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I wrote a utility that helps find areas where you could optimize your program using a frozen string instead of a string literal, it's called [let_it_go](https://github.com/schneems/let_it_go). After going through the output and adding `.freeze` I was able to eliminate the creation of 1,114 string objects on EVERY request to [codetriage](codetriage.com). How does this impact execution? To look at memory: ```ruby require 'get_process_mem' mem = GetProcessMem.new GC.start GC.disable 1_114.times { " " } before = mem.mb after = mem.mb GC.enable puts "Diff: #{after - before} mb" ``` Creating 1,114 string objects results in `Diff: 0.03125 mb` of RAM allocated on every request. Or 1mb every 32 requests. To look at raw speed: ```ruby require 'benchmark/ips' number_of_objects_reduced = 1_114 Benchmark.ips do |x| x.report("freeze") { number_of_objects_reduced.times { " ".freeze } } x.report("no-freeze") { number_of_objects_reduced.times { " " } } end ``` We get the results ``` Calculating ------------------------------------- freeze 1.428k i/100ms no-freeze 609.000 i/100ms ------------------------------------------------- freeze 14.363k (± 8.5%) i/s - 71.400k no-freeze 6.084k (± 8.1%) i/s - 30.450k ``` Now we can do some maths: ```ruby ips = 6_226k # iterations / 1 second call_time_before = 1.0 / ips # seconds per iteration ips = 15_254 # iterations / 1 second call_time_after = 1.0 / ips # seconds per iteration diff = call_time_before - call_time_after number_of_objects_reduced * diff * 100 # => 0.4530373333993266 miliseconds saved per request ``` So we're shaving off 1 second of execution time for every 220 requests. Is this going to be an insane speed boost to any Rails app: nope. Should we merge it: yep. p.s. If you know of a method call that doesn't modify a string input such as [String#gsub](b0e2da69f0/lib/let_it_go/core_ext/string.rb (L37)) please [give me a pull request to the appropriate file](b0e2da69f0/lib/let_it_go/core_ext/string.rb (L37)), or open an issue in LetItGo so we can track and freeze more strings. Keep those strings Frozen 
93 lines
2.8 KiB
Ruby
93 lines
2.8 KiB
Ruby
module ActionDispatch
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module Journey # :nodoc:
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class Router # :nodoc:
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class Utils # :nodoc:
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# Normalizes URI path.
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#
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# Strips off trailing slash and ensures there is a leading slash.
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# Also converts downcase url encoded string to uppercase.
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#
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# normalize_path("/foo") # => "/foo"
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# normalize_path("/foo/") # => "/foo"
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# normalize_path("foo") # => "/foo"
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# normalize_path("") # => "/"
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# normalize_path("/%ab") # => "/%AB"
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def self.normalize_path(path)
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path = "/#{path}"
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path.squeeze!('/'.freeze)
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path.sub!(%r{/+\Z}, ''.freeze)
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path.gsub!(/(%[a-f0-9]{2})/) { $1.upcase }
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path = '/' if path == ''.freeze
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path
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end
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# URI path and fragment escaping
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# http://tools.ietf.org/html/rfc3986
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class UriEncoder # :nodoc:
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ENCODE = "%%%02X".freeze
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US_ASCII = Encoding::US_ASCII
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UTF_8 = Encoding::UTF_8
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EMPTY = "".force_encoding(US_ASCII).freeze
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DEC2HEX = (0..255).to_a.map{ |i| ENCODE % i }.map{ |s| s.force_encoding(US_ASCII) }
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ALPHA = "a-zA-Z".freeze
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DIGIT = "0-9".freeze
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UNRESERVED = "#{ALPHA}#{DIGIT}\\-\\._~".freeze
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SUB_DELIMS = "!\\$&'\\(\\)\\*\\+,;=".freeze
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ESCAPED = /%[a-zA-Z0-9]{2}/.freeze
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FRAGMENT = /[^#{UNRESERVED}#{SUB_DELIMS}:@\/\?]/.freeze
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SEGMENT = /[^#{UNRESERVED}#{SUB_DELIMS}:@]/.freeze
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PATH = /[^#{UNRESERVED}#{SUB_DELIMS}:@\/]/.freeze
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def escape_fragment(fragment)
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escape(fragment, FRAGMENT)
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end
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def escape_path(path)
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escape(path, PATH)
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end
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def escape_segment(segment)
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escape(segment, SEGMENT)
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end
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def unescape_uri(uri)
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encoding = uri.encoding == US_ASCII ? UTF_8 : uri.encoding
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uri.gsub(ESCAPED) { |match| [match[1, 2].hex].pack('C') }.force_encoding(encoding)
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end
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protected
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def escape(component, pattern)
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component.gsub(pattern){ |unsafe| percent_encode(unsafe) }.force_encoding(US_ASCII)
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end
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def percent_encode(unsafe)
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safe = EMPTY.dup
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unsafe.each_byte { |b| safe << DEC2HEX[b] }
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safe
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end
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end
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ENCODER = UriEncoder.new
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def self.escape_path(path)
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ENCODER.escape_path(path.to_s)
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end
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def self.escape_segment(segment)
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ENCODER.escape_segment(segment.to_s)
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end
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def self.escape_fragment(fragment)
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ENCODER.escape_fragment(fragment.to_s)
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end
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def self.unescape_uri(uri)
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ENCODER.unescape_uri(uri)
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end
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end
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end
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end
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end
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