Gzip: gzip, needs, ob

by: MarcosBLPosted on 2003-10-10 at 09:19:50ID: 9528724

Just use this class... my first response, don't be rude, if you need help just ask. Code © from Leknor

<?php

// News: I had once said that when PHP4.0.5 comes out I will reccomend the built in
// ob_gzhandler over my code unless you are generating flash or images on the fly.
//
// I was wrong. PHP4.0.5 is out and ob_gzhandler doesn't work for me.

// Note: This is rather cool: http://Leknor.com/code/gziped.php
// It will calculate the effects of this class on a page.
// compression level, cpu time, download time, etc

// Note: this may better for some sites:
// http://www.remotecommunications.com/apache/mod_gzip/
// I've read that the above doesn't work with php output.

class gzip_encode {
/*
* gzip_encode - a class to gzip encode php output
*
* By Sandy McArthur, Jr. <Leknor@Leknor.com>
*
* Copyright 2001 (c) All Rights Reserved, All Responsibility Yours.
*
* This code is released under the GNU LGPL Go read it over here:
* http://www.gnu.org/copyleft/lesser.html
*
* I do make one optional request, I would like an account on or a
* copy of where this code is used. If that is not possible then
* an email would be cool.
*
* How to use:
* 1. Output buffering has to be turned on. You can do this with ob_start()
* <http://php.net/manual/function.ob-start.php> or in the php config
* file. Nothing bad happens if output buffering isn't turned on, your
* page just won't get compressed.
* 2. Include the class file.
* 3. At the _very_ end of your script create an instance of the encode
* class.
*
* eg:
* ------------Start of file----------
* |<?php
* | ob_start();
* | include('class.gzip_encode.php');
* |?>
* |<HTML>
* |... the page ...
* |</HTML>
* |<?php
* | new gzip_encode();
* |?>
* -------------End of file-----------
*
* Things to note:
* 1. There is no space before the beginning of the file and the '<?php' tag
* 2. The ob_start() line is optional if output buffering is turned on in
* the main config file.
* 3. Turning on and off output buffering just won't work.
* 4. There must be nothing after the last '?>' tag at the end of the file.
* Be careful of a space hiding there.
* 5. There are better ways to compress served content but I think this is
* the only way to compress php output.
* 6. Your auto_prepend_file is a good place for the ob_start() and
* your auto_append_file is a good place for new gzip_encode().
* 7. If you put new gzip_encode() in your auto.append file then you can
* call ob_end_flush() in your script to disable compression.
*
* This was written from scratch from info freely available on the web.
*
* These site(s) were useful to me:
* http://www.php.net/manual/
* http://www.ietf.org/rfc/rfc2616.txt (Sections: 3.5, 14.3, 14.11)
*
* Requirments:
* PHP 4.0.1+: I use the '===' operator, and output buffering, crc32();
* zlib: Needed for the gzip encoding. (Odds are you have it)
*
* Benchmarks:
* Take a look at http://Leknor.com/code/gziped.php and feed it a page to
* get an idea of how it will preform on your data or page.
*
* To Do:
* 1. I have reports of no content errors. I can't seem to duplicate this.
* Please visit my discussion boards if you think you may be able to help
* 2. The Accept-Encoding isn't handled to spec. Check out 14.3 in RFC 2616
* to see how it should be done.
*
* Change Log:
* 0.67: Added Vary header to aid in caching.
* 0.66: Big bug fix. It wouldn't compress when it should.
* 0.65: Fix for PHP-4.0.5 suddenly removing the connection_timeout() function.
* 0.62: Fixed a typo
* 0.61: Detect file types more like described in the magic number files, also
* added detection for gzip and pk zip files.
* 0.6: Detect common file types that shouldn't be compressed, mainly
* for images and swf (Shockwave Flash doesn't really accept gzip)
* 0.53: Made gzip_accepted() method so everyone can detect if a page
* will be gzip'ed with ease.
* 0.52: Detection and graceful handling of improper install/missing libs
* 0.51: Added FreeBSD load average detection.
* 0.5: Passing true as the first parameter will try to calculate the
* compression level from the server's load average. Passing true
* as the second parameter will turn on debugging.
* 0.4: No longer uses a temp file to compress the output. Should speed
* thing up a bit and reduce wear on your hard disk. Also test if
* the http headers have been sent.
* 0.31: Made a small change to the tempnam() line to hopefully be more
* portable.
* 0.3: Added code for the 'x-gzip'. This is untested, I don't know of
* any browser that uses it but the RFC said to look out for it.
* 0.2: Checks for 'gzip' in the Accept-Encoding header
* 0.1: First working version.
*
* Thanks To (Suggestions and stuff):
* ?@boas.anthro.mnsu.edu http://php.net/manual/function.gzcompress.php
* Kaoslord <kaoslord@chaos-productions.com>
* Michael R. Gile <gilem@wsg.net>
* Christian Hamm <chh@admaster.de>
* Anil Madhavapeddy <anil@recoil.org>
*
* The most recent version is available at:
* http://Leknor.com/code/
*
*/

var $_version = 0.67; // Version of the gzip_encode class

var $level; // Compression level
var $encoding; // Encoding type
var $crc; // crc of the output
var $size; // size of the uncompressed content
var $gzsize; // size of the compressed content

/*
* gzip_encode constructor - gzip encodes the current output buffer
* if the browser supports it.
*
* Note: all arguments are optionial.
*
* You can specify one of the following for the first argument:
* 0: No compression
* 1: Min compression
* ... Some compression (integer from 1 to 9)
* 9: Max compression
* true: Determin the compression level from the system load. The
* higher the load the less the compression.
*
* You can specify one of the following for the second argument:
* true: Don't actully output the compressed form but run as if it
* had. Used for debugging.
*/
function gzip_encode($level = 3, $debug = false) {
global $HTTP_ACCEPT_ENCODING;
if (!function_exists('gzcompress')) {
trigger_error('gzcompress not found, ' .
'zlib needs to be installed for gzip_encode',
E_USER_WARNING);
return;
}
if (!function_exists('crc32')) {
trigger_error('crc32() not found, ' .
'PHP >= 4.0.1 needed for gzip_encode', E_USER_WARNING);
return;
}
if (headers_sent()) return;
if (connection_status() !== 0) return;
$encoding = $this->gzip_accepted();
if (!$encoding) return;
$this->encoding = $encoding;

if ($level === true) {
$level = $this->get_complevel();
}
$this->level = $level;

$contents = ob_get_contents();
if ($contents === false) return;

$gzdata = "\x1f\x8b\x08\x00\x00\x00\x00\x00"; // gzip header
$size = strlen($contents);
$crc = crc32($contents);
$gzdata .= gzcompress($contents, $level);
$gzdata = substr($gzdata, 0, strlen($gzdata) - 4); // fix crc bug
$gzdata .= pack("V",$crc) . pack("V", $size);

$this->size = $size;
$this->crc = $crc;
$this->gzsize = strlen($gzdata);

if ($debug) {
return;
}

ob_end_clean();
Header('Content-Encoding: ' . $encoding);
Header('Vary: Accept-Encoding');
Header('Content-Length: ' . strlen($gzdata));
Header('X-Content-Encoded-By: class.gzip_encode '.$this->_version);

echo $gzdata;
}

/*
* gzip_accepted() - Test headers for Accept-Encoding: gzip
*
* Returns: if proper headers aren't found: false
* if proper headers are found: 'gzip' or 'x-gzip'
*
* Tip: using this function you can test if the class will gzip the output
* without actually compressing it yet, eg:
* if (gzip_encode::gzip_accepted()) {
* echo "Page will be gziped";
* }
* note the double colon syntax, I don't know where it is documented but
* somehow it got in my brain.
*/
function gzip_accepted() {
global $HTTP_ACCEPT_ENCODING;
if (strpos($HTTP_ACCEPT_ENCODING, 'gzip') === false) return false;
if (strpos($HTTP_ACCEPT_ENCODING, 'x-gzip') === false) {
$encoding = 'gzip';
} else {
$encoding = 'x-gzip';
}

// Test file type. I wish I could get HTTP response headers.
$magic = substr(ob_get_contents(),0,4);
if (substr($magic,0,2) === '^_') {
// gzip data
$encoding = false;
} else if (substr($magic,0,3) === 'GIF') {
// gif images
$encoding = false;
} else if (substr($magic,0,2) === "\xFF\xD8") {
// jpeg images
$encoding = false;
} else if (substr($magic,0,4) === "\x89PNG") {
// png images
$encoding = false;
} else if (substr($magic,0,3) === 'FWS') {
// Don't gzip Shockwave Flash files. Flash on windows incorrectly
// claims it accepts gzip'd content.
$encoding = false;
} else if (substr($magic,0,2) === 'PK') {
// pk zip file
$encoding = false;
}

return $encoding;
}

/*
* get_complevel() - The level of compression we should use.
*
* Returns an int between 0 and 9 inclusive.
*
* Tip: $gzleve = gzip_encode::get_complevel(); to get the compression level
* that will be used with out actually compressing the output.
*
* Help: if you use an OS other then linux please send me code to make
* this work with your OS - Thanks
*/
function get_complevel() {
$uname = posix_uname();
switch ($uname['sysname']) {
case 'Linux':
$cl = (1 - $this->linux_loadavg()) * 10;
$level = (int)max(min(9, $cl), 0);
break;
case 'FreeBSD':
$cl = (1 - $this->freebsd_loadavg()) * 10;
$level = (int)max(min(9, $cl), 0);
break;
default:
$level = 3;
break;
}
return $level;
}

/*
* linux_loadavg() - Gets the max() system load average from /proc/loadavg
*
* The max() Load Average will be returned
*/
function linux_loadavg() {
$buffer = "0 0 0";
$f = fopen("/proc/loadavg","r");
if (!feof($f)) {
$buffer = fgets($f, 1024);
}
fclose($f);
$load = explode(" ",$buffer);
return max((float)$load[0], (float)$load[1], (float)$load[2]);
}

/*
* freebsd_loadavg() - Gets the max() system load average from uname(1)
*
* The max() Load Average will be returned
*
* I've been told the code below will work on solaris too, anyone wanna
* test it?
*/
function freebsd_loadavg() {
$buffer= `uptime`;
ereg("averag(es|e): ([0-9][.][0-9][0-9]), ([0-9][.][0-9][0-9]), ([0-9][.][0-9][0-9]*)", $buffer, $load);

return max((float)$load[2], (float)$load[3], (float)$load[4]);
}
}

?>

by: cool888Posted on 2003-10-10 at 10:29:54ID: 9529150

thanks for the class file, but how can I check wether that the page is gzipped? Is there a line to show this page is gzipped?

by: MarcosBLPosted on 2003-10-10 at 10:39:54ID: 9529204

Just take a look at headers, or simply use this test page:

http://leknor.com/code/gziped.php

If you take a look at the comments in the class file, you will se anexample of use, as well as comments from the autor and this url i have just given you. :)

Sorry if my explain isn't better, is my first response to a question... i don't even know well how all this works : ) If you need something more, just give me a shout.

by: jayrodPosted on 2003-10-11 at 09:29:36ID: 9533133

What exactly does this compress marco? just curious. by the way nice code

by: MarcosBLPosted on 2003-10-11 at 11:25:38ID: 9533455

This compresion just compress the code after the page being generated, then sent it to the browser, compressed, and the browser (99,9% of them supports gzip) uncompress the data and show it to you. The benefits ? The transfer of the server reduces drastically, because you only send a medium of 25% of the original data (not counting images, flash, etc, only text, images and so are yet compressed). You pay less for your transfer, and the page reach the visitor about a 25% more quickly, because less data goes trought the line.

And every server usually have the gzip module, the only thing you need to run this class. In my server, for example, i reduced the trasnfer (About 180000 daily hits) from 20 Gb per month to 4,6 Gb per month.

Sorry for my bad english, i am spanish, and self-learned english. If my explanation isn't clear, just say and i'll try to find documentation in english.

by: DoppyNLPosted on 2003-10-13 at 03:01:42ID: 9539009

ob_start ("ob_gzhandler");

This should work just fine, no need to use some fancy class.

by: DoppyNLPosted on 2003-10-23 at 05:02:48ID: 9605882

Got it working?
Still having some problems?
Did anyone help?

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Gzip

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