We have a multibranch pipeline which after being triggered immediately splits into 6 stages for various linux and windows platforms. The sequence of each of the pipelines goes like this:

• Obtain branch source (checkout scm)
• Obtain platform specific thirdparties (p4sync)
• Obtain common thirdparties (p4sync)
• Build/Test/Archive/Etc

The problem I am having is pinning the thirdparty syncs to the same changelist as the branch, because each instance of a sync can set the P4_CHANGELIST environment variable (which seems to be updated globally) to a different value, so unless I perform a single sync ahead of all the others just to get the changelist and store it, I have a race condition.

What I would like to do is be able to put this at the start of my script, before I enter the pipeline block:

env.GLOBAL_P4_CHANGELIST = scm.getChangelist()

Which would ensure I have a global reference to the changelist that triggered the build to use for pinning the subsequent thirdparty syncs,  that isn't overridden by any subsequent uses of p4sync.

I see that PerforceScm has a property P4Ref revision. Can this be exposed in the manner I'd like?

My current workaround consists of either wrapping an initial checkout in a lock step so that I can set the global variable after a first sync has completed (this delays all other parallel stages by the time it takes to sync, which can be up to 10 minutes currently)

lock("$env.JOB_NAME-GLOBAL_P4_CHANGELIST"){
    if ( !env.GLOBAL_P4_CHANGELIST ){
        checkout scm
        env.GLOBAL_P4_CHANGELIST = "$env.P4_CHANGELIST"
        env.GLOBAL_P4_CHANGELIST_STAGE = "$env.STAGE_NAME"
    }
    echo "GLOBAL_P4_CHANGELIST = $env.GLOBAL_P4_CHANGELIST"
    echo "GLOBAL_P4_CHANGELIST_STAGE = $env.GLOBAL_P4_CHANGELIST_STAGE"
}
if ( ! (env.STAGE_NAME == $env.GLOBAL_P4_CHANGELIST_STAGE) ){
    checkout scm
}

or by trying to use a lock on updating the variable immediately after a checkout scm, which still has a race condition.