| # Base64 encoder with URL-safe scheme |
| |
| [](https://github.com/apache/couchdb-b64url/actions/workflows/ci.yml) |
| |
| This is a simple NIF that is responsible for quickly encoding and |
| decoding Base64 URL values: |
| |
| ```erlang |
| 1> Thing = b64url:encode("Hello, CouchDB!"). |
| <<"SGVsbG8sIENvdWNoREIh">> |
| 2> b64url:decode(Thing). |
| <<"Hello, CouchDB!">> |
| ``` |
| |
| ## Performance |
| |
| This implementation is faster than the Erlang version in OTP 26-28, |
| especially for larger binaries (1000+ bytes). To benchmark clone |
| erlperf repo and run `./benchmark.sh` script. In the future, it's |
| plausible Erlang OTP's base64 module may become faster than the NIF, |
| due to improvements in the JIT capabilities but it's not there yet. |
| |
| ``` |
| ./benchmark.sh |
| |
| [...] |
| |
| --- bytes: 100 ----- |
| Code || QPS Time Rel |
| encode_otp_100 1 1613 Ki 620 ns 100% |
| encode_nif_100 1 1391 Ki 719 ns 86% |
| Code || QPS Time Rel |
| decode_nif_100 1 1453 Ki 688 ns 100% |
| decode_otp_100 1 1395 Ki 716 ns 96% |
| |
| [...] |
| |
| --- bytes: 1000 ----- |
| Code || QPS Time Rel |
| encode_nif_1000 1 369 Ki 2711 ns 100% |
| encode_otp_1000 1 204 Ki 4904 ns 55% |
| Code || QPS Time Rel |
| decode_nif_1000 1 455 Ki 2196 ns 100% |
| decode_otp_1000 1 178 Ki 5612 ns 39% |
| |
| [...] |
| |
| --- bytes: 10000000 ----- |
| Code || QPS Time Rel |
| encode_nif_10000000 1 45 22388 us 100% |
| encode_otp_10000000 1 19 51724 us 43% |
| Code || QPS Time Rel |
| decode_nif_10000000 1 55 18078 us 100% |
| decode_otp_10000000 1 17 60020 us 30% |
| ``` |
| |
| ## Timeslice Consumption |
| |
| NIF implementations must take care to avoid doing [lengthy |
| work](https://www.erlang.org/doc/man/erl_nif.html#lengthy_work) in a single |
| invocation. This library will yield back to the Erlang VM as needed when |
| operating on a large string, maintaining a partial result until it can resume |
| operation. The current implementation uses a conservative heuristic that |
| estimates 64 bytes of encoding / decoding to consume 1% of a timeslice, so input |
| strings shorter than ~6k should be encoded / decoded within a single invocation, |
| and the library should not adversely affect the responsiveness of the VM in any |
| way. |
