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

• 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!

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"
		

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

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

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