README.rdoc

Path: README.rdoc
Last Update: Fri Dec 23 00:21:30 +0000 2016

Thread-local accessors for your classes

Yet another tiny library to tackle this problem.

Install with: gem install schoefmax-tlattr_accessors —source=http://gems.github.com

Example

  require 'rubygems'
  require 'tlattr_accessors'

  class ThreadExample
    extend ThreadLocalAccessors
    tlattr_accessor :foo

    def test
      self.foo = "bla"
      Thread.new {
        puts foo                  # prints "nil"
        self.foo = "blubb"
        puts foo                  # prints "blubb"
      }.join
      puts foo                    # prints "bla"
    end
  end

  ThreadExample.new.test

If you want to enable them globally, add this somewhere (e.g. an initializer in Rails)

  Object.send :extend, ThreadLocalAccessors

Default values

Adding true as last parameter will cause the first value set on the attribute to act as default value for all other threads:

  tlattr_accessor :yeah, :baby, true

  def test_default
    self.yeah = "bla"
    Thread.new {
      puts yeah                  # prints "bla"
      puts baby                  # prints "nil"
      self.baby = "blubb"
      self.yeah = "blabla"
    }.join
    puts yeah                    # prints "bla"
    puts baby                    # prints "blubb"
  end

Getters and Setters

This gem doesn‘t support tlattr or tlattr_reader|writer for the simple reason that they don‘t make any sense here (you don‘t have an "instance variable", so you need both methods). If you want to hide one of them from your API, you can always make them private:

  tlattr_accessor :foo
  private :foo= # hide the setter

Performance

The Thread.current-Hash is a global namespace. Using it to store thread-local variables safely requires carefully crafted keys, which tend to be rather expensive to compute. This hurts performance if the attribute is accessed frequently. Therefore, this library uses a different approach, which is a lot faster: The values are stored in a separate hash which is keyed by the object_id of the thread. Finalizers make sure no memory is leaked when threads finish (see the spec).

Running specs

If you haven‘t already, install the rspec gem, then run:

  spec spec

(c) 2009, Max Schoefmann <max (a) pragmatic-it de> Released under the MIT license

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