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Improving the performance of callbacks by keeping a hash of the

callbacks in the CallbackChain, so you don't have to iterate over all
callbacks when checking for duplicates.

Benchmark results when the tests in
activerecord/test/cases/associations_test.rb were run with and without
the change:

== On master (when scanning all of the callbacks):

 ---------------------------------------------------------
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 ---------------------------------------------------------

  1.85     9.26      0.82    18412     0.04     0.05
ActiveSupport::Callbacks::Callback#matches?
  1.22    12.32      0.54    18412     0.03     0.08
ActiveSupport::Callbacks::Callback#duplicates?
  0.93    14.61      0.41    19600     0.02     0.21
ActiveSupport::Callbacks::CallbackChain#remove_duplicates

Finished tests in 1.217065s, 30.4010 tests/s, 53.4072 assertions/s.
 ---------------------------------------------------------

== On my branch (when using a hash to check callback duplication):

 ---------------------------------------------------------
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 ---------------------------------------------------------
  0.15    29.63      0.06     1188     0.05     0.72
ActiveSupport::Callbacks::CallbackChain#handle_duplicates
  0.00    40.50      0.00       84     0.00     0.12
ActiveSupport::Callbacks::Callback#matches?
  0.00    40.50      0.00       84     0.00     0.12
ActiveSupport::Callbacks::Callback#duplicates?
  0.00    40.50      0.00       91     0.00     0.22
ActiveSupport::Callbacks::CallbackChain#scan_and_remove_duplicates

Finished tests in 1.117757s, 33.1020 tests/s, 58.1522 assertions/s.
 ---------------------------------------------------------
  • Loading branch information...
commit 58151ce461e559b7ba8a05a2fa9c9628f19c771b 1 parent 6a5ab08
@wangjohn wangjohn authored
Showing with 33 additions and 11 deletions.
  1. +33 −11 activesupport/lib/active_support/callbacks.rb
View
44 activesupport/lib/active_support/callbacks.rb
@@ -132,6 +132,10 @@ def next_id
@@_callback_sequence += 1
end
+ def object_filter?
+ @_is_object_filter
+ end
+
def matches?(_kind, _filter)
if @_is_object_filter
_filter_matches = @filter.to_s.start_with?(_method_name_for_object_filter(_kind, _filter, false))
@@ -337,6 +341,7 @@ def initialize(name, config)
:terminator => "false",
:scope => [ :kind ]
}.merge!(config)
+ @callbacks_hash = Hash.new { |h, k| h[k] = [] }
end
def compile
@@ -361,20 +366,37 @@ def prepend(*callbacks)
private
- def append_one(callback)
- remove_duplicates(callback)
- push(callback)
- end
+ def append_one(callback)
+ handle_duplicates(callback)
+ push(callback)
+ end
- def prepend_one(callback)
- remove_duplicates(callback)
- unshift(callback)
- end
+ def prepend_one(callback)
+ handle_duplicates(callback)
+ unshift(callback)
+ end
- def remove_duplicates(callback)
- delete_if { |c| callback.duplicates?(c) }
- end
+ # We check to see if this callback already exists. If it does (i.e. if
+ # +callback.duplicates?(c)+ for any callback +c+ in the list of
+ # callbacks), then we delete the previously defined callback.
+ #
+ # We make use of the rep-invariant that only one callback exists which
+ # might match the new callback. The +@callbacks_hash+ is keyed on the
+ # +kind+ and +filter+ of the callback, the attributes used to check if
+ # two callbacks match.
+ def handle_duplicates(callback)
+ if callback.object_filter?
+ scan_and_remove_duplicates(callback)
+ else
+ hash_key = [callback.kind, callback.filter]
+ delete @callbacks_hash[hash_key] if @callbacks_hash[hash_key]
+ @callbacks_hash[hash_key] = callback
+ end
+ end
+ def scan_and_remove_duplicates(callback)
+ delete_if { |c| callback.duplicates?(c) }
+ end
end
module ClassMethods
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