The benchmark results

benchmarks

Result of running bm.rb four times (which runs 100K iterations of encode or decode 
over a set of values), taking the "user" column from the results:

+------------------+--------+---------+---------+---------+---------+
|                  | Method | 1st run | 2nd run | 3rd run | 4th run |
+------------------+--------+---------+---------+---------+---------+
| Baseline         | Decode |    1.92 |    1.92 |    1.94 |    2.22 |
|                  | Encode |    1.90 |    1.91 |    1.91 |    1.92 |
+------------------+--------+---------+---------+---------+---------+
| Constant Strings | Decode |    2.07 |    1.81 |    1.82 |    1.84 |
|                  | Encode |    2.14 |    1.71 |    1.77 |    1.79 |
+------------------+--------+---------+---------+---------+---------+
| Pack Cache       | Decode |    2.15 |    2.10 |    2.01 |    2.03 |
|                  | Encode |    2.00 |    2.05 |    1.86 |    1.86 |
+------------------+--------+---------+---------+---------+---------+

Using the pack cache patch is in almost all cases slower than using literal strings, 
whereas constant strings is considerably faster.

bm.rb

$: << 'lib'

require 'benchmark'
require 'bigdecimal'
require 'amq/protocol/table'

# this sample data was taken from the specs, removed the BigDecimal examples 
# since they skewed the test results (one of the patches optimized for that too)

timestamp = Time.utc(2010, 12, 31, 23, 58, 59)

data = {
  Hash.new                 => "\x00\x00\x00\x00",
  {"test" => 1}            => "\x00\x00\x00\n\x04testI\x00\x00\x00\x01",
  {"test" => "string"}     => "\x00\x00\x00\x10\x04testS\x00\x00\x00\x06string",
  {"test" => Hash.new}     => "\x00\x00\x00\n\x04testF\x00\x00\x00\x00",
  {"test" => timestamp}    => "\x00\x00\x00\x0e\x04testT\x00\x00\x00\x00M\x1enC"
}

iterations = 100_000

Benchmark.bmbm do |bm|
  bm.report('Decode') do
    iterations.times do
      data.each do |key, value|
        AMQ::Protocol::Table.decode(value)
      end
    end
  end

  bm.report('Encode') do
    iterations.times do
      data.each do |key, value|
        AMQ::Protocol::Table.encode(key)
      end
    end
  end
end

run.sh

# runs the benchmarks on the three relevant commits

baseline='cdd01bc3779b9e2e414275ccfb79823cd8823593'
constant_strings='b95225cf763b7242c808ad47889dd2ab3bf35a97'
pack_cache='b6d8133e55a65de16c0c44662c0e4ad90874747c'

echo 'BASELINE'
git co $baseline
ruby bm.rb
echo

echo 'CONSTANT STRINGS'
git co $constant_strings
ruby bm.rb
echo

echo 'PACK CACHE'
git co $pack_cache
ruby bm.rb
echo

sample output

BASELINE
Previous HEAD position was b6d8133... Changed from constants using PACK_CACHE
HEAD is now at cdd01bc... These are identical.
Rehearsal ------------------------------------------
Decode   1.950000   0.010000   1.960000 (  1.960757)
Encode   1.950000   0.000000   1.950000 (  1.953454)
--------------------------------- total: 3.910000sec

             user     system      total        real
Decode   2.220000   0.010000   2.230000 (  2.264727)
Encode   1.920000   0.000000   1.920000 (  1.912063)


CONSTANT STRINGS
Previous HEAD position was cdd01bc... These are identical.
HEAD is now at b95225c... Replaced literal strings with constants
Rehearsal ------------------------------------------
Decode   1.830000   0.000000   1.830000 (  1.828105)
Encode   1.760000   0.010000   1.770000 (  1.759748)
--------------------------------- total: 3.600000sec

             user     system      total        real
Decode   1.840000   0.000000   1.840000 (  1.845521)
Encode   1.790000   0.000000   1.790000 (  1.789752)


PACK CACHE
Previous HEAD position was b95225c... Replaced literal strings with constants
HEAD is now at b6d8133... Changed from constants using PACK_CACHE
Rehearsal ------------------------------------------
Decode   2.300000   0.010000   2.310000 (  2.375506)
Encode   1.880000   0.010000   1.890000 (  1.883791)
--------------------------------- total: 4.200000sec

             user     system      total        real
Decode   2.030000   0.000000   2.030000 (  2.034270)
Encode   1.860000   0.010000   1.870000 (  1.868044)