PHP 7 in 2017

Techweek

Bucharest

May 26, 2017

http://talks.php.net/techweek

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>

Story Time

1995 computers were slow!
32M of memory was a lot! (typical home PC had 8)
100 Mbps ethernet didn't exist yet
The data volume wasn't necessarily smaller

SELECT * FROM logins

1 second per MB transferred
Ate up server memory quickly
Rarely needed them all

mSQL 1.0 Patch 9         20 - Oct - 1995
---------------------------------------

    o Fixed close of stdin in keyFD handling (new key code)
    o Fixed memory leak in the client library
    o Fixed force close of UNIX socket when over-ridden by the
        environment variable
    o Fixed a couple of core dumps introduced by the new key code
    o Replace sorting code with a new algorithm (mmap only)
    o Fixed bug in msqlUpdate() that reported a duplicate key error
        if you updated the key field to the same value.
    o Merged in the LIMIT patch from Rasmus Lerdorf <rasmus@io.org>
    o Fixed locale problem with LANG make variable
    o Inlined a few calls to bcopy and bcmp for performance
    o Removed libmisc.a  All misc finctions are now in libmsql.a
    o Fixed problem with field definition info (eg IS_PRI_KEY) being
        destroyed after a join.
    o Added a msql_tmpnam() function to get around the NeXT's
        problem with it's own tmpnam().

Focus on the Ecosystem

LAMP wasn't an accident
♥ shared hosting ISPs

✔ 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 7.1

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/techweek

Report Bugs

Useful bug reports, please!