdateNewBlock(long firstDataBlockOffset)
                              throws IOException,
                                     CorruptHFileException
```
    抛出:
    
    IOException
    
    CorruptHFileException
  - loadBlockAndSeekToKey
```
protected int loadBlockAndSeekToKey(HFileBlock seekToBlock,
                                    Cell nextIndexedKey,
                                    boolean rewind,
                                    Cell key,
                                    boolean seekBefore)
                             throws IOException
```
    抛出:
    
    IOException
  - checkKeyLen
```
protected final boolean checkKeyLen(int v)
```
    参数:
    
    v -
    
    返回:
    
    True if v <= 0 or v > current block buffer limit.
  - checkLen
```
protected final boolean checkLen(int v)
```
    参数:
    
    v -
    
    返回:
    
    True if v < 0 or v > current block buffer limit.
  - checkKeyValueLen
```
protected final void checkKeyValueLen()
```
    Check key and value lengths are wholesome.
  - updateCurrentBlock
```
protected void updateCurrentBlock(HFileBlock newBlock)
                           throws IOException
```
    Updates the current block to be the given HFileBlock. Seeks to the the first key/value pair.
    
    参数:
    
    newBlock - the block to make current
    
    抛出:
    
    IOException
  - getFirstKeyCellInBlock
```
protected Cell getFirstKeyCellInBlock(HFileBlock curBlock)
```
  - getKeyString
```
public String getKeyString()
```
    从接口复制的说明: HFileScanner
    
    Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8. You must call HFileScanner.seekTo(Cell) before this method.
    
    指定者:
    
    getKeyString 在接口中 HFileScanner
    
    返回:
    
    key as a string
  - getValueString
```
public String getValueString()
```
    从接口复制的说明: HFileScanner
    
    Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8. You must call HFileScanner.seekTo(Cell) before this method.
    
    指定者:
    
    getValueString 在接口中 HFileScanner
    
    返回:
    
    value as a string
  - compareKey
```
public int compareKey(CellComparator comparator,
                      Cell key)
```
  - shipped
```
public void shipped()
             throws IOException
```
    从接口复制的说明: Shipper
    
    Called after a batch of rows scanned and set to be returned to client. Any in between cleanup can be done here.
    
    指定者:
    
    shipped 在接口中 Shipper
    
    抛出:
    
    IOException

类 HFileReaderImpl.HFileScannerImpl

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

cacheBlocks

pread

isCompaction

blockFetches

reader

nextIndexedKey

curBlock

prevBlocks

构造器详细资料

HFileScannerImpl

方法详细资料

isSeeked

toString

assertSeeked

getReader

close

readKeyValueLen

readMvccVersion

blockSeek

getNextIndexedKey

seekTo

reseekTo

seekTo

seekBefore

readNextDataBlock

getEffectiveDataBlockEncoding

getCell

getKey

getValue

setNonSeekedState

next

seekTo

processFirstDataBlock

readAndUpdateNewBlock

loadBlockAndSeekToKey

checkKeyLen

checkLen

checkKeyValueLen

updateCurrentBlock

getFirstKeyCellInBlock

getKeyString

getValueString

compareKey

shipped