| 1 | #!/usr/bin/env bash |
| 2 | # sccache for a workflow's Rust builds. Every rustc call that makes a |
| 3 | # library is looked up by what it compiles (sources, flags, toolchain, |
| 4 | # dependencies) in the repository's Actions cache, the one `actions/cache` |
| 5 | # uses, through sccache's GitHub Actions backend. A checkout gives every |
| 6 | # source file a new mtime, so Cargo calls rustc again for the workspace's |
| 7 | # own crates however much of `target/` was restored; with sccache, the |
| 8 | # crates whose inputs did not change come back from the cache instead of |
| 9 | # being compiled. Binaries, cdylibs (a Worker's own crate), proc macros and |
| 10 | # test harnesses are linked, and sccache compiles those as before. |
| 11 | # |
| 12 | # bash scripts/sccache.sh install # a step before the first cargo |
| 13 | # bash scripts/sccache.sh stats # the last step, with if: always() |
| 14 | # |
| 15 | # install downloads the pinned release and checks its sha256, starts the |
| 16 | # server (which reads and writes a check entry in the cache), and only then |
| 17 | # sets RUSTC_WRAPPER for the steps after it. If anything there fails, the |
| 18 | # job builds as it did without sccache, and the step says why. A release |
| 19 | # tag's run only reads: a run restores from its own ref, then its base, then |
| 20 | # main, so what a tag saved no later run would read |
| 21 | # (docs.g1t.sh/guides/actions/#the-cache); it reads what main's runs saved, |
| 22 | # the Caches workflow's among them. |
| 23 | # stats prints the server's hits and misses, and adds them to the job's |
| 24 | # summary. |
| 25 | # |
| 26 | # See the Actions guide's "Caching Rust builds". |
| 27 | set -euo pipefail |
| 28 | |
| 29 | VERSION=0.18.0 |
| 30 | TARGET=x86_64-unknown-linux-musl |
| 31 | # sccache-v0.18.0-x86_64-unknown-linux-musl.tar.gz, from the release's |
| 32 | # .sha256 file. |
| 33 | SHA256=45f1447fbe231e3037bde351ef70677dd212216c8d62ae7ca409fecc4d6acc89 |
| 34 | |
| 35 | BIN="$HOME/.cargo/bin" |
| 36 | SCCACHE="$BIN/sccache" |
| 37 | |
| 38 | # What sccache and Cargo read, here and in the steps after this one. |
| 39 | export SCCACHE_GHA_ENABLED=true |
| 40 | # One server for the whole job: its statistics are the job's. |
| 41 | export SCCACHE_IDLE_TIMEOUT=0 |
| 42 | # If the server goes away mid-build, rustc runs without it. |
| 43 | export SCCACHE_IGNORE_SERVER_IO_ERROR=1 |
| 44 | # sccache cannot cache incremental builds; a fresh checkout gains nothing |
| 45 | # from them anyway. |
| 46 | export CARGO_INCREMENTAL=0 |
| 47 | # Read only, on a tag: sccache's GHA backend then makes no CreateCacheEntry |
| 48 | # call, and still looks every compile up. |
| 49 | if [ "${GITHUB_REF_TYPE:-}" = tag ]; then |
| 50 | export SCCACHE_GHA_RW_MODE=READ_ONLY |
| 51 | fi |
| 52 | |
| 53 | warn() { echo "::warning title=sccache::$1, so this job builds without it"; } |
| 54 | |
| 55 | fetch() { |
| 56 | local name="sccache-v${VERSION}-${TARGET}" |
| 57 | local dir="${RUNNER_TEMP:-/tmp}/sccache-${VERSION}" |
| 58 | if [ -x "$SCCACHE" ] && [ "$("$SCCACHE" --version 2>/dev/null | awk '{print $2}')" = "$VERSION" ]; then |
| 59 | return 0 |
| 60 | fi |
| 61 | mkdir -p "$dir" "$BIN" |
| 62 | curl -fsSL --retry 3 -o "$dir/$name.tar.gz" "https://github.com/mozilla/sccache/releases/download/v${VERSION}/${name}.tar.gz" || return 1 |
| 63 | echo "${SHA256} $dir/$name.tar.gz" | sha256sum -c --quiet - || return 1 |
| 64 | tar -xzf "$dir/$name.tar.gz" -C "$dir" || return 1 |
| 65 | install -m 0755 "$dir/$name/sccache" "$SCCACHE" |
| 66 | } |
| 67 | |
| 68 | install_sccache() { |
| 69 | if [ -z "${ACTIONS_RUNTIME_TOKEN:-}" ] || [ -z "${ACTIONS_CACHE_URL:-}${ACTIONS_RESULTS_URL:-}" ]; then |
| 70 | warn "The job has no Actions cache to use (ACTIONS_RUNTIME_TOKEN, ACTIONS_CACHE_URL)" |
| 71 | return 0 |
| 72 | fi |
| 73 | if ! fetch; then |
| 74 | warn "sccache ${VERSION} could not be downloaded or did not match its checksum" |
| 75 | return 0 |
| 76 | fi |
| 77 | if ! "$SCCACHE" --start-server; then |
| 78 | warn "sccache's server did not start (it could not read the cache)" |
| 79 | return 0 |
| 80 | fi |
| 81 | { |
| 82 | echo "RUSTC_WRAPPER=$SCCACHE" |
| 83 | echo "SCCACHE_GHA_ENABLED=$SCCACHE_GHA_ENABLED" |
| 84 | echo "SCCACHE_IDLE_TIMEOUT=$SCCACHE_IDLE_TIMEOUT" |
| 85 | echo "SCCACHE_IGNORE_SERVER_IO_ERROR=$SCCACHE_IGNORE_SERVER_IO_ERROR" |
| 86 | echo "CARGO_INCREMENTAL=$CARGO_INCREMENTAL" |
| 87 | if [ -n "${SCCACHE_GHA_RW_MODE:-}" ]; then echo "SCCACHE_GHA_RW_MODE=$SCCACHE_GHA_RW_MODE"; fi |
| 88 | } >> "$GITHUB_ENV" |
| 89 | if [ -n "${SCCACHE_GHA_RW_MODE:-}" ]; then |
| 90 | echo "sccache ${VERSION}: rustc goes through it from here on, reading this repository's Actions cache; a tag's run saves nothing to it." |
| 91 | else |
| 92 | echo "sccache ${VERSION}: rustc goes through it from here on, cached in this repository's Actions cache." |
| 93 | fi |
| 94 | } |
| 95 | |
| 96 | stats() { |
| 97 | if [ -z "${RUSTC_WRAPPER:-}" ] || [ ! -x "$SCCACHE" ]; then |
| 98 | echo "sccache was not used in this job." |
| 99 | return 0 |
| 100 | fi |
| 101 | local out |
| 102 | out="$("$SCCACHE" --show-stats 2>&1)" || true |
| 103 | echo "$out" |
| 104 | if [ -n "${GITHUB_STEP_SUMMARY:-}" ]; then |
| 105 | { |
| 106 | echo "### sccache" |
| 107 | echo |
| 108 | echo '```' |
| 109 | echo "$out" |
| 110 | echo '```' |
| 111 | } >> "$GITHUB_STEP_SUMMARY" |
| 112 | fi |
| 113 | } |
| 114 | |
| 115 | case "${1:-}" in |
| 116 | install) install_sccache ;; |
| 117 | stats) stats ;; |
| 118 | *) |
| 119 | echo "usage: bash scripts/sccache.sh install|stats" >&2 |
| 120 | exit 2 |
| 121 | ;; |
| 122 | esac |