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perf: cut get-impacted-targets --depEdgesFile CPU by about half #621

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Merged
tinder-maxwellelliott merged 1 commit into from
Nov 4, 2026
Merged

perf: cut get-impacted-targets --depEdgesFile CPU by about half #621

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33 changes: 21 additions & 12 deletions src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,12 +5,14 @@ use bazel_diff::fingerprint;
use bazel_diff::git::{self, DerivationPolicy, Git};
use bazel_diff::hash::{generate_hashes, HashOptions};
use bazel_diff::model::{
filter_and_sort_labels, impacted_targets, impacted_targets_with_distances, HashFileData,
dep_edges_from_slice, filter_and_sort_labels, impacted_targets,
impacted_targets_with_distances, HashFileData,
};
use bazel_diff::module_graph::{bzlmod_enabled_for, impacted_with_module_changes};
use bazel_diff::partial::{self, Classification, Glob};
use clap::{ArgAction, Args, Parser, Subcommand, ValueEnum};
use serde::Serialize;
use std::borrow::Cow;
use std::collections::{BTreeMap, BTreeSet, HashSet};
use std::fs::{self, File};
use std::io::{self, BufWriter, Write};
Expand Down Expand Up @@ -992,16 +994,23 @@ fn run_get_impacted(args: &GetImpactedTargetsArgs, verbose: bool) -> Result<()>
let target_types = (!args.target_type.is_empty())
.then(|| args.target_type.iter().cloned().collect::<HashSet<_>>());
let output = if let Some(dep_edges_file) = &args.dep_edges_file {
let dep_edges: BTreeMap<String, Vec<String>> =
serde_json::from_slice(&fs::read(dep_edges_file)?)?;
let module_impacted = impacted_with_module_changes(&from, &to, Some(&bazel))?;
let hash_impacted = impacted_targets(&from.hashes, &to.hashes, None, false)?
.into_iter()
.collect::<BTreeSet<_>>();
let mut distance_from = from.hashes.clone();
for label in module_impacted.difference(&hash_impacted) {
distance_from.remove(label);
}
let dep_edges = dep_edges_from_slice(&fs::read(dep_edges_file)?)?;
// Targets impacted only through a module change are made to look new, so they report
// distance 0. With an unchanged module graph there are none (the module-aware set is the
// hash diff itself), so the starting hashes are used as they are: no second diff, no copy.
let distance_from = if from.module_graph_json == to.module_graph_json {
Cow::Borrowed(&from.hashes)
} else {
let module_impacted = impacted_with_module_changes(&from, &to, Some(&bazel))?;
let hash_impacted = impacted_targets(&from.hashes, &to.hashes, None, false)?
.into_iter()
.collect::<BTreeSet<_>>();
let mut distance_from = from.hashes.clone();
for label in module_impacted.difference(&hash_impacted) {
distance_from.remove(label);
}
Cow::Owned(distance_from)
};
serde_json::to_string(&impacted_targets_with_distances(
&distance_from,
&to.hashes,
Expand Down Expand Up @@ -1035,7 +1044,7 @@ fn run_explain(args: &ExplainArgs, verbose: bool) -> Result<()> {
let to = HashFileData::read(&args.final_hashes)
.context("Incorrect final hashes: file doesn't exist or can't be read.")?;
ensure_same_mode(&from, &to)?;
let dep_edges: BTreeMap<String, Vec<String>> = serde_json::from_slice(
let dep_edges = dep_edges_from_slice(
&fs::read(&args.dep_edges_file)
.context("Incorrect dep edges file: file doesn't exist or can't be read.")?,
)
Expand Down
164 changes: 129 additions & 35 deletions src/model.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use serde::ser::{SerializeMap, SerializeStruct};
use serde::{Deserialize, Deserializer, Serialize, Serializer};
use serde_json::{Map, Value};
use std::borrow::Cow;
use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
use std::collections::{BTreeMap, HashMap, HashSet};
use std::fmt;
use std::fs;
use std::path::Path;
Expand Down Expand Up @@ -320,6 +320,40 @@ impl<'de> Deserialize<'de> for JsonStr<'de> {
}
}

/// Parses a `--depEdgesFile` (`{label: [dependency labels]}`). `generate-hashes` writes it from a
/// sorted map, so the entries are collected and the map built in one bulk pass, as for [`Hashes`],
/// instead of searching the tree for every label; a repeated label keeps its last value, as
/// deserializing straight into a `BTreeMap` does.
pub fn dep_edges_from_slice(bytes: &[u8]) -> serde_json::Result<BTreeMap<String, Vec<String>>> {
struct DepEdges(BTreeMap<String, Vec<String>>);

impl<'de> Deserialize<'de> for DepEdges {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
struct DepEdgesVisitor;

impl<'de> Visitor<'de> for DepEdgesVisitor {
type Value = DepEdges;

fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
formatter.write_str("an object mapping labels to label arrays")
}

fn visit_map<A: MapAccess<'de>>(self, mut map: A) -> Result<Self::Value, A::Error> {
let mut entries = Vec::with_capacity(map.size_hint().unwrap_or(0));
while let Some(entry) = map.next_entry::<String, Vec<String>>()? {
entries.push(entry);
}
Ok(DepEdges(entries.into_iter().collect()))
}
}

deserializer.deserialize_map(DepEdgesVisitor)
}
}

serde_json::from_slice::<DepEdges>(bytes).map(|edges| edges.0)
}

/// The `{label: "kind#hash~direct"}` object, parsed entry by entry.
struct Hashes(BTreeMap<String, TargetHash>);

Expand All @@ -335,12 +369,16 @@ impl<'de> Deserialize<'de> for Hashes {
}

fn visit_map<A: MapAccess<'de>>(self, mut map: A) -> Result<Self::Value, A::Error> {
let mut hashes = BTreeMap::new();
// `generate-hashes` writes labels in sorted order, so collecting the entries and
// building the map in one bulk pass replaces a root-to-leaf search (a string
// comparison per level) for every insert. `BTreeMap::from_iter` sorts stably and
// keeps the last value for a repeated label, exactly as repeated inserts would.
let mut entries = Vec::with_capacity(map.size_hint().unwrap_or(0));
while let Some((label, value)) = map.next_entry::<String, JsonStr<'de>>()? {
let hash = TargetHash::parse(&value.0).map_err(de::Error::custom)?;
hashes.insert(label, hash);
entries.push((label, hash));
}
Ok(Hashes(hashes))
Ok(Hashes(entries.into_iter().collect()))
}
}

Expand Down Expand Up @@ -374,11 +412,18 @@ impl<'de> Deserialize<'de> for HashFileData {

fn visit_map<A: MapAccess<'de>>(self, mut map: A) -> Result<Self::Value, A::Error> {
let mut data = HashFileData::default();
// Entries of the bare shape, buffered for one bulk build like `Hashes` does. They
// all follow the last `"hashes"` key (which replaces everything before it), so
// they are applied last, each overriding an earlier value for its label.
let mut bare = Vec::new();
// Labels always start with `//`, `@` or a repository name, so the two wrapper
// keys cannot collide with one.
while let Some(key) = map.next_key::<JsonStr<'de>>()? {
match &*key.0 {
"hashes" => data.hashes = map.next_value::<Hashes>()?.0,
"hashes" => {
bare.clear();
data.hashes = map.next_value::<Hashes>()?.0;
}
"metadata" => {
let metadata = map.next_value::<Metadata>()?;
data.module_graph_json = metadata.module_graph_json;
Expand All @@ -390,10 +435,15 @@ impl<'de> Deserialize<'de> for HashFileData {
label => {
let value = map.next_value::<JsonStr<'de>>()?;
let hash = TargetHash::parse(&value.0).map_err(de::Error::custom)?;
data.hashes.insert(label.to_owned(), hash);
bare.push((label.to_owned(), hash));
}
}
}
if data.hashes.is_empty() {
data.hashes = bare.into_iter().collect();
} else {
data.hashes.extend(bare);
}
Ok(data)
}
}
Expand Down Expand Up @@ -605,51 +655,53 @@ pub fn impacted_types(
.collect()
}

fn calculate_distance(
label: &str,
dep_edges: &BTreeMap<String, Vec<String>>,
fn calculate_distance<'a>(
label: &'a str,
dep_edges: &'a BTreeMap<String, Vec<String>>,
impact_types: &HashMap<String, ImpactType>,
memo: &mut HashMap<String, (usize, usize)>,
visiting: &mut BTreeSet<String>,
memo: &mut HashMap<&'a str, (usize, usize)>,
visiting: &mut HashSet<&'a str>,
) -> (usize, usize) {
if let Some(distance) = memo.get(label) {
return *distance;
}
if impact_types.get(label) == Some(&ImpactType::Direct) {
memo.insert(label.to_owned(), (0, 0));
memo.insert(label, (0, 0));
return (0, 0);
}
if !visiting.insert(label.to_owned()) {
if !visiting.insert(label) {
return (0, 0);
}
// Labels are borrowed from the impact map and the dep-edges file for the whole walk, so the
// memo, the cycle guard and the dependency list allocate no strings.
let impacted_deps = dep_edges
.get(label)
.into_iter()
.flatten()
.map(String::as_str)
.filter(|dep| impact_types.contains_key(*dep))
.cloned()
.collect::<Vec<_>>();
if impacted_deps.is_empty() {
eprintln!(
"[Warn] {label} was indirectly impacted, but has no impacted dependencies in the dep-edges file. Falling back to distance 0 -- see https://github.com/Tinder/bazel-diff/issues/268"
);
visiting.remove(label);
memo.insert(label.to_owned(), (0, 0));
memo.insert(label, (0, 0));
return (0, 0);
}
let label_package = label.split(':').next().unwrap_or(label);
let mut target_distance = usize::MAX;
let mut package_distance = usize::MAX;
for dep in impacted_deps {
let (dep_target, dep_package) =
calculate_distance(&dep, dep_edges, impact_types, memo, visiting);
calculate_distance(dep, dep_edges, impact_types, memo, visiting);
target_distance = target_distance.min(dep_target.saturating_add(1));
package_distance = package_distance
.min(dep_package + usize::from(dep.split(':').next().unwrap_or(&dep) != label_package));
.min(dep_package + usize::from(dep.split(':').next().unwrap_or(dep) != label_package));
}
visiting.remove(label);
let result = (target_distance, package_distance);
memo.insert(label.to_owned(), result);
memo.insert(label, result);
result
}

Expand All @@ -661,23 +713,19 @@ pub fn impacted_targets_with_distances(
exclude_external: bool,
) -> Result<Vec<ImpactedTargetWithDistance>> {
let impact_types = impacted_types(from, to);
let mut memo = HashMap::new();
let mut memo = HashMap::with_capacity(impact_types.len());
// Every walk removes what it adds, so one guard serves all of them.
let mut visiting = HashSet::new();
for label in impact_types.keys() {
calculate_distance(
label,
dep_edges,
&impact_types,
&mut memo,
&mut BTreeSet::new(),
);
calculate_distance(label, dep_edges, &impact_types, &mut memo, &mut visiting);
}
let mut impacted = memo
let impacted = memo
.into_iter()
.filter(|(label, _)| !exclude_external || !label.starts_with("//external:"))
.filter_map(|(label, (target_distance, package_distance))| {
match accepts(&label, to, target_types) {
match accepts(label, to, target_types) {
Ok(true) => Some(Ok(ImpactedTargetWithDistance {
label,
label: label.to_owned(),
target_distance,
package_distance,
})),
Expand All @@ -686,13 +734,23 @@ pub fn impacted_targets_with_distances(
}
})
.collect::<Result<Vec<_>>>()?;
impacted.sort_by_key(|target| {
(
kind_rank(to.get(&target.label).or_else(|| from.get(&target.label))),
target.label.clone(),
)
// Rank each label once and sort the pairs. A key closure would look the label up in both maps
// and clone it on every comparison: O(n log n) lookups and allocations for an n-label result.
// The labels are distinct (they are the memo's keys), so an unstable sort orders them exactly
// as a stable one would.
let mut ranked = impacted
.into_iter()
.map(|target| {
let rank = kind_rank(to.get(&target.label).or_else(|| from.get(&target.label)));
(rank, target)
})
.collect::<Vec<_>>();
ranked.sort_unstable_by(|(left_rank, left), (right_rank, right)| {
left_rank
.cmp(right_rank)
.then_with(|| left.label.cmp(&right.label))
});
Ok(impacted)
Ok(ranked.into_iter().map(|(_, target)| target).collect())
}

#[cfg(test)]
Expand Down Expand Up @@ -908,6 +966,42 @@ mod tests {
assert!(reordered.dep_edges.is_empty());
}

#[test]
fn bulk_built_maps_match_insertion_for_unsorted_and_repeated_labels() {
// The readers build their maps in one pass; out-of-order and repeated labels must still
// land exactly as entry-by-entry inserts would place them: sorted, last value wins.
for bytes in [
br#"{"//b:b":"b~b","//a:a":"a~a","//b:b":"c~c"}"#.as_slice(),
br#"{"hashes":{"//b:b":"b~b","//a:a":"a~a","//b:b":"c~c"}}"#.as_slice(),
] {
let parsed = HashFileData::from_slice(bytes).unwrap();
assert_eq!(
parsed.hashes,
BTreeMap::from([
("//a:a".into(), target("", "a", "a")),
("//b:b".into(), target("", "c", "c")),
])
);
}
// Bare labels after a wrapper override it; a wrapper after bare labels replaces them.
let after = HashFileData::from_slice(br#"{"hashes":{"//a:a":"a~a"},"//a:a":"b~b"}"#);
assert_eq!(after.unwrap().hashes["//a:a"], target("", "b", "b"));
let before =
HashFileData::from_slice(br#"{"//z:z":"z~z","hashes":{"//a:a":"a~a"}}"#).unwrap();
assert_eq!(before.hashes.keys().collect::<Vec<_>>(), ["//a:a"]);

let edges =
dep_edges_from_slice(br#"{"//b:b":["//a:a"],"//a:a":[],"//b:b":["//c:c"]}"#).unwrap();
assert_eq!(
edges,
BTreeMap::from([
("//a:a".to_owned(), vec![]),
("//b:b".to_owned(), vec!["//c:c".to_owned()]),
])
);
assert!(dep_edges_from_slice(br#"{"//a:a":"//b:b"}"#).is_err());
}

#[test]
fn rejects_malformed_hash_files() {
for invalid in [
Expand Down
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