Improve sanitize_sql_like performance

[jonathanhefner]

This improves performance and reduces memory allocations for sanitize_sql_like across multiple use cases.

Benchmark script

require "benchmark/memory"
require "benchmark/ips"

def old_sanitize_sql_like(string, escape_character = "\\")
  pattern = Regexp.union(escape_character, "%", "_")
  string.gsub(pattern) { |x| [escape_character, x].join }
end

def new_sanitize_sql_like(string, escape_character = "\\")
  if string.include?(escape_character) && escape_character != "%" && escape_character != "_"
    string = string.gsub(escape_character, '\0\0')
  end

  string.gsub(/(?=[%_])/, escape_character)
end

[
  "no-special-characters",
  "one_wildcard",
  "one\\escape",
  "two_wildcards%and\\two\\escapes",
].each do |string|
  puts "\n= #{string.inspect} ".ljust(72, "=")

  Benchmark.memory do |x|
    # Warmup:
    old_sanitize_sql_like(string)
    new_sanitize_sql_like(string)

    x.report("old") { old_sanitize_sql_like(string) }
    x.report("new") { new_sanitize_sql_like(string) }
  end

  puts

  Benchmark.ips do |x|
    x.report("old") { old_sanitize_sql_like(string) }
    x.report("new") { new_sanitize_sql_like(string) }
    x.compare!
  end
end

Benchmark results:

= "no-special-characters" =============================================
Calculating -------------------------------------
                 old   875.000  memsize (     0.000  retained)
                        10.000  objects (     0.000  retained)
                         5.000  strings (     0.000  retained)
                 new    40.000  memsize (     0.000  retained)
                         1.000  objects (     0.000  retained)
                         1.000  strings (     0.000  retained)

Warming up --------------------------------------
                 old     9.483k i/100ms
                 new   119.791k i/100ms
Calculating -------------------------------------
                 old     95.694k (± 0.3%) i/s -    483.633k in   5.053985s
                 new      1.228M (± 0.5%) i/s -      6.229M in   5.072317s

Comparison:
                 new:  1228094.1 i/s
                 old:    95694.3 i/s - 12.83x  (± 0.00) slower

= "one_wildcard" ======================================================
Calculating -------------------------------------
                 old     1.395k memsize (     0.000  retained)
                        15.000  objects (     0.000  retained)
                         6.000  strings (     0.000  retained)
                 new   440.000  memsize (     0.000  retained)
                         3.000  objects (     0.000  retained)
                         1.000  strings (     0.000  retained)

Warming up --------------------------------------
                 old     6.527k i/100ms
                 new    30.205k i/100ms
Calculating -------------------------------------
                 old     65.255k (± 0.6%) i/s -    326.350k in   5.001318s
                 new    300.058k (± 0.5%) i/s -      1.510M in   5.033333s

Comparison:
                 new:   300057.6 i/s
                 old:    65255.2 i/s - 4.60x  (± 0.00) slower

= "one\\escape" =======================================================
Calculating -------------------------------------
                 old     1.395k memsize (     0.000  retained)
                        15.000  objects (     0.000  retained)
                         6.000  strings (     0.000  retained)
                 new   560.000  memsize (     0.000  retained)
                         6.000  objects (     0.000  retained)
                         2.000  strings (     0.000  retained)

Warming up --------------------------------------
                 old     6.506k i/100ms
                 new    24.312k i/100ms
Calculating -------------------------------------
                 old     65.467k (± 0.4%) i/s -    331.806k in   5.068392s
                 new    245.704k (± 0.5%) i/s -      1.240M in   5.046485s

Comparison:
                 new:   245703.8 i/s
                 old:    65466.9 i/s - 3.75x  (± 0.00) slower

= "two_wildcards%and\\two\\escapes" ===================================
Calculating -------------------------------------
                 old     1.755k memsize (     0.000  retained)
                        24.000  objects (     0.000  retained)
                         8.000  strings (     0.000  retained)
                 new   832.000  memsize (     0.000  retained)
                         8.000  objects (     0.000  retained)
                         3.000  strings (     0.000  retained)

Warming up --------------------------------------
                 old     5.265k i/100ms
                 new    12.360k i/100ms
Calculating -------------------------------------
                 old     52.698k (± 0.3%) i/s -    268.515k in   5.095425s
                 new    124.006k (± 0.3%) i/s -    630.360k in   5.083351s

Comparison:
                 new:   124006.2 i/s
                 old:    52697.9 i/s - 2.35x  (± 0.00) slower