Context Files Losing Parameters

I had the same issue. Cleared out /var/cache/aastra and reprovisioned phones. It hasn't happened since but I am getting ready to put this system into production and you have me a little worried now.

I had the same problem occur using the default poll interval of 1800. I also am only using three phones. Could the action uri xml sip notify and action uri poll be conflicting? Is the action URI poll even necessary now that the scripts use xml sip notify?

All,

I have reproduced the problem which was coming from race conditions in the save_user_context function as the 3 scripts were trying to write at the same time.
Here is a quick fix to solve this issue, I will do a better solution in the next version of the scripts.

In asterisk/cfwd.php
Line 80
Replace Aastra_save_user_context($user,'cfwd',$data);
By if($cf!=$last) Aastra_save_user_context($user,'cfwd',$data,'cf');
Line 115
Replace Aastra_save_user_context($user,'cfwd',$data);
By Aastra_save_user_context($user,'cfwd',$data,'cf');

In asterisk/daynight.php
Line 160
Replace Aastra_save_user_context($user,'daynight',$data);
By Aastra_save_user_context($user,'daynight',$data,'dn');
Line 205
Replace Aastra_save_user_context($user,'daynight',$data);
By if($night!=$last) Aastra_save_user_context($user,'daynight',$data,'dn');

In asterisk/dnd.php
Line 111
Replace Aastra_save_user_context($user,'dnd',$data);
By Aastra_save_user_context($user,'dnd',$data,'dnd');
Line 151
Replace Aastra_save_user_context($user,'dnd',$data);
By if($dnd!=$last) Aastra_save_user_context($user,'dnd',$data,'dnd');

In include/AastraCommon.php
Line 839
Replace function Aastra_get_user_context($user,$appli)
By function Aastra_get_user_context($user,$appli,$special='')
Line 845
Replace $file=AASTRA_PATH_CACHE.$user.".context";
By
if($special=='') $file=AASTRA_PATH_CACHE.$user.".context";
else $file=AASTRA_PATH_CACHE.$user."-".$special.".context";
Line 869
Replace function Aastra_save_user_context($user,$appli,$data)
By function Aastra_save_user_context($user,$appli,$data,$special='')
Line 875
Replace $file=AASTRA_PATH_CACHE.$user.".context";
By
if($special=='') $file=AASTRA_PATH_CACHE.$user.".context";
else $file=AASTRA_PATH_CACHE.$user."-".$special.".context";

I checked my fix with 5 phones plooing every seconds, as now each application has its own context file updated only when needed, it should work. I will work on a more elegant solution for the future.

Can you implement the fix and let me know if everything is fixed.

Thanks for finding this one.

Regards

Aastra1

The solution proposed above has several problems.
1) (Serious) The saving is done to application-specific context files, but the reading is always from the main context file. Effectively, the saves don't do anything.
2) (Serious) If the reading *were* done from the application-specific context files, then startup.php would have to be altered to create those files in the first case.
3) (Minor) The "special" parameter seems to duplicate the application parameter. Seems like one should be enough.

I think that the solution *may* be much simpler; locking the context file properly while writing to it, so that other processes cannot read from it before it is completely written. Here's the proposed fix:

AastraCommon.php
888,891c888,895
$value)
---
> if (flock($handle, LOCK_EX))
> {
> foreach($array as $key=>$value)
> {
> fputs($handle,'['.$key.']'."\n");
> fputs($handle,'data='.$value['data']."\n");
> }
> flock($handle, LOCK_UN);

(The tabs got lost in the above diff files, but you get the idea.)

I would also support your idea of writing out the file only when needed, like this:

cfwd.php
80c80
---
> if ($cf!=$last) Aastra_save_user_context($user,'cfwd',$data);

dnd.php
151c151
---
> if($dnd!=$last) Aastra_save_user_context($user,'dnd',$data);

daynight.php
205c205
---
> if($night!=$last) Aastra_save_user_context($user,'daynight',$data);

I have the first part of this fix in place now, and it seems to be working. I will test it overnight and see if the problem is solved, then report back.

Hmmm. The change I made didn't work -- in fact, the context files got even more mangled.

I'm going to have to dig deeper into what's happening here. I'll report back when I come up with something.

Got it!

You were most likely correct that the Aastra_readINIfile function needed to lock the context file as well, so I tried that, but with no luck. Then after some research and careful thought, I figured out what was wrong. A file cannot be locked until after it is opened. Opening it with mode "w" will immediately truncate the file contents, allowing other processes to read an empty file before the lock can be placed. The solution is to open the file with mode "r+" and then explicitly truncate the contents *after* the lock is in place. Here is the patch:

--- AastraCommon.php.orig	2008-10-28 13:11:52.000000000 -0400
+++ AastraCommon.php	2008-10-29 16:16:02.000000000 -0400
@@ -582,7 +582,21 @@
 ###################################################################################################
 function Aastra_readINIfile ($filename, $commentchar, $delim) 
 {
-$array1 = @file($filename);
+$array1 = array();
+$handle = @fopen($filename, "r");
+if ($handle)
+	{
+	if (flock($handle, LOCK_SH))
+		{
+		while (!feof($handle))
+			{
+			$array1[] = fgets($handle);
+			}
+		flock($handle, LOCK_UN);
+		}   
+	fclose($handle);
+	}
+
 $section = '';
 foreach ($array1 as $filedata) 
 	{
@@ -882,13 +896,18 @@
 $array[$appli]['data']=base64_encode(serialize($data));
 
 # Create cache file
-$handle = @fopen($file, "w");
+$handle = @fopen($file, "r+");
 if($handle)
 	{
-	foreach($array as $key=>$value)
+	if (flock($handle, LOCK_EX))
 		{
-		fputs($handle,'['.$key.']'."\n");
-		fputs($handle,'data='.$value['data']."\n");
+        	ftruncate($handle, 0);
+		foreach($array as $key=>$value)
+			{
+			fputs($handle,'['.$key.']'."\n");
+			fputs($handle,'data='.$value['data']."\n");
+			}
+		flock($handle, LOCK_UN);
 		}
 	fclose($handle);
 	}

This fix has been in place for the last 24 hours, and not one context file has lost parameters.

I also think I will add the tiny mods listed above to dnd.php, cfwd.php and daynight.php so that the context file will not be written to when the status hasn't changed. I'm pretty sure it introduces a theoretical opportunity for the context file to get out of sync, perhaps if a user presses a button at the same time as the polling occurs, so it may not be ideal for everyone. But I suspect the chances of that are minimal, and the fix is easy. Since it will reduce my server's I/O load by about 330 writes per minute, it's worth it to me.

Thanks!

In case anyone else has had this happen with large numbers of phones and needs to fix the "key" parameters in the context files *without* hosing the other data, here is a simple way. There's a program and a script to run it against all the files. Note that the program has hard-coded values and will need to be changed based on your setup.

fixcontext.php

#!/usr/bin/php

fixcontext.sh (to be run from /var/www/html/aastra/asterisk)

#!/bin/bash

ls -1 /var/cache/aastra/*.context | cut -d/ -f5 | cut -d. -f1 | xargs ./fixcontext.php

Hope this helps!