HFileReaderV2.ScannerV2 (Apache HBase

java.lang.Object
- org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner
- - org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2
  - - org.apache.hadoop.hbase.io.hfile.HFileReaderV2.ScannerV2

所有已实现的接口:

HFileScanner

直接已知子类:

HFileReaderV3.ScannerV3

封闭类:

HFileReaderV2
```
protected static class HFileReaderV2.ScannerV2
extends HFileReaderV2.AbstractScannerV2
```
Implementation of HFileScanner interface.

字段概要
- 从类继承的字段 org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2
  block, nextIndexedKey
- 从类继承的字段 org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner
  blockBuffer, blockFetches, cacheBlocks, currKeyLen, currMemstoreTS, currMemstoreTSLen, currValueLen, isCompaction, pread

构造器概要

构造器
构造器和说明
`HFileReaderV2.ScannerV2(HFileReaderV2 r, boolean cacheBlocks, boolean pread, boolean isCompaction)`

方法概要

方法
限定符和类型	方法和说明
`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)`
`int`	`compareKey(KeyValue.KVComparator comparator, byte[] key, int offset, int length)` Compare the given key against the current key
`int`	`compareKey(KeyValue.KVComparator comparator, Cell key)`
`protected Cell`	`formNoTagsKeyValue()`
`protected int`	`getCellBufSize()`
`protected ByteBuffer`	`getFirstKeyInBlock(HFileBlock curBlock)`
`ByteBuffer`	`getKey()` Gets a buffer view to the current key.
`String`	`getKeyString()` Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8.
`Cell`	`getKeyValue()`
`protected int`	`getNextCellStartPosition()`
`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.
`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 void`	`readKeyValueLen()`
`protected void`	`readMvccVersion()`
`protected void`	`readMvccVersion(int position)` Read mvcc.
`boolean`	`seekTo()` Positions this scanner at the start of the file.
`protected void`	`setNonSeekedState()`
`protected void`	`updateCurrBlock(HFileBlock newBlock)` Updates the current block to be the given `HFileBlock`.

从类继承的方法 org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2
getEffectiveDataBlockEncoding, getNextIndexedKey, readNextDataBlock, reseekTo, reseekTo, seekBefore, seekBefore, seekTo, seekTo, seekTo

从类继承的方法 org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner
assertSeeked, close, getReader, isSeeked, reseekTo, seekBefore, seekTo, toString

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

- 构造器详细资料
  - HFileReaderV2.ScannerV2
```
public HFileReaderV2.ScannerV2(HFileReaderV2 r,
                       boolean cacheBlocks,
                       boolean pread,
                       boolean isCompaction)
```
- 方法详细资料
  - getKeyValue
```
public Cell getKeyValue()
```
    返回:
    Instance of KeyValue.
  - formNoTagsKeyValue
```
protected Cell formNoTagsKeyValue()
```
  - getCellBufSize
```
protected int getCellBufSize()
```
  - getKey
```
public ByteBuffer getKey()
```
    从接口复制的说明: HFileScanner
    
    Gets a buffer view to the current key. You must call HFileScanner.seekTo(byte[]) before this method.
    
    返回:
    byte buffer for the key. The limit is set to the key size, and the position is 0, the start of the buffer view.
  - compareKey
```
public int compareKey(KeyValue.KVComparator comparator,
             byte[] key,
             int offset,
             int length)
```
    从类复制的说明: HFileReaderV2.AbstractScannerV2
    
    Compare the given key against the current key
    
    指定者:
    
    compareKey 在类中 HFileReaderV2.AbstractScannerV2
    
    返回:
    -1 is the passed key is smaller than the current key, 0 if equal and 1 if greater
  - 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(byte[]) before this method.
    
    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.
    
    返回:
    true if successfully navigated to the next key/value
    
    抛出:
    
    IOException
  - getNextCellStartPosition
```
protected int getNextCellStartPosition()
```
  - seekTo
```
public boolean seekTo()
               throws IOException
```
    Positions this scanner at the start of the file.
    
    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
  - loadBlockAndSeekToKey
```
protected int loadBlockAndSeekToKey(HFileBlock seekToBlock,
                        Cell nextIndexedKey,
                        boolean rewind,
                        Cell key,
                        boolean seekBefore)
                             throws IOException
```
    指定者:
    
    loadBlockAndSeekToKey 在类中 HFileReaderV2.AbstractScannerV2
    
    抛出:
    
    IOException
  - updateCurrBlock
```
protected void updateCurrBlock(HFileBlock newBlock)
```
    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
  - 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.
  - readKeyValueLen
```
protected void readKeyValueLen()
```
  - readMvccVersion
```
protected void readMvccVersion(int position)
```
    Read mvcc. Does checks to see if we even need to read the mvcc at all.
    
    参数:
    position -
  - readMvccVersion
```
protected void readMvccVersion()
```
  - 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)
  - getFirstKeyInBlock
```
protected ByteBuffer getFirstKeyInBlock(HFileBlock curBlock)
```
    指定者:
    
    getFirstKeyInBlock 在类中 HFileReaderV2.AbstractScannerV2
  - 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(byte[]) before this method.
    
    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(byte[]) before this method.
    
    返回:
    value as a string
  - compareKey
```
public int compareKey(KeyValue.KVComparator comparator,
             Cell key)
```
    指定者:
    
    compareKey 在类中 HFileReaderV2.AbstractScannerV2

类 HFileReaderV2.ScannerV2

字段概要

从类继承的字段 org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2

从类继承的字段 org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner

构造器概要

方法概要

从类继承的方法 org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2

从类继承的方法 org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner

从类继承的方法 java.lang.Object

构造器详细资料

HFileReaderV2.ScannerV2

方法详细资料

getKeyValue

formNoTagsKeyValue

getCellBufSize

getKey

compareKey

getValue

setNonSeekedState

next

getNextCellStartPosition

seekTo

loadBlockAndSeekToKey

updateCurrBlock

checkKeyLen

checkLen

checkKeyValueLen

readKeyValueLen

readMvccVersion

readMvccVersion

blockSeek

getFirstKeyInBlock

getKeyString

getValueString

compareKey