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require 'concurrent/atomic_reference/concurrent_update_error'
module Concurrent
# Define update methods that use direct paths
#
# @!visibility private
# @!macro internal_implementation_note
module AtomicDirectUpdate
# @!macro [attach] atomic_reference_method_update
#
# Pass the current value to the given block, replacing it
# with the block's result. May retry if the value changes
# during the block's execution.
#
# @yield [Object] Calculate a new value for the atomic reference using
# given (old) value
# @yieldparam [Object] old_value the starting value of the atomic reference
#
# @return [Object] the new value
def update
true until compare_and_set(old_value = get, new_value = yield(old_value))
new_value
end
# @!macro [attach] atomic_reference_method_try_update
#
# Pass the current value to the given block, replacing it
# with the block's result. Return nil if the update fails.
#
# @yield [Object] Calculate a new value for the atomic reference using
# given (old) value
# @yieldparam [Object] old_value the starting value of the atomic reference
#
# @note This method was altered to avoid raising an exception by default.
# Instead, this method now returns `nil` in case of failure. For more info,
# please see: https://github.com/ruby-concurrency/concurrent-ruby/pull/336
#
# @return [Object] the new value, or nil if update failed
def try_update
old_value = get
new_value = yield old_value
return unless compare_and_set old_value, new_value
new_value
end
# @!macro [attach] atomic_reference_method_try_update!
#
# Pass the current value to the given block, replacing it
# with the block's result. Raise an exception if the update
# fails.
#
# @yield [Object] Calculate a new value for the atomic reference using
# given (old) value
# @yieldparam [Object] old_value the starting value of the atomic reference
#
# @note This behavior mimics the behavior of the original
# `AtomicReference#try_update` API. The reason this was changed was to
# avoid raising exceptions (which are inherently slow) by default. For more
# info: https://github.com/ruby-concurrency/concurrent-ruby/pull/336
#
# @return [Object] the new value
#
# @raise [Concurrent::ConcurrentUpdateError] if the update fails
def try_update!
old_value = get
new_value = yield old_value
unless compare_and_set(old_value, new_value)
if $VERBOSE
raise ConcurrentUpdateError, "Update failed"
else
raise ConcurrentUpdateError, "Update failed", ConcurrentUpdateError::CONC_UP_ERR_BACKTRACE
end
end
new_value
end
end
end
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