Class: SupportTableCache::FiberLocals

Inherits:
Object
  • Object
show all
Defined in:
lib/support_table_cache/fiber_locals.rb

Overview

Utility class for managing fiber-local variables. All values are stored in a single hash inside the fiber's native local storage (Thread.current, which is fiber-local in Ruby) so the fiber-local namespace is not polluted with individual keys. Because the state lives on the fiber itself, it is garbage collected along with the fiber and cannot leak or be picked up by another fiber.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ FiberLocals

Returns a new instance of FiberLocals.



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# File 'lib/support_table_cache/fiber_locals.rb', line 10

def initialize
  @locals_key = :"support_table_cache_locals_#{object_id}"
end

Instance Method Details

#[](key) ⇒ Object 



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# File 'lib/support_table_cache/fiber_locals.rb', line 14

def [](key)
  locals = Thread.current[@locals_key]
  locals[key] if locals
end

#with(key, value) ⇒ Object 



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# File 'lib/support_table_cache/fiber_locals.rb', line 19

def with(key, value)
  locals = Thread.current[@locals_key]
  if locals.nil?
    locals = {}
    Thread.current[@locals_key] = locals
  end

  exists = locals.key?(key)
  previous_value = locals[key]
  locals[key] = value

  begin
    yield
  ensure
    if exists
      locals[key] = previous_value
    else
      locals.delete(key)
      Thread.current[@locals_key] = nil if locals.empty?
    end
  end
end