# Logging

The following environment variables control logging from Tracker daemons:

  * `TRACKER_VERBOSITY`: takes a value of 1, 2 or 3 and causes increasing
    amounts of log output from Tracker code to be written to stdout.
  * `G_MESSAGES_DEBUG`: controls log output from GLib-based libraries that
    are used in the Tracker process. Use `G_MESSAGES_DEBUG=all` for maximal
    log output.

Internally, Tracker will set `G_MESSAGES_DEBUG=Tracker` if `TRACKER_VERBOSITY`
is set and `G_MESSAGES_DEBUG` is not set, to enable printing of its own log
messages to stdout.

You can set these variables when using `tracker-sandbox`, and when running the
Tracker test suite. Note that Meson will not print log output from tests by
default, use `meson test --verbose` or `meson test --print-errorlogs` to
enable.

The functional tests understand an additional variable, `TRACKER_TESTS_VERBOSE`
with can be set to `1` or `yes` to see detailed logging from the test harness
itself, and full log output from the internal D-Bus daemon. By default, these
tests filter output from the D-Bus daemon to only show log messages from
Tracker processes. Anything written directly to stdout, for example by
`g_print()` or by the dbus-daemon itself, will not be displayed unless
`TRACKER_TESTS_VERBOSE` is set.

When working with GitLab CI, you can use the
[Run Pipeline dialog](https://gitlab.gnome.org/GNOME/tracker/pipelines/new)
to set the values of these variables and increase the verbosity of the tests in
CI.

# Attaching a debugger to Tracker daemons

Tracker daemons are not started directly. Instead they are started by the D-Bus
daemon by request. When using tracker-sandbox or the functional-tests, it's
difficult to start the daemon manually under `gdb`.

Instead, we recommend adding a 10 second timeout at the top of the daemon's
main() function. In Vala code, try this:

    print("Pausing to attach debugger. Run: gdb attach %i\n", Posix.getpid());
    Posix.usleep(10 * 1000 * 1000);
    print("Waking up again\n");

Run the test, using the `meson build --timeout-multiplier=10000`
option to avoid your process being killed by the test runner. When you see
the 'Pausing' message, run the `gdb attach``command in another terminal within
10 seconds.

# Running Tracker daemons under Valgrind

The Tracker daemons are launched using D-Bus autolaunch. When running them from
the source tree using tracker-sandbox or the functional tests, the commandline
is controlled by the D-Bus .service.in files stored in `./tests/services`. Just
change the `Exec=` line to add Valgrind, like this:

    Exec=/usr/bin/valgrind @abs_top_builddir@/src/tracker-store/tracker-store

By default the tracker-sandbox utility and the functional-tests will only
show output from Tracker code. For the functional-tests, set
TRACKER_TESTS_VERBOSE=1 to see output from Valgrind. For tracker-sandbox use
the `--debug-dbus` option.