Skip to content

ci: scope SpotBugs to a PR's changed modules (per-module skip) #1400

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
joaodinissf wants to merge 3 commits into
base: master
Choose a base branch
from
Draft

ci: scope SpotBugs to a PR's changed modules (per-module skip) #1400

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
49210e7
ci: fast static analysis with early-fail lint + inline SARIF
joaodinissf May 30, 2026
2ffb917
ci: add restore-keys to the maven-verify Maven cache
joaodinissf May 31, 2026
0b31263
ci: scope SpotBugs to the PR's changed modules (per-module skip)
joaodinissf May 31, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
78 changes: 78 additions & 0 deletions .github/scripts/compute-spotbugs-skip.sh
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,78 @@
#!/usr/bin/env bash
#
# Scope SpotBugs to a pull request's changed modules.
#
# Default is RUN (analyze). On a PR this injects <spotbugs.skip>true</spotbugs.skip>
# into every UNCHANGED reactor module's pom, so spotbugs-maven-plugin skips the goal —
# and therefore the per-module JVM fork (SpotBugsMojo gates on `skip` before forking) —
# for those modules. The full-reactor compile is left intact (a changed module is still
# analysed with its complete aux-classpath). Master/snapshot builds run a full scan;
# this script is invoked on pull_request only.
#
# Why this and not -Dspotbugs.onlyAnalyze: onlyAnalyze is one clean flag, but SpotBugs
# applies its class screener too late (after the per-module fork + class scan), so it
# only trimmed ~17% of the goal vs ~88% for this per-module skip (measured on this
# reactor). A small upstream SpotBugs early-exit (skip the run when no application class
# matches the screener) would make onlyAnalyze competitive; if that ever lands, switch
# to onlyAnalyze and delete this script.
#
# Run from the repository root. Usage: compute-spotbugs-skip.sh <base-sha>
set -euo pipefail
base="${1:?base sha required}"

changed=$(git diff --name-only --diff-filter=ACMR "${base}...HEAD")

# 1) A change to shared build/config can affect any module -> full scan (skip nothing).
# Fail safe: the worst case here is "analyse everything", never "analyse nothing".
while IFS= read -r f; do
[ -n "$f" ] || continue
case "$f" in
pom.xml | ddk-parent/* | .mvn/* | *.target | .github/* | *[Ss]pot[Bb]ugs*[Ee]xclude*)
echo "Build/config change ($f) -> full SpotBugs scan (no skips)."
exit 0
;;
esac
done <<EOF
${changed}
EOF

# 2) Changed top-level module directories (the reactor module == top-level dir here).
changed_mods=$(printf '%s\n' "${changed}" | grep '/' | cut -d/ -f1 | sort -u)

# 3) Reactor module dirs from ddk-parent's <modules> (strip the leading ../).
# ddk-parent is NOT in its own <modules>, so it can never be skip-injected — which
# is what prevents an accidental inherited (global) skip.
module_dirs=$(grep -oE '<module>\.\./[^<]+</module>' ddk-parent/pom.xml \
| sed -E 's#.*\.\./([^<]+)</module>#\1#')

# 4) Idempotently inject the skip property; handle poms with and without <properties>.
# sed -i.bak + rm is portable across GNU (CI) and BSD (local) sed.
inject_skip() {
local pom="$1/pom.xml"
[ -f "$pom" ] || return 0
if grep -q '<spotbugs\.skip>' "$pom"; then return 0; fi
if grep -q '<properties>' "$pom"; then
sed -i.bak 's#<properties>#<properties>\n <spotbugs.skip>true</spotbugs.skip>#' "$pom"
else
sed -i.bak 's#</project># <properties>\n <spotbugs.skip>true</spotbugs.skip>\n </properties>\n</project>#' "$pom"
fi
rm -f "$pom.bak"
}

# 5) Skip every reactor module that was not touched by this PR.
kept=0
skipped=0
while IFS= read -r mod; do
[ -n "$mod" ] || continue
if printf '%s\n' "${changed_mods}" | grep -qx "$mod"; then
kept=$((kept + 1))
else
inject_skip "$mod"
skipped=$((skipped + 1))
fi
done <<EOF
${module_dirs}
EOF

echo "SpotBugs scope: scanning ${kept} changed module(s), skipping ${skipped} unchanged."
echo "Changed modules: ${changed_mods:-<none>}"
184 changes: 175 additions & 9 deletions .github/workflows/verify.yml
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,8 +1,27 @@
name: verify
on:
pull_request:

# Code Scanning needs write access to upload SARIF results for inline annotations.
permissions:
contents: read
security-events: write

jobs:
pmd:
# Fast, early-fail lint lane: PMD + Checkstyle (+ CPD). Turns red in a few
# minutes on any violation, independent of the long build below, so a stray
# PMD/Checkstyle issue is reported immediately rather than after `verify`.
#
# `compile` is in the same invocation as the analysis goals: PMD's
# type-resolving rules (e.g. InvalidLogMessageFormat on the SLF4J
# trailing-Throwable idiom) need Tycho's aux-classpath, which a fresh `mvn`
# does not inherit from a prior step's target/classes.
#
# `--fail-never` lets every module produce its report (no Maven cascade-skip),
# so the uploaded SARIF — and therefore the inline annotations — are complete.
# The gate is a jq count over the merged SARIFs; compile errors still halt
# (MojoExecutionException is not suppressed by --fail-never).
lint:
runs-on: ubuntu-24.04
steps:
- uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
Expand All @@ -12,26 +31,174 @@ jobs:
java-version: '21'
- name: Set up Workspace Environment Variable
run: echo "WORKSPACE=${{ github.workspace }}" >> $GITHUB_ENV
- name: PMD Check
run: mvn pmd:pmd pmd:cpd pmd:check pmd:cpd-check -f ./ddk-parent/pom.xml --batch-mode --fail-at-end
checkstyle:
- name: Cache Maven dependencies
uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
with:
path: /home/runner/.m2/repository
key: ${{ runner.os }}-maven-0-${{ hashFiles('**/pom.xml') }}
restore-keys: ${{ runner.os }}-maven-0-

- name: PMD + Checkstyle reports (SARIF)
# PMD: SarifRenderer FQCN — emits pmd.sarif.json AND keeps pmd.xml.
# Checkstyle: output.format=sarif — SARIF content in checkstyle-result.xml.
# CPD is excluded here: the global -Dformat flag uses PMD's Renderer
# hierarchy and would ClassCastException CPD's CPDReportRenderer.
run: |
mvn -T 2C -f ./ddk-parent/pom.xml --batch-mode --fail-never \
compile \
pmd:pmd checkstyle:checkstyle \
-Dformat=net.sourceforge.pmd.renderers.SarifRenderer \
-Dcheckstyle.output.format=sarif

- name: CPD report (separate invocation — no SARIF support)
# CPD has no SARIF renderer; emits cpd.xml only. Run standalone so the
# PMD -Dformat flag isn't in scope.
# NOTE: project CPD token threshold is currently very high (issue #1339),
# which effectively disables detection; re-tune once #1339 lands.
run: |
mvn -T 2C -f ./ddk-parent/pom.xml --batch-mode --fail-never \
compile \
pmd:cpd-check

- name: Merge per-module SARIFs (PMD + Checkstyle)
if: always()
# Code Scanning accepts one run per category per upload; each analyzer
# writes one SARIF per module, so concatenate each analyzer's results
# into a single run under .sarif-merged/.
run: |
mkdir -p .sarif-merged
# Merge per-module SARIFs into one run. Filter to JSON-parseable files:
# the ddk-parent aggregator writes a plain-XML checkstyle-result.xml that
# would break jq, and modules with no findings may emit non-SARIF stubs.
merge() { # $1 = find-glob, $2 = output
local f valid=()
while IFS= read -r f; do
jq -e . "$f" >/dev/null 2>&1 && valid+=("$f")
done < <(find . -path "$1")
if [ ${#valid[@]} -gt 0 ]; then
jq -s '{
"$schema": .[0]."$schema", version: .[0].version,
runs: [{ tool: .[0].runs[0].tool,
results: [.[].runs[].results[]?],
invocations: [.[].runs[].invocations[]?] }]
}' "${valid[@]}" > "$2"
fi
}
merge '*/target/pmd.sarif.json' .sarif-merged/pmd.sarif
merge '*/target/checkstyle-result.xml' .sarif-merged/checkstyle.sarif

- name: Gate on PMD / CPD / Checkstyle violations
run: |
set -eu
sarif_total=$(jq '[.runs[].results[]?] | length' \
.sarif-merged/pmd.sarif .sarif-merged/checkstyle.sarif 2>/dev/null \
| awk '{s+=$1} END {print s+0}')
cpd_total=$(find . -name 'cpd.xml' -path '*/target/*' -exec grep -c '<duplication ' {} + 2>/dev/null \
| awk -F: '{s+=$2} END {print s+0}')
echo "PMD/Checkstyle SARIF violations: $sarif_total"
echo "CPD duplications: $cpd_total"
if [ "$sarif_total" != "0" ] || [ "$cpd_total" != "0" ]; then
echo "::error::Static analysis found violations (PMD/CPD/Checkstyle)."
exit 1
fi

- name: Upload PMD/Checkstyle SARIF to Code Scanning
if: always()
uses: github/codeql-action/upload-sarif@7fd177fa680c9881b53cdab4d346d32574c9f7f4 # v3.35.4
with:
sarif_file: .sarif-merged
category: lint

# SpotBugs is the slow critical-path analysis (the experiments' durable
# finding), so it runs in its own parallel lane and never delays `lint`.
spotbugs:
runs-on: ubuntu-24.04
env:
MAVEN_OPTS: -Xmx4g
steps:
- uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
with:
fetch-depth: 0 # need the PR base commit to diff the changed modules
- uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5
with:
distribution: 'temurin'
java-version: '21'
- name: Set up Workspace Environment Variable
run: echo "WORKSPACE=${{ github.workspace }}" >> $GITHUB_ENV
- name: Checkstyle Check
run: mvn checkstyle:checkstyle checkstyle:check -f ./ddk-parent/pom.xml --batch-mode --fail-at-end
- name: Cache Maven dependencies
uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
with:
path: /home/runner/.m2/repository
key: ${{ runner.os }}-maven-0-${{ hashFiles('**/pom.xml') }}
restore-keys: ${{ runner.os }}-maven-0-

- name: Scope SpotBugs to the PR's changed modules
# Injects <spotbugs.skip>true> into unchanged module poms so the per-module
# SpotBugs fork is skipped for them (the lever that actually scopes the cost).
# Full compile is preserved (correct aux-classpath); a build/config change ->
# full scan. pull_request only; master/snapshot run a full scan.
run: bash .github/scripts/compute-spotbugs-skip.sh "${{ github.event.pull_request.base.sha }}"

- name: SpotBugs report (SARIF)
# sarifOutput=true emits spotbugsSarif.json (also writes spotbugsXml.xml).
# jgit.dirtyWorkingTree=ignore: the scope step intentionally edits poms, so the
# working tree is dirty here; this job releases nothing, so we tell Tycho's jgit
# build-qualifier to use the last commit's timestamp instead of failing (the
# repo keeps jgit.dirtyWorkingTree=error for maven-verify / releases).
run: |
mvn -T 2C -f ./ddk-parent/pom.xml --batch-mode --fail-never \
compile \
spotbugs:spotbugs \
-Dspotbugs.sarifOutput=true \
-Djgit.dirtyWorkingTree=ignore

- name: Merge per-module SpotBugs SARIFs
if: always()
run: |
mkdir -p .sarif-merged
valid=()
while IFS= read -r f; do
jq -e . "$f" >/dev/null 2>&1 && valid+=("$f")
done < <(find . -path '*/target/spotbugsSarif.json')
if [ ${#valid[@]} -gt 0 ]; then
jq -s '{
"$schema": .[0]."$schema", version: .[0].version,
runs: [{ tool: .[0].runs[0].tool,
results: [.[].runs[].results[]?],
invocations: [.[].runs[].invocations[]?] }]
}' "${valid[@]}" > .sarif-merged/spotbugs.sarif
fi

- name: Gate on SpotBugs violations
run: |
set -eu
sb_total=$(jq '[.runs[].results[]?] | length' .sarif-merged/spotbugs.sarif 2>/dev/null || echo 0)
echo "SpotBugs SARIF violations: $sb_total"
if [ "$sb_total" != "0" ]; then
echo "::error::SpotBugs found violations."
exit 1
fi

- name: Upload SpotBugs SARIF to Code Scanning
# Skip when nothing was scanned (e.g. a docs-only PR -> all modules skipped):
# an empty .sarif-merged would otherwise fail upload-sarif ("No SARIF files").
if: ${{ always() && hashFiles('.sarif-merged/spotbugs.sarif') != '' }}
uses: github/codeql-action/upload-sarif@7fd177fa680c9881b53cdab4d346d32574c9f7f4 # v3.35.4
with:
sarif_file: .sarif-merged
category: spotbugs

line-endings:
runs-on: ubuntu-24.04
steps:
- uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
- name: Check LF line endings
run: bash .github/scripts/check-line-endings.sh

# Build + tests only. Static analysis now lives in the `lint` and `spotbugs`
# jobs, so the redundant checkstyle/pmd/spotbugs goals are dropped from here —
# this is the wall-clock long pole and no longer re-runs analysis.
# No `-T 2C`: tests are not known to pass reliably under reactor parallelism.
maven-verify:
runs-on: ubuntu-24.04
steps:
Expand All @@ -50,10 +217,9 @@ jobs:
with:
path: /home/runner/.m2/repository
key: ${{ runner.os }}-maven-0-${{ hashFiles('**/pom.xml') }}
restore-keys: ${{ runner.os }}-maven-0-
- name: Build with Maven within a virtual X Server Environment
# Run pmd:pmd and pmd:cpd first to generate reports for all modules, then run pmd:check and pmd:cpd-check
# This ensures all violations are collected and reported before the build fails
run: xvfb-run mvn clean verify checkstyle:check pmd:pmd pmd:cpd pmd:check pmd:cpd-check spotbugs:check -f ./ddk-parent/pom.xml --batch-mode --fail-at-end
run: xvfb-run mvn clean verify -f ./ddk-parent/pom.xml --batch-mode --fail-at-end
- name: Fail on missing surefire reports
if: always()
run: bash .github/scripts/check-surefire-reports.sh
Expand Down
65 changes: 65 additions & 0 deletions docs/ci-measurement-protocol.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,65 @@
# CI timing-measurement protocol

How to get **trustworthy** numbers for a CI-shape change. Written because the
earlier experiment program (2026-05) produced numbers that can't be trusted:
single samples, taken during an Eclipse p2 mirror-flaky window, against a CI
shape that has since changed. Don't repeat that.

## What we're measuring

- **Wall-clock** per run = the slowest job (what a developer waits for).
- **Per-job duration** = the analysis bottleneck (settles e.g. spotbugs-vs-maven-verify).
- **Failure latency** = time-to-red on a *planted* lint violation — the metric the
early-fail goal actually cares about. Measure it separately.

Wall-clock is the headline, but per-job + failure-latency are what tell you *why*.

## Noise floor (observed on this repo's `verify` runs)

Per-job spread across recent runs — any change must beat this to be real signal:

| Job | median | spread (±) |
|---|---|---|
| line-endings | ~5s | ±3s |
| checkstyle (old shape) | ~115s | ±~104s (≈90%!) |
| pmd (old shape) | ~191s | ±63s |
| maven-verify | ~869s (~14.5m) | ±~93s (≈11%) |

**Decision rule:** accept candidate B as faster than A only if
`median(B) < median(A) − 2 × IQR(A)`. For maven-verify a real win must exceed ~100s;
for checkstyle, ~200s. Anything smaller is noise.

## Protocol

1. **Pre-flight — confirm mirrors are healthy.** Run one throwaway build; if
target-platform resolution stalls or errors, **stop** — the window is bad
(this is what voided the 2026-05-09 numbers). Measure only on a clean window.
2. **Warm the caches.** Run 3–5 discard builds first so `~/.m2` + `.cache/tycho`
are populated; cold-cache runs have a different (network-bound) profile.
3. **Sample.** N = 15–20 `workflow_dispatch` runs per candidate, back-to-back in a
≤30-minute window. Run A and B **interleaved within ≤10 minutes** of each other
so they see the same mirror weather and runner-pool load.
4. **Report medians + IQR**, per job *and* total wall-clock. Never a single sample,
never the mean.
5. **Pin `ubuntu-24.04`** (not a matrix) for consistent runner hardware.
6. **Record per-sample metadata:** cache hit/miss, run start time, headSha.
7. **Failure latency:** plant a synthetic PMD/Checkstyle violation, measure how long
until the `lint` check goes red (independent of the build job).

## Why not just trust the old experiment numbers

- Single sample each (no repetition).
- 2026-05-09 mirror-flaky window → resolution time is contaminated and varies per job
even within one dispatch.
- Numbers disagree across rounds (sequential measured 21m one round, 33m another).
- `#1369` reshaped master's CI after the experiments ran, so their baseline is stale.

## What is *not* a timing lever (validated)

- **Local p2 mirror**: with a warm `~/.m2`/`.cache/tycho`, offline resolution is
~equal to online (measured 5s vs 6s) — a mirror's steady-state speedup is ~0.
Its only value is cold-cache + flaky-mirror insurance; deferred per the rare-flake
rule.
- **`-Dtycho.mode=maven` on a gate pass**: marginal on a warm cache (resolution is
already seconds); and it *breaks* PMD type-resolving rules (strips the classpath →
false positives). Not used.
Loading
Loading