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rails--rails/actionpack/lib/action_dispatch/journey/nodes/node.rb
Theo Julienne 16a80882f9 actionpack: Improve performance by allowing routes with custom regexes in the FSM.
The FSM used to find matching routes was previously limited to patterns
that contained parameters with the default regexp / no constraints. In
large route sets where many parameters are constrained by custom regexp,
these routes all fall back on a slow linear search over the route list.

These custom regexes were not previously able to be included in the FSM
because it transitioned between nodes using only fragments of the URI,
or path separators [/.?], but a custom regex may cross a path separator
boundary. To work around this, the TransitionTable is improved to
support remembering a point within the matching string that we started,
and continuing to attempt to match from that point up to the end of each
token. Only parameters not on a path separator boundary must still match
with a linear search after this change (e.g. `/foo-:bar/`).

This results in performance for constrainted routes that matches that of
ones using the default regexp.

Benchmark:
https://gist.github.com/theojulienne/e91fc338d180e1710e29c81a5d701fab

Before:
```
Calculating -------------------------------------
    without params      6.466k (±12.7%) i/s -     31.648k in   5.009453s
params without constraints
                        5.867k (±12.9%) i/s -     28.842k in   5.032637s
params with constraints
                      909.661  (± 7.9%) i/s -      4.536k in   5.023534s
```

After:
```
Calculating -------------------------------------
    without params      6.387k (±11.9%) i/s -     31.728k in   5.068939s
params without constraints
                        5.824k (±13.2%) i/s -     28.650k in   5.043701s
params with constraints
                        5.406k (±11.7%) i/s -     26.931k in   5.076412s
```

For github.com which has many constrainted parameters, a random sampling
of 10 URL patterns can be matched approximately 2-4x faster than before.

This commit fixes symbols as constrains as tested in
6ab985da28
2021-01-06 09:54:44 +11:00

151 lines
3 KiB
Ruby

# frozen_string_literal: true
require "action_dispatch/journey/visitors"
module ActionDispatch
module Journey # :nodoc:
module Nodes # :nodoc:
class Node # :nodoc:
include Enumerable
attr_accessor :left, :memo
def initialize(left)
@left = left
@memo = nil
end
def each(&block)
Visitors::Each::INSTANCE.accept(self, block)
end
def to_s
Visitors::String::INSTANCE.accept(self, "")
end
def to_dot
Visitors::Dot::INSTANCE.accept(self)
end
def to_sym
name.to_sym
end
def name
-left.tr("*:", "")
end
def type
raise NotImplementedError
end
def symbol?; false; end
def literal?; false; end
def terminal?; false; end
def star?; false; end
def cat?; false; end
def group?; false; end
end
class Terminal < Node # :nodoc:
alias :symbol :left
def terminal?; true; end
end
class Literal < Terminal # :nodoc:
def literal?; true; end
def type; :LITERAL; end
end
class Dummy < Literal # :nodoc:
def initialize(x = Object.new)
super
end
def literal?; false; end
end
class Slash < Terminal # :nodoc:
def type; :SLASH; end
end
class Dot < Terminal # :nodoc:
def type; :DOT; end
end
class Symbol < Terminal # :nodoc:
attr_accessor :regexp
alias :symbol :regexp
attr_reader :name
DEFAULT_EXP = /[^.\/?]+/
GREEDY_EXP = /(.+)/
def initialize(left, regexp = DEFAULT_EXP)
super(left)
@regexp = regexp
@name = -left.tr("*:", "")
end
def default_regexp?
regexp == DEFAULT_EXP
end
def type; :SYMBOL; end
def symbol?; true; end
end
class Unary < Node # :nodoc:
def children; [left] end
end
class Group < Unary # :nodoc:
def type; :GROUP; end
def group?; true; end
end
class Star < Unary # :nodoc:
attr_accessor :regexp
def initialize(left)
super(left)
# By default wildcard routes are non-greedy and must match something.
@regexp = /.+?/
end
def star?; true; end
def type; :STAR; end
def name
left.name.tr "*:", ""
end
end
class Binary < Node # :nodoc:
attr_accessor :right
def initialize(left, right)
super(left)
@right = right
end
def children; [left, right] end
end
class Cat < Binary # :nodoc:
def cat?; true; end
def type; :CAT; end
end
class Or < Node # :nodoc:
attr_reader :children
def initialize(children)
@children = children
end
def type; :OR; end
end
end
end
end