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Backport thread-local variables from Ruby 2.0
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70
activesupport/lib/active_support/core_ext/thread.rb
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70
activesupport/lib/active_support/core_ext/thread.rb
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class Thread
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LOCK = Mutex.new # :nodoc:
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# Returns the value of a thread local variable that has been set. Note that
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# these are different than fiber local values.
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#
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# Thread local values are carried along with threads, and do not respect
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# fibers. For example:
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#
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# Thread.new {
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# Thread.current.thread_variable_set("foo", "bar") # set a thread local
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# Thread.current["foo"] = "bar" # set a fiber local
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#
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# Fiber.new {
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# Fiber.yield [
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# Thread.current.thread_variable_get("foo"), # get the thread local
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# Thread.current["foo"], # get the fiber local
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# ]
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# }.resume
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# }.join.value # => ['bar', nil]
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#
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# The value <tt>"bar"</tt> is returned for the thread local, where +nil+ is returned
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# for the fiber local. The fiber is executed in the same thread, so the
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# thread local values are available.
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def thread_variable_get(key)
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locals[key.to_sym]
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end
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# Sets a thread local with +key+ to +value+. Note that these are local to
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# threads, and not to fibers. Please see Thread#thread_variable_get for
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# more information.
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def thread_variable_set(key, value)
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locals[key.to_sym] = value
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end
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# Returns an an array of the names of the thread-local variables (as Symbols).
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#
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# thr = Thread.new do
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# Thread.current.thread_variable_set(:cat, 'meow')
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# Thread.current.thread_variable_set("dog", 'woof')
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# end
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# thr.join #=> #<Thread:0x401b3f10 dead>
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# thr.thread_variables #=> [:dog, :cat]
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#
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# Note that these are not fiber local variables. Please see Thread#thread_variable_get
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# for more details.
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def thread_variables
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locals.keys
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end
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# Returns <tt>true</tt> if the given string (or symbol) exists as a
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# thread-local variable.
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#
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# me = Thread.current
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# me.thread_variable_set(:oliver, "a")
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# me.thread_variable?(:oliver) #=> true
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# me.thread_variable?(:stanley) #=> false
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#
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# Note that these are not fiber local variables. Please see Thread#thread_variable_get
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# for more details.
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def thread_variable?(key)
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locals.has_key?(key.to_sym)
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end
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private
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def locals
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@locals || LOCK.synchronize { @locals ||= {} }
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end
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end unless Thread.instance_methods.include?(:thread_variable_set)
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77
activesupport/test/core_ext/thread_test.rb
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77
activesupport/test/core_ext/thread_test.rb
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require 'abstract_unit'
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require 'active_support/core_ext/thread'
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class ThreadExt < ActiveSupport::TestCase
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def test_main_thread_variable_in_enumerator
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assert_equal Thread.main, Thread.current
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Thread.current.thread_variable_set :foo, "bar"
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thread, value = Fiber.new {
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Fiber.yield [Thread.current, Thread.current.thread_variable_get(:foo)]
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}.resume
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assert_equal Thread.current, thread
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assert_equal Thread.current.thread_variable_get(:foo), value
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end
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def test_thread_variable_in_enumerator
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Thread.new {
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Thread.current.thread_variable_set :foo, "bar"
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thread, value = Fiber.new {
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Fiber.yield [Thread.current, Thread.current.thread_variable_get(:foo)]
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}.resume
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assert_equal Thread.current, thread
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assert_equal Thread.current.thread_variable_get(:foo), value
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}.join
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end
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def test_thread_variables
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assert_equal [], Thread.new { Thread.current.thread_variables }.join.value
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t = Thread.new {
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Thread.current.thread_variable_set(:foo, "bar")
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Thread.current.thread_variables
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}
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assert_equal [:foo], t.join.value
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end
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def test_thread_variable?
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refute Thread.new { Thread.current.thread_variable?("foo") }.join.value
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t = Thread.new {
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Thread.current.thread_variable_set("foo", "bar")
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}.join
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assert t.thread_variable?("foo")
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assert t.thread_variable?(:foo)
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refute t.thread_variable?(:bar)
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end
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def test_thread_variable_strings_and_symbols_are_the_same_key
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t = Thread.new {}.join
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t.thread_variable_set("foo", "bar")
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assert_equal "bar", t.thread_variable_get(:foo)
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end
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def test_thread_variable_frozen
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t = Thread.new { }.join
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t.freeze
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assert_raises(RuntimeError) do
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t.thread_variable_set(:foo, "bar")
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end
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end
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def test_thread_variable_security
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t = Thread.new { sleep }
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assert_raises(SecurityError) do
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Thread.new { $SAFE = 4; t.thread_variable_get(:foo) }.join
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end
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assert_raises(SecurityError) do
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Thread.new { $SAFE = 4; t.thread_variable_set(:foo, :baz) }.join
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end
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end
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end
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