Correctly escape ASCII control characters in strings

[raphlinus]

This patch escapes ASCII control characters in the range 0x00...0x1f, in accordance with the JSON spec.

Fixes #51

[raphlinus]

Sorry, I wrote the issue # wrong when I uploaded.

[oli-obk]

Since you are concerned about execution speed, could you post some benchmarks before and after?

[PaulGrandperrin]

• last common commit of Correctly escape ASCII control characters in strings #58 and Correctly escape ASCII control characters in strings #65 (7bc9b0a)

test bench_log::bench_copy                                      ... bench:          35 ns/iter (+/- 2) = 17285 MB/s
test bench_log::bench_decoder                                   ... bench:      18,073 ns/iter (+/- 1,326) = 33 MB/s
test bench_log::bench_deserializer                              ... bench:       5,493 ns/iter (+/- 137) = 110 MB/s
test bench_log::bench_encoder                                   ... bench:       3,336 ns/iter (+/- 56) = 181 MB/s
test bench_log::bench_manual_serialize_my_mem_writer0_escape    ... bench:       3,252 ns/iter (+/- 399) = 186 MB/s
test bench_log::bench_manual_serialize_my_mem_writer0_no_escape ... bench:       2,003 ns/iter (+/- 50) = 302 MB/s
test bench_log::bench_manual_serialize_my_mem_writer1_escape    ... bench:       1,934 ns/iter (+/- 78) = 312 MB/s
test bench_log::bench_manual_serialize_my_mem_writer1_no_escape ... bench:       1,124 ns/iter (+/- 163) = 538 MB/s
test bench_log::bench_manual_serialize_vec_escape               ... bench:       2,052 ns/iter (+/- 163) = 294 MB/s
test bench_log::bench_manual_serialize_vec_no_escape            ... bench:       1,315 ns/iter (+/- 36) = 460 MB/s
test bench_log::bench_serializer                                ... bench:       2,605 ns/iter (+/- 112) = 232 MB/s
test bench_log::bench_serializer_my_mem_writer0                 ... bench:       3,613 ns/iter (+/- 689) = 167 MB/s
test bench_log::bench_serializer_my_mem_writer1                 ... bench:       2,190 ns/iter (+/- 35) = 276 MB/s
test bench_log::bench_serializer_slice                          ... bench:       3,069 ns/iter (+/- 1,791) = 197 MB/s
test bench_log::bench_serializer_vec                            ... bench:       2,369 ns/iter (+/- 352) = 255 MB/s

• the PR Correctly escape ASCII control characters in strings #58 (632a555)

test bench_log::bench_copy                                      ... bench:          35 ns/iter (+/- 2) = 17285 MB/s
test bench_log::bench_decoder                                   ... bench:      18,576 ns/iter (+/- 170) = 32 MB/s
test bench_log::bench_deserializer                              ... bench:       5,594 ns/iter (+/- 905) = 108 MB/s
test bench_log::bench_encoder                                   ... bench:       3,214 ns/iter (+/- 174) = 188 MB/s
test bench_log::bench_manual_serialize_my_mem_writer0_escape    ... bench:       3,692 ns/iter (+/- 310) = 163 MB/s
test bench_log::bench_manual_serialize_my_mem_writer0_no_escape ... bench:       1,998 ns/iter (+/- 196) = 302 MB/s
test bench_log::bench_manual_serialize_my_mem_writer1_escape    ... bench:       2,580 ns/iter (+/- 37) = 234 MB/s
test bench_log::bench_manual_serialize_my_mem_writer1_no_escape ... bench:       1,103 ns/iter (+/- 39) = 548 MB/s
test bench_log::bench_manual_serialize_vec_escape               ... bench:       2,698 ns/iter (+/- 199) = 224 MB/s
test bench_log::bench_manual_serialize_vec_no_escape            ... bench:       1,286 ns/iter (+/- 117) = 470 MB/s
test bench_log::bench_serializer                                ... bench:       3,188 ns/iter (+/- 67) = 189 MB/s
test bench_log::bench_serializer_my_mem_writer0                 ... bench:       4,138 ns/iter (+/- 330) = 146 MB/s
test bench_log::bench_serializer_my_mem_writer1                 ... bench:       2,707 ns/iter (+/- 55) = 223 MB/s
test bench_log::bench_serializer_slice                          ... bench:       3,786 ns/iter (+/- 2,035) = 159 MB/s
test bench_log::bench_serializer_vec                            ... bench:       2,914 ns/iter (+/- 74) = 207 MB/s

• this PR Correctly escape ASCII control characters in strings #65 (c5c9532)

test bench_log::bench_copy                                      ... bench:          35 ns/iter (+/- 3) = 17285 MB/s
test bench_log::bench_decoder                                   ... bench:      18,109 ns/iter (+/- 1,484) = 33 MB/s
test bench_log::bench_deserializer                              ... bench:       5,599 ns/iter (+/- 315) = 108 MB/s
test bench_log::bench_encoder                                   ... bench:       3,346 ns/iter (+/- 263) = 180 MB/s
test bench_log::bench_manual_serialize_my_mem_writer0_escape    ... bench:       3,279 ns/iter (+/- 72) = 184 MB/s
test bench_log::bench_manual_serialize_my_mem_writer0_no_escape ... bench:       1,958 ns/iter (+/- 272) = 308 MB/s
test bench_log::bench_manual_serialize_my_mem_writer1_escape    ... bench:       2,122 ns/iter (+/- 164) = 285 MB/s
test bench_log::bench_manual_serialize_my_mem_writer1_no_escape ... bench:       1,089 ns/iter (+/- 101) = 555 MB/s
test bench_log::bench_manual_serialize_vec_escape               ... bench:       2,267 ns/iter (+/- 186) = 266 MB/s
test bench_log::bench_manual_serialize_vec_no_escape            ... bench:       1,315 ns/iter (+/- 125) = 460 MB/s
test bench_log::bench_serializer                                ... bench:       2,672 ns/iter (+/- 74) = 226 MB/s
test bench_log::bench_serializer_my_mem_writer0                 ... bench:       3,840 ns/iter (+/- 178) = 157 MB/s
test bench_log::bench_serializer_my_mem_writer1                 ... bench:       2,373 ns/iter (+/- 491) = 254 MB/s
test bench_log::bench_serializer_slice                          ... bench:       3,230 ns/iter (+/- 1,879) = 187 MB/s
test bench_log::bench_serializer_vec                            ... bench:       2,477 ns/iter (+/- 198) = 244 MB/s

Here are the most noticeable between the last common commit and #58
manual_serialize_my_mem_writer1_escape : 75% of original speed
manual_serialize_vec_escape: 76% of original speed
serializer: 81% of original speed
serializer_my_mem_writer1: 81% of original speed
serializer_slice: 81% of original speed
serializer_vec: 81% of original speed

Here are the most noticeable between the last common commit and #65
manual_serialize_my_mem_writer1_escape : 91% of original speed
manual_serialize_vec_escape: 91% of original speed
serializer: 97% of original speed
serializer_my_mem_writer1: 92% of original speed
serializer_slice: 95% of original speed
serializer_vec: 96% of original speed

Conclusion:
This code is significantly faster than #58, I'll try to investigate if this comes from the different logic used or the fact that it escapes fewer characters.

[PaulGrandperrin]

After some tests, the difference really comes from the fact that fewer characters are escaped than #58 .

[raphlinus]

Thanks @PaulGrandperrin for the benchmarks! I was planning to do them but didn't get around to it.

[raphlinus]

Yay!