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[Qemu-block] [PATCH v2 0/6] Stable output of blockdev format specific in


From: Daniel P. Berrange
Subject: [Qemu-block] [PATCH v2 0/6] Stable output of blockdev format specific info
Date: Fri, 9 Sep 2016 18:41:55 +0100

This is an update of the bits of this previous
series which were not merged

  https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg01723.html

The problem addressed in this series is that the
'qemu-img info' command does not have a stable
output format for the image specific info objects.

The QAPI types are first converted to QDicts,
and then printed with custom code to recurse over
the QDicts. This causes information about the object
field ordering to be thrown away, and fields are
printed in whatever order they appear in the QDict
hash buckets. This is not a big deal historically
since none of the image formats had nested data
structures, but with the LUKS blockdev this style
of random ordering looks very unpleasant.

To address this, the patch series introduces a
TextOutputVisitor class that is designed to be
able to print out arbitrarily nested QAPI types
directly, in a format that is identical to that
currently used with 'qemu-img info'. Consult
the patch in question to actually see the output
format, and compare test-string-output-visitor.c
with test-text-output-visitor.c to see how we
really do have 2 completely distinct output formats
that don't share any significant characteristics
beyond both being "plain text".

Changed in v2:

 - Pulled code for printing sized value out into the
   cutils file via qemu_sztostr* methods
 - Added unit test for text output visitor
 - Convert block code to use qemu_sztostr* methods
 - Convert string output visitor code to use
   qemu_sztostr* methods
 - Document the string output visitor format against
   its constructor
 - Document the text otput visitor format against
   its constructor.
 - Adjustments to block i/o tests to take account of
   stable field ordering
 - Adjustments to block i/o tests to take account of
   simpified size format when ending in a .0

Daniel P. Berrange (6):
  cutils: add helpers for formatting sized values
  qapi: convert StringOutputVisitor to use qemu_szutostr
  qapi: assert that visitor impls have required callbacks
  qapi: add a text output visitor for pretty printing types
  block: convert to use the qemu_szutostr functions
  block: convert to use qapi_stringify_ImageInfoSpecific

 block/qapi.c                         | 163 +++-------------
 include/qapi/string-output-visitor.h |  28 ++-
 include/qapi/text-output-visitor.h   |  77 ++++++++
 include/qemu/cutils.h                |  12 ++
 qapi/Makefile.objs                   |   1 +
 qapi/qapi-visit-core.c               |  15 ++
 qapi/string-output-visitor.c         |  20 +-
 qapi/text-output-visitor.c           | 349 +++++++++++++++++++++++++++++++++
 tests/Makefile.include               |   5 +-
 tests/qemu-iotests/095.out           |   2 +-
 tests/qemu-iotests/104.out           |   2 +-
 tests/test-cutils.c                  |  96 +++++++++
 tests/test-string-output-visitor.c   |  22 +++
 tests/test-text-output-visitor.c     | 366 +++++++++++++++++++++++++++++++++++
 util/cutils.c                        |  78 ++++++++
 15 files changed, 1079 insertions(+), 157 deletions(-)
 create mode 100644 include/qapi/text-output-visitor.h
 create mode 100644 qapi/text-output-visitor.c
 create mode 100644 tests/test-text-output-visitor.c

-- 
2.7.4




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