Guide to Tracing

OpenSync has support for tracing the application calls that can be very helpfull to find and fix a problem quickly.

Note for Gentoo users: You need to build libopensync with debug useflag enabled.

The first thing you should do is to turn on tracing by setting the environment variable:

mkdir /var/tmp/os
export OSYNC_TRACE=/var/tmp/os
export SYNCML_TRACE=/var/tmp/os

If you're not using syncml plugin, $SYNCML_TRACE variable has no effect.

You can include sensitive data by setting the OSYNC_NOPRIVACY environment variable:

export OSYNC_NOPRIVACY=1

Warning: this just effects the OSYNC_TRACE-files, the SYNCML_TRACE-files will still contain sensitive data. When passing those forward, remember to remove the file(s) that contains syncml trace.

When you run some opensync command now, opensync will generated a couple of Thread*.log files like this:

/var/tmp/os% ls
Thread1076193760.log  Thread1076260000.log  Thread1104583600.log  Thread1113836464.log  Thread1130621872.log

Each of these files corresponds to one thread in opensync (we have to use a separate file for each thread so that the threads do not step on each others toes while accessing the files and to maintain readability)

Inside each file you will find a call hierachy with a timestamp like this:

[1113061111.389599]     >>>>>>>  osengine_new(0x804f318, 0xbffff598)
[1113061111.389699]             [CLI] DEBUG: Creating new client 0x805c238
[1113061111.389745]             [CLI] DEBUG: Creating new client 0x805ec28
[1113061111.389781]             >>>>>>>  osengine_mappingtable_new(0x805de98)
[1113061111.389807]                     osengine_mappingview_new(0x805ed68)
[1113061111.389828]                     osengine_mappingview_new(0x805f170)
[1113061111.389848]             <<<<<<<  osengine_mappingtable_new: 0x805f118
[1113061111.389868]     <<<<<<<  osengine_new: 0x805de98

This means that someone called osengine_new (notice that all call parameters are listed) which then called osengine_mappingtable_new.

if there was an error in a function it will be labeled like this:

[1113059956.276641]     >>>>>>>  osync_member_read_config(0x804e1b0, 0xbffff854, 0xbffff858, 0xbffff8f8)
[1113059956.276689]          [OSYNC] DEBUG: Unable to read file /tmp/plgtest.4HeEbc/evo2-sync.conf: No such file or directory
[1113059956.276714]     <--- ERROR --- osync_member_read_config: Unable to open file /tmp/plgtest.4HeEbc/evo2-sync.conf for reading: No such file or directory

So you can quickly search for errors by doing grep ERROR * or less * in the log directory. In less, letters n moves to next file, p to previous, /ERR searches string ERR.