PHP in 2018

Festival de Software Libre

Puerto Vallarta

Oct.28, 2017

http://talks.php.net/fsl17

Rasmus Lerdorf
@rasmus

1980s

1990s

1993

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>

#define ishex(x) (((x) >= '0' && (x) <= '9') || ((x) >= 'a' && \
                   (x) <= 'f') || ((x) >= 'A' && (x) <= 'F'))

int htoi(char *s) {
	int     value;
	char    c;

	c = s[0];
	if(isupper(c)) c = tolower(c);
	value=(c >= '0' && c <= '9' ? c - '0' : c - 'a' + 10) * 16;

	c = s[1];
	if(isupper(c)) c = tolower(c);
	value += c >= '0' && c <= '9' ? c - '0' : c - 'a' + 10;

	return(value);
}

void main(int argc, char *argv[]) {
	char *params, *data, *dest, *s, *tmp;
	char *name, *age;

	puts("Content-type: text/html\r\n");
	puts("<HTML><HEAD><TITLE>Form Example</TITLE></HEAD>");
	puts("<BODY><H1>My Example Form</H1>");
	puts("<FORM action=\"form.cgi\" method=\"GET\">");
	puts("Name: <INPUT type=\"text\" name=\"name\">");
	puts("Age: <INPUT type=\"text\" name=\"age\">");
	puts("<BR><INPUT type=\"submit\">");
	puts("</FORM>");

	data = getenv("QUERY_STRING");
	if(data && *data) {
		params = data; dest = data;
    	while(*data) {
			if(*data=='+') *dest=' ';
			else if(*data == '%' && ishex(*(data+1))&&ishex(*(data+2))) {
				*dest = (char) htoi(data + 1);
				data+=2;
			} else *dest = *data;
			data++;
			dest++;
		}
		*dest = '\0';
		s = strtok(params,"&");
		do {
			tmp = strchr(s,'=');
			if(tmp) {
				*tmp = '\0';
				if(!strcmp(s,"name")) name = tmp+1;
				else if(!strcmp(s,"age")) age = tmp+1;
			}
		} while(s=strtok(NULL,"&"));

		printf("Hi %s, you are %s years old\n",name,age);
	}
	puts("</BODY></HTML>");
}

1993

use CGI qw(:standard);
print header;
print start_html('Form Example'),
    h1('My Example Form'),
    start_form,
    "Name: ", textfield('name'),
    p,
    "Age: ", textfield('age'),
    p,
    submit,
    end_form;
if(param()) {
    print "Hi ",em(param('name')),
        "You are ",em(param('age')),
        " years old";
}
print end_html;

1994-1995

<html><head><title>Form Example</title></head>
<body><h1>My Example Form</h1>
<form action="form.phtml" method="POST">
Name: <input type="text" name="name">
Age: <input type="text" name="age">
<br><input type="submit">
</form>
<?if($name):?>
Hi <?echo $name?>, you are <?echo $age?> years old
<?endif?>
</body></html>

✔ engine improvements

100%+ performance gain on most real-world applications
Lower memory usage, sometimes drastically lower

JIT?

Improve CPU cache usage

Step 1: Decrease overall data
Step 2: Better data locality and less indirections
Step 3: Save the world!

zval size reduced from 24 to 16 bytes
Hashtable size reduced from 72 to 56 bytes
Hashtable bucket size reduced from 72 to 32 bytes
Immutable array optimization

$a = [];
for($i=0; $i < 100000;$i++) {
    $a[] = ['abc','def','ghi','jkl','mno','pqr'];
}
echo memory_get_usage(true);

// PHP 5.x  109M
// PHP 7.0   42M no opcache
// PHP 7.0    6M with opcache enabled

New memory allocator similar to jemalloc
Faster hashtable iteration API
Array duplication optimization
PCRE JIT enabled by default
Precomputed string hashes
Fast ZPP (ZendParseParameters) implementation
Faster stack-allocated zvals (instead of heap)
Optimized VM calling
Global register variables with gcc 4.8+
plus hundreds of micro-optimizations

JIT?

GCC Feedback-Directed Optimization (FDO)

$ gcc --version
gcc (Debian 6.3.0-14) 6.3.0 20170415

$ make clean
$ make -j8 prof-gen
...
$ sapi/cgi/php-cgi -T 1000 /var/www/wordpress/index.php > /dev/null
$ make prof-clean
$ make -j8 prof-use

PHP 7 in production

Saving the Planet?

Around 2 billion sites on the web
On 10 million physical machines
PHP drives at least 50%

Currently ~5% PHP 7 Adoption
which is about 250k physical servers

3000 KWH/year per server costs approx. US$400
Data center cooling doubles that
0.5kg CO2 per KWH

At 5% Adoption

US $200M savings
750M KWH Savings
375M kg less CO2

At 100% Adoption

$4B savings
15B KWH Savings
7.5B kg less CO2

Do your part

Upgrade to PHP 7!

PHP 7.2

Initial DCE and SCCP optimizations

Parameter Type Widening

class Orig {
  public function fn(array $arg) {  }
}
class Wider extends Orig {
  public function fn($arg) { }
}

In PHP 7.1 you would get:

Warning: Declaration of Wider::fn($arg) should be 
         compatible with Orig::fn(array $arg)

Allow trailing commas everywhere

// Arrays (already possible)
$array = [1, 2, 3,];

// Grouped namepaces
use Foo\Bar\{ Foo, Bar, Baz, };
 
// Function/method arguments (call)
fooCall($arg1, $arg2, $arg3,);

use Foo\Bar\{ Foo, Bar, Baz, };

class Foo implements
    // Interface implementations on a class
    FooInterface,
    BarInterface,
    BazInterface,
{
    // Trait implementations on a class
    use
        FooTrait,
        BarTrait,
        BazTrait,
    ;
 
    // Class member lists
    const
        A = 1010,
        B = 1021,
        C = 1032,
        D = 1043,
    ;

Object typehint

function fn(object $obj): object {
	return json_decode('{}');
}
fn("not an object");

Warning: Uncaught TypeError: Argument 1 passed to fn() must be an object,
         string given, called in php shell code on line 1 and defined in ...

Deprecate unquoted strings

echo HELLO;

Warning: Use of undefined constant HELLO - assumed 'HELLO' (this will throw
         an Error in a future version of PHP) in php shell code on line 1

extra headers array arg for mail() and mb_send_mail()

$to      = 'nobody@example.com';
$subject = 'the subject';
$message = 'hello';
$headers = ['From'     => 'webmaster@example.com',
            'Reply-To' => 'webmaster@example.com',
            'X-Mailer' => 'PHP/' . phpversion() ];

mail($to, $subject, $message, $headers);

Argon2i added to password_hash()

$options = [
    'memory_cost' => 2048,
    'time_cost' => 10,
    'threads' => 2
];
echo password_hash("rasmuslerdorf", PASSWORD_ARGON2I, $options);

$argon2i$v=19$m=2048,t=10,p=2$akUuWkoxRDlMSi5TVGhYLg$j0D1Cl4aR8UMHOGGx5JtZ1BmCApr8RmOJA9qFWm5mz8

Add Sodium Crypto Library

// On Alice's computer:
$msg = 'This comes from Alice.';
$signed_msg = sodium_crypto_sign($msg, $secret_sign_key);

// On Bob's computer:
$original_msg = sodium_crypto_sign_open($signed_msg, $alice_sign_publickey);
if ($original_msg === false) {
    throw new Exception("Invalid signature");
} else {
    echo $original_msg; // Displays "This comes from Alice."
}

see: https://paragonie.com/book/pecl-libsodium

Things that may break your code

mcrypt extension has been removed
__autoload() deprecated, use spl_autoload_register()
create_function() deprecated, use anonymous functions
each() deprecated, use foreach()
read_exif_data() deprecated, use exif_read_data()

Full details are at:

https://github.com/php/php-src/blob/PHP-7.2/UPGRADING

And for extension authors:

https://github.com/php/php-src/blob/PHP-7.2/UPGRADING.INTERNALS

Dead Code Elimination (DCE)

Escape Analysis

Sparse Conditional Constant Propagation

php -d opcache.optimization_level=-1 -d opcache.opt_debug_level=0x20000 script

function fn() {
    $a = 1;
    return 0;
}

PHP 7.1

fn: (lines=2, args=0, vars=1, tmps=0)
L0:   ASSIGN CV0($a) int(1)
L1:   RETURN int(0)

PHP 7.2

fn: (lines=1, args=0, vars=0, tmps=0)
L0:   RETURN int(0)

function foo(string $s1, string $s2, string $s3, string $s4) {
    $x = ($s1 . $s2) . ($s3 . $s4);
    $x = 0;
    return $x;
}

PHP 7.1                                   PHP 7.2
foo: (lines=10, args=4, vars=5, tmps=3)   foo: (lines=5, args=4, vars=4, tmps=3)
L0:   CV0($s1) = RECV 1                   L0:   CV0($s1) = RECV 1
L1:   CV1($s2) = RECV 2                   L1:   CV1($s2) = RECV 2
L2:   CV2($s3) = RECV 3                   L2:   CV2($s3) = RECV 3
L3:   CV3($s4) = RECV 4                   L3:   CV3($s4) = RECV 4
L4:   T6 = CONCAT CV0($s1) CV1($s2)       L4:   RETURN int(0)
L5:   T7 = CONCAT CV2($s3) CV3($s4)
L6:   T5 = CONCAT T6 T7
L7:   ASSIGN CV4($x) T5
L8:   ASSIGN CV4($x) int(0)
L9:   RETURN CV4($x)

Try to trick it

function foo($a) {
    $b = $a += 3;
    return $a;
}

PHP 7.2

foo: (lines=3, args=1, vars=1, tmps=1)
L0:   CV0($a) = RECV 1
L1:   ASSIGN_ADD CV0($a) int(3)
L2:   RETURN CV0($a)

But...

function foo(int $x, int $y) {
    $a = [$x];
    $a[1] = $y;
    $a = $y;
    return $a;
}

PHP 7.2                                    PHP 7.3
foo: (lines=7, args=2, vars=3, tmps=1)     foo: (lines=4, args=2, vars=3, tmps=0)
L0:   CV0($x) = RECV 1                     L0:     CV0($x) = RECV 1
L1:   CV1($y) = RECV 2                     L1:     CV1($y) = RECV 2
L2:   CV2($a) = INIT_ARRAY 1 CV0($x) NEXT  L2:     CV2($a) = QM_ASSIGN CV1($y)
L3:   ASSIGN_DIM CV2($a) int(1)            L3:     RETURN CV2($a)
L4:   OP_DATA CV1($y)
L5:   ASSIGN CV2($a) CV1($y)
L6:   RETURN CV2($a)

class A { }
function foo(int $x) {
    $a = new A;
    $a->foo = $x;
    return $x;
}

PHP 7.3

foo: (lines=2, args=1, vars=1, tmps=0)
L0:   CV0($x) = RECV 1
L1:   RETURN CV0($x)

class A {
    function __destruct() {}
}
function foo(int $x) {
    $a = new A;
    $a->foo = $x;
    return $x;
}

PHP 7.3

foo: (lines=7, args=1, vars=2, tmps=1)
L0:   CV0($x) = RECV 1
L1:   V2 = NEW 0 string("A")
L2:   DO_FCALL
L3:   CV1($a) = QM_ASSIGN V2
L4:   ASSIGN_OBJ CV1($a) string("foo")
L5:   OP_DATA CV0($x)
L6:   RETURN CV0($x)

function foo() {
    $a = 1;
    $b = $a + 2;
    $a += $b;
    return $a;
}

PHP 7.2

foo: (lines=1, args=0, vars=0, tmps=1)
L0:   RETURN int(4)

PHP 7.3

foo: (lines=1, args=0, vars=0, tmps=0)
L0:   RETURN int(4)

function foo(int $x) {
    if ($x) {
        $a = [0,1];
    } else {
        $a = [0,2];
    }
    return $a[0];
}

PHP 7.3

foo: (lines=2, args=1, vars=1, tmps=0)
L0:   CV0($x) = RECV 1
L1:   RETURN int(0)

function foo() {
    $o = new stdClass();
    $o->foo = 0;
    $i = 1;
    $c = $i < 2;
    if ($c) {
        $k = 2 * $i;
        $o->foo = $i;
        echo $o->foo;
    }
    $o->foo += 2;
    $o->foo++;
    return $o->foo;
}

PHP 7.3

foo: (lines=2, args=0, vars=0, tmps=0)
L0:   ECHO int(1)
L1:   RETURN int(4)

Static Analysis

github.com/phan/phan

It can catch dumb mistakes

$a = [1,2,3];
if(count($a > 1)) {
    echo "Test";
}

% phan test.php
test.php:2 PhanTypeComparisonFromArray array to int comparison

Check phpdoc comments

class C {
    /** @var int $prop */
    public $prop;

    /**
     * @param string $arg
     * @return int
     */
    function test(?$arg) {
        $this->prop = $arg;
        return $arg;
    }
}

% phan test.php
test.php:9 PhanTypeMismatchDeclaredParamNullable Doc-block of $arg in test
           is phpdoc param type string which is not a permitted replacement
           of the nullable param type ?string declared in the signature 
           ('?T' should be documented as 'T|null' or '?T')
test.php:10 PhanTypeMismatchProperty Assigning string to property
            but \C::prop is int
test.php:11 PhanTypeMismatchReturn Returning type string 
            but test() is declared to return int

Help with refactoring

class C {
    /**
     * @deprecated
     */
    static function legacy_function() { }
}

C::legacy_function();

% phan test.php
test.php:8 PhanDeprecatedFunction Call to deprecated function 
           \C::legacy_function() defined at test.php:5

Install with composer

$ composer require --dev phan/phan

Create .phan/config.php

<?php
use \Phan\Issue;
return [
    'should_visit_all_nodes' => true,
    'minimum_severity' => Issue::SEVERITY_LOW,
    'directory_list' => [ 'src', 'vendor' ],
    'exclude_analysis_directory_list' => [ 'vendor' ]
];

$ ./vendor/bin/phan

Type Safety

Legacy code

class Data {
    function __construct($data) {
        $this->haystack = $data;
    }
    function find($needle) {
        return in_array($needle, $this->haystack, true);
    }
}
$storage = new Data(['apple','orange','banana']);

$fruit = false;
$storage->find($fruit);

Going straight to strict types risks runtime fatals

<?php declare(strict_types=1);
class Data {
    function __construct(array $data) {
        $this->haystack = $data;
    }
    function find(string $needle):bool {
        return in_array($needle, $this->haystack, true);
    }
}
$storage = new Data(['apple','orange','banana']);

$fruit = false;
$storage->find($fruit);

Fatal error: Uncaught TypeError: Argument 1 passed to Data::find() must be of the type string, boolean given,
                                 called in test.php on line 13 and defined in test.php:6
Stack trace:
#0 test.php(13): Data->find(false)
#1 {main}
thrown in test.php on line 6

Intermediate step

class Data {
    /** @var array $haystack */
    public $haystack;

    /**
     * @param array $data
     */
    function __construct($data) {
        $this->haystack = $data;
    }
    /**
     * @param string $needle
     * @return bool
     */
    function find($needle) {
        return in_array($needle, $this->haystack, true);
    }
}
$storage = new Data(['apple','orange','banana']);

$fruit = false;
$storage->find($fruit);

$ phan test.php
test.php:22 PhanTypeMismatchArgument Argument 1 (needle) is bool
            but \Data::find() takes string defined at test.php:15

Thank You

http://talks.php.net/fsl17

https://github.com/phan/phan

https://paragonie.com/book/pecl-libsodium

https://github.com/php/php-src/blob/PHP-7.2/UPGRADING

https://bugs.php.net

Report Bugs

Useful bug reports, please!