Add Tasks/RepeatRedis

Tasks/README.md

@@ -26,6 +26,7 @@ Custom tasks may be defined literally and via custom parameters, see [Repeat](Re
 - [File](File) shows the custom task `file`, an incremental task with simplified syntax, somewhat similar to Rake's `file`.
 - [Repeat](Repeat) shows the custom task `repeat` which is invoked periodically in a build script (schedule) with such tasks.
 - [Repeat2](Repeat2) shows the alternative way with using the special command `repeat` which turns tasks into repeatable.
+- [RepeatRedis](RepeatRedis) is similar to `Repeat2` but it uses Redis for task records instead of CLIXML files.
 - [Retry](Retry) shows the custom task `retry` which retries its action on failures several times depending on parameters.
 
 ## Known issues

Tasks/RepeatRedis/README.md

@@ -0,0 +1,10 @@
+
+This demo is similar to [Repeat2](../Repeat2) but it uses Redis for task records instead of CLIXML files.
+This requires [FarNet.Redis](https://www.powershellgallery.com/packages/FarNet.Redis).
+
+[Repeat.tasks.ps1](Repeat.tasks.ps1) defines `repeat` parameters.
+It is designed for using in any build script, not just this demo.
+
+The build script [Repeat.build.ps1](Repeat.build.ps1) shows repeat-tasks.
+
+See also [Repeat](../Repeat).

Tasks/RepeatRedis/Repeat.build.ps1

@@ -0,0 +1,31 @@
+<#
+.Synopsis
+	Example of repeat-tasks.
+
+.Description
+	See "Repeat.tasks.ps1" for the details of `repeat`.
+
+.Example
+	Invoke-Build * Repeat.build.ps1
+
+	This command checks all repeat-tasks and invokes some of them as needed.
+	The script is supposed to be invoked periodically, manually or scheduled.
+#>
+
+# Import helpers and specify the task prefix.
+. .\Repeat.tasks.ps1 temp:repeat:test-repeat-tasks:
+
+# Synopsis: Repeat every minute.
+task task1 (repeat 0:1 {
+	"Doing $($Task.Name)..."
+})
+
+# Synopsis: Repeat every hour.
+task task2 (repeat 1:0 {
+	"Doing $($Task.Name)..."
+})
+
+# Synopsis: Repeat every day.
+task task3 (repeat 1:0:0:0 {
+	"Doing $($Task.Name)..."
+})

Tasks/RepeatRedis/Repeat.tasks.ps1

@@ -0,0 +1,84 @@
+<#
+.Synopsis
+	Defines repeat-task parameters `repeat` using Redis.
+
+.Description
+	Build scripts dot-source this script in order to use `repeat`.
+	Repeat-tasks are invoked periodically with specified periods.
+
+	Normal task parameters:
+		- Name, Inputs, Outputs, Partial
+
+	Custom repeat parameters:
+		- Span -- task period
+		- Jobs -- task jobs
+		- If -- task condition
+
+	Script scope names:
+		Alias: repeat -- makes repeat-tasks parameters
+		Variables: $db -- Redis database, used internally but may be used by tasks as well
+		Functions: New-Repeat, Test-Repeat, Complete-Repeat -- used internally
+
+.Parameter RedisTaskPrefix
+		Specifies Redis prefix for task strings.
+
+.Parameter RedisConfiguration
+		Optional Redis configuration string.
+		Default: $env:FARNET_REDIS_CONFIGURATION
+#>
+
+param(
+	[Parameter(Mandatory=1)]
+	[string]$RedisTaskPrefix
+	,
+	[string]$RedisConfiguration
+)
+
+if (!$WhatIf) {
+	Import-Module FarNet.Redis
+	$db = Open-Redis -Configuration $RedisConfiguration
+}
+
+# "DSL" for scripts.
+Set-Alias repeat New-Repeat
+
+# Creates repeat-task parameters.
+function New-Repeat(
+	[Parameter(Position=0, Mandatory=1)]
+	[timespan]$Span
+	,
+	[Parameter(Position=1)]
+	[object[]]$Jobs
+	,
+	[object]$If=$true
+)
+{
+	@{
+		Jobs = $Jobs
+		If = {Test-Repeat}
+		Done = {Complete-Repeat}
+		Data = @{If = $If; Span = $Span}
+	}
+}
+
+# Works as tasks `If`. The original condition is processed first. If it is true
+# then the Redis task key is tested. If it exists then the task is skipped.
+function Test-Repeat {
+	$_ = $Task.Data.If
+	if ($_ -is [scriptblock]) {
+		$_ = & $_
+	}
+
+	if ($_) {
+		!(Get-RedisKey ($RedisTaskPrefix + $Task.Name) -TimeToLive)
+	}
+}
+
+# Works as tasks `Done`, on success sets Redis task string and time to live.
+function Complete-Repeat {
+	$key = $RedisTaskPrefix + $Task.Name
+	$now = [datetime]::Now.ToString('s')
+	if (!$Task.Error) {
+		Set-RedisString $key $now -TimeToLive $Task.Data.Span
+	}
+}