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Flatten the call stacks ActiveSupport::Callbacks produces, fix #18011. #18294

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Jan 2, 2015
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Flatten the call stacks ActiveSupport::Callbacks produces, fix #18011. #18294

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190 changes: 116 additions & 74 deletions activesupport/lib/active_support/callbacks.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -121,22 +121,22 @@ def call(env)
ENDING = End.new

class Before
def self.build(next_callback, user_callback, user_conditions, chain_config, filter)
def self.build(callback_sequence, user_callback, user_conditions, chain_config, filter)
halted_lambda = chain_config[:terminator]

if chain_config.key?(:terminator) && user_conditions.any?
halting_and_conditional(next_callback, user_callback, user_conditions, halted_lambda, filter)
halting_and_conditional(callback_sequence, user_callback, user_conditions, halted_lambda, filter)
elsif chain_config.key? :terminator
halting(next_callback, user_callback, halted_lambda, filter)
halting(callback_sequence, user_callback, halted_lambda, filter)
elsif user_conditions.any?
conditional(next_callback, user_callback, user_conditions)
conditional(callback_sequence, user_callback, user_conditions)
else
simple next_callback, user_callback
simple callback_sequence, user_callback
end
end

def self.halting_and_conditional(next_callback, user_callback, user_conditions, halted_lambda, filter)
lambda { |env|
def self.halting_and_conditional(callback_sequence, user_callback, user_conditions, halted_lambda, filter)
callback_sequence.before do |env|
target = env.target
value = env.value
halted = env.halted
Expand All @@ -148,13 +148,14 @@ def self.halting_and_conditional(next_callback, user_callback, user_conditions,
target.send :halted_callback_hook, filter
end
end
next_callback.call env
}

env
end
end
private_class_method :halting_and_conditional

def self.halting(next_callback, user_callback, halted_lambda, filter)
lambda { |env|
def self.halting(callback_sequence, user_callback, halted_lambda, filter)
callback_sequence.before do |env|
target = env.target
value = env.value
halted = env.halted
Expand All @@ -166,180 +167,184 @@ def self.halting(next_callback, user_callback, halted_lambda, filter)
target.send :halted_callback_hook, filter
end
end
next_callback.call env
}

env
end
end
private_class_method :halting

def self.conditional(next_callback, user_callback, user_conditions)
lambda { |env|
def self.conditional(callback_sequence, user_callback, user_conditions)
callback_sequence.before do |env|
target = env.target
value = env.value

if user_conditions.all? { |c| c.call(target, value) }
user_callback.call target, value
end
next_callback.call env
}

env
end
end
private_class_method :conditional

def self.simple(next_callback, user_callback)
lambda { |env|
def self.simple(callback_sequence, user_callback)
callback_sequence.before do |env|
user_callback.call env.target, env.value
next_callback.call env
}

env
end
end
private_class_method :simple
end

class After
def self.build(next_callback, user_callback, user_conditions, chain_config)
def self.build(callback_sequence, user_callback, user_conditions, chain_config)
if chain_config[:skip_after_callbacks_if_terminated]
if chain_config.key?(:terminator) && user_conditions.any?
halting_and_conditional(next_callback, user_callback, user_conditions)
halting_and_conditional(callback_sequence, user_callback, user_conditions)
elsif chain_config.key?(:terminator)
halting(next_callback, user_callback)
halting(callback_sequence, user_callback)
elsif user_conditions.any?
conditional next_callback, user_callback, user_conditions
conditional callback_sequence, user_callback, user_conditions
else
simple next_callback, user_callback
simple callback_sequence, user_callback
end
else
if user_conditions.any?
conditional next_callback, user_callback, user_conditions
conditional callback_sequence, user_callback, user_conditions
else
simple next_callback, user_callback
simple callback_sequence, user_callback
end
end
end

def self.halting_and_conditional(next_callback, user_callback, user_conditions)
lambda { |env|
env = next_callback.call env
def self.halting_and_conditional(callback_sequence, user_callback, user_conditions)
callback_sequence.after do |env|
target = env.target
value = env.value
halted = env.halted

if !halted && user_conditions.all? { |c| c.call(target, value) }
user_callback.call target, value
end

env
}
end
end
private_class_method :halting_and_conditional

def self.halting(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
def self.halting(callback_sequence, user_callback)
callback_sequence.after do |env|
unless env.halted
user_callback.call env.target, env.value
end

env
}
end
end
private_class_method :halting

def self.conditional(next_callback, user_callback, user_conditions)
lambda { |env|
env = next_callback.call env
def self.conditional(callback_sequence, user_callback, user_conditions)
callback_sequence.after do |env|
target = env.target
value = env.value

if user_conditions.all? { |c| c.call(target, value) }
user_callback.call target, value
end

env
}
end
end
private_class_method :conditional

def self.simple(next_callback, user_callback)
lambda { |env|
env = next_callback.call env
def self.simple(callback_sequence, user_callback)
callback_sequence.after do |env|
user_callback.call env.target, env.value

env
}
end
end
private_class_method :simple
end

class Around
def self.build(next_callback, user_callback, user_conditions, chain_config)
def self.build(callback_sequence, user_callback, user_conditions, chain_config)
if chain_config.key?(:terminator) && user_conditions.any?
halting_and_conditional(next_callback, user_callback, user_conditions)
halting_and_conditional(callback_sequence, user_callback, user_conditions)
elsif chain_config.key? :terminator
halting(next_callback, user_callback)
halting(callback_sequence, user_callback)
elsif user_conditions.any?
conditional(next_callback, user_callback, user_conditions)
conditional(callback_sequence, user_callback, user_conditions)
else
simple(next_callback, user_callback)
simple(callback_sequence, user_callback)
end
end

def self.halting_and_conditional(next_callback, user_callback, user_conditions)
lambda { |env|
def self.halting_and_conditional(callback_sequence, user_callback, user_conditions)
callback_sequence.around do |env, &run|
target = env.target
value = env.value
halted = env.halted

if !halted && user_conditions.all? { |c| c.call(target, value) }
user_callback.call(target, value) {
env = next_callback.call env
env = run.call env
env.value
}

env
else
next_callback.call env
run.call env
end
}
end
end
private_class_method :halting_and_conditional

def self.halting(next_callback, user_callback)
lambda { |env|
def self.halting(callback_sequence, user_callback)
callback_sequence.around do |env, &run|
target = env.target
value = env.value

if env.halted
next_callback.call env
run.call env
else
user_callback.call(target, value) {
env = next_callback.call env
env = run.call env
env.value
}
env
end
}
end
end
private_class_method :halting

def self.conditional(next_callback, user_callback, user_conditions)
lambda { |env|
def self.conditional(callback_sequence, user_callback, user_conditions)
callback_sequence.around do |env, &run|
target = env.target
value = env.value

if user_conditions.all? { |c| c.call(target, value) }
user_callback.call(target, value) {
env = next_callback.call env
env = run.call env
env.value
}
env
else
next_callback.call env
run.call env
end
}
end
end
private_class_method :conditional

def self.simple(next_callback, user_callback)
lambda { |env|
def self.simple(callback_sequence, user_callback)
callback_sequence.around do |env, &run|
user_callback.call(env.target, env.value) {
env = next_callback.call env
env = run.call env
env.value
}
env
}
end
end
private_class_method :simple
end
Expand Down Expand Up @@ -392,17 +397,17 @@ def duplicates?(other)
end

# Wraps code with filter
def apply(next_callback)
def apply(callback_sequence)
user_conditions = conditions_lambdas
user_callback = make_lambda @filter

case kind
when :before
Filters::Before.build(next_callback, user_callback, user_conditions, chain_config, @filter)
Filters::Before.build(callback_sequence, user_callback, user_conditions, chain_config, @filter)
when :after
Filters::After.build(next_callback, user_callback, user_conditions, chain_config)
Filters::After.build(callback_sequence, user_callback, user_conditions, chain_config)
when :around
Filters::Around.build(next_callback, user_callback, user_conditions, chain_config)
Filters::Around.build(callback_sequence, user_callback, user_conditions, chain_config)
end
end

Expand Down Expand Up @@ -467,6 +472,42 @@ def conditions_lambdas
end
end

# Execute before and after filters in a sequence instead of
# chaining them with nested lambda calls, see:
# https://github.com/rails/rails/issues/18011
class CallbackSequence
def initialize(&call)
@call = call
@before = []
@after = []
end

def before(&before)
@before.unshift(before)
self
end

def after(&after)
@after.push(after)
self
end

def around(&around)
CallbackSequence.new do |*args|
around.call(*args) {
self.call(*args)
}
end
end

def call(*args)
@before.each { |b| b.call(*args) }
value = @call.call(*args)
@after.each { |a| a.call(*args) }
value
end
end

# An Array with a compile method.
class CallbackChain #:nodoc:#
include Enumerable
Expand Down Expand Up @@ -511,8 +552,9 @@ def initialize_copy(other)

def compile
@callbacks || @mutex.synchronize do
@callbacks ||= @chain.reverse.inject(Filters::ENDING) do |chain, callback|
callback.apply chain
final_sequence = CallbackSequence.new { |env| Filters::ENDING.call(env) }
@callbacks ||= @chain.reverse.inject(final_sequence) do |callback_sequence, callback|
callback.apply callback_sequence
end
end
end
Expand Down