Azure PowerShell Caching Idea

Az.Module.Cache.psm1

$Script:cache ??= [ordered]@{}

<#
.EXAMPLE
Import-Module .\Az.Module.Cache.psm1
$servers = Get-CachedItem -ValueFactory { Get-AzResource -ResourceType "Microsoft.Sql/servers" } -Verbose
#>
function Get-CachedItem {
    param(
        [Parameter(Mandatory = $true)]
        [scriptblock]$ValueFactory,

        [Parameter(Mandatory = $false)]
        [int]$ExpiresInMinutes = 5
    )

    [TimeSpan]$ExpirationTime = [TimeSpan]::FromMinutes($ExpiresInMinutes)

    # Hash the command in a safe deterministic way
    $commandAst = [System.Management.Automation.Language.Parser]::ParseInput($ValueFactory.ToString(), [ref]$null, [ref]$null)
    $commandBase64 = [Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes($commandAst.ToString()))

    # Tack on the subscription to avoid bugs when switching subscriptions
    $subscription = (Get-AzContext) ?? "NA"
    $Key = "$($subscription.Subscription.Id):$($commandBase64)"

    $cachedItem = Get-CachedItemFromCache $Key
    if ($cachedItem -and (Get-Date) -lt $cachedItem.Expires) {
        # Item exists in cache and hasn't expired, return the cached value
        Write-Verbose "Cache Hit Found"
        return $cachedItem.Value
    }

    Write-Verbose "Cache Miss, Adding Record"
    # Item doesn't exist in cache or has expired, generate a new value and cache it
    $value = Invoke-Command $ValueFactory
    $expires = (Get-Date).Add($ExpirationTime)
    Add-CachedItemToCache $Key $value $expires

    Remove-ExpiredCache
    return $value
}

function Get-CachedItemFromCache {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Key
    )
    return ($Script:cache.Contains($Key)) `
        ? $Script:cache[$Key] 
        : $null
}

function Add-CachedItemToCache {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Key,
        [Parameter(Mandatory = $true)]
        $Value,
        [Parameter(Mandatory = $true)]
        [DateTime]$Expires
    )
    $Script:cache[$Key] = [PSCustomObject]@{
        Value   = $Value
        Expires = $Expires
    }
}

# For debugging JIC
function Get-Cache {
    
    return $Script:cache
}

function Clear-Cache {
    $Script:cache = [ordered]@{}
}

function Remove-ExpiredCache {
    # This is to prevent editing an enumeration while looping on it
    $keys = $Script:cache.GetEnumerator() | ForEach-Object { $_.Key }
    $keys | ForEach-Object {
        if ((Get-Date) -ge $Script:cache[$_].Expires) {
            Write-Verbose "Removing Stale Cache Entry $_"
            $Script:cache.Remove($_)
        }
    }
}