functions/Get-PSRetryDelay.ps1
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<#
.SYNOPSIS Used to return a retry delay time based on the provided [RetryMultiplier] and [RetryCount] values. .DESCRIPTION The Get-PSRetryDelay function evaluates the provided [RetryMultiplier] (optional) and [RetryCount] values and returns the expected retry delay time to use. By default, the function will return a fixed retry delay time based on the [RetryMultiplier]. To simplify use, a default value is provided for the [RetryMultiplier] (2). This value can also be specified at invocation. To provide additional control over the retry logic, this function can operate in 3 modes: - Fixed (default) : Retry using a fixed time period, as specified by -RetryMultiplier (Alias = RetryDelay) - Linear : Retry using a linear backoff, calculated as the multiple of -RetryMultiplier and the -RetryCount value - Exponential : Retry using an exponential backoff, calculated as the RetryCount value to the power of the -RetryMultiplier value .EXAMPLE Get-PSRetryDelay -RetryCount 3 2 Runs command with default settings .EXAMPLE 3 | Get-PSRetryDelay 2 Runs command with default settings using pipeline input .EXAMPLE Get-PSRetryDelay -RetryMultiplier 5 -RetryCount 3 -Linear 15 Runs command with custom multiplier and linear back-off .EXAMPLE Get-PSRetryDelay -RetryMultiplier 2 -RetryCount 6 -Exponential 64 Runs command with custom multiplier and exponential back-off #> function Get-PSRetryDelay { [CmdletBinding(PositionalBinding = $true)] [OutputType([int])] param ( [Parameter(Mandatory = $false, Position=0, ParameterSetName = 'Fixed')] [Parameter(Mandatory = $false, Position=0, ParameterSetName = 'Linear')] [Parameter(Mandatory = $false, Position=0, ParameterSetName = 'Exponential')] [Alias("RetryDelay")] [int]$RetryMultiplier = 2, [Parameter(Mandatory = $true, ValueFromPipeline, Position=1, ParameterSetName = 'Fixed')] [Parameter(Mandatory = $true, ValueFromPipeline, Position=1, ParameterSetName = 'Linear')] [Parameter(Mandatory = $true, ValueFromPipeline, Position=1, ParameterSetName = 'Exponential')] [int]$RetryCount, [Parameter(Mandatory = $true, ParameterSetName = 'Fixed')] [switch]$Linear, [Parameter(Mandatory = $true, ParameterSetName = 'Exponential')] [switch]$Exponential ) # Use begin block to validate input parameters (fail fast) begin { $MinimumRetryMultiplierWithExponential = 2 if ($Exponential -and $RetryMultiplier -lt $MinimumRetryMultiplierWithExponential) { Write-Error "The provided value [$RetryMultiplier] is less than the minimum required value [$MinimumRetryMultiplierWithExponential] for -RetryMultiplier when using -Exponential." exit } } # Use process block to get the calculate and return the retry delay time process { if ($Exponential) { return [int][math]::Pow($RetryMultiplier, $RetryCount) } elseif ($Linear) { return [int][math]::BigMul($RetryMultiplier, $RetryCount) } else { return [int]$RetryMultiplier } } } |