QLoggingCategory - get default rules?

Dariusz

Hey

How can I get default rules from qt loging ?

When I do something like this >

    QLoggingCategory::setFilterRules(""
                  "*.debug=true\n"
                  "*.critical=true\n"
                  "*.warning=true\n"
                  "*.info=true\n"
                  "");

I get a LOT more print than I usually get. So I'd like to see what other things gets logged so I can control it a little better.
TIA!

jeremy_k

@Dariusz That's what the QLoggingCategory::installFilter function lets you do.

#include <QApplication>
#include <QLoggingCategory>
#include <QLabel>
#include <cstdio>

 QLoggingCategory::CategoryFilter oldFilter;

void myCategoryFilter(QLoggingCategory *category)
{
    printf("pre-filter  %s: debug:%d info:%d warning:%d critical:%d\n",
           category->categoryName(),
           category->isDebugEnabled(),
           category->isInfoEnabled(),
           category->isWarningEnabled(),
           category->isCriticalEnabled());
    if (oldFilter) {
        oldFilter(category);
        printf("post-filter %s: debug:%d info:%d warning:%d critical:%d\n",
               category->categoryName(),
               category->isDebugEnabled(),
               category->isInfoEnabled(),
               category->isWarningEnabled(),
               category->isCriticalEnabled());
    }
    fflush(stdout);
}

int main(int argc, char *argv[])
{
    oldFilter = QLoggingCategory::installFilter(myCategoryFilter);
    // Use some Qt functionality to cause categories to be registered
    QApplication a(argc, argv);
    QLabel label("text");
    label.show();
    return a.exec();
}

Sample ouput:

pre-filter  qt.qpa: debug:1 info:1 warning:1 critical:1
post-filter qt.qpa: debug:0 info:0 warning:1 critical:1
pre-filter  qt.qpa.screen: debug:1 info:1 warning:1 critical:1
post-filter qt.qpa.screen: debug:0 info:0 warning:0 critical:1
pre-filter  qt.accessibility.cache: debug:1 info:1 warning:1 critical:1
post-filter qt.accessibility.cache: debug:0 info:1 warning:1 critical:1
...

jeremy_k

QLoggingCategory::installFilter() looks like it can handle this.

For each category passed into the filter:

Call QLoggingCategory::isCriticalEnabled, isDebugEnabled, etc for the source code configuration.
Call the initially installed filter
Call isCriticalEnabled, etc for the configuration file and environment variable configuration

KH-219Design

I'm not sure I'm interpreting the thrust of the question correctly.

Nevertheless...

I think part of the question is how to basically figure out an exhaustive list of what is being enabled by using the snippet of code:

    QLoggingCategory::setFilterRules(""
                  "*.debug=true\n"
                  "*.critical=true\n"
                  "*.warning=true\n"
                  "*.info=true\n"
                  "");

As you said, it is indeed a LOT.

The first thing I thought of in terms of figuring out what the deluge consists of...

... I navigated to where I keep a copy of the source code to the whole Qt framework itself, and ran this:

# in a bash terminal:

grep -rwh Q_LOGGING_CATEGORY | grep '"qt\.' | sort | uniq | awk -F\" '{print $2}' | sort | uniq

This produces a list of 230 logging categories internal to Qt itself.

However, even this list of 230 categories is not exhaustive, because I have not cloned 100% of the framework, but rather only certain modules (including qtbase, qtdeclarative, and a handful of others).

I will post the list in a separate message (right after this one). Hopefully the forum software will put scrollbars around it.

Because Qt is consistent in naming its categories with the prefix qt., you can enable all of your own logging categories but none from Qt by doing something like this before launching the program:

export QT_LOGGING_RULES="*=true;qt*=false;"

KH-219Design

the output of my bash expression:

qt.accessibility.atspi
qt.accessibility.atspi.creation
qt.accessibility.cache
qt.accessibility.core
qt.bluetooth
qt.bluetooth.android
qt.bluetooth.bluez
qt.bluetooth.ios
qt.bluetooth.osx
qt.bluetooth.qml
qt.bluetooth.windows
qt.bluetooth.winrt
qt.bluetooth.winrt.service.thread
qt.corecon
qt.core.filesystemwatcher
qt.corelib.tests.itemmodels
qt.core.qabstractitemmodel.checkindex
qt.core.qmetaobject.connectslotsbyname
qt.core.socketnotifier_deprecation
qt.distanceField
qt.egl.xlib.debug
qt.eventdispatcher
qt.eventdispatcher.activity
qt.eventdispatcher.timers
qt.examples.imagegestures
qt.examples.pdfviewer
qt.gifrecorder
qt.glx
qt.gui.dnd
qt.gui.drawhelper
qt.gui.icc
qt.gui.shortcutmap
qt.gui.textureio
qt.imageformat.pdf
qt.labs.platform.dialogs
qt.labs.platform.menus
qt.labs.platform.tray
qt.labs.settings
qt.mm.camera
qt.mm.videorender
qt.modeltest
qt.multimedia.alsa.output
qt.multimedia.audioinput
qt.multimedia.audiointerface
qt.multimedia.audiooutput
qt.multimedia.deviceinfo
qt.multimedia.plugin
qt.multimedia.plugins.android
qt.multimedia.plugins.directshow
qt.multimedia.plugins.directshow.renderfilter
qt.multimedia.utils
qt.multimedia.video
qt.network.http2
qt.network.monitor
qt.network.socket
qt.network.socket.verbose
qt.network.ssl
qt.nfc.neard
qt.opengl.diskcache
qt.pdf.document
qt.pdf.links
qt.pdf.navigationstack
qt.pdf.search
qt.positioning.geoclue
qt.positioning.geoclue2
qt.positioning.serialnmea
qt.positioning.winrt
qt.qdoc
qt.qml.binding.removal
qt.qml.diskcache
qt.qml.gc.allocatorStats
qt.qml.gc.statistics
qt.qml.tablemodel
qt.qpa
qt.qpa.accessibility
qt.qpa.application
qt.qpa.backingstore
qt.qpa.backingstore.iosurface
qt.qpa.clipboard
qt.qpa.cocoa.notifications
qt.qpa.dialogs
qt.qpa.drawing
qt.qpa.egldeviceintegration
qt.qpa.eglfs.kms
qt.qpa.events
qt.qpa.events.reader
qt.qpa.fb
qt.qpa.fonts
qt.qpa.gl
qt.qpa.glcontext
qt.qpa.input
qt.qpa.input.devices
qt.qpa.input.events
qt.qpa.input.gestures
qt.qpa.input.keymap
qt.qpa.input.methods
qt.qpa.input.methods.serialize
qt.qpa.input.mouse
qt.qpa.input.tablet
qt.qpa.input.touch
qt.qpa.menu
qt.qpa.menus
qt.qpa.mime
qt.qpa.openglcontext
qt.qpa.peeker
qt.qpa.plugin
qt.qpa.screen
qt.qpa.screen.updates
qt.qpa.theme
qt.qpa.tray
qt.qpa.trayicon
qt.qpa.tuio.bundle
qt.qpa.tuio.handler
qt.qpa.tuio.message
qt.qpa.tuio.set
qt.qpa.tuio.source
qt.qpa.uiautomation
qt.qpa.vnc
qt.qpa.wayland
qt.qpa.wayland.backingstore
qt.qpa.wayland.input
qt.qpa.window
qt.qpa.windows
qt.qpa.xcb
qt.qpa.xdnd
qt.qpa.xkeyboard
qt.quick.boundaryrule
qt.quick.canvas
qt.quick.controls.control.itemmanagement
qt.quick.controls.imagine
qt.quick.controls.splitview
qt.quick.controls.splitview.mouse
qt.quick.controls.splitview.state
qt.quick.controls.style
qt.quick.controls.tools.testbench.assetfixer.brief
qt.quick.controls.tools.testbench.assetfixer.verbose
qt.quick.controls.tumbler
qt.quick.controls.tumblerview
qt.quick.dialogs.registration
qt.quick.dialogs.window
qt.quick.dirty
qt.quick.focus
qt.quick.gesture.target
qt.quick.handler.active
qt.quick.handler.dispatch
qt.quick.handler.drag
qt.quick.handler.grab
qt.quick.handler.hover
qt.quick.handler.parent
qt.quick.handler.pinch
qt.quick.handler.tap
qt.quick.handler.wheel
qt.quick.hover.trace
qt.quick.image
qt.quick.itemview.delegaterecycling
qt.quick.itemview.lifecycle
qt.quick.mouse
qt.quick.mouse.target
qt.quick.pathview
qt.quick.pointer.events
qt.quick.pointer.grab
qt.quick.pointer.tests
qt.quick.sharedimage
qt.quick.tablet
qt.quick.tableview.lifecycle
qt.quick.tests
qt.quick.touch
qt.quick.touch.target
qt.quick.wheel.target
qt.quick.window.transient
qt.rhi.general
qt.scaling
qt.scenegraph.general
qt.scenegraph.info
qt.scenegraph.renderloop
qt.scenegraph.softwarecontext.abstractrenderer
qt.scenegraph.softwarecontext.pixmapRenderer
qt.scenegraph.softwarecontext.renderable
qt.scenegraph.softwarecontext.renderer
qt.scenegraph.textureio
qt.scenegraph.time.compilation
qt.scenegraph.time.glyph
qt.scenegraph.time.renderer
qt.scenegraph.time.renderloop
qt.scenegraph.time.texture
qt.shape.time.sync
qt.speech.tts.android
qt.speech.tts.flite
qt.svg
qt.svg.draw
qt.test
qt.text.browser
qt.text.drawing
qt.text.font.db
qt.text.font.match
qt.text.hittest
qt.text.layout
qt.text.layout.table
qt.text.markdown
qt.text.markdown.writer
qt.text.tests
qt.v4.asm
qt.virtualkeyboard
qt.virtualkeyboard.hunspell
qt.virtualkeyboard.lipi
qt.virtualkeyboard.myscript
qt.virtualkeyboard.openwnn
qt.virtualkeyboard.pinyin
qt.virtualkeyboard.t9write
qt.virtualkeyboard.tcime
qt.virtualkeyboard.tests.manual.x11vkbtest.filehelper
qt.virtualkeyboard.tests.manual.x11vkbtest.memorymonitor
qt.virtualkeyboard.tests.manual.x11vkbtest.testlanguagechange
qt.virtualkeyboard.tests.manual.x11vkbtest.testthread
qt.virtualkeyboard.tests.manual.x11vkbwrapper.handleatspievents
qt.virtualkeyboard.tests.manual.x11vkbwrapper.handlekeyevents
qt.virtualkeyboard.tests.manual.x11vkbwrapper.handlelanguagechange
qt.vulkan
qt.waylandcompositor
qt.waylandcompositor.hardwareintegration
qt.waylandcompositor.inputmethods
qt.webengine.webchanneltransport
qt.widgets.gestures
qt.widgets.painting
qt.widgets.tests
qt.widgets.tests.qfilesystemmodel
qt.winrtrunner
qt.winrtrunner.app
qt.xkbcommon
qt.xkb.compose

Dariusz

@KH-219Design Thanks lots! Whoa there is lots of tags O_O. But... how do I get the currently enabled tags? Is there a way to retrieve the list?
I know that not everything gets printed as if I do *.debug=true/etc/etc I get more prints. So I wonder if there is a path for that? Or all get set up dynamically?

jeremy_k

@Dariusz That's what the QLoggingCategory::installFilter function lets you do.

#include <QApplication>
#include <QLoggingCategory>
#include <QLabel>
#include <cstdio>

 QLoggingCategory::CategoryFilter oldFilter;

void myCategoryFilter(QLoggingCategory *category)
{
    printf("pre-filter  %s: debug:%d info:%d warning:%d critical:%d\n",
           category->categoryName(),
           category->isDebugEnabled(),
           category->isInfoEnabled(),
           category->isWarningEnabled(),
           category->isCriticalEnabled());
    if (oldFilter) {
        oldFilter(category);
        printf("post-filter %s: debug:%d info:%d warning:%d critical:%d\n",
               category->categoryName(),
               category->isDebugEnabled(),
               category->isInfoEnabled(),
               category->isWarningEnabled(),
               category->isCriticalEnabled());
    }
    fflush(stdout);
}

int main(int argc, char *argv[])
{
    oldFilter = QLoggingCategory::installFilter(myCategoryFilter);
    // Use some Qt functionality to cause categories to be registered
    QApplication a(argc, argv);
    QLabel label("text");
    label.show();
    return a.exec();
}

Sample ouput:

pre-filter  qt.qpa: debug:1 info:1 warning:1 critical:1
post-filter qt.qpa: debug:0 info:0 warning:1 critical:1
pre-filter  qt.qpa.screen: debug:1 info:1 warning:1 critical:1
post-filter qt.qpa.screen: debug:0 info:0 warning:0 critical:1
pre-filter  qt.accessibility.cache: debug:1 info:1 warning:1 critical:1
post-filter qt.accessibility.cache: debug:0 info:1 warning:1 critical:1
...