Method: ConcurrentSHM::Channel.new

Defined in:
lib/concurrent-shm/channel.rb

.new(shm, depth:, width:, offset: 0, autosize: true) ⇒ Channel

Allocates a channel in a shared memory space at the specified offset, optionally initializing the space to the required size. The class of the returned channel depends on the width and depth.

| Depth | Width | Behavior |-|-|- | 0 | 0 | Unbuffered, zero-width | 0 | Positive | Unbuffered, fixed-width | 0 | Negative | Unbuffered, variable-width | 1 | 0 | Single-buffered, zero-width | 1 | Positive | Single-buffered, fixed-width | 1 | Negative | Single-buffered, variable-width | 2+ | 0 | Buffered, zero-width | 2+ | Positive | Buffered, fixed-width | 2+ | Negative | Not supported (buffered, variable-width)

When allocating a variable-width channel, width is inverted and passed as capacity.

Parameters:

  • shm (SharedMemory) —

    the shared memory space

  • offset (Integer) (defaults to: 0) —

    the offset to place the channel at in the shared memory space

  • autosize (Boolean) (defaults to: true) —

    whether to initialize the space to the required size

  • depth (Integer) —

    the channel buffer depth

  • width (Integer) —

    the channel data width

Returns:

Raises:

  • (ArgumentError) —

    if depth is not an integer, width is not an integer, or depth is negative

  • (RangeError) —

    if the offset is not a multiple of 16, or the shared memory space is not large enough



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# File 'lib/concurrent-shm/channel.rb', line 396

def new(shm, depth:, width:, offset: 0, autosize: true)
  raise ArgumentError, "Depth is not an integer" unless depth.is_a?(Integer)
  raise ArgumentError, "Width is not an integer" unless width.is_a?(Integer)
  raise ArgumentError, "Depth must be positive" if depth < 0

  args = { offset: offset, autosize: autosize }

  if depth == 0
    if width < 0
      Unbuffered::Variable.new(shm, capacity: -width, **args)
    elsif width > 0
      Unbuffered::Fixed.new(shm, width: width, **args)
    else
      Unbuffered::Empty.new(shm, **args)
    end

  elsif depth == 1
    if width < 0
      SingleBuffered::Variable.new(shm, capacity: -width, **args)
    elsif width > 0
      SingleBuffered::Fixed.new(shm, width: width, **args)
    else
      SingleBuffered::Empty.new(shm, **args)
    end

  else
    if width < 0
      raise "Buffered variable-width mode is not supported"
    elsif width > 0
      Buffered::Fixed.new(shm, depth: depth, width: width, **args)
    else
      Buffered::Empty.new(shm, depth: depth, **args)
    end
  end
end