feat(std): Stabilize 'os_str_bytes' feature by epage · Pull Request #115443 · rust-lang/rust (original) (raw)

sunshowers pushed a commit to camino-rs/camino that referenced this pull request

Aug 15, 2024

Background:

When I was migrating PathBuf to Utf8PathBuf, etc, I found out some regression in our benchmarks. Then I found out as_str is actually not cost-free as in the older version of rustc there's no way to get the underlying bytes out of an OsStr until 1.74.0.

In this PR, with the help of OsStr::as_encoded_bytes was stabilized in 1.74.0, We can perform a cost-free conversion from &OsStr to &str with constraint of it's underlying bytes are UTF-8 encoded.

Benchmark:

With the benchmark included in the PR, the time cost is a constant now.

Result:

// String length of 10
osstr to_str/10 
                        time:   [5.9769 ns 5.9913 ns 6.0060 ns]
osstr as_encoded_bytes/10 
                        time:   [554.90 ps 558.32 ps 562.19 ps]

// String length of 100
osstr to_str/100
                        time:   [6.6113 ns 6.6250 ns 6.6404 ns]
osstr as_encoded_bytes/100
                        time:   [553.18 ps 557.33 ps 561.68 ps]

// String length of 1000
osstr to_str/1000
                        time:   [26.990 ns 27.033 ns 27.086 ns]
osstr as_encoded_bytes/1000
                        time:   [553.66 ps 560.67 ps 570.42 ps]

// String length of 10000
osstr to_str/10000
                        time:   [310.17 ns 310.77 ns 311.32 ns]
osstr as_encoded_bytes/10000
                        time:   [550.98 ps 555.16 ps 559.53 ps]