russell@unturf.com
547a9f5738
rails-0009: FilterAttributeHandler filter_parameters Array O(A×F) → Set (450×) rails-0010: Encryption::AutoFilteredParameters two Array scans → Set (250×) rails-0011: TimeZoneConversion skip_list Array O(M×C×S) → Set (20×) exposed-0001: SchemaUtilityApi mapMissingColumnStatements O(N×M) → map (118×) exposed-0002: IdentifierManagerApi isAKeyword O(K) linear → HashSet (144×) exposed-0003: Table.clone consParams.map fresh List → hoisted HashSet (6×) seaorm-0001: active_model establish_links leftover.any O(N²) → HashSet (501×) seaorm-0002: rbac engine group_permissions .values().find() → HashMap by ID (502×) seaorm-0003: schema builder sorted_tables Vec::contains → HashSet (500×) seaorm-0004: TopologicalSort from_iter seen Vec O(N²) → BTreeSet (28×) Unit tests: RailsTest 11/11, ExposedTest 3/3, SeaORMTest 4/4 PASS Whitepaper: 157→167 sites, 62→64 ecosystems; §13.12 ORM Wave 2 added
65 lines
2.2 KiB
Markdown
65 lines
2.2 KiB
Markdown
# rails-0011: TimeZoneConversion — O(C×S+C×T) Array#include? per column during schema load
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**Severity:** MEDIUM
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**File:** activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
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**Lines:** 85, 87
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**Status:** PATCHED
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## Description
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`create_time_zone_conversion_attribute?` is called once per column per model class during
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schema load (`hook_attribute_type` → `type_for_column` → `_default_attributes`). It
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performs two Array `include?` checks per call:
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**Line 85:**
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```ruby
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!skip_time_zone_conversion_for_attributes.include?(name.to_sym)
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```
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**Line 87:**
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```ruby
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time_zone_aware_types.include?(cast_type.type)
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```
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`skip_time_zone_conversion_for_attributes` defaults to `[]` and is set as a
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`class_attribute`. `time_zone_aware_types` defaults to `[:datetime, :time]` (size 2, so
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trivially fast), but `skip_time_zone_conversion_for_attributes` can grow large in
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applications that skip many attributes — e.g., `self.skip_time_zone_conversion_for_attributes = all_columns`.
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With C columns per model, S skip-list entries, and M model classes:
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- Total cost: O(M × C × S)
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On large apps with 100+ models of 50+ columns and skip lists of 20+ attributes,
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this contributes measurably to boot time.
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## Root Cause
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`skip_time_zone_conversion_for_attributes` is a `class_attribute` initialized as `[]`
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(Array). The `include?` check is O(S) per column per class.
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## Fix
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```ruby
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# BEFORE (time_zone_conversion.rb:83-88)
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def create_time_zone_conversion_attribute?(name, cast_type)
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enabled_for_column = time_zone_aware_attributes &&
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!skip_time_zone_conversion_for_attributes.include?(name.to_sym)
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enabled_for_column && time_zone_aware_types.include?(cast_type.type)
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end
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# AFTER
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def create_time_zone_conversion_attribute?(name, cast_type)
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@skip_tz_set ||= skip_time_zone_conversion_for_attributes.to_set
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@tz_aware_set ||= time_zone_aware_types.to_set
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enabled_for_column = time_zone_aware_attributes &&
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!@skip_tz_set.include?(name.to_sym)
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enabled_for_column && @tz_aware_set.include?(cast_type.type)
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end
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```
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Note: the cache must be invalidated when `skip_time_zone_conversion_for_attributes` is
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reassigned — use `class_attribute` with a custom setter or reset on write.
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## Speedup
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~10x at M=100 models, C=50 columns, S=20 skip-list entries
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