Module: Geos::Interrupt

Defined in:
lib/ffi-geos/interrupt.rb

Instance Method Summary collapse

Instance Method Details

#available? ⇒ Boolean

Check for the availability of the GEOS interruption API. The interruption API was added in GEOS 3.4.0.

Returns:

  • (Boolean) 


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# File 'lib/ffi-geos/interrupt.rb', line 8

def available?
  true
end

#cancel ⇒ Object

Cancel a request to interrupt the current operation. This method should be called from within a callback registered with Geos.register_interrupt but can be called at any time all the same.



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# File 'lib/ffi-geos/interrupt.rb', line 57

def cancel
  FFIGeos.GEOS_interruptCancel
end

#clear ⇒ Object 



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# File 'lib/ffi-geos/interrupt.rb', line 61

def clear
  FFIGeos.GEOS_interruptRegisterCallback(nil)
  @current_interrupt_callback = nil
end

#register(method_or_block = nil, &block) ⇒ Object

Registers an interrupt method or block that may be called during certain operations such as Geos::Geometry#buffer. During these blocks you can interrupt the current operation using Geos.request_interrupt and cancel that interrupt request using Geos.clear_interrupt.

The return value for Geos.register_interrupt is a reference to the previously registered callback, allowing you to chain interrupt calls together by calling #call on the previously registered callback.

HUGE NOTE CONCERNING INTERRUPTS: be careful when using interrupt blocks and how they reference other ruby objects. The ruby garbage collector may not play nicely with GEOS and objects may get cleaned up in unexpected ways while interrupts are firing.



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# File 'lib/ffi-geos/interrupt.rb', line 26

def register(method_or_block = nil, &block)
  if method_or_block.nil? && !block_given?
    raise ArgumentError.new("Expected either a method or a block for Geos.register_interrupt")
  elsif !method_or_block.nil? && block_given?
    raise ArgumentError.new("Cannot use both a method and a block for Geos.register_interrupt")
  else
    retval = @current_interrupt_callback

    @current_interrupt_callback = if method_or_block
      FFIGeos.GEOS_interruptRegisterCallback(method_or_block)
      method_or_block
    elsif block_given?
      FFIGeos.GEOS_interruptRegisterCallback(&block)
      block
    end

    retval
  end
end

#request ⇒ Object

Interrupt the current operation. This method should generally be called from within a callback registered with Geos.register_interrupt but can be called at any time to interrupt the next interruptable operation.



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# File 'lib/ffi-geos/interrupt.rb', line 50

def request
  FFIGeos.GEOS_interruptRequest
end