[regression] Mir deb packages with versioned names cannot be installed simultaneously any more

[Daniel van Vugt]

Mir has some packages with ABI-versioned names (libmirserver17, libmirclient7) so that multiple versions can be installed simultaneously, in theory. However this plan is not working;

Package: libmirserver17
Section: libs
Architecture: i386 amd64 armhf arm64
Multi-Arch: same
Pre-Depends: ${misc:Pre-Depends}
Depends: ${misc:Depends},
         ${shlibs:Depends},
         libmirplatform (= ${binary:Version}),
         libmirplatformgraphics-mesa (= ${binary:Version}) |
           libmirplatformgraphics-android (= ${binary:Version}),

When we bump an ABI number, we also increase the ${binary:Version}. So you can see from the names that libmirplatform* can only have one version installed at a time. And that indirectly means that libmirserverN can never be installed simultaneously with libmirserverN+1.

This also leads to annoying CI failures as we're seeing this week:

The following packages have unmet dependencies:
 libmirserver16 : Depends: libmirplatform (= 0.1.6+14.04.20140310-0ubuntu1) but 0.1.7+autopilot0 is to be installed
                  Depends: libmirplatformgraphics-mesa (= 0.1.6+14.04.20140310-0ubuntu1) but 0.1.7+autopilot0 is to be installed or
                           libmirplatformgraphics-android (= 0.1.6+14.04.20140310-0ubuntu1) but 0.1.7+autopilot0 is to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

There are at least two possible solutions I can think of so far:

(1) Change our Depends' to not use straight equality. So we must change:
   libmirplatform (= ${binary:Version}),
to:
   libmirplatform (>= ${binary:Version}),
or even to
   libmirplatform (>= some_older_version_based_on_real_requirements),

(2) Change libplatform* to include some ABI number in their names. Not ideal.

I like (1).

[Chris Halse Rogers (raof)]

3) Install libmirplatform in directories corresponding to the SOVER. I prefer this even more, because we then don't have plugin objects polluting the default loader path.

[Daniel van Vugt (vanvugt)]

Interesting. Although there are sometimes cases when you do want to treat a plugin as a shared library (e.g. plugin dependencies).
This is the reason why I've seen multiple projects continue to name their plugins:
    libfoo.so
instead of the simpler:
    foo.so
Just because there's a chance you might sometimes want to treat it as a library.

[Michael Terry (mterry)]

Would (1) even work? If libmirplatform is changing ABI, the old libmirserver7 wouldn't work with it, eh? I'd expect you'd need (2) in that case.

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:mir/devel at revision None, scheduled for release in mir, milestone Unknown

[Daniel van Vugt (vanvugt)]

Fix backported to lp:mir/0.6 at revision 1839.

[Daniel van Vugt (vanvugt)]

mir (0.6.0+14.10.20140811-0ubuntu1) utopic; urgency=medium

[Daniel van Vugt (vanvugt)]

Sorry for the confusion. Most of the 0.7.0 series got merged into 0.6.0 at a late stage. I've verified everything in 0.6.0 is also fixed in 0.7.0. So although the branched fixes in 0.7.0 have not been "released" yet, the equivalent fixes in 0.6.0 have. No need to mention them in 0.7 any more.

[Daniel van Vugt (vanvugt)]

Oops. Actually this never was really fixed. We haven't converted libmir*platform*.so yet...

More work is still coming: lp:~raof/mir/privatise-all-the-things

[Daniel van Vugt (vanvugt)]

Is there a simpler/faster way to resolve this bug? It seems like it will be holding up the Mir 0.8 release now:
https://code.launchpad.net/~vanvugt/mir/server-ABI-26/+merge/233142

[Daniel van Vugt (vanvugt)]

Bumped to critical per comment #9.

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:mir/devel at revision None, scheduled for release in mir, milestone Unknown

[Launchpad Janitor (janitor)]

This bug was fixed in the package mir - 0.8.0+14.10.20141010-0ubuntu1

---------------
mir (0.8.0+14.10.20141010-0ubuntu1) utopic; urgency=medium

  [ Daniel van Vugt ]
  * New upstream release 0.8.0 (https://launchpad.net/mir/+milestone/0.8.0)
    - Enhancements:
      . Less sensitivity to ABI breaks - many headers unused by external
        projects are now hidden and not installed by -dev packaes. If you
        require any headers that are missing, just ask.
      . Touchspots: --enable-touchspots to servers; visually shows touch
        locations (warning: This affects performance LP: #1373692).
      . Client performance reporting: Any Mir client can now get accurate
        performance information (frame rate, render time, buffer lag etc)
        logged to stdout. Just set env MIR_CLIENT_PERF_REPORT=log
      . Further improved touch responsiveness, with less lag and smoother
        scrolling (so long as you don't enable touchspots).
      . Slightly faster builds using precompiled headers.
      . Turn hardware overlays on by default. When in use, this halves the
        CPU usage of a Mir server. Already enabled in unity-system-compositor.
      . More scripting to detect ABI breaks.
      . Improved src/ tree consistency (renamed "src/shared" to "src/common").
      . Improved fatal signal design: Changed from SIGTERM to SIGHUP delivered
        to clients on unexpected server disconnection.
      . Improved library/package design to allow concurrent installations
        of different Mir versions without conflicts.
      . Fd reception code is now common to client and server.
    - ABI summary: Servers need rebuilding, but clients do not;
      . Mirclient ABI unchanged at 8
      . Mircommon ABI bumped to 2
      . Mirplatform ABI bumped to 3
      . Mirserver ABI bumped to 26
    - API changes between Mir 0.7 and 0.8:
      . Lots of headers removed from the public SDK! We have only hidden
        headers not known to be used by any known projects. Please let us
        know if anything is missing - https://bugs.launchpad.net/mir/+filebug
      . graphics::Platform - interface changed significantly.
      . Lots of server API changes to support touchspots.
      . File descriptors now passed as type Fd instead of int32_t.
    - Bug fixes:
      . [regression] Mir deb packages with versioned names cannot be installed
        simultaneously any more (LP: #1293944)
      . A frozen client can hang the whole server (LP: #1350207)
      . QtMir FTBFS: fatal error: mir/input/input_channel.h: No such file or
        directory (LP: #1365934)
      . [regression] platform-api fails to build against Mir 0.8 (LP: #1368354)
      . Mir FTBFS with gcc 4.9.1-14 (utopic update):
        auto_unblock_thread.h:44:46: error: no matching function for call to
        ‘std::thread::thread(<brace-enclosed initializer list>)’ (LP: #1369389)
      . [regression] Compositing is jerky and stutters during touch events
        (LP: #1372850)
      . unit test fails: AndroidInputReceiverSetup.slow_raw_input_doesnt_cause_
        frameskipping (LP: #1373826)
      . intermittent hang in TestClientInput (LP: #1338612)
      . TestClientInput.scene_obscure_mo...

[Launchpad Janitor (janitor)]

This bug was fixed in the package mir - 0.8.0+14.10.20141005-0ubuntu1

---------------
mir (0.8.0+14.10.20141005-0ubuntu1) 14.09; urgency=medium

  [ Daniel van Vugt ]
  * New upstream release 0.8.0 (https://launchpad.net/mir/+milestone/0.8.0)
    - Enhancements:
      . Less sensitivity to ABI breaks - many headers unused by external
        projects are now hidden and not installed by -dev packaes. If you
        require any headers that are missing, just ask.
      . Touchspots: --enable-touchspots to servers; visually shows touch
        locations (warning: This affects performance LP: #1373692).
      . Client performance reporting: Any Mir client can now get accurate
        performance information (frame rate, render time, buffer lag etc)
        logged to stdout. Just set env MIR_CLIENT_PERF_REPORT=log
      . Further improved touch responsiveness, with less lag and smoother
        scrolling (so long as you don't enable touchspots).
      . Slightly faster builds using precompiled headers.
      . Turn hardware overlays on by default. When in use, this halves the
        CPU usage of a Mir server. Already enabled in unity-system-compositor.
      . More scripting to detect ABI breaks.
      . Improved src/ tree consistency (renamed "src/shared" to "src/common").
      . Improved fatal signal design: Changed from SIGTERM to SIGHUP delivered
        to clients on unexpected server disconnection.
      . Improved library/package design to allow concurrent installations
        of different Mir versions without conflicts.
      . Fd reception code is now common to client and server.
    - ABI summary: Servers need rebuilding, but clients do not;
      . Mirclient ABI unchanged at 8
      . Mircommon ABI bumped to 2
      . Mirplatform ABI bumped to 3
      . Mirserver ABI bumped to 26
    - API changes between Mir 0.7 and 0.8:
      . Lots of headers removed from the public SDK! We have only hidden
        headers not known to be used by any known projects. Please let us
        know if anything is missing - https://bugs.launchpad.net/mir/+filebug
      . graphics::Platform - interface changed significantly.
      . Lots of server API changes to support touchspots.
      . File descriptors now passed as type Fd instead of int32_t.
    - Bug fixes:
      . [regression] Mir deb packages with versioned names cannot be installed
        simultaneously any more (LP: #1293944)
      . A frozen client can hang the whole server (LP: #1350207)
      . QtMir FTBFS: fatal error: mir/input/input_channel.h: No such file or
        directory (LP: #1365934)
      . [regression] platform-api fails to build against Mir 0.8 (LP: #1368354)
      . Mir FTBFS with gcc 4.9.1-14 (utopic update):
        auto_unblock_thread.h:44:46: error: no matching function for call to
        ‘std::thread::thread(<brace-enclosed initializer list>)’ (LP: #1369389)
      . [regression] Compositing is jerky and stutters during touch events
        (LP: #1372850)
      . unit test fails: AndroidInputReceiverSetup.slow_raw_input_doesnt_cause_
        frameskipping (LP: #1373826)
      . intermittent hang in TestClientInput (LP: #1338612)
      . TestClientInput.scene_obscure_mot...