[Spice-devel] [PATCH v2 0/4] Add context to SpiceCoreInterface

[Frediano Ziglio]

This patchset want to solve the problem of not having a context in
SpiceCoreInterface.  SpiceCoreInterface defines a set of callbacks to
handle events in spice-server.  These callbacks allow to handle timers,
watch for file descriptors and send channel events.  All these callbacks
does not accept a context (usually in C passed as a void* parameter) so
they is hard for them to differentiate the interface specified.
Unfortunately this structure is used even internally from different
contextes for instance every RedWorker thread have a different context. To
solve this issue some workarounds are used. Currently for timers a variable
depending on the current thread is used while for watches the opaque
parameter to pass to the event callback is used as it currently points just
to RedChannelClient structure.  This however impose some implicit
maintanance problem in the future. What happen for instance if for some
reason a timer is registered during worker initialization, run in another
thread? What if we decide to register a file descriptor callback for
something not a RedChannelClient?  Could be that the program will run
without any issue till some bytes changes and weird thing could happen.

The implementation of this solution is done implementing an internal "core"
interface that have context specification and use it to differentiate the
context instead of relying to some other, hard to maintain, detail. Then an
adapter structure (name inpired to the adapter pattern) will provide the
internal core interface using the external, public, definition (in the
future this technique can be used to extend the external interface without
breaking the ABI).

First patches are intended to be just mechanical changes to make easier to
understand the idea. Note that not all callbacks
from the public SpiceCoreInterface have a context (a "const
SpiceCoreInterfaceInternal *" argument) but this can be easily extended.
Last patch is the main reason for these patches.

Changes from v1:
- updated all patches comments including mostly of this description
  on third one;
- limit rcc scope on last patch as suggested by Christophe.

Frediano Ziglio (4):
  channel: add a new internal SpiceCoreInterface
  channel: build adapter for public core interface
  channel: add interface parameters to SpiceCoreInterfaceInternal
  channel: use iface parameter to distinguish interface context

 server/char-device.c         |  4 +--
 server/inputs-channel.c      |  2 +-
 server/main-channel.c        |  2 +-
 server/main-dispatcher.c     |  6 ++--
 server/main-dispatcher.h     |  2 +-
 server/red-channel.c         | 18 ++++++-----
 server/red-channel.h         |  6 ++--
 server/red-common.h          | 15 +++++++++
 server/red-worker.c          | 21 ++++++------
 server/reds-stream.c         |  4 +--
 server/reds.c                | 77 ++++++++++++++++++++++++++++++++++++++------
 server/reds.h                |  2 +-
 server/sound.c               |  2 +-
 server/spice_timer_queue.c   |  3 +-
 server/spice_timer_queue.h   |  3 +-
 server/tests/test_playback.c |  1 -
 16 files changed, 121 insertions(+), 47 deletions(-)

-- 
2.4.3