org.apache.accumulo.core.file.map
Class MyMapFile.Reader

java.lang.Object
  org.apache.accumulo.core.file.map.MyMapFile.Reader

All Implemented Interfaces:

FileSKVIterator, SortedKeyValueIterator<Key,Value>, InterruptibleIterator

Enclosing class:

MyMapFile

public static class MyMapFile.Reader
extends Object
implements FileSKVIterator

Provide access to an existing map.

Constructor Summary

	MyMapFile.Reader(org.apache.hadoop.fs.FileSystem fs, String dirName, org.apache.hadoop.conf.Configuration conf) Construct a map reader for the named map.
	MyMapFile.Reader(org.apache.hadoop.fs.FileSystem fs, String dirName, org.apache.hadoop.io.WritableComparator comparator, org.apache.hadoop.conf.Configuration conf) Construct a map reader for the named map using the named comparator.
protected	MyMapFile.Reader(org.apache.hadoop.fs.FileSystem fs, String dirName, org.apache.hadoop.io.WritableComparator comparator, org.apache.hadoop.conf.Configuration conf, boolean open) Hook to allow subclasses to defer opening streams until further initialization is complete.

Method Summary

void	close() Close the map.
void	closeDeepCopies()
protected MySequenceFile.Reader	createDataFileReader(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path dataFile, org.apache.hadoop.conf.Configuration conf) Override this method to specialize the type of MySequenceFile.Reader returned.
SortedKeyValueIterator<Key,Value>	deepCopy(IteratorEnvironment env) Creates a deep copy of this iterator as though seek had not yet been called.
void	dropIndex()
void	finalKey(org.apache.hadoop.io.WritableComparable key) Reads the final key from the file.
org.apache.hadoop.io.Writable	get(org.apache.hadoop.io.WritableComparable key, org.apache.hadoop.io.Writable val) Return the value for the named key, or null if none exists.
org.apache.hadoop.io.WritableComparable	getClosest(org.apache.hadoop.io.WritableComparable key, org.apache.hadoop.io.Writable val) Finds the record that is the closest match to the specified key.
org.apache.hadoop.io.WritableComparable	getClosest(org.apache.hadoop.io.WritableComparable key, org.apache.hadoop.io.Writable val, boolean before) Finds the record that is the closest match to the specified key.
org.apache.hadoop.io.WritableComparable	getClosest(org.apache.hadoop.io.WritableComparable key, org.apache.hadoop.io.Writable val, boolean before, org.apache.hadoop.io.WritableComparable lastKey)
Key	getFirstKey()
int	getIndexPosition(org.apache.hadoop.io.WritableComparable key)
Class	getKeyClass() Returns the class of keys in this file.
Key	getLastKey()
DataInputStream	getMetaStore(String name)
Key	getTopKey() Returns top key.
Value	getTopValue() Returns top value.
Class	getValueClass() Returns the class of values in this file.
boolean	hasTop() Returns true if the iterator has more elements.
void	init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, IteratorEnvironment env) Initializes the iterator.
org.apache.hadoop.io.WritableComparable	midKey() Get the key at approximately the middle of the file.
void	next() Advances to the next K,V pair.
boolean	next(org.apache.hadoop.io.WritableComparable key, org.apache.hadoop.io.Writable val) Read the next key/value pair in the map into key and val.
protected void	open(org.apache.hadoop.fs.FileSystem fs, String dirName, org.apache.hadoop.io.WritableComparator comparator, org.apache.hadoop.conf.Configuration conf)
void	printIndex()
void	reset() Re-positions the reader before its first key.
void	seek(Range range, Collection<ByteSequence> columnFamilies, boolean inclusive) Seeks to the first key in the Range, restricting the resulting K,V pairs to those with the specified columns.
boolean	seek(org.apache.hadoop.io.WritableComparable key) Positions the reader at the named key, or if none such exists, at the first entry after the named key.
boolean	seek(org.apache.hadoop.io.WritableComparable key, org.apache.hadoop.io.WritableComparable lastKey)
void	setInterruptFlag(AtomicBoolean flag)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MyMapFile.Reader

public MyMapFile.Reader(org.apache.hadoop.fs.FileSystem fs,
                        String dirName,
                        org.apache.hadoop.conf.Configuration conf)
                 throws IOException

Construct a map reader for the named map.

Throws:

IOException

MyMapFile.Reader

public MyMapFile.Reader(org.apache.hadoop.fs.FileSystem fs,
                        String dirName,
                        org.apache.hadoop.io.WritableComparator comparator,
                        org.apache.hadoop.conf.Configuration conf)
                 throws IOException

Construct a map reader for the named map using the named comparator.

Throws:

IOException

MyMapFile.Reader

protected MyMapFile.Reader(org.apache.hadoop.fs.FileSystem fs,
                           String dirName,
                           org.apache.hadoop.io.WritableComparator comparator,
                           org.apache.hadoop.conf.Configuration conf,
                           boolean open)
                    throws IOException

Hook to allow subclasses to defer opening streams until further initialization is complete.

Throws:

IOException

See Also:

createDataFileReader(FileSystem, Path, Configuration)

Method Detail

getKeyClass

public Class getKeyClass()

Returns the class of keys in this file.

getValueClass

public Class getValueClass()

Returns the class of values in this file.

deepCopy

public SortedKeyValueIterator<Key,Value> deepCopy(IteratorEnvironment env)

Description copied from interface: SortedKeyValueIterator

Creates a deep copy of this iterator as though seek had not yet been called. init should be called on an iterator before deepCopy is called. init should not need to be called on the copy that is returned by deepCopy; that is, when necessary init should be called in the deepCopy method on the iterator it returns. The behavior is unspecified if init is called after deepCopy either on the original or the copy.

Specified by:

deepCopy in interface SortedKeyValueIterator<Key,Value>

Parameters:

env - IteratorEnvironment environment in which iterator is being run.

Returns:

SortedKeyValueIterator a copy of this iterator (with the same source and settings).

closeDeepCopies

public void closeDeepCopies()
                     throws IOException

Specified by:

closeDeepCopies in interface FileSKVIterator

Throws:

IOException

open

protected void open(org.apache.hadoop.fs.FileSystem fs,
                    String dirName,
                    org.apache.hadoop.io.WritableComparator comparator,
                    org.apache.hadoop.conf.Configuration conf)
             throws IOException

Throws:

IOException

createDataFileReader

protected MySequenceFile.Reader createDataFileReader(org.apache.hadoop.fs.FileSystem fs,
                                                     org.apache.hadoop.fs.Path dataFile,
                                                     org.apache.hadoop.conf.Configuration conf)
                                              throws IOException

Override this method to specialize the type of MySequenceFile.Reader returned.

Throws:

IOException

reset

public void reset()
           throws IOException

Re-positions the reader before its first key.

Throws:

IOException

midKey

public org.apache.hadoop.io.WritableComparable midKey()
                                               throws IOException

Get the key at approximately the middle of the file.

Throws:

IOException

finalKey

public void finalKey(org.apache.hadoop.io.WritableComparable key)
              throws IOException

Reads the final key from the file.

Parameters:

key - key to read into

Throws:

IOException

seek

public boolean seek(org.apache.hadoop.io.WritableComparable key)
             throws IOException

Positions the reader at the named key, or if none such exists, at the first entry after the named key. Returns true iff the named key exists in this map.

Throws:

IOException

seek

public boolean seek(org.apache.hadoop.io.WritableComparable key,
                    org.apache.hadoop.io.WritableComparable lastKey)
             throws IOException

Throws:

IOException

getIndexPosition

public int getIndexPosition(org.apache.hadoop.io.WritableComparable key)
                     throws IOException

Throws:

IOException

printIndex

public void printIndex()
                throws IOException

Throws:

IOException

next

public boolean next(org.apache.hadoop.io.WritableComparable key,
                    org.apache.hadoop.io.Writable val)
             throws IOException

Read the next key/value pair in the map into key and val. Returns true if such a pair exists and false when at the end of the map

Throws:

IOException

get

public org.apache.hadoop.io.Writable get(org.apache.hadoop.io.WritableComparable key,
                                         org.apache.hadoop.io.Writable val)
                                  throws IOException

Return the value for the named key, or null if none exists.

Throws:

IOException

getClosest

public org.apache.hadoop.io.WritableComparable getClosest(org.apache.hadoop.io.WritableComparable key,
                                                          org.apache.hadoop.io.Writable val)
                                                   throws IOException

Finds the record that is the closest match to the specified key. Returns key or if it does not exist, at the first entry after the named key. - *

Parameters:

key - - key that we're trying to find - *

val - - data value if key is found - *

Returns:

- the key that was the closest match or null if eof.

Throws:

IOException

getClosest

public org.apache.hadoop.io.WritableComparable getClosest(org.apache.hadoop.io.WritableComparable key,
                                                          org.apache.hadoop.io.Writable val,
                                                          boolean before)
                                                   throws IOException

Finds the record that is the closest match to the specified key.

Parameters:

key - - key that we're trying to find

val - - data value if key is found

before - - IF true, and key does not exist, return the first entry that falls just before the key. Otherwise, return the record that sorts just after.

Returns:

- the key that was the closest match or null if eof.

Throws:

IOException

getClosest

public org.apache.hadoop.io.WritableComparable getClosest(org.apache.hadoop.io.WritableComparable key,
                                                          org.apache.hadoop.io.Writable val,
                                                          boolean before,
                                                          org.apache.hadoop.io.WritableComparable lastKey)
                                                   throws IOException

Throws:

IOException

close

public void close()
           throws IOException

Close the map.

Specified by:

close in interface FileSKVIterator

Throws:

IOException

getTopKey

public Key getTopKey()

Description copied from interface: SortedKeyValueIterator

Returns top key. Can be called 0 or more times without affecting behavior of next() or hasTop(). Note that in minor compaction scope and in non-full major compaction scopes the iterator may see deletion entries. These entries should be preserved by all iterators except ones that are strictly scan-time iterators that will never be configured for the minc or majc scopes. Deletion entries are only removed during full major compactions.

Specified by:

getTopKey in interface SortedKeyValueIterator<Key,Value>

Returns:

K

getTopValue

public Value getTopValue()

Description copied from interface: SortedKeyValueIterator

Returns top value. Can be called 0 or more times without affecting behavior of next() or hasTop().

Specified by:

getTopValue in interface SortedKeyValueIterator<Key,Value>

Returns:

V

hasTop

public boolean hasTop()

Description copied from interface: SortedKeyValueIterator

Returns true if the iterator has more elements.

Specified by:

hasTop in interface SortedKeyValueIterator<Key,Value>

Returns:

true if the iterator has more elements.

init

public void init(SortedKeyValueIterator<Key,Value> source,
                 Map<String,String> options,
                 IteratorEnvironment env)
          throws IOException

Description copied from interface: SortedKeyValueIterator

Initializes the iterator. Data should not be read from the source in this method.

Specified by:

init in interface SortedKeyValueIterator<Key,Value>

Parameters:

source - SortedKeyValueIterator source to read data from.

options - Map map of string option names to option values.

env - IteratorEnvironment environment in which iterator is being run.

Throws:

IOException - unused.

next

public void next()
          throws IOException

Description copied from interface: SortedKeyValueIterator

Advances to the next K,V pair. Note that in minor compaction scope and in non-full major compaction scopes the iterator may see deletion entries. These entries should be preserved by all iterators except ones that are strictly scan-time iterators that will never be configured for the minc or majc scopes. Deletion entries are only removed during full major compactions.

Specified by:

next in interface SortedKeyValueIterator<Key,Value>

Throws:

IOException - if an I/O error occurs.

seek

public void seek(Range range,
                 Collection<ByteSequence> columnFamilies,
                 boolean inclusive)
          throws IOException

Description copied from interface: SortedKeyValueIterator

Seeks to the first key in the Range, restricting the resulting K,V pairs to those with the specified columns. An iterator does not have to stop at the end of the range. The whole range is provided so that iterators can make optimizations. Seek may be called multiple times with different parameters after SortedKeyValueIterator.init(org.apache.accumulo.core.iterators.SortedKeyValueIterator, java.util.Map, org.apache.accumulo.core.iterators.IteratorEnvironment) is called. Iterators that examine groups of adjacent key/value pairs (e.g. rows) to determine their top key and value should be sure that they properly handle a seek to a key in the middle of such a group (e.g. the middle of a row). Even if the client always seeks to a range containing an entire group (a,c), the tablet server could send back a batch of entries corresponding to (a,b], then reseek the iterator to range (b,c) when the scan is continued. columnFamilies is used, at the lowest level, to determine which data blocks inside of an RFile need to be opened for this iterator. This set of data blocks is also the set of locality groups defined for the given table. If no columnFamilies are provided, the data blocks for all locality groups inside of the correct RFile will be opened and seeked in an attempt to find the correct start key, irregardless of the startKey in the range. In an Accumulo instance in which multiple locality groups exist for a table, it is important to ensure that columnFamilies is properly set to the minimum required column families to ensure that data from separate locality groups is not inadvertently read.

Specified by:

seek in interface SortedKeyValueIterator<Key,Value>

Parameters:

range - Range of keys to iterate over.

columnFamilies - Collection of column families to include or exclude.

inclusive - boolean that indicates whether to include (true) or exclude (false) column families.

Throws:

IOException - if an I/O error occurs.

getFirstKey

public Key getFirstKey()
                throws IOException

Specified by:

getFirstKey in interface FileSKVIterator

Throws:

IOException

getLastKey

public Key getLastKey()
               throws IOException

Specified by:

getLastKey in interface FileSKVIterator

Throws:

IOException

getMetaStore

public DataInputStream getMetaStore(String name)
                             throws IOException

Specified by:

getMetaStore in interface FileSKVIterator

Throws:

IOException

dropIndex

public void dropIndex()

setInterruptFlag

public void setInterruptFlag(AtomicBoolean flag)

Specified by:

setInterruptFlag in interface InterruptibleIterator