Changes in object input structure use cached values rather than starting new runs for exec

[mahesh-panchal]

Bug report

Expected behavior and actual behavior

Changes to objects passed as input should trigger new runs when using -resume. When changing an object's structure, e.g. putting it in an array, or map, the process uses the cached values from before, rather than executing new runs.

Steps to reproduce the problem

First run:

workflow {
    Channel.of(
        [ id:'foo', taxid: '632'],
        [ id:'bar', taxid: '632']
    )
    | TASK
    | view
}

process TASK {
    input:
    val meta

    exec:
    file("$task.workDir/node_id.txt").text = meta.taxid
    
    output:
    tuple val(meta), path('node_id.txt'), emit: node_id
}

Changed code (run 2):

workflow {
    Channel.of(
        [map:[ id:'foo', taxid: '632']],
        [map:[ id:'bar', taxid: '632']]
    )
    | TASK
    | view
}

process TASK {
    input:
    val meta

    exec:
    file("$task.workDir/node_id.txt").text = meta.taxid
    
    output:
    tuple val(meta), path('node_id.txt'), emit: node_id
}

Program output

Run 1:

$ nextflow run main.nf 
N E X T F L O W  ~  version 23.10.1
Launching `main.nf` [zen_leibniz] DSL2 - revision: eaf2b5bb3d
executor >  local (2)
[31/f024e0] process > TASK (2) [100%] 2 of 2 ✔
[[id:foo, taxid:632], /workspace/Nextflow_sandbox/work/8e/853bdb1d954eef65d82eb81ba481e1/node_id.txt]
[[id:bar, taxid:632], /workspace/Nextflow_sandbox/work/31/f024e0f621ef2b27d3567887a7c5d3/node_id.txt]

Run 2: Expect error due to change in input object structure, but uses cached values instead.

$ nextflow run main.nf -resume
N E X T F L O W  ~  version 23.10.1
Launching `main.nf` [cheesy_allen] DSL2 - revision: 8074d4d3e0
[6b/fb2322] process > TASK (1) [100%] 2 of 2, cached: 2 ✔
[[id:bar, taxid:632], /workspace/Nextflow_sandbox/work/56/2935d71088d17207dab38381590386/node_id.txt]
[[id:foo, taxid:632], /workspace/Nextflow_sandbox/work/6b/fb2322b25197873c2aaf6f0c75084e/node_id.txt]

Environment

• Nextflow version: 23.10.1
• Java version: openjdk 17.0.10-internal 2024-01-16
• Operating system: Linux (Gitpod)
• Bash version: GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)

[bentsherman]

This is happening because maps are hashed by hashing their values:

nextflow/modules/nf-commons/src/main/nextflow/util/CacheHelper.java

Lines 171 to 176 in 2165a14

	if( value instanceof Map ) {
	// note: should map be order invariant as Set ?
	for( Object item : ((Map)value).values() )
	hasher = CacheHelper.hasher( hasher, item, mode );
	return hasher;
	}

So there is no difference between a value and value in a map, or even changing the keys of the map, though changing the order will change the hash.