Make background tasks lazy

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## HEAD
 
+- Fix: Background task name lookup is now lazy, this fixes a bug when using `:::>- pre.erb background.start(...)` (https://github.com/zombocom/rundoc/pull/95)
+
 ## 4.1.1
 
 - Fix: Visibility forwarding for `pre.erb` was accidentally reversed, this is now fixed. (https://github.com/zombocom/rundoc/pull/93)

lib/rundoc/code_command/background/log/clear.rb

@@ -1,15 +1,20 @@
 class Rundoc::CodeCommand::Background::Log
   class Clear < Rundoc::CodeCommand
     def initialize(name:)
-      @spawn = Rundoc::CodeCommand::Background::ProcessSpawn.find(name)
+      @name = name
+      @background = nil
+    end
+
+    def background
+      @background ||= Rundoc::CodeCommand::Background::ProcessSpawn.find(@name)
     end
 
     def to_md(env = {})
       ""
     end
 
     def call(env = {})
-      @spawn.log.truncate(0)
+      background.log.truncate(0)
       ""
     end
   end

lib/rundoc/code_command/background/log/read.rb

@@ -1,15 +1,20 @@
 class Rundoc::CodeCommand::Background::Log
   class Read < Rundoc::CodeCommand
     def initialize(name:)
-      @spawn = Rundoc::CodeCommand::Background::ProcessSpawn.find(name)
+      @name = name
+      @background = nil
+    end
+
+    def background
+      @background ||= Rundoc::CodeCommand::Background::ProcessSpawn.find(@name)
     end
 
     def to_md(env = {})
       ""
     end
 
     def call(env = {})
-      @spawn.log.read
+      background.log.read
     end
   end
 end

lib/rundoc/code_command/background/start.rb

@@ -3,35 +3,43 @@
 class Rundoc::CodeCommand::Background
   class Start < Rundoc::CodeCommand
     def initialize(command, name:, wait: nil, timeout: 5, log: Tempfile.new("log"), out: "2>&1", allow_fail: false)
+      @timeout = timeout
       @command = command
       @name = name
       @wait = wait
       @allow_fail = allow_fail
-      FileUtils.touch(log)
+      @log = log
+      @redirect = out
+      FileUtils.touch(@log)
 
-      @spawn = ProcessSpawn.new(
+      @background = nil
+    end
+
+    def background
+      @background ||= ProcessSpawn.new(
         @command,
-        timeout: timeout,
-        log: log,
-        out: out
-      )
-      puts "Spawning commmand: `#{@spawn.command}`"
-      ProcessSpawn.add(@name, @spawn)
+        timeout: @timeout,
+        log: @log,
+        out: @redirect
+      ).tap do |spawn|
+        puts "Spawning commmand: `#{spawn.command}`"
+        ProcessSpawn.add(@name, spawn)
+      end
     end
 
     def to_md(env = {})
       "$ #{@command}"
     end
 
     def call(env = {})
-      @spawn.wait(@wait)
-      @spawn.check_alive! unless @allow_fail
+      background.wait(@wait)
+      background.check_alive! unless @allow_fail
 
-      @spawn.log.read
+      background.log.read
     end
 
     def alive?
-      !!@spawn.alive?
+      !!background.alive?
     end
   end
 end

lib/rundoc/code_command/background/stdin_write.rb

@@ -6,10 +6,15 @@ class StdinWrite < Rundoc::CodeCommand
     def initialize(contents, name:, wait:, timeout: 5, ending: $/)
       @contents = contents
       @ending = ending
-      @spawn = Rundoc::CodeCommand::Background::ProcessSpawn.find(name)
       @wait = wait
+      @name = name
       @timeout_value = Integer(timeout)
       @contents_written = nil
+      @background = nil
+    end
+
+    def background
+      @background ||= Rundoc::CodeCommand::Background::ProcessSpawn.find(@name)
     end
 
     # The command is rendered (`:::>-`) by the output of the `def call` method.
@@ -20,11 +25,11 @@ def to_md(env = {})
     # The contents produced by the command (`:::->`) are rendered by the `def to_md` method.
     def call(env = {})
       writecontents
-      @spawn.log.read
+      background.log.read
     end
 
     def writecontents
-      @contents_written ||= @spawn.stdin_write(
+      @contents_written ||= background.stdin_write(
         contents,
         wait: @wait,
         ending: @ending,

lib/rundoc/code_command/background/stop.rb

@@ -1,16 +1,21 @@
 class Rundoc::CodeCommand::Background
   class Stop < Rundoc::CodeCommand
     def initialize(name:)
-      @spawn = Rundoc::CodeCommand::Background::ProcessSpawn.find(name)
+      @name = name
+      @background = nil
+    end
+
+    def background
+      @background ||= Rundoc::CodeCommand::Background::ProcessSpawn.find(@name)
     end
 
     def to_md(env = {})
       ""
     end
 
     def call(env = {})
-      @spawn.stop
-      @spawn.log.read
+      background.stop
+      background.log.read
     end
   end
 end

lib/rundoc/code_command/background/wait.rb

@@ -1,17 +1,22 @@
 class Rundoc::CodeCommand::Background
   class Wait < Rundoc::CodeCommand
     def initialize(name:, wait:, timeout: 5)
-      @spawn = Rundoc::CodeCommand::Background::ProcessSpawn.find(name)
+      @name = name
       @wait = wait
       @timeout_value = Integer(timeout)
+      @background = nil
+    end
+
+    def background
+      @background ||= Rundoc::CodeCommand::Background::ProcessSpawn.find(name)
     end
 
     def to_md(env = {})
       ""
     end
 
     def call(env = {})
-      @spawn.wait(@wait, @timeout_value)
+      background.wait(@wait, @timeout_value)
       ""
     end
   end

test/rundoc/code_commands/background_test.rb

@@ -4,15 +4,19 @@ class BackgroundTest < Minitest::Test
   def test_stdin_with_cat_echo
     Dir.mktmpdir do |dir|
       Dir.chdir(dir) do
-        background_start = Rundoc::CodeCommand::Background::Start.new("cat",
-          name: "cat")
-        background_start.call
-
-        output = Rundoc::CodeCommand::Background::StdinWrite.new(
+        # Intentionally out of order, should not raise an error as long as "cat"
+        # command exists at execution time
+        stdin_write = Rundoc::CodeCommand::Background::StdinWrite.new(
           "hello there",
           name: "cat",
           wait: "hello"
-        ).call
+        )
+
+        background_start = Rundoc::CodeCommand::Background::Start.new("cat",
+          name: "cat")
+
+        background_start.call
+        output = stdin_write.call
         assert_equal("hello there" + $/, output)
 
         Rundoc::CodeCommand::Background::Log::Clear.new(