Class: WordIterator

Source Location: /lib/index_bundle_iterators/word_iterator.php

Class Overview

IndexBundleIterator
   |
   --WordIterator

Used to iterate through the documents associated with a word in an IndexArchiveBundle. It also makes it easy to get the summaries of these documents.

Author(s):

Chris Pollett

Variables

Constants

Methods

Inherited Constants

Class: IndexBundleIterator

IndexBundleIterator::RESULTS_PER_BLOCK

Inherited Variables

Class: IndexBundleIterator

IndexBundleIterator::$count_block
IndexBundleIterator::$current_block_fresh
IndexBundleIterator::$num_docs
IndexBundleIterator::$pages
IndexBundleIterator::$results_per_block
IndexBundleIterator::$seen_docs

Inherited Methods

Class: IndexBundleIterator

IndexBundleIterator::advance(): Forwards the iterator one group of docs
IndexBundleIterator::advanceSeenDocs(): Updates the seen_docs count during an advance() call
IndexBundleIterator::computeRelevance(): Computes a relevancy score for a posting offset with respect to this
IndexBundleIterator::currentDocsWithWord(): Gets the current block of doc ids and score associated with the this iterators word
IndexBundleIterator::currentGenDocOffsetWithWord(): Gets the doc_offset and generation for the next document that would be return by this iterator
IndexBundleIterator::findDocsWithWord(): Hook function used by currentDocsWithWord to return the current block of docs if it is not cached
IndexBundleIterator::genDocOffsetCmp(): Compares two arrays each containing a (generation, offset) pair.
IndexBundleIterator::getCurrentDocsForKeys(): Gets the summaries associated with the keys provided the keys
IndexBundleIterator::nextDocsWithWord(): Get the current block of doc summaries for the word iterator and advances the current pointer to the next block of documents. If a doc index is the next block must be of docs after this doc_index
IndexBundleIterator::reset(): Returns the iterators to the first document block that it could iterate
IndexBundleIterator::setResultsPerBlock(): Sets the value of the result_per_block field. This field controls the maximum number of results that can be returned in one go by currentDocsWithWord()

Class Details

[line 54]
Used to iterate through the documents associated with a word in an IndexArchiveBundle. It also makes it easy to get the summaries of these documents.

A description of how words and the documents containing them are stored is given in the documentation of IndexArchiveBundle.

Tags:

author:	Chris Pollett
see:	IndexArchiveBundle

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Class Variables

$current_generation =

[line 105]

Numeric number of current shard

Type:

int

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$current_offset =

[line 111]

The current byte offset in the IndexShard

Type:

int

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$dictionary_info =

[line 78]

An array of shard generation and posting list offsets, lengths, and

numbers of documents

Type:

array

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$empty =

[line 130]

Keeps track of whether the word_iterator list is empty because the

word does not appear in the index shard

Type:

int

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$feed_info =

[line 87]

Type:

mixed

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$feed_shard_name =

[line 83]

Type:

mixed

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$filter =

[line 137]

Keeps track of whether the word_iterator list is empty because the

word does not appear in the index shard

Type:

int

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$generation_pointer =

[line 99]

Index into dictionary_info corresponding to the current shard

Type:

int

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$index_name =

[line 65]

The timestamp of the index is associated with this iterator

Type:

string

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$last_offset =

[line 123]

Last Offset of word occurence in the IndexShard

Type:

int

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$next_offset =

[line 71]

The next byte offset in the IndexShard

Type:

int

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$num_generations =

[line 93]

The total number of shards that have data for this word

Type:

int

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$start_offset =

[line 117]

Starting Offset of word occurence in the IndexShard

Type:

int

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$word_key =

[line 60]

hash of word that the iterator iterates over

Type:

string

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Class Methods

constructor __construct [line 156]

WordIterator __construct(
string
$word_key, string
$index_name, [bool
$raw = false], [
&$filter = NULL], int
$limit, array
$filter)

Creates a word iterator with the given parameters.

Parameters:

string	$word_key	hash of word or phrase to iterate docs of
string	$index_name	time_stamp of the to use
int	$limit	the first element to return from the list of docs iterated over
bool	$raw	whether the $word_key is our variant of base64 encoded
array	$filter	an array of hashes of domains to filter from results
	&$filter

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method advance [line 424]

void advance(
[array
$gen_doc_offset = null])

Forwards the iterator one group of docs

Overrides IndexBundleIterator::advance() (Forwards the iterator one group of docs)

Parameters:

array

$gen_doc_offset

a generation, doc_offset pair. If set, the must be of greater than or equal generation, and if equal the next block must all have $doc_offsets larger than or equal to this value

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method advanceGeneration [line 478]

void advanceGeneration(
[int
$generation = null])

Switches which index shard is being used to return occurrences of the word to the next shard containing the word

Parameters:

int

$generation

generation to advance beyond

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method advanceSeenDocs [line 393]

void advanceSeenDocs(
)

Updates the seen_docs count during an advance() call

Overrides IndexBundleIterator::advanceSeenDocs() (Updates the seen_docs count during an advance() call)

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method computeRelevance [line 245]

float computeRelevance(
int
$generation, int
$posting_offset)

Computes a relevancy score for a posting offset with respect to this

iterator and generation

Tags:

return:

a relevancy score based on BM25F.

Overrides IndexBundleIterator::computeRelevance() (Computes a relevancy score for a posting offset with respect to this)

Parameters:

int	$generation	the generation the posting offset is for
int	$posting_offset	an offset into word_docs to compute the relevance of

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method currentGenDocOffsetWithWord [line 510]

mixed currentGenDocOffsetWithWord(
)

Gets the doc_offset and generation for the next document that would be return by this iterator

Tags:

return:

an array with the desired document offset and generation; -1 on fail

Overrides IndexBundleIterator::currentGenDocOffsetWithWord() (Gets the doc_offset and generation for the next document that would be return by this iterator)

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method findDocsWithWord [line 314]

mixed findDocsWithWord(
)

Hook function used by currentDocsWithWord to return the current block of docs if it is not cached

Tags:

return:

doc ids and score if there are docs left, -1 otherwise

Overrides IndexBundleIterator::findDocsWithWord() (Hook function used by currentDocsWithWord to return the current block of docs if it is not cached)

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method reset [line 279]

void reset(
)

Returns the iterators to the first document block that it could iterate

over

Overrides IndexBundleIterator::reset() (Returns the iterators to the first document block that it could iterate)

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Class Constants

HOST_KEY_POS = 17

[line 140]

Host Key position + 1 (first char says doc, inlink or eternal link)

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KEY_LEN = 8

[line 143]

Length of a doc key

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