[imp] IMP Memory usage

[sotero at uolsinectis.com.ar]

Hi.
I have been doing some simple tests with IMP4. It's a great piece of
  software and excellent functionality.
  I'm setting it up to be used by several thousands of clients and although
  it'll run in pretty big machines (a couple of Dual Xeon 2.8Ghz, 2Gb Ram,
  SCSI RAID 6) I am evaluating some more of the cpu/memory intensive
  caracteristics (compression, mime decode, text processing -Filter class-).
  We allow our clients mails up to 13Mb each. Now, I tested IMP with a 8Mb
  attachment and got:

  (I started using a 20Mb limit)

    PHP Fatal error:  Allowed memory size of 20971520 bytes exhausted (tried
  to allocate 10646241 bytes) in /usr/local/lib/php/Horde/MIME/Part.php on
  line 306

  and after moving to 50Mb limit:

    PHP Fatal error:  Allowed memory size of 50331648 bytes exhausted (tried
  to allocate 10646241 bytes) in /usr/local/lib/php/Horde/MIME/Part.php on
  line 1209

  I think 10646241 is the sizes of the base 64 encoded attachment.
  After a short following of the code, I found lot of memory copies. Don't
  know if they´re unnecesary, but I took a chance and made some changes:

  After this:
  Index: lib/MIME/Contents.php
  ===================================================================
  RCS file: /repository/imp/lib/MIME/Contents.php,v
  retrieving revision 1.155
  diff -u -b -r1.155 Contents.php
  --- lib/MIME/Contents.php       7 Jan 2005 19:09:07 -0000       1.155
  +++ lib/MIME/Contents.php       14 Jan 2005 15:28:03 -0000
  @@ -155,15 +155,14 @@
         *
         * @return string  The text of the part.
         */
  -    function getBodyPart($id)
  +    function &getBodyPart($id)
        {
  -        $contents = '';

            if (!isset($this->_bodypart[$id])) {
                $this->_bodypart[$id] =
  @imap_fetchbody($GLOBALS['imp']['stream'], $this->_index, $id, FT_UID);
            }

  -        return ($contents . $this->_bodypart[$id]);
  +        return !empty($this->_bodypart[$id])?$this->_bodypart[$id]:'';
        }

  And

  Index: Part.php
  ===================================================================
  RCS file: /repository/framework/MIME/MIME/Part.php,v
  retrieving revision 1.178
  diff -u -b -r1.178 Part.php
  --- Part.php    3 Jan 2005 13:09:09 -0000       1.178
  +++ Part.php    14 Jan 2005 15:40:09 -0000
  @@ -301,9 +301,9 @@
         * @param string $contents           The part body.
         * @param optional string $encoding  The current encoding of the
  contents.
         */
  -    function setContents($contents, $encoding = null)
  +    function setContents(&$contents, $encoding = null)
        {
  -        $this->_contents = $contents;
  +        $this->_contents = &$contents;
            $this->_flags['contentsSet'] = true;
            $this->_currentEncoding = (is_null($encoding)) ?
  $this->getCurrentEncoding() : MIME::encoding($encoding, MIME_STRING);
        }
  @@ -382,7 +382,7 @@
         */
        function transferDecodeContents()
        {
  -        $contents = $this->transferDecode();
  +        $contents = &$this->transferDecode();
            $this->_currentEncoding = $this->_flags['lastTransferDecode'];
            $this->setTransferEncoding($this->_currentEncoding);

  @@ -1190,7 +1190,8 @@
         */
        function transferDecode()
        {
  -        $contents = $this->getContents();
  +
  +        $contents = &$this->getContents();
            $encoding = $this->getCurrentEncoding();

            /* If the contents are empty, return now. */

  I was able to download the attachment with the same php.ini settings. Can
  anyone see a problem with this?

  --
  Juan Germano
  Ingeniería de Portal
  UOLSinectis Argentina