PHP 7 in 2017

WeAreDevelopers

Vienna

May 12, 2017

http://talks.php.net/vienna17

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!

engine improvements

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

Exceptions on Fatals

function call_method($obj) {
    $obj->method();
}
call_method(null);
Fatal error: Uncaught Error: Call to a member function method() on null in file:2
Stack trace:
#0 file(4): call_method(NULL)
#1 {main}
  thrown in file on line 2
try {
    call_method(null);
} catch (Error $e) {
    echo "Caught Exception: {$e->getMessage()}\n";
}
Caught Exception: Call to a member function method() on null

PHP 7 Exception Hierarchy


  • Throwable
  • Exception implements Throwable
  • Error implements Throwable
  • TypeError extends Error
  • ParseError extends Error

Return Types

function get_config(): array {
    return 42;
}
get_config();
Fatal error: Uncaught TypeError: Return value of get_config() must be
of the type array, integer returned in file:2
Stack trace:
#0 file(4): get_config()
#1 {main}
  thrown in file on line 2

Coercive Scalar Types

function logmsg(string $msg, int $level, float $severity) {
    var_dump($msg);      // string(1) "1"
    var_dump($level);    // int(2)
    var_dump($severity); // float(3)
}
logmsg(1, "2.5 bananas", 3);
Notice: A non well formed numeric value encountered in file on line 2

Strict Scalar Types

declare(strict_types=1);
...
logmsg(1, "2.5", 3);
Fatal error: Uncaught TypeError: Argument 1 passed to logmsg() must be of the
type string, integer given, called in file on line 7 and defined in file:3
Stack trace:
#0 file(7): logmsg(1, '2.5', 3)
#1 {main}
  thrown in file on line 2

Anonymous Classes

return new class($controller) implements Page {
    public function __construct($controller) {
        /* ... */
    }
    /* ... */
};

class MyObject extends MyStuff {
    public function getInterface() {
        return new class implements MyInterface {
            /* ... */
        };
    }
}

Coalesce Operator

$a = NULL;
$b = 0;
$c = 2;

echo $a ?? $b; // 0
echo $c ?? $b; // 2
echo $a ?? $b ?? $c; // 0
echo $a ?? $x ?? $c; // 2

Spaceship Operator

function cmp_php5($a, $b) {
    return ($a < $b) ? -1 : (($a >$b) ? 1 : 0);
}

function cmp_php7($a, $b) {
    return $a <=> $b;
}

Removal of many deprecated features
     (Your PHP4 code will break!)

- ext/ereg (use ext/pcre instead)
- preg_replace() eval modifier (use preg_replace_callback() instead)
- ext/mysql (use ext/mysqli or ext/pdo_mysql instead)
- Assignment of new by reference
- Scoped calls of non-static methods from incompatible $this context

- dl() in php-fpm
- set_magic_quotes_runtime() and magic_quotes_runtime()
- set_socket_blocking() (use stream_set_blocking() instead)
- mcrypt_generic_end() (use mcrypt_generic_deinit() instead)
- mcrypt_ecb, mcrypt_cbc, mcrypt_cfb and mcrypt_ofb 
  (use mcrypt_encrypt() and mcrypt_decrypt() instead)
- datefmt_set_timezone_id() and IntlDateFormatter::setTimeZoneID() 
  (use datefmt_set_timezone() or IntlDateFormatter::setTimeZone() instead)

- xsl.security_prefs (use XsltProcessor::setSecurityPrefs() instead)
- iconv.input_encoding, iconv.output_encoding, iconv.internal_encoding,
  mbstring.http_input, mbstring.http_output and mbstring.internal_encoding
  (use php.input_encoding, php.internal_encoding and php.output_encoding instead)

- $is_dst parameter of the mktime() and gmmktime() functions
- # style comments in ini files (use ; style comments instead)
- String category names in setlocale() (use LC_* constants instead)
- Unsafe curl file uploads (use CurlFile instead)
- PDO::PGSQL_ATTR_DISABLE_NATIVE_PREPARED_STATEMENT driver option 
  (use PDO::ATTR_EMULATE_PREPARES instead)
- CN_match and SNI_server_name stream context option (use peer_name instead)

New reserved words:

  • bool
  • int
  • float
  • string
  • null
  • false
  • true
  • resource
  • object
  • mixed
  • numeric

64-bit integer support on Windows

Cleanup edge-case integer overflow/underflow

Support for strings with length >= 2^31 bytes in 64 bit builds.

Parse error on invalid numeric literals

$mask = 0855;  // Parse error: Invalid numeric literal

Uniform variable syntax

// left-to-right
$this->$belongs_to['column']
// vs.
$this->{$belongs_to['column']}

// support missing combinations of operations
$foo()['bar']()
[$obj1, $obj2][0]->prop
getStr(){0}
 
// support nested ::
$foo['bar']::$baz
$foo::$bar::$baz
$foo->bar()::baz()
 
// support nested ()
foo()()
$foo->bar()()
Foo::bar()()
$foo()()
 
// support operations on arbitrary (...) expressions
(...)['foo']
(...)->foo
(...)->foo()
(...)::$foo
(...)::foo()
(...)()
 
// two more practical examples for the last point
(function() { ... })()
($obj->closure)()
 
// support all operations on dereferencable scalars
// (not very useful)
"string"->toLower()
[$obj, 'method']()
'Foo'::$bar

Unicode Codepoint Escape Syntax

echo "\u{202E}Right-to-left text";

echo " \u{26BD}";
‮Right-to-left text ⚽		

ICU IntlChar class added to intl extension

CSPRNG

$int   = random_int(-500, 500);
$bytes = random_bytes(10);

var_dump( $int );
var_dump( bin2hex($bytes) );
int(226)
string(20) "84748d59da7b3040901b"
		

PHP 7.1

void return type

function should_return_nothing(): void {
    return 1; // Fatal error: A void function must not return a value
}

Nullable types

function answer(int $a, ?int $b): ?int  {
    if($a > $b) return $a;
    else return null;
}

Iterable pseudo-type

function foo(iterable $iterable) {
    foreach ($iterable as $value) {
        // ...
    }
}
function bar(): iterable {
    return [1, 2, 3];
}

Negative string offsets

$str='abcdef';
var_dump($str[-2]); // => string(1) "e"

List keys

list($first, $second, $third) = [1, 2, 3];
[$first, $second, $third] = [1, 2, 3];

Warn about invalid strings in arithmetic

$numberOfApples = "10 apples" + "5 pears";
Notice: A non well formed numeric string encountered in example.php on line 2
Notice: A non well formed numeric string encountered in example.php on line 2

Class constant visibility

class Token {
    // Constants default to public
    const PUBLIC_CONST = 0;
 
    private const PRIVATE_CONST = 0;
    protected const PROTECTED_CONST = 0;
    public const PUBLIC_CONST_TWO = 0;

Things that may break your code

  • new 'void' and 'iterable' keywords
  • rand() and srand() are now aliased to mt_rand() and mt_srand()
  • Mersenne Twister algorithm has been tweaked
  • Calling a function with too few args is now an Error instead of a Warning
  • Dropped support for sslv2 streams
  • Dropped support for mcrypt

Static Analysis



github.com/etsy/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: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 etsy/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

https://github.com/rlerdorf/phan
https://bugs.php.net
http://talks.php.net/vienna17



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