php教程

FAM 函数

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User Contributed Notes

Yassin Ezbakhe <yassin88 at gmail dot com> 31-Aug-2005 04:16
I make a VERY simple class that monitors a folder (and its subfolders) for new or removed files. I use it in order to auto index a folder where I have all my eBooks into a MySQL database.

CLASS FILE:

<?php
class FileAlterationMonitor
{
    private $scanFolder, $initialFoundFiles;

    public function __construct($scanFolder)
    {
        $this->scanFolder = $scanFolder;
        $this->updateMonitor();
    }

    private function _arrayValuesRecursive($array)
    {
        $arrayValues = array();

        foreach ($array as $value)
        {
            if (is_scalar($value) OR is_resource($value))
            {
                 $arrayValues[] = $value;
            }
            elseif (is_array($value))
            {
                 $arrayValues = array_merge( $arrayValues, $this->_arrayValuesRecursive($value));
            }
        }

        return $arrayValues;
    }

    private function _scanDirRecursive($directory)
    {
        $folderContents = array();
        $directory = realpath($directory).DIRECTORY_SEPARATOR;

        foreach (scandir($directory) as $folderItem)
        {
            if ($folderItem != "." AND $folderItem != "..")
            {
                if (is_dir($directory.$folderItem.DIRECTORY_SEPARATOR))
                {
                    $folderContents[$folderItem] = $this->_scanDirRecursive( $directory.$folderItem."\\");
                }
                else
                {
                    $folderContents[] = $folderItem;
                }
            }
        }

        return $folderContents;
    }

    public function getNewFiles()
    {
        $finalFoundFiles = $this->_arrayValuesRecursive( $this->_scanDirRecursive($this->scanFolder));

        if ($this->initialFoundFiles != $finalFoundFiles)
        {
            $newFiles = array_diff($finalFoundFiles, $this->initialFoundFiles);
            return empty($newFiles) ? FALSE : $newFiles;
        }
    }

    public function getRemovedFiles()
    {
        $finalFoundFiles = $this->_arrayValuesRecursive( $this->_scanDirRecursive($this->scanFolder));

        if ($this->initialFoundFiles != $finalFoundFiles)
        {
            $removedFiles = array_diff( $this->initialFoundFiles, $finalFoundFiles);
            return empty($removedFiles) ? FALSE : $removedFiles;
        }
    }

    public function updateMonitor()
    {
        $this->initialFoundFiles = $this->_arrayValuesRecursive($this->_scanDirRecursive( $this->scanFolder));
    }
}
?>

A simple script that uses this class could be like this one (use it with PHP CLI):

<?php

$f = new FileAlterationMonitor($MY_FOLDER_TO_MONITOR)

while (TRUE)
{
    sleep(1);

    if ($newFiles = $f->getNewFiles())
    {
        // Code to handle new files
        // $newFiles is an array that contains added files
    }

    if ($removedFiles = $f->getRemovedFiles())
    {
        // Code to handle removed files
        // $newFiles is an array that contains removed files
    }

    $f->updateMonitor();
}
ca50015 at yahoo dot com 27-Nov-2004 09:17
if u want do recursive monitoring on directory tree,
dont use fam_monitor_directory()
try to use fam_monitor_collection() instead
:)
b e n a d l e r -at- g m x -d-o-t- net 11-Aug-2004 10:57
in the example above, I would not use the while(1) and sleep() functions, since then you're back at waiting and polling for file changes, which you were trying to avoid using fam.

Instead, you can use while(fam_next_event($resource)), which blocks until there is an event. No polling, no useless wasting of cpu  cycles.

Anyway, I have some problems with fam: It is very limited and almost useless.

 - You cannot monitor a directory tree easily, since fam_monitor_directory() is non-recursive. Its an ugly hack, but you can go through each subdir and also monitor it with fam_monitor_directory().

 - When you do that, you will have another problem: The events you get contain the code and the filename, but not the pathname of the file that caused the event. Thus, if you monitor two or more directories, and they possibly contain files with the same basename, you cannot find out what file has changed. One ugly solution might be to create a new fam_resource for each directory you want to monitor, but then you cannot use fam_next_event() in your while loop anymore.

 - When a big file is saved (i.e. with photoshop via samba), you get file_changed events pretty much every second the file is being written to. It is not possible to receive ONE event AFTER the file operation is done.

I'm not sure, but I think most of this is not PHPs fault. Its just that fam (or dnotify, which fam uses on linux) sucks very badly. If you search on google, it seems everyone hates fam/dnotify (even linus), but noone has done anything about it yet.

If you find out how to work around thing, or if I'm completely wrong about all of this, please post here! Thanks!
sergiopaternoster at no_spam_tiscali dot it 21-May-2004 09:20
Here is a simple script to check changes etc. to a file.
<?php

/* opens a connection to the FAM service daemon */
$fam_res = fam_open ();

/*
 * The second argument is the full pathname
 * of the file to monitor.
 * Note that you can't use relative pathnames.
*/
$nres = fam_monitor_file ( $fam_res, '/home/sergio/test/fam/file_to_monitor.log');

while(1){
    if( fam_pending ( $fam_res ) ) $arr = (fam_next_event($fam_res)) ;
    switch ($arr['code']){
        case 1:
            echo "FAMChanged\n";
            break;
        case 2:
            echo "FAMDeleted\n";
            break;
        case 3:
            echo "FAMStartExecuting\n";
            break;
        case 4:
            echo "FAMStopExecuting\n";
            break;
        case 5:
            echo "FAMCreated\n";
            break;
        case 6:
            echo "FAMMoved\n";
            break;
        case 7:
            echo "FAMAcknowledge\n";
            break;
        case 8:
            echo "FAMExists\n";
            break;
        case 9:
            echo "FAMEndExist\n";
            break;
        default:
            break;
    }
    if(isset($arr)) unset($arr);
   
    /* In order to avoid too much CPU load */
    usleep(5000);
}

/* Close FAM connection */
fam_close($fam_res);

?>
Hope this could help.
God Belss PHP!
regards
Sergio Paternoster

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