1: <?php
 2: /**
 3:  * Simple interface for tracking memory consumption.
 4:  *
 5:  * <code>
 6:  *  $t = new Horde_Support_Memory;
 7:  *  $t->push();
 8:  *  $used = $t->pop();
 9:  * </code>
10:  *
11:  * Do not expect too much of this memory tracker. Profiling memory is not
12:  * trivial as your placement of the measurements may obscure important
13:  * information. As a trivial example: Assuming that your script used 20 MB of
14:  * memory befory you call push() the information you get when calling pop()
15:  * might only tell you that there was less than 20 MB of memory consumed in
16:  * between the two calls. Take the changes to internal memory handling of PHP in
17:  * between the different versions into account
18:  * (http://de3.php.net/manual/en/features.gc.performance-considerations.php) and
19:  * you should get an idea about why you might be cautious about the values you
20:  * get from this memory tracker.
21:  *
22:  * Copyright 2011-2012 Horde LLC (http://www.horde.org/)
23:  *
24:  * @category   Horde
25:  * @package    Support
26:  * @license    http://www.horde.org/licenses/bsd
27:  */
28: class Horde_Support_Memory
29: {
30:     /**
31:      * Holds the starting memory consumption.
32:      *
33:      * @var array
34:      */
35:     protected $_start = array();
36: 
37:     /**
38:      * Current index for stacked trackers.
39:      *
40:      * @var integer
41:      */
42:     protected $_idx = 0;
43: 
44:     /**
45:      * Push a new tracker on the stack.
46:      */
47:     public function push()
48:     {
49:         $start = $this->_start[$this->_idx++] = array(
50:             memory_get_usage(),
51:             memory_get_peak_usage(),
52:             memory_get_usage(true),
53:             memory_get_peak_usage(true)
54:         );
55:         return $start;
56:     }
57: 
58:     /**
59:      * Pop the latest tracker and return the difference with the current
60:      * memory situation.
61:      *
62:      * @return array The change in memory allocated via emalloc() in between the
63:      *               push() and the pop() call. The array holds four values: the
64:      *               first one indicates the change in current usage of memory
65:      *               while the second value indicates any changes in the peak
66:      *               amount of memory used. The third and fourth value show
67:      *               current and peak usage as well but indicate the real memory
68:      *               usage and not just the part allocated via emalloc(),
69:      */
70:     public function pop()
71:     {
72:         if (! ($this->_idx > 0)) {
73:             throw new Exception('No timers have been started');
74:         }
75:         $start = $this->_start[--$this->_idx];
76:         return array(
77:             memory_get_usage() - $start[0],
78:             memory_get_peak_usage() - $start[1],
79:             memory_get_usage(true) - $start[2],
80:             memory_get_peak_usage(true) - $start[3]
81:         );
82:     }
83: 
84: }
85: