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subscriber: use state machine to parse EnvFilter directives #3243

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Merged
merged 1 commit into from
May 8, 2025
Merged

subscriber: use state machine to parse EnvFilter directives #3243

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5 changes: 3 additions & 2 deletions tracing-subscriber/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ rust-version = "1.63.0"
default = ["smallvec", "fmt", "ansi", "tracing-log", "std"]
alloc = ["tracing-core/alloc", "portable-atomic-util?/alloc"]
std = ["alloc", "tracing-core/std"]
env-filter = ["matchers", "regex", "once_cell", "tracing", "std", "thread_local"]
env-filter = ["matchers", "once_cell", "tracing", "std", "thread_local"]
fmt = ["registry", "std"]
ansi = ["fmt", "nu-ansi-term"]
registry = ["sharded-slab", "thread_local", "std"]
Expand All @@ -39,14 +39,15 @@ critical-section = ["tracing-core/critical-section", "tracing?/critical-section"
# formatters.
local-time = ["time/local-offset"]
nu-ansi-term = ["dep:nu-ansi-term"]
# For backwards compatibility only
regex = []

[dependencies]
tracing-core = { path = "../tracing-core", version = "0.2", default-features = false }

# only required by the `env-filter` feature
tracing = { optional = true, path = "../tracing", version = "0.2", default-features = false }
matchers = { optional = true, version = "0.1.0" }
regex = { optional = true, version = "1.6.0", default-features = false, features = ["std", "unicode-case", "unicode-perl"] }
smallvec = { optional = true, version = "1.9.0" }
once_cell = { optional = true, version = "1.13.0" }

Expand Down
201 changes: 111 additions & 90 deletions tracing-subscriber/src/filter/env/directive.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,6 @@ use crate::filter::{
env::{field, FieldMap},
level::LevelFilter,
};
use once_cell::sync::Lazy;
use regex::Regex;
use std::{cmp::Ordering, fmt, iter::FromIterator, str::FromStr};
use tracing_core::{span, Level, Metadata};

Expand Down Expand Up @@ -120,99 +118,122 @@ impl Directive {
}

pub(super) fn parse(from: &str, regex: bool) -> Result<Self, ParseError> {
static DIRECTIVE_RE: Lazy<Regex> = Lazy::new(|| {
Regex::new(
r"(?x)
^(?P<global_level>(?i:trace|debug|info|warn|error|off|[0-5]))$ |
# ^^^.
# `note: we match log level names case-insensitively
^
(?: # target name or span name
(?P<target>[\w:-]+)|(?P<span>\[[^\]]*\])
){1,2}
(?: # level or nothing
=(?P<level>(?i:trace|debug|info|warn|error|off|[0-5]))?
# ^^^.
# `note: we match log level names case-insensitively
)?
$
",
)
.unwrap()
});
static SPAN_PART_RE: Lazy<Regex> =
Lazy::new(|| Regex::new(r"(?P<name>[^\]\{]+)?(?:\{(?P<fields>[^\}]*)\})?").unwrap());
static FIELD_FILTER_RE: Lazy<Regex> =
// TODO(eliza): this doesn't _currently_ handle value matchers that include comma
// characters. We should fix that.
Lazy::new(|| {
Regex::new(
r"(?x)
(
# field name
[[:word:]][[[:word:]]\.]*
# value part (optional)
(?:=[^,]+)?
)
# trailing comma or EOS
(?:,\s?|$)
",
)
.unwrap()
});

let caps = DIRECTIVE_RE.captures(from).ok_or_else(ParseError::new)?;
let mut cur = Self {
level: LevelFilter::TRACE,
target: None,
in_span: None,
fields: Vec::new(),
};

#[derive(Debug)]
enum ParseState {
Start,
LevelOrTarget { start: usize },
Span { span_start: usize },
Field { field_start: usize },
Fields,
Target,
Level { level_start: usize },
Complete,
}

if let Some(level) = caps
.name("global_level")
.and_then(|s| s.as_str().parse().ok())
{
return Ok(Directive {
level,
..Default::default()
});
use ParseState::*;
let mut state = Start;
for (i, c) in from.trim().char_indices() {
state = match (state, c) {
(Start, '[') => Span { span_start: i + 1 },
(Start, c) if !['-', ':', '_'].contains(&c) && !c.is_alphanumeric() => {
return Err(ParseError::new())
}
(Start, _) => LevelOrTarget { start: i },
(LevelOrTarget { start }, '=') => {
cur.target = Some(from[start..i].to_owned());
Level { level_start: i + 1 }
}
(LevelOrTarget { start }, '[') => {
cur.target = Some(from[start..i].to_owned());
Span { span_start: i + 1 }
}
(LevelOrTarget { start }, ',') => {
let (level, target) = match &from[start..] {
"" => (LevelFilter::TRACE, None),
level_or_target => match LevelFilter::from_str(level_or_target) {
Ok(level) => (level, None),
Err(_) => (LevelFilter::TRACE, Some(level_or_target.to_owned())),
},
};

cur.level = level;
cur.target = target;
Complete
}
(state @ LevelOrTarget { .. }, _) => state,
(Target, '=') => Level { level_start: i + 1 },
(Span { span_start }, ']') => {
cur.in_span = Some(from[span_start..i].to_owned());
Target
}
(Span { span_start }, '{') => {
cur.in_span = match &from[span_start..i] {
"" => None,
_ => Some(from[span_start..i].to_owned()),
};
Field { field_start: i + 1 }
}
(state @ Span { .. }, _) => state,
(Field { field_start }, '}') => {
cur.fields.push(match &from[field_start..i] {
"" => return Err(ParseError::new()),
field => field::Match::parse(field, regex)?,
});
Fields
}
(Field { field_start }, ',') => {
cur.fields.push(match &from[field_start..i] {
"" => return Err(ParseError::new()),
field => field::Match::parse(field, regex)?,
});
Field { field_start: i + 1 }
}
(state @ Field { .. }, _) => state,
(Fields, ']') => Target,
(Level { level_start }, ',') => {
cur.level = match &from[level_start..i] {
"" => LevelFilter::TRACE,
level => LevelFilter::from_str(level)?,
};
Complete
}
(state @ Level { .. }, _) => state,
_ => return Err(ParseError::new()),
};
}

let target = caps.name("target").and_then(|c| {
let s = c.as_str();
if s.parse::<LevelFilter>().is_ok() {
None
} else {
Some(s.to_owned())
match state {
LevelOrTarget { start } => {
let (level, target) = match &from[start..] {
"" => (LevelFilter::TRACE, None),
level_or_target => match LevelFilter::from_str(level_or_target) {
Ok(level) => (level, None),
// Setting the target without the level enables every level for that target
Err(_) => (LevelFilter::TRACE, Some(level_or_target.to_owned())),
},
};

cur.level = level;
cur.target = target;
}
});

let (in_span, fields) = caps
.name("span")
.and_then(|cap| {
let cap = cap.as_str().trim_matches(|c| c == '[' || c == ']');
let caps = SPAN_PART_RE.captures(cap)?;
let span = caps.name("name").map(|c| c.as_str().to_owned());
let fields = caps
.name("fields")
.map(|c| {
FIELD_FILTER_RE
.find_iter(c.as_str())
.map(|c| field::Match::parse(c.as_str(), regex))
.collect::<Result<Vec<_>, _>>()
})
.unwrap_or_else(|| Ok(Vec::new()));
Some((span, fields))
})
.unwrap_or_else(|| (None, Ok(Vec::new())));

let level = caps
.name("level")
.and_then(|l| l.as_str().parse().ok())
// Setting the target without the level enables every level for that target
.unwrap_or(LevelFilter::TRACE);
Level { level_start } => {
cur.level = match &from[level_start..] {
"" => LevelFilter::TRACE,
level => LevelFilter::from_str(level)?,
};
}
Target | Complete => {}
_ => return Err(ParseError::new()),
};

Ok(Self {
level,
target,
in_span,
fields: fields?,
})
Ok(cur)
}
}

Expand Down