New SPL Features in PHP 5.3

New SPL Features in PHP 5.3

Matthew Turland
TEK-X
May 20, 2010

Hi! My name is…

• Senior Platform Engineer for Synacor, Inc.
• Former author and TE for php|architect
• Author of Web Scraping with PHP
• Past contributor to Zend Framework
• Lead developer of Phergie
• ULL alumni with a BS in computer science

And I work for…

• Provides internet solutions to ISPs, media
companies, and advertisers
• International company with offices in Buffalo,
New York City, Los Angeles, and Amsterdam
• Clientele includes most of the top 20 cable
providers in the United States
• Great company – join us!

What about you?

• Used the SPL before?
• Using PHP 5.3?
• Computer science background?
• Knowledge of data structures?

Pre-5.3 SPL Features

• Classes: ArrayObject, SplFileInfo, SplSubject,
SplObserver, etc.
• Iterators: RecursiveIteratorIterator,
FilterIterator, LimitIterator, etc.
• Interfaces: ArrayAccess, Countable, Iterator,
IteratorAggregate, etc.
• Functions: spl_autoload_register,
iterator_to_array, spl_object_hash, etc.

Containers

“A container is a class, a data structure, or
an abstract data type whose instances are
collections of other objects. They are used
to store objects in an organized way
following specific access rules.”

Container (data structure) - Wikipedia

Why containers?

• We already have arrays and strings!
array() 'string'

Two excellent reasons

• Versus traditional arrays, there is potential for:
– Less CPU usage
– Less memory usage

Arrays are (not always) great

• Flexible general purpose container
• Underlying hash table algorithm is not always
ideal for the task at hand

Warning: Benchmarks Ahead

• Lies, Outrageous Lies, and Benchmarks
• PHP 5.3.2 compiled on Ubuntu 9.10
• Intel Core2Duo 1.83 GHz, 4 GB DDR2 RAM
• Performance results are shown in executions
per second rather than time per execution to
avoid really small numbers
• Code and results

SplFixedArray - What

• Like an array, but with a fixed length
• Only allows integers >= 0 for keys
• Can be resized, but at a cost
• Not compatible with array functions

SplFixedArray - When

• It’s best to use this when:
– You know in advance how many elements you
want to store (e.g. mysql_num_rows)
– You only need to access elements in sequential
order

SplFixedArray - Code
<?php
$a = array();
for ($i = 0; $i < $argv[1]; $i++) {
$a[$i] = $i;
$i = $a[$i];
}
<?php
$a = new SplFixedArray($argv[1]);
for ($i = 0; $i < $argv[1]; $i++) {
$a[$i] = $i;
$i = $a[$i];
}

SplDoublyLinkedList - What

• Mainly intended as a parent class
• Same unlimited size as arrays without the
associated hash map algorithm
• Less performance, but more memory
efficiency

SplDoublyLinkedList - When

– You do not know in advance how many elements
you want to store
– You only need to access elements in sequential
order

SplDoublyLinkedList - Code
<?php
$a = array();
for ($i = 0; $i < $argv[1]; $i++) {
$a[] = $i;
$i = $a[$i];
}
<?php
$a = new SplDoublyLinkedList($argv[1]);
for ($i = 0; $i < $argv[1]; $i++) {
$a[] = $i;
$i = $a[$i];
}

SplStack - What

• 2 operations
– Push: [] for both array and SplStack
– Pop: array_pop() vs SplStack::pop()
• Last In, First Out (LIFO)
– The last item pushed onto the top of the stack is
the first item that will be popped off of the top of
the stack

SplStack - When

you want to store
– You only ever need to access the last element you
stored

SplStack - Code

<?php
$a = array();
for($i = 0; $i < $argv[1]; $i++) {
$a[] = $i;
}
for($i = 0; $i < $argv[1]; $i++) {
array_pop($a);
}

SplStack - Code (cont.)

<?php
$a = new SplStack;
for($i = 0; $i < $argv[1]; $i++) {
$a[] = $i;
}
for($i = 0; $i < $argv[1]; $i++) {
$a->pop();
}

SplQueue - What

• 2 operations
– Enqueue: [] for both array and SplQueue
– Dequeue: array_shift() vs SplQueue::dequeue()
• First In, First Out (FIFO)
– The first item added to the end of the queue will
be the first item removed from the front of the
queue

SplQueue - When

you want to store
– You only ever need to access the remaining
element that was stored earliest

SplQueue - Code

<?php
$a = array();
for($i = 0; $i < $argv[1]; $i++) {
$a[] = $i;
}
for($i = 0; $i < $argv[1]; $i++) {
array_shift($a);
}

SplQueue - Code (cont.)

<?php
$a = new SplQueue;
for($i = 0; $i < $argv[1]; $i++) {
$a[] = $i;
}
for($i = 0; $i < $argv[1]; $i++) {
$a->dequeue();
}

SplHeap - What
• 2 operations
– Insert: [] + sort vs SplHeap::insert()
– Remove: array_shift() vs SplHeap::extract()
• Internally reorders items based on comparison
– SplHeap::compare() can be overridden
• Subclasses
– SplMinHeap
– SplMaxHeap
• Better worst-case scenario performance
versus arrays (heap sort versus quick sort)

SplHeap - When

you want to store
– You need to access elements in an order based on
how they compare to each other

SplMinHeap - Code

<?php
$a = array();
for($i = 0; $i < $argv[1]; $i++) {
$a[] = rand(1, $argv[1]);
sort($a);
}
for($i = 0; $i < $argv[1]; $i++) {
array_shift($a);
}

SplMinHeap - Code (cont.)

<?php
$a = new SplMinHeap;
for($i = 0; $i < $argv[1]; $i++) {
$a->insert(rand(1, $argv[1]));
}
for($i = 0; $i < $argv[1]; $i++) {
$a->extract();
}

SplPriorityQueue - What

• Accepts a priority with the element value
• Element with highest priority comes out first
• Priorities may be of any comparable type
• SplPriorityQueue::compare() can be
overridden
• Operates similarly to a heap
– In fact, it uses a heap internally for storage

SplPriorityQueue - When

you want to store
– You need to access elements in an order based on
how priority values associated with those
elements compare to each other

SplPriorityQueue - Code
<?php
$threshold = $argv[1] * 0.1;
$a = array();
$i = 0;
do {
if ($i <= $argv[1]) {
$a[] = array($i, rand(1, 10));
usort($a, 'priority_sort');
}
if ($i > $threshold) {
array_shift($a);
}
$i++;
} while (count($a));
function priority_sort($a, $b) {
return $a[1] - $b[1];
}

SplPriorityQueue - Code (cont.)
<?php
$threshold = $argv[1] * 0.1;
$a = new SplPriorityQueue;
$i = 0;
do {
if ($i < 1) {
$a->insert($i, rand(1,10));
}
if ($i > $threshold) {
$a->extract();
}
$i++;
} while (count($a));

The Composite Hash Map

Just pretend the red pills are objects.

SplObjectStorage - What
• Combination of two data structures
– Composite hash map: a hash map with objects for
keys; the spl_object_hash() function must be used
for arrays to have this capability
– Set: focuses on a group of values rather than
individual values with operations like union,
intersection, difference, and element_of; no
concept of sequential order
• Currently lacks a method for the intersection
operation

SplObjectStorage - When

– You need to store data using composite (i.e. non-
scalar) keys
– You need the ability to access data using set
operations more so than accessing it in a
particular order

SplObjectStorage - Code
<?php
$a = array();
for ($i = 0; $i < $argv[1]; $i++) {
$object = new stdClass;
$a[spl_object_hash($object)] = $object;
}
$a = array();
$b = array();
for ($i = 0; $i < $argv[1]; $i++) {
$a[] = rand(1, $argv[1]);
$b[] = rand(1, $argv[1]);
}
$c = array_merge($a, $b);
$c = array_diff($a, $b);

SplObjectStorage - Code (cont.)
<?php
$a = new SplObjectStorage;
for ($i = 0; $i < $argv[1]; $i++) {
$object = new stdClass;
$a->attach($object, $object);
}
$a = new SplObjectStorage;
$b = new SplObjectStorage;
for ($i = 0; $i < $argv[1]; $i++) {
$a->attach((object) rand(1, $argv[1]));
$b->attach((object) rand(1, $argv[1]));
}
$c = clone $a;
$c->addAll($b);
$c = clone $a;
$c->removeAll($b);

Thank this guy

• Etienne Kneuss did a lot of the work on the
new SPL features in PHP 5.3

Some great SPL resources

• SPL in the PHP manual
• Etienne Kneuss' blog
• "SPL to the Rescue" by Elizabeth Smith
• “SPL, a bridge not too far” by Michelangelo
van Dam
• This presentation as a blog post

Possible future SPL features

• Graphs
– Contain nodes and edges connecting them
– Directional / non-directional
– Cyclic / acyclic
– Connected / unconnected
– Edge costs
• Trees
– Acyclic unidirectional graph
– Hierarchical in nature

Feedback, please!

http://joind.in/1577

That’s all, folks

• Any questions?
• http://synacor.com
• http://matthewturland.com
• me@matthewturland.com
• @elazar on Twitter
• Elazar on the Freenode IRC network

New SPL Features in PHP 5.3

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à New SPL Features in PHP 5.3

Similaire à New SPL Features in PHP 5.3 (20)

Plus de Matthew Turland

Plus de Matthew Turland (15)

Dernier

Dernier (20)

New SPL Features in PHP 5.3