DPL: add allocator to forward a fair::mq::Message payload by shallow copy

[ehellbar]

---

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• TPC: make IDC/CMV distribute a pure forwarding device + minor improvements #15583 (3 commits)
• -> DPL: add allocator to forward a fair::mq::Message payload by shallow copy #15577 (2 commits)

[ktf]

don't we already have an helper which does that?

[ehellbar]

I don't see it, at least not for what I am doing here.

I define the getter e.g. in https://github.com/AliceO2Group/AliceO2/pull/15577/changes#diff-5d24f98b5c6098b6ad0a1ab814450dec590c82b86147d85c5a34afa0521171a6R239, where I use the DataRefIndices directly since we anyway calculate them in the InputRecordIterator.

There is https://github.com/AliceO2Group/AliceO2/blob/dev/Framework/Core/include/Framework/DataModelViews.h#L209, but it uses some indices from which the vector indices need to be computed first, so it is more expensive than what I need to do. Or are you referring to something else?

[alibuild]

Error while checking build/O2/fullCI_slc9 for b4570d8 at 2026-07-15 10:32:

## sw/BUILD/O2-full-system-test-latest/log
command /sw/slc9_x86-64/O2/slc9_x86-64-slc9_x86-64-local14/prodtests/full-system-test/dpl-workflow.sh had nonzero exit code 137
[8835:internal-dpl-injected-dummy-sink]: [10:31:41][ERROR] Failed binding socket internal-dpl-injected-dummy-sink.metric-feedback[0].push, address: ipc://@metric-feedback-0, reason: Address already in use
[8835:internal-dpl-injected-dummy-sink]: [10:31:41][ERROR] failed to attach channel metric-feedback[0] (bind on ipc://@metric-feedback-0)
[8835:internal-dpl-injected-dummy-sink]: [10:31:41][ERROR] 1 of the binding channels could not initialize. Initial configuration incomplete.
[8835:internal-dpl-injected-dummy-sink]: [10:31:41][FATAL] error while setting up workflow in o2-raw-file-reader-workflow: 1 of the binding channels could not initialize. Initial configuration incomplete.
[ERROR] Workflow crashed - PID 8835 (internal-dpl-injected-dummy-sink) did not exit correctly however it's not clear why. Exit code forced to 128.
[ERROR] Workflow crashed - PID 8621 (internal-dpl-ccdb-backend) was killed abnormally with Killed and exited code was set to 137.
[ERROR]  - Device internal-dpl-ccdb-backend: pid 8621 (exit 137)
[ERROR]  - Device internal-dpl-injected-dummy-sink: pid 8835 (exit 128)
[INFO]    - First error: [10:31:41][FATAL] error while setting up workflow in o2-raw-file-reader-workflow: 1 of the binding channels could not initialize. Initial configuration incomplete.
[ERROR] SEVERE: Device internal-dpl-ccdb-backend (8621) returned with 137


## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
grep: error-log.txt: binary file matches
++ GRERR=1
++ [[ 1 == 0 ]]
++ mkdir -p /sw/INSTALLROOT/0885982598b98d52ac8f61a26ebd822e3685bc3a/slc9_x86-64/o2checkcode/1.0-local153/etc/modulefiles
++ alibuild-generate-module
+ HAS_BIN=
+ HAS_LIB=
+ HAS_CMAKE=
+ HAS_ROOT=
+ '[' 0 '!=' 0 ']'
+ cat
+ printf 'if ![ is-loaded '\''BASE/1.0'\'' ] {\n module load BASE/1.0\n}'
+ echo 'BUILD_REQUIRES=CMake alibuild-recipe-tools defaults-release'
BUILD_REQUIRES=CMake alibuild-recipe-tools defaults-release
+ FULL_BUILD_REQUIRES='FairCMakeModules Alice-GRID-Utils bz2 safe_int MPFR defaults-release Python-modules-list alibuild-recipe-tools date UUID CMake pytorch_cpuinfo googlebenchmark double-conversion ninja-fortran O2-customization json-c ninja'
+ echo 'FULL_BUILD_REQUIRES=FairCMakeModules Alice-GRID-Utils bz2 safe_int MPFR defaults-release Python-modules-list alibuild-recipe-tools date UUID CMake pytorch_cpuinfo googlebenchmark double-conversion ninja-fortran O2-customization json-c ninja'
FULL_BUILD_REQUIRES=FairCMakeModules Alice-GRID-Utils bz2 safe_int MPFR defaults-release Python-modules-list alibuild-recipe-tools date UUID CMake pytorch_cpuinfo googlebenchmark double-conversion ninja-fortran O2-customization json-c ninja
++ env
++ cut -f1 -d=
++ grep -v '^DEFAULT_'
++ grep -v PKGREVISION
++ grep -v ALIBUILD_RECIPE_TOOLS
++ sed -e s/_REVISION//
++ grep REVISION
+ for x in $(env | cut -f1 -d= | grep -v "^DEFAULT_" | grep -v PKGREVISION | grep -v ALIBUILD_RECIPE_TOOLS | grep REVISION | sed -e 's/_REVISION//')
++ eval 'echo $LIBFFI_REVISION'
+++ echo 10
+ REVISION_VALUE=10
++ eval 'echo $LIBFFI_VERSION'
[0 more errors; see full log]

Full log here.