org.apache.accumulo.core.iterators.system

Class SequenceFileIterator

java.lang.Object

org.apache.accumulo.core.iterators.system.SequenceFileIterator

All Implemented Interfaces:

AutoCloseable, FileSKVIterator, SortedKeyValueIterator<Key,Value>, InterruptibleIterator, YieldingKeyValueIterator<Key,Value>

public class SequenceFileIterator
extends Object
implements FileSKVIterator

Constructor Summary

Constructors

Constructor and Description
SequenceFileIterator(org.apache.hadoop.io.SequenceFile.Reader reader, boolean readValue)

Method Summary

Modifier and Type	Method and Description
void	close()
void	closeDeepCopies()
SequenceFileIterator	deepCopy(IteratorEnvironment env) Creates a deep copy of this iterator as though seek had not yet been called.
Key	getFirstKey()
Key	getLastKey()
DataInputStream	getMetaStore(String name)
FileSKVIterator	getSample(SamplerConfigurationImpl sampleConfig)
Key	getTopKey() Returns top key.
Value	getTopValue() Returns top value.
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.
void	next() Advances to the next K,V pair.
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.
void	setInterruptFlag(AtomicBoolean flag)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.accumulo.core.iterators.YieldingKeyValueIterator

enableYielding

Constructor Detail

SequenceFileIterator

public SequenceFileIterator(org.apache.hadoop.io.SequenceFile.Reader reader,
                            boolean readValue)
                     throws IOException

Throws:

IOException

Method Detail

deepCopy

public SequenceFileIterator 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. A proper implementation would call deepCopy on the source.

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

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.

For performance reasons, iterators reserve the right to reuse objects returned by getTopKey when SortedKeyValueIterator.next() is called, changing the data that the object references. Iterators that need to save an object returned by getTopKey ought to copy the object's data into a new object in order to avoid aliasing bugs.

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().

For performance reasons, iterators reserve the right to reuse objects returned by getTopValue when SortedKeyValueIterator.next() is called, changing the underlying data that the object references. Iterators that need to save an object returned by getTopValue ought to copy the object's data into a new object in order to avoid aliasing bugs.

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. Note that if this iterator has yielded (@see YieldingKeyValueIterator.enableYielding(YieldCallback)), this this method must return false.

Specified by:

hasTop in interface SortedKeyValueIterator<Key,Value>

Returns:

true if the iterator has more elements.

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<K, V>, java.util.Map<java.lang.String, java.lang.String>, 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, regardless 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.

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.

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface FileSKVIterator

Throws:

IOException

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

setInterruptFlag

public void setInterruptFlag(AtomicBoolean flag)

Specified by:

setInterruptFlag in interface InterruptibleIterator

getSample

public FileSKVIterator getSample(SamplerConfigurationImpl sampleConfig)

Specified by:

getSample in interface FileSKVIterator