Class: Concurrent::Edge::LockFreeStack

Inherits:
Synchronization::Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/concurrent/edge/lock_free_stack.rb

Defined Under Namespace

Classes: Empty, Node

Constant Summary collapse

EMPTY = 
Empty[nil, nil]

Instance Method Summary collapse

Constructor Details

#initialize ⇒ LockFreeStack

Returns a new instance of LockFreeStack.



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 24

def initialize
  @Head = AtomicReference.new EMPTY
  ensure_ivar_visibility!
end

Instance Method Details

#clear ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 63

def clear
  while true
    head = @Head.get
    return false if head == EMPTY
    return true if @Head.compare_and_set head, EMPTY
  end
end

#compare_and_clear(head) ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 59

def compare_and_clear(head)
  @Head.compare_and_set head, EMPTY
end

#compare_and_pop(head) ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 48

def compare_and_pop(head)
  @Head.compare_and_set head, head.next_node
end

#compare_and_push(head, value) ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 33

def compare_and_push(head, value)
  @Head.compare_and_set head, Node[value, head]
end

#each ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 73

def each
  return to_enum unless block_given?
  it = peek
  until it.equal?(EMPTY)
    yield it.value
    it = it.next_node
  end
  self
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/concurrent/edge/lock_free_stack.rb', line 29

def empty?
  @Head.get.equal? EMPTY
end

#peek ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 44

def peek
  @Head.get
end

#pop ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 52

def pop
  while true
    head = @Head.get
    return head.value if @Head.compare_and_set head, head.next_node
  end
end

#push(value) ⇒ Object 



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# File 'lib/concurrent/edge/lock_free_stack.rb', line 37

def push(value)
  while true
    head = @Head.get
    return self if @Head.compare_and_set head, Node[value, head]
  end
end