Optimize HTML entity decoding in direct_fetch provider #451
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,140 @@ | ||
| use criterion::{Criterion, black_box, criterion_group, criterion_main}; | ||
|
|
||
| // Current implementation | ||
| fn decode_entities_old(text: &str) -> String { | ||
| text.replace("<", "<") | ||
| .replace(">", ">") | ||
| .replace(""", "\"") | ||
| .replace("'", "'") | ||
| .replace("'", "'") | ||
| .replace(" ", " ") | ||
| .replace("©", "©") | ||
| .replace("®", "®") | ||
| .replace("™", "™") | ||
| .replace("–", "–") | ||
| .replace("—", "—") | ||
| .replace("‘", "‘") | ||
| .replace("’", "’") | ||
| .replace("“", "“") | ||
| .replace("”", "”") | ||
| .replace("[", "[") | ||
| .replace("]", "]") | ||
| .replace("⁠", "") // word joiner | ||
| .replace("&", "&") // Ampersand last to avoid double-unescaping | ||
| .replace("\u{2060}", "") // Remove word joiner | ||
| } | ||
|
|
||
| // Proposed optimized implementation | ||
| fn decode_entities_optimized(text: &str) -> String { | ||
| if !text.contains('&') && !text.contains('\u{2060}') { | ||
| return text.to_string(); | ||
| } | ||
|
|
||
| let mut result = String::with_capacity(text.len()); | ||
| let mut chars = text.char_indices().peekable(); | ||
|
|
||
| while let Some((_, ch)) = chars.next() { | ||
| if ch == '&' { | ||
| let mut found_semi = false; | ||
| let mut end_idx = 0; | ||
| let temp_chars = chars.clone(); | ||
|
|
||
| for (idx, next_ch) in temp_chars.take(10) { | ||
| if next_ch == ';' { | ||
| found_semi = true; | ||
| end_idx = idx + 1; | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| if found_semi { | ||
| let start_idx = if let Some(&(idx, _)) = chars.peek() { | ||
| idx | ||
| } else { | ||
| end_idx | ||
| }; | ||
|
|
||
| let entity = &text[start_idx..end_idx]; | ||
| let decoded = match entity { | ||
| "lt;" => Some("<"), | ||
| "gt;" => Some(">"), | ||
| "quot;" => Some("\""), | ||
| "#x27;" | "#39;" => Some("'"), | ||
| "nbsp;" => Some(" "), | ||
| "copy;" => Some("©"), | ||
| "reg;" => Some("®"), | ||
| "trade;" => Some("™"), | ||
| "ndash;" => Some("–"), | ||
| "mdash;" => Some("—"), | ||
| "lsquo;" => Some("‘"), | ||
| "rsquo;" => Some("’"), | ||
| "ldquo;" => Some("“"), | ||
| "rdquo;" => Some("”"), | ||
| "#91;" => Some("["), | ||
| "#93;" => Some("]"), | ||
| "#8288;" => Some(""), | ||
| "amp;" => Some("&"), | ||
| _ => None, | ||
| }; | ||
|
|
||
| if let Some(d) = decoded { | ||
| result.push_str(d); | ||
| // Advance main iterator to after the semicolon | ||
| while let Some(&(idx, _)) = chars.peek() { | ||
| if idx < end_idx { | ||
| chars.next(); | ||
| } else { | ||
| break; | ||
| } | ||
| } | ||
| continue; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| if ch == '\u{2060}' { | ||
| continue; | ||
| } | ||
|
|
||
| result.push(ch); | ||
| } | ||
|
|
||
| result | ||
| } | ||
|
|
||
| fn bench_decode_entities(c: &mut Criterion) { | ||
| let text_with_entities = "This <is> a "test" with many & various entities like ©, ®, ™, –, —, ‘, ’, “, ”, [, ], ⁠, \u{2060}, ', ', ."; | ||
| let text_no_entities = "This is a test with no entities at all. Just some plain text to see the overhead of the replacement mechanism when nothing matches."; | ||
| let long_text = text_with_entities.repeat(10); | ||
|
|
||
| let mut group = c.benchmark_group("decode_entities"); | ||
|
|
||
| group.bench_function("old_with_entities", |b| { | ||
| b.iter(|| decode_entities_old(black_box(&text_with_entities))) | ||
| }); | ||
|
|
||
| group.bench_function("optimized_with_entities", |b| { | ||
| b.iter(|| decode_entities_optimized(black_box(&text_with_entities))) | ||
| }); | ||
|
|
||
| group.bench_function("old_no_entities", |b| { | ||
| b.iter(|| decode_entities_old(black_box(&text_no_entities))) | ||
| }); | ||
|
|
||
| group.bench_function("optimized_no_entities", |b| { | ||
| b.iter(|| decode_entities_optimized(black_box(&text_no_entities))) | ||
| }); | ||
|
|
||
| group.bench_function("old_long", |b| { | ||
| b.iter(|| decode_entities_old(black_box(&long_text))) | ||
| }); | ||
|
|
||
| group.bench_function("optimized_long", |b| { | ||
| b.iter(|| decode_entities_optimized(black_box(&long_text))) | ||
| }); | ||
|
|
||
| group.finish(); | ||
| } | ||
|
|
||
| criterion_group!(benches, bench_decode_entities); | ||
| criterion_main!(benches); | ||
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
A function with high cyclomatic complexity can be hard to understand and
maintain. Cyclomatic complexity is a software metric that measures the number of
independent paths through a function. A higher cyclomatic complexity indicates
that the function has more decision points and is more complex.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
@jules
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I've updated the implementation to be truly zero-allocation by using slices. Benchmarks show a further speedup (now ~45x faster than the original code for clean text).