Class: Phronomy::Task::ImmediateBackend

Inherits:
Backend
  • Object
show all
Defined in:
lib/phronomy/task/immediate_backend.rb

Overview

Synchronous task backend that executes the block on the calling thread.

Used by Runtime::FakeScheduler to allow tests to verify cooperative scheduling behaviour without spawning additional Threads. The block runs to completion before #initialize returns, so #await and #join always return immediately.

Thread count invariant: +ImmediateBackend+ never creates a new Thread.

Instance Method Summary collapse

Constructor Details

#initialize(task:, &block) ⇒ ImmediateBackend

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Executes +block+ synchronously on the calling thread. Saves and restores +Task.current+ so nested ImmediateBackend tasks compose correctly.

Parameters:

Yield Returns:

  • (Object) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 21

def initialize(task:, &block)
  super
  @value = nil
  @error = nil
  previous_task = Thread.current[:phronomy_current_task]
  Thread.current[:phronomy_current_task] = task
  task.transition!(:running)
  begin
    @value = block.call
    task.transition!(:completed, value: @value)
  rescue CancellationError => e
    task.transition!(:cancelled, error: e)
    @error = e
  rescue => e
    task.transition!(:failed, error: e)
    @error = e
  ensure
    task.transition!(:cancelled) unless task.done?
    Thread.current[:phronomy_current_task] = previous_task
  end
end

Instance Method Details

#alive? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Always +false+ — block has already completed by the time the task is visible to callers.

Returns:

  • (Boolean) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 69

def alive?
  false
end

#await ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns the block's return value, or re-raises its exception.

Returns:

  • (Object)

Raises:

  • (Exception) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 47

def await
  raise @error if @error

  @value
end

#cancel! ⇒ self

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

No-op: the block has already completed.

Returns:

  • (self) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 76

def cancel!
  self
end

#completed_error ⇒ Exception?

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Exception, nil) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 61

def completed_error
  @error
end

#completed_value ⇒ Object?

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Object, nil) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 55

def completed_value
  @value
end

#join(_limit = nil) ⇒ self

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns immediately — nothing to wait for.

Parameters:

  • limit (Numeric, nil) —

    ignored

Returns:

  • (self) 


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# File 'lib/phronomy/task/immediate_backend.rb', line 84

def join(_limit = nil)
  self
end