lostecho/ripgrep
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

regex: make multi-literal searcher faster

Browse Source 
This makes the case of searching for a dictionary of a very large number
of literals much much faster. (~10x or so.) In particular, we achieve this
by short-circuiting the construction of a full regex when we know we have
a simple alternation of literals. Building the regex for a large dictionary
(>100,000 literals) turns out to be quite slow, even if it internally will
dispatch to Aho-Corasick.

Even that isn't quite enough. It turns out that even *parsing* such a regex
is quite slow. So when the -F/--fixed-strings flag is set, we short
circuit regex parsing completely and jump straight to Aho-Corasick.

We aren't quite as fast as GNU grep here, but it's much closer (less than
2x slower).

In general, this is somewhat of a hack. In particular, it seems plausible
that this optimization could be implemented entirely in the regex engine.
Unfortunately, the regex engine's internals are just not amenable to this
at all, so it would require a larger refactoring effort. For now, it's
good enough to add this fairly simple hack at a higher level.

Unfortunately, if you don't pass -F/--fixed-strings, then ripgrep will
be slower, because of the aforementioned missing optimization. Moreover,
passing flags like `-i` or `-S` will cause ripgrep to abandon this
optimization and fall back to something potentially much slower. Again,
this fix really needs to happen inside the regex engine, although we
might be able to special case -i when the input literals are pure ASCII
via Aho-Corasick's `ascii_case_insensitive`.

Fixes #497, Fixes #838
This commit is contained in:
Andrew Gallant
2019-04-07 18:43:01 -04:00
parent 743d64f2e4
commit 09108b7fda
10 changed files with 354 additions and 63 deletions
Download Patch File Download Diff File Expand all files Collapse all files

214
grep-regex/src/matcher.rs
View File

@@ -8,6 +8,7 @@ use regex::bytes::{CaptureLocations, Regex};
use config::{Config, ConfiguredHIR};
use crlf::CRLFMatcher;
use error::Error;
use multi::MultiLiteralMatcher;
use word::WordMatcher;
/// A builder for constructing a `Matcher` using regular expressions.
@@ -52,7 +53,7 @@ impl RegexMatcherBuilder {
}
let matcher = RegexMatcherImpl::new(&chir)?;
trace!("final regex: {:?}", matcher.regex().to_string());
trace!("final regex: {:?}", matcher.regex());
Ok(RegexMatcher {
config: self.config.clone(),
matcher: matcher,
@@ -61,6 +62,29 @@ impl RegexMatcherBuilder {
})
}
/// Build a new matcher from a plain alternation of literals.
///
/// Depending on the configuration set by the builder, this may be able to
/// build a matcher substantially faster than by joining the patterns with
/// a `|` and calling `build`.
pub fn build_literals<B: AsRef<str>>(
&self,
literals: &[B],
) -> Result<RegexMatcher, Error> {
let slices: Vec<_> = literals.iter().map(|s| s.as_ref()).collect();
if !self.config.can_plain_aho_corasick() || literals.len() < 40 {
return self.build(&slices.join("|"));
}
let matcher = MultiLiteralMatcher::new(&slices)?;
let imp = RegexMatcherImpl::MultiLiteral(matcher);
Ok(RegexMatcher {
config: self.config.clone(),
matcher: imp,
fast_line_regex: None,
non_matching_bytes: ByteSet::empty(),
})
}
/// Set the value for the case insensitive (`i`) flag.
///
/// When enabled, letters in the pattern will match both upper case and
@@ -348,6 +372,8 @@ impl RegexMatcher {
enum RegexMatcherImpl {
/// The standard matcher used for all regular expressions.
Standard(StandardMatcher),
/// A matcher for an alternation of plain literals.
MultiLiteral(MultiLiteralMatcher),
/// A matcher that strips `\r` from the end of matches.
///
/// This is only used when the CRLF hack is enabled and the regex is line
@@ -370,16 +396,23 @@ impl RegexMatcherImpl {
} else if expr.needs_crlf_stripped() {
Ok(RegexMatcherImpl::CRLF(CRLFMatcher::new(expr)?))
} else {
if let Some(lits) = expr.alternation_literals() {
if lits.len() >= 40 {
let matcher = MultiLiteralMatcher::new(&lits)?;
return Ok(RegexMatcherImpl::MultiLiteral(matcher));
}
}
Ok(RegexMatcherImpl::Standard(StandardMatcher::new(expr)?))
}
}
/// Return the underlying regex object used.
fn regex(&self) -> &Regex {
fn regex(&self) -> String {
match *self {
RegexMatcherImpl::Word(ref x) => x.regex(),
RegexMatcherImpl::CRLF(ref x) => x.regex(),
RegexMatcherImpl::Standard(ref x) => &x.regex,
RegexMatcherImpl::Word(ref x) => x.regex().to_string(),
RegexMatcherImpl::CRLF(ref x) => x.regex().to_string(),
RegexMatcherImpl::MultiLiteral(_) => "<N/A>".to_string(),
RegexMatcherImpl::Standard(ref x) => x.regex.to_string(),
}
}
}
@@ -399,6 +432,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.find_at(haystack, at),
MultiLiteral(ref m) => m.find_at(haystack, at),
CRLF(ref m) => m.find_at(haystack, at),
Word(ref m) => m.find_at(haystack, at),
}
@@ -408,6 +442,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.new_captures(),
MultiLiteral(ref m) => m.new_captures(),
CRLF(ref m) => m.new_captures(),
Word(ref m) => m.new_captures(),
}
@@ -417,6 +452,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.capture_count(),
MultiLiteral(ref m) => m.capture_count(),
CRLF(ref m) => m.capture_count(),
Word(ref m) => m.capture_count(),
}
@@ -426,6 +462,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.capture_index(name),
MultiLiteral(ref m) => m.capture_index(name),
CRLF(ref m) => m.capture_index(name),
Word(ref m) => m.capture_index(name),
}
@@ -435,6 +472,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.find(haystack),
MultiLiteral(ref m) => m.find(haystack),
CRLF(ref m) => m.find(haystack),
Word(ref m) => m.find(haystack),
}
@@ -450,6 +488,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.find_iter(haystack, matched),
MultiLiteral(ref m) => m.find_iter(haystack, matched),
CRLF(ref m) => m.find_iter(haystack, matched),
Word(ref m) => m.find_iter(haystack, matched),
}
@@ -465,6 +504,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.try_find_iter(haystack, matched),
MultiLiteral(ref m) => m.try_find_iter(haystack, matched),
CRLF(ref m) => m.try_find_iter(haystack, matched),
Word(ref m) => m.try_find_iter(haystack, matched),
}
@@ -478,6 +518,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.captures(haystack, caps),
MultiLiteral(ref m) => m.captures(haystack, caps),
CRLF(ref m) => m.captures(haystack, caps),
Word(ref m) => m.captures(haystack, caps),
}
@@ -494,6 +535,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.captures_iter(haystack, caps, matched),
MultiLiteral(ref m) => m.captures_iter(haystack, caps, matched),
CRLF(ref m) => m.captures_iter(haystack, caps, matched),
Word(ref m) => m.captures_iter(haystack, caps, matched),
}
@@ -510,6 +552,9 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.try_captures_iter(haystack, caps, matched),
MultiLiteral(ref m) => {
m.try_captures_iter(haystack, caps, matched)
}
CRLF(ref m) => m.try_captures_iter(haystack, caps, matched),
Word(ref m) => m.try_captures_iter(haystack, caps, matched),
}
@@ -524,6 +569,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.captures_at(haystack, at, caps),
MultiLiteral(ref m) => m.captures_at(haystack, at, caps),
CRLF(ref m) => m.captures_at(haystack, at, caps),
Word(ref m) => m.captures_at(haystack, at, caps),
}
@@ -540,6 +586,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.replace(haystack, dst, append),
MultiLiteral(ref m) => m.replace(haystack, dst, append),
CRLF(ref m) => m.replace(haystack, dst, append),
Word(ref m) => m.replace(haystack, dst, append),
}
@@ -559,6 +606,9 @@ impl Matcher for RegexMatcher {
Standard(ref m) => {
m.replace_with_captures(haystack, caps, dst, append)
}
MultiLiteral(ref m) => {
m.replace_with_captures(haystack, caps, dst, append)
}
CRLF(ref m) => {
m.replace_with_captures(haystack, caps, dst, append)
}
@@ -572,6 +622,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.is_match(haystack),
MultiLiteral(ref m) => m.is_match(haystack),
CRLF(ref m) => m.is_match(haystack),
Word(ref m) => m.is_match(haystack),
}
@@ -585,6 +636,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.is_match_at(haystack, at),
MultiLiteral(ref m) => m.is_match_at(haystack, at),
CRLF(ref m) => m.is_match_at(haystack, at),
Word(ref m) => m.is_match_at(haystack, at),
}
@@ -597,6 +649,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.shortest_match(haystack),
MultiLiteral(ref m) => m.shortest_match(haystack),
CRLF(ref m) => m.shortest_match(haystack),
Word(ref m) => m.shortest_match(haystack),
}
@@ -610,6 +663,7 @@ impl Matcher for RegexMatcher {
use self::RegexMatcherImpl::*;
match self.matcher {
Standard(ref m) => m.shortest_match_at(haystack, at),
MultiLiteral(ref m) => m.shortest_match_at(haystack, at),
CRLF(ref m) => m.shortest_match_at(haystack, at),
Word(ref m) => m.shortest_match_at(haystack, at),
}
@@ -710,7 +764,9 @@ impl Matcher for StandardMatcher {
at: usize,
caps: &mut RegexCaptures,
) -> Result<bool, NoError> {
Ok(self.regex.captures_read_at(&mut caps.locs, haystack, at).is_some())
Ok(self.regex.captures_read_at(
&mut caps.locations_mut(), haystack, at,
).is_some())
}
fn shortest_match_at(
@@ -737,54 +793,84 @@ impl Matcher for StandardMatcher {
/// index of the group using the corresponding matcher's `capture_index`
/// method, and then use that index with `RegexCaptures::get`.
#[derive(Clone, Debug)]
pub struct RegexCaptures {
/// Where the locations are stored.
locs: CaptureLocations,
/// These captures behave as if the capturing groups begin at the given
/// offset. When set to `0`, this has no affect and capture groups are
/// indexed like normal.
///
/// This is useful when building matchers that wrap arbitrary regular
/// expressions. For example, `WordMatcher` takes an existing regex `re`
/// and creates `(?:^|\W)(re)(?:$|\W)`, but hides the fact that the regex
/// has been wrapped from the caller. In order to do this, the matcher
/// and the capturing groups must behave as if `(re)` is the `0`th capture
/// group.
offset: usize,
/// When enable, the end of a match has `\r` stripped from it, if one
/// exists.
strip_crlf: bool,
pub struct RegexCaptures(RegexCapturesImp);
#[derive(Clone, Debug)]
enum RegexCapturesImp {
AhoCorasick {
/// The start and end of the match, corresponding to capture group 0.
mat: Option<Match>,
},
Regex {
/// Where the locations are stored.
locs: CaptureLocations,
/// These captures behave as if the capturing groups begin at the given
/// offset. When set to `0`, this has no affect and capture groups are
/// indexed like normal.
///
/// This is useful when building matchers that wrap arbitrary regular
/// expressions. For example, `WordMatcher` takes an existing regex
/// `re` and creates `(?:^|\W)(re)(?:$|\W)`, but hides the fact that
/// the regex has been wrapped from the caller. In order to do this,
/// the matcher and the capturing groups must behave as if `(re)` is
/// the `0`th capture group.
offset: usize,
/// When enable, the end of a match has `\r` stripped from it, if one
/// exists.
strip_crlf: bool,
},
}
impl Captures for RegexCaptures {
fn len(&self) -> usize {
self.locs.len().checked_sub(self.offset).unwrap()
match self.0 {
RegexCapturesImp::AhoCorasick { .. } => 1,
RegexCapturesImp::Regex { ref locs, offset, .. } => {
locs.len().checked_sub(offset).unwrap()
}
}
}
fn get(&self, i: usize) -> Option<Match> {
if !self.strip_crlf {
let actual = i.checked_add(self.offset).unwrap();
return self.locs.pos(actual).map(|(s, e)| Match::new(s, e));
}
match self.0 {
RegexCapturesImp::AhoCorasick { mat, .. } => {
if i == 0 {
mat
} else {
None
}
}
RegexCapturesImp::Regex { ref locs, offset, strip_crlf } => {
if !strip_crlf {
let actual = i.checked_add(offset).unwrap();
return locs.pos(actual).map(|(s, e)| Match::new(s, e));
}
// currently don't support capture offsetting with CRLF stripping
assert_eq!(self.offset, 0);
let m = match self.locs.pos(i).map(|(s, e)| Match::new(s, e)) {
None => return None,
Some(m) => m,
};
// If the end position of this match corresponds to the end position
// of the overall match, then we apply our CRLF stripping. Otherwise,
// we cannot assume stripping is correct.
if i == 0 || m.end() == self.locs.pos(0).unwrap().1 {
Some(m.with_end(m.end() - 1))
} else {
Some(m)
// currently don't support capture offsetting with CRLF
// stripping
assert_eq!(offset, 0);
let m = match locs.pos(i).map(|(s, e)| Match::new(s, e)) {
None => return None,
Some(m) => m,
};
// If the end position of this match corresponds to the end
// position of the overall match, then we apply our CRLF
// stripping. Otherwise, we cannot assume stripping is correct.
if i == 0 || m.end() == locs.pos(0).unwrap().1 {
Some(m.with_end(m.end() - 1))
} else {
Some(m)
}
}
}
}
}
impl RegexCaptures {
pub(crate) fn simple() -> RegexCaptures {
RegexCaptures(RegexCapturesImp::AhoCorasick { mat: None })
}
pub(crate) fn new(locs: CaptureLocations) -> RegexCaptures {
RegexCaptures::with_offset(locs, 0)
}
@@ -793,15 +879,53 @@ impl RegexCaptures {
locs: CaptureLocations,
offset: usize,
) -> RegexCaptures {
RegexCaptures { locs, offset, strip_crlf: false }
RegexCaptures(RegexCapturesImp::Regex {
locs, offset, strip_crlf: false,
})
}
pub(crate) fn locations(&mut self) -> &mut CaptureLocations {
&mut self.locs
pub(crate) fn locations(&self) -> &CaptureLocations {
match self.0 {
RegexCapturesImp::AhoCorasick { .. } => {
panic!("getting locations for simple captures is invalid")
}
RegexCapturesImp::Regex { ref locs, .. } => {
locs
}
}
}
pub(crate) fn locations_mut(&mut self) -> &mut CaptureLocations {
match self.0 {
RegexCapturesImp::AhoCorasick { .. } => {
panic!("getting locations for simple captures is invalid")
}
RegexCapturesImp::Regex { ref mut locs, .. } => {
locs
}
}
}
pub(crate) fn strip_crlf(&mut self, yes: bool) {
self.strip_crlf = yes;
match self.0 {
RegexCapturesImp::AhoCorasick { .. } => {
panic!("setting strip_crlf for simple captures is invalid")
}
RegexCapturesImp::Regex { ref mut strip_crlf, .. } => {
*strip_crlf = yes;
}
}
}
pub(crate) fn set_simple(&mut self, one: Option<Match>) {
match self.0 {
RegexCapturesImp::AhoCorasick { ref mut mat } => {
*mat = one;
}
RegexCapturesImp::Regex { .. } => {
panic!("setting simple captures for regex is invalid")
}
}
}
}