HalfStoreFileReader (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.regionserver.StoreFile.Reader
- - org.apache.hadoop.hbase.io.HalfStoreFileReader

```
@InterfaceAudience.Private
public class HalfStoreFileReader
extends StoreFile.Reader
```
A facade for a HFile.Reader that serves up either the top or bottom half of a HFile where 'bottom' is the first half of the file containing the keys that sort lowest and 'top' is the second half of the file with keys that sort greater than those of the bottom half. The top includes the split files midkey, of the key that follows if it does not exist in the file.
This type works in tandem with the Reference type. This class is used reading while Reference is used writing.
This file is not splitable. Calls to midkey() return null.

Field Summary

Fields
Modifier and Type	Field and Description
`private byte[]`	`firstKey`
`private boolean`	`firstKeySeeked`
`private static org.apache.commons.logging.Log`	`LOG`
`protected Cell`	`splitCell`
`protected byte[]`	`splitkey`
`(package private) boolean`	`top`

Fields inherited from class org.apache.hadoop.hbase.regionserver.StoreFile.Reader
bloomFilterType, deleteFamilyBloomFilter, generalBloomFilter, sequenceID, timeRangeTracker

Constructor Summary

Constructors
Constructor and Description
`HalfStoreFileReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path p, CacheConfig cacheConf, Reference r, org.apache.hadoop.conf.Configuration conf)` Creates a half file reader for a normal hfile.
`HalfStoreFileReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path p, FSDataInputStreamWrapper in, long size, CacheConfig cacheConf, Reference r, org.apache.hadoop.conf.Configuration conf)` Creates a half file reader for a hfile referred to by an hfilelink.

Method Summary

Methods
Modifier and Type	Method and Description
`long`	`getEntries()`
`long`	`getFilterEntries()` The number of Bloom filter entries in this store file, or an estimate thereof, if the Bloom filter is not loaded.
`byte[]`	`getFirstKey()`
`byte[]`	`getLastKey()`
`HFileScanner`	`getScanner(boolean cacheBlocks, boolean pread, boolean isCompaction)` Warning: Do not write further code which depends on this call.
`protected boolean`	`isTop()`
`byte[]`	`midkey()`
`boolean`	`passesKeyRangeFilter(Scan scan)` Checks whether the given scan rowkey range overlaps with the current storefile's

Methods inherited from class org.apache.hadoop.hbase.regionserver.StoreFile.Reader
close, getBloomFilterType, getComparator, getDeleteFamilyCnt, getHFileMinorVersion, getHFileReader, getHFileVersion, getLastRowKey, getMaxTimestamp, getScanner, getSequenceID, getStoreFileScanner, getStoreFileScanner, getTotalBloomSize, getTotalUncompressedBytes, indexSize, isBulkLoaded, isPrimaryReplicaReader, length, loadBloomfilter, loadFileInfo, passesDeleteFamilyBloomFilter, passesGeneralBloomFilter, setBulkLoaded, setDeleteFamilyBloomFilterFaulty, setGeneralBloomFilterFaulty, setReplicaStoreFile, setSequenceID

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - LOG
```
private static final org.apache.commons.logging.Log LOG
```
  - top
```
final boolean top
```
  - splitkey
```
protected final byte[] splitkey
```
  - splitCell
```
protected final Cell splitCell
```
  - firstKey
```
private byte[] firstKey
```
  - firstKeySeeked
```
private boolean firstKeySeeked
```
- Constructor Detail
  - HalfStoreFileReader
```
public HalfStoreFileReader(org.apache.hadoop.fs.FileSystem fs,
                   org.apache.hadoop.fs.Path p,
                   CacheConfig cacheConf,
                   Reference r,
                   org.apache.hadoop.conf.Configuration conf)
                    throws IOException
```
    Creates a half file reader for a normal hfile.
    
    Parameters:
    fs - fileystem to read from
    p - path to hfile
    cacheConf -
    r - original reference file (contains top or bottom)
    conf - Configuration
    
    Throws:
    
    IOException
  - HalfStoreFileReader
```
public HalfStoreFileReader(org.apache.hadoop.fs.FileSystem fs,
                   org.apache.hadoop.fs.Path p,
                   FSDataInputStreamWrapper in,
                   long size,
                   CacheConfig cacheConf,
                   Reference r,
                   org.apache.hadoop.conf.Configuration conf)
                    throws IOException
```
    Creates a half file reader for a hfile referred to by an hfilelink.
    
    Parameters:
    fs - fileystem to read from
    p - path to hfile
    in - FSDataInputStreamWrapper
    size - Full size of the hfile file
    cacheConf -
    r - original reference file (contains top or bottom)
    conf - Configuration
    
    Throws:
    
    IOException
- Method Detail
  - isTop
```
protected boolean isTop()
```
  - getScanner
```
public HFileScanner getScanner(boolean cacheBlocks,
                      boolean pread,
                      boolean isCompaction)
```
    Description copied from class: StoreFile.Reader
    
    Warning: Do not write further code which depends on this call. Instead use getStoreFileScanner() which uses the StoreFileScanner class/interface which is the preferred way to scan a store with higher level concepts.
    
    Overrides:
    
    getScanner in class StoreFile.Reader
    
    Parameters:
    cacheBlocks - should we cache the blocks?
    pread - use pread (for concurrent small readers)
    isCompaction - is scanner being used for compaction?
    
    Returns:
    the underlying HFileScanner
  - passesKeyRangeFilter
```
public boolean passesKeyRangeFilter(Scan scan)
```
    Description copied from class: StoreFile.Reader
    
    Checks whether the given scan rowkey range overlaps with the current storefile's
    
    Overrides:
    
    passesKeyRangeFilter in class StoreFile.Reader
    
    Parameters:
    scan - the scan specification. Used to determine the rowkey range.
    
    Returns:
    true if there is overlap, false otherwise
  - getLastKey
```
public byte[] getLastKey()
```
    Overrides:
    
    getLastKey in class StoreFile.Reader
  - midkey
```
public byte[] midkey()
              throws IOException
```
    Overrides:
    
    midkey in class StoreFile.Reader
    
    Throws:
    
    IOException
  - getFirstKey
```
public byte[] getFirstKey()
```
    Overrides:
    
    getFirstKey in class StoreFile.Reader
  - getEntries
```
public long getEntries()
```
    Overrides:
    
    getEntries in class StoreFile.Reader
  - getFilterEntries
```
public long getFilterEntries()
```
    Description copied from class: StoreFile.Reader
    
    The number of Bloom filter entries in this store file, or an estimate thereof, if the Bloom filter is not loaded. This always returns an upper bound of the number of Bloom filter entries.
    
    Overrides:
    
    getFilterEntries in class StoreFile.Reader
    
    Returns:
    an estimate of the number of Bloom filter entries in this file

Class HalfStoreFileReader

Field Summary

Fields inherited from class org.apache.hadoop.hbase.regionserver.StoreFile.Reader

Constructor Summary

Method Summary

Methods inherited from class org.apache.hadoop.hbase.regionserver.StoreFile.Reader

Methods inherited from class java.lang.Object

Field Detail

LOG

top

splitkey

splitCell

firstKey

firstKeySeeked

Constructor Detail

HalfStoreFileReader

HalfStoreFileReader

Method Detail

isTop

getScanner

passesKeyRangeFilter

getLastKey

midkey

getFirstKey

getEntries

getFilterEntries