Class: Foobara::WeakObjectHash

Inherits:
Object
  • Object
show all
Defined in:
foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb,
foobara-0.2.2/projects/weak_object_hash/lib/foobara/weak_object_hash.rb

Overview

TODO: a possible optimization: have a certain number of records before the Weakref approach kicks in that way we don’t just immediately clear out useful information without any actual memory burden

Defined Under Namespace

Classes: ClosedError

Instance Method Summary collapse

Constructor Details

#initialize(skip_finalizer: false) ⇒ WeakObjectHash

Returns a new instance of WeakObjectHash.



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 9

def initialize(skip_finalizer: false)
  if skip_finalizer
    self.skip_finalizer = true
  end
  self.monitor = Monitor.new
  self.object_ids_to_weak_refs_and_values = {}
end

Instance Method Details

#[](object) ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 38

def [](object)
  object_id = object.object_id

  if closed?
    raise ClosedError, "Cannot retrieve objects from a closed WeakObjectHash"
  end

  monitor.synchronize do
    pair = object_ids_to_weak_refs_and_values[object_id]

    return nil unless pair

    weak_ref, value = pair

    if weak_ref.weakref_alive?
      if skip_finalizer?
        if weak_ref.__getobj__ == object
          value
        else
          # :nocov:
          object_ids_to_weak_refs_and_values.delete(object_id)
          nil
          # :nocov:
        end
      else
        value
      end
    else
      # Seems unreachable... if it's been garbage collected how could we have a reference to the object
      # to pass it in?
      # :nocov:
      object_ids_to_weak_refs_and_values.delete(object_id)
      nil
      # :nocov:
    end
  end
end

#[]=(object, value) ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 17

def []=(object, value)
  object_id = object.object_id
  weak_ref = WeakRef.new(object)

  if closed?
    raise ClosedError, "Cannot add objects to a closed WeakObjectHash"
  end

  monitor.synchronize do
    delete(object)

    object_ids_to_weak_refs_and_values[object_id] = [weak_ref, value]

    unless skip_finalizer?
      ObjectSpace.define_finalizer(object, finalizer_proc)
    end

    value
  end
end

#clear ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 189

def clear
  monitor.synchronize do
    unless skip_finalizer?
      object_ids_to_weak_refs_and_values.each_value do |pair|
        weak_ref = pair.first

        if weak_ref.weakref_alive?
          ObjectSpace.undefine_finalizer(weak_ref.__getobj__)
        end
      end
    end

    object_ids_to_weak_refs_and_values.clear
  end
end

#close! ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 175

def close!
  if closed?
    raise ClosedError, "Already closed"
  end

  monitor.synchronize do
    self.closed = true
    clear
    @finalizer_proc = nil
    self.object_ids_to_weak_refs_and_values = nil
    self.monitor = nil
  end
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 205

def closed?
  closed
end

#delete(object) ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 76

def delete(object)
  object_id = object.object_id

  monitor.synchronize do
    pair = object_ids_to_weak_refs_and_values.delete(object_id)

    return nil unless pair

    weak_ref, value = pair

    if weak_ref.weakref_alive?

      if skip_finalizer?
        if weak_ref.__getobj__ == object
          value
        end
      else
        # Hmmm, there's seemingly no safe way to remove the finalizer for the previous entry
        # if it exists. This is because we can only remove all finalizers on object. Not only
        # the ones we've created.
        # We will just do this anyway with that caveat and maybe make this configuratble in the future.
        unless skip_finalizer?
          ObjectSpace.undefine_finalizer(object)
        end

        value
      end
    end
  end
end

#each_pair ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 107

def each_pair
  monitor.synchronize do
    object_ids_to_weak_refs_and_values.each_pair do |object_id, pair|
      weak_ref, value = pair

      if weak_ref.weakref_alive?
        yield weak_ref.__getobj__, value
      else
        object_ids_to_weak_refs_and_values.delete(object_id)
      end
    end
  end

  self
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 171

def empty?
  size == 0
end

#keys ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 135

def keys
  keys = []

  monitor.synchronize do
    each_pair do |key, _value|
      keys << key
    end
  end

  keys
end

#size ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 147

def size
  size = 0
  to_delete = nil

  monitor.synchronize do
    object_ids_to_weak_refs_and_values.each_pair do |object_id, pair|
      weak_ref = pair.first

      if weak_ref.weakref_alive?
        size += 1
      else
        to_delete ||= []
        to_delete << object_id
      end
    end

    to_delete&.each do |object_id|
      object_ids_to_weak_refs_and_values.delete(object_id)
    end
  end

  size
end

#skip_finalizer? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 209

def skip_finalizer?
  @skip_finalizer
end

#values ⇒ Object 



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# File 'foobara-0.2.2/projects/weak_object_hash/src/weak_object_hash.rb', line 123

def values
  values = []

  monitor.synchronize do
    each_pair do |_key, value|
      values << value
    end
  end

  values
end