0cc11596c1
glibc has a system where, if it fails to perform Happy Eyeballs host
name resolution in parallel, it will do it sequentially.
We triggered this because our docker setup was not responding to
systemd-resolved's AAAA queries over IPv6.
The bug in glibc was then that it would poll for 4999ms after sending
the first of the two queries. __Every time__ we do mdns host lookup.
In tst_QTcpSocket this happens multiple times in ::initTestCase for the
proxy global-datatags. That means we would be stuck polling for
4999ms*5 (number of proxy addresses to look up) before every test-case
that would use proxy (even if the test just does a return in the
proxy-case). Plus another 4999ms for any mdns lookup we would need to
perform during the test.
This led to the test severely slowing down and timing out quite often.
Work around this by doing full mDNS before trying DNS.
This will let us resolve multi-label mDNS addresses.
Fixes: QTBUG-107696
Change-Id: I26c6b356b4c9712f4ac6d3613998ee448c0ca504
Reviewed-by: Dimitrios Apostolou <jimis@qt.io>
(cherry picked from commit 5c6814fb18)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
HOW TO BUILD Qt 6
Synopsis
System requirements
- C++ compiler supporting the C++17 standard
- CMake 3.16 or newer
- Ninja 1.8 or newer
- Python 3
For more details, see also https://doc.qt.io/qt-6/build-sources.html
Linux, Mac:
cd <path>/<source_package>
./configure -prefix $PWD/qtbase
cmake --build .
Windows:
- Open a command prompt.
- Ensure that the following tools can be found in the path:
- Supported compiler (Visual Studio 2019 or later, or MinGW-builds gcc 8.1 or later)
- Python 3 ([https://www.python.org/downloads/windows/] or from Microsoft Store)
cd <path>\<source_package>
configure -prefix %CD%\qtbase
cmake --build .
More details follow.
Build!
Qt is built with CMake, and a typical
configure && cmake --build . build process is used.
If Ninja is installed, it is automatically chosen as CMake generator.
Some relevant configure options (see configure -help):
-releaseCompile and link Qt with debugging turned off.-debugCompile and link Qt with debugging turned on.
Example for a release build:
./configure -prefix $PWD/qtbase
cmake --build .
Example for a developer build: (enables more autotests, builds debug version of libraries, ...)
./configure -developer-build
cmake --build .
See output of ./configure -help for documentation on various options to
configure.
The above examples will build whatever Qt modules have been enabled by default in the build system.
It is possible to build selected repositories with their dependencies by doing
a ninja <repo-name>/all. For example, to build only qtdeclarative,
and the modules it depends on:
./configure
ninja qtdeclarative/all
This can save a lot of time if you are only interested in a subset of Qt.
Hints
The submodule repository qtrepotools contains useful scripts for
developers and release engineers. Consider adding qtrepotools/bin
to your PATH environment variable to access them.
Building Qt from git
See http://wiki.qt.io/Building_Qt_6_from_Git and README.git for more information. See http://wiki.qt.io/Qt_6 for the reference platforms.
Documentation
After configuring and compiling Qt, building the documentation is possible by running
cmake --build . --target docs
After having built the documentation, you need to install it with the following command:
cmake --build . --target install_docs
The documentation is installed in the path specified with the
configure argument -docdir.
Information about Qt's documentation is located in qtbase/doc/README
Note: Building the documentation is only tested on desktop platforms.