update dependencies and rebuild

fixes #17

.github/workflows/selftest.yml

@@ -0,0 +1,29 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  selftest:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+
+    name: Test Action on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          override: true
+
+      - uses: ./
+
+      - run: |
+          cargo install cargo-deny --locked
+          cargo check
+          cargo test

.gitignore

@@ -1 +1,2 @@
 node_modules
+/target

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## 1.3.0
+
+- Use Rust toolchain file as additional cache key.
+- Allow for a configurable target-dir.
+
+## 1.2.0
+
+- Cache `~/.cargo/bin`.
+- Support for custom `$CARGO_HOME`.
+- Add a `cache-hit` output.
+- Add a new `sharedKey` option that overrides the automatic job-name based key.
+
+## 1.1.0
+
+- Add a new `working-directory` input.
+- Support caching git dependencies.
+- Lots of other improvements.
+
+## 1.0.2
+
+- Don’t prune targets that have a different name from the crate, but do prune targets from the workspace.
+
 ## 1.0.1
 
 - Improved logging output.

Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+publish = false
+name = "rust-cache"
+version = "0.1.0"
+authors = ["Arpad Borsos <arpad.borsos@googlemail.com>"]
+edition = "2018"
+
+[dev-dependencies]
+reqwest = "0.11.0"
+actix-web = { git = "https://github.com/actix/actix-web.git", rev = "bd26083f333ecf63e3eb444748250364ce124f5e" }

README.md

@@ -1,47 +1,87 @@
 # Rust Cache Action
 
-A GitHub Action that implements smart caching for rust/cargo projects
-
-## Inputs
-
-- `key` - An optional key for the `target` cache. This is useful in case you
-  have different jobs for test / check / clippy, etc
+A GitHub Action that implements smart caching for rust/cargo projects with
+sensible defaults.
 
 ## Example usage
 
 ```yaml
-- uses: Swatinem/rust-cache@v1
+# selecting a toolchain either by action or manual `rustup` calls should happen
+# before the plugin, as it uses the current rustc version as its cache key
+- uses: actions-rs/toolchain@v1
   with:
-    key: test
+    profile: minimal
+    toolchain: stable
+
+- uses: Swatinem/rust-cache@v1
 ```
 
-## Specifics
+## Inputs
 
-This action tries to be better than just caching the following directories:
+: `key`
+An optional key that is added to the automatic cache key.
 
-```
-~/.cargo/registry
-~/.cargo/git
-target
-```
+: `sharedKey`
+An additional key that is stable over multiple jobs.
 
-It disables incremental compilation and only caches dependencies. The
-assumption is that we will likely recompile the own crate(s) anyway.
+: `working-directory`
+The working directory the action operates in, is case the cargo project is not
+located in the repo root.
 
-It also separates the cache into 4 groups, each treated differently:
+: `target-dir`
+The target directory that should be cleaned and persisted, defaults to `./target`.
 
-- Registry Index: `~/.cargo/registry/index/<registry>`:
+## Outputs
 
-  This is always restored from its latest snapshot, and persisted based on the
-  most recent revision.
+: `cache-hit`
 
-- Registry Cache: `~/.cargo/registry/cache/<registry>`:
+This is a boolean flag that will be set to `true` when there was an exact cache hit.
 
-  Automatically keyed by the lockfile/toml hash, and is being pruned to only
-  persist the dependencies that are being used.
+## Cache Effectiveness
 
-- target: `./target`
+This action only caches the _dependencies_ of a crate, so is more effective if
+the dependency / own code ratio is higher.
 
-  Automatically keyed by the lockfile/toml hash, and is being pruned to only
-  persist the dependencies that are being used. This is especially throwing
-  away any intermediate artifacts.
+It is also most effective for repositories with a `Cargo.lock` file. Library
+repositories with only a `Cargo.toml` file have limited benefits, as cargo will
+_always_ use the most up-to-date dependency versions, which may not be cached.
+
+Usage with Stable Rust is most effective, as a cache is tied to the Rust version.
+Using it with Nightly Rust is less effective as it will throw away the cache every day.
+
+## Versioning
+
+I use the `v1` branch similar to `master` development, so if you want to have
+a more stable experience, please use a fixed revision or tag.
+
+## Cache Details
+
+The cache currently caches the following directories:
+
+- `~/.cargo/registry/index`
+- `~/.cargo/registry/cache`
+- `~/.cargo/git`
+- `./target`
+
+This cache is automatically keyed by:
+
+- the github `job`,
+- the rustc release / host / hash, and
+- a hash of the `Cargo.lock` / `Cargo.toml` files (if present).
+- a hash of the `rust-toolchain` / `rust-toolchain.toml` files (if present).
+
+An additional input `key` can be provided if the builtin keys are not sufficient.
+
+Before persisting, the cache is cleaned of intermediate artifacts and
+anything that is not a workspace dependency.
+In particular, no caching of workspace crates will be done. For
+this reason, this action will automatically set `CARGO_INCREMENTAL=0` to
+disable incremental compilation.
+
+The action will try to restore from a previous `Cargo.lock` version as well, so
+lockfile updates should only re-build changed dependencies.
+
+Additionally, the action automatically works around
+[cargo#8603](https://github.com/rust-lang/cargo/issues/8603) /
+[actions/cache#403](https://github.com/actions/cache/issues/403) which would
+otherwise corrupt the cache on macOS builds.

action.yml

@@ -1,10 +1,22 @@
 name: "Rust Cache"
-description: "A GitHub Action that implements smart caching for rust/cargo projects"
+description: "A GitHub Action that implements smart caching for rust/cargo projects with sensible defaults."
 author: "Arpad Borsos <arpad.borsos@googlemail.com>"
 inputs:
   key:
-    description: "An explicit key for restoring and saving the target cache"
+    description: "An additional key for the cache"
     required: false
+  sharedKey:
+    description: "An additional cache key that is stable over multiple jobs"
+    required: false
+  working-directory:
+    description: "The working directory this action should operate in"
+    required: false
+  target-dir:
+    description: "The target dir that should be cleaned and persisted, defaults to `./target`"
+    required: false
+outputs:
+  cache-hit:
+    description: "A boolean value that indicates an exact match was found"
 runs:
   using: "node12"
   main: "dist/restore/index.js"

package.json

@@ -1,8 +1,8 @@
 {
   "private": true,
   "name": "rust-cache",
-  "version": "1.0.1",
-  "description": "A GitHub Action that implements smart caching for rust/cargo projects",
+  "version": "1.2.0",
+  "description": "A GitHub Action that implements smart caching for rust/cargo projects with sensible defaults.",
   "keywords": [
     "actions",
     "rust",
@@ -17,20 +17,22 @@
   "bugs": {
     "url": "https://github.com/Swatinem/rust-cache/issues"
   },
-  "funding": "https://github.com/sponsors/Swatinem",
+  "funding": {
+    "url": "https://github.com/sponsors/Swatinem"
+  },
   "homepage": "https://github.com/Swatinem/rust-cache#readme",
   "dependencies": {
-    "@actions/cache": "^1.0.2",
-    "@actions/core": "^1.2.6",
+    "@actions/cache": "^1.0.7",
+    "@actions/core": "^1.3.0",
     "@actions/exec": "^1.0.4",
-    "@actions/glob": "^0.1.0",
-    "@actions/io": "^1.0.2"
+    "@actions/glob": "^0.1.2",
+    "@actions/io": "^1.1.0"
   },
   "devDependencies": {
-    "@vercel/ncc": "^0.24.1",
-    "typescript": "^4.0.3"
+    "@vercel/ncc": "^0.28.6",
+    "typescript": "^4.3.2"
   },
   "scripts": {
-    "prepare": "ncc build -o dist/restore src/restore.ts && ncc build -o dist/save src/save.ts"
+    "prepare": "ncc build --target es2020 -o dist/restore src/restore.ts && ncc build --target es2020 -o dist/save src/save.ts"
   }
 }

src/common.ts

@@ -1,31 +1,41 @@
 import * as core from "@actions/core";
 import * as exec from "@actions/exec";
 import * as glob from "@actions/glob";
+import * as io from "@actions/io";
 import crypto from "crypto";
 import fs from "fs";
 import os from "os";
 import path from "path";
 
+process.on("uncaughtException", (e) => {
+  core.info(`[warning] ${e.message}`);
+});
+
+const cwd = core.getInput("working-directory");
+// TODO: this could be read from .cargo config file directly
+const targetDir = core.getInput("target-dir") || "./target";
+if (cwd) {
+  process.chdir(cwd);
+}
+
+export const stateBins = "RUST_CACHE_BINS";
+export const stateKey = "RUST_CACHE_KEY";
+const stateHash = "RUST_CACHE_HASH";
+
 const home = os.homedir();
+const cargoHome = process.env.CARGO_HOME || path.join(home, ".cargo");
 export const paths = {
-  index: path.join(home, ".cargo/registry/index"),
-  cache: path.join(home, ".cargo/registry/cache"),
-  git: path.join(home, ".cargo/git/db"),
-  target: "target",
+  cargoHome,
+  index: path.join(cargoHome, "registry/index"),
+  cache: path.join(cargoHome, "registry/cache"),
+  git: path.join(cargoHome, "git"),
+  target: targetDir,
 };
 
 interface CacheConfig {
-  name: string;
-  path: string;
+  paths: Array<string>;
   key: string;
-  restoreKeys?: Array<string>;
-}
-
-interface Caches {
-  index: CacheConfig;
-  cache: CacheConfig;
-  // git: CacheConfig;
-  target: CacheConfig;
+  restoreKeys: Array<string>;
 }
 
 const RefKey = "GITHUB_REF";
@@ -34,51 +44,67 @@ export function isValidEvent(): boolean {
   return RefKey in process.env && Boolean(process.env[RefKey]);
 }
 
-export async function getCaches(): Promise<Caches> {
-  const rustKey = await getRustKey();
-  let lockHash = core.getState("lockHash");
+export async function getCacheConfig(): Promise<CacheConfig> {
+  let lockHash = core.getState(stateHash);
   if (!lockHash) {
     lockHash = await getLockfileHash();
-    core.saveState("lockHash", lockHash);
-  }
-  let targetKey = core.getInput("key");
-  if (targetKey) {
-    targetKey = `${targetKey}-`;
+    core.saveState(stateHash, lockHash);
   }
 
-  const registryIndex = `v0-registry-index`;
-  const registryCache = `v0-registry-cache`;
-  const target = `v0-target-${targetKey}${rustKey}`;
+  let key = `v0-rust-`;
+
+  const sharedKey = core.getInput("sharedKey");
+  if (sharedKey) {
+    key += `${sharedKey}-`;
+  } else {
+    const inputKey = core.getInput("key");
+    if (inputKey) {
+      key += `${inputKey}-`;
+    }
+
+    const job = process.env.GITHUB_JOB;
+    if (job) {
+      key += `${job}-`;
+    }
+  }
+
+  key += await getRustKey();
+
   return {
-    index: {
-      name: "Registry Index",
-      path: paths.index,
-      key: `${registryIndex}-`,
-      restoreKeys: [registryIndex],
-    },
-    cache: {
-      name: "Registry Cache",
-      path: paths.cache,
-      key: `${registryCache}-${lockHash}`,
-      restoreKeys: [registryCache],
-    },
-    // git: {
-    //   name: "Git Dependencies",
-    //   path: paths.git,
-    //   key: "git-db",
-    // },
-    target: {
-      name: "Target",
-      path: paths.target,
-      key: `${target}-${lockHash}`,
-      restoreKeys: [target],
-    },
+    paths: [
+      path.join(cargoHome, "bin"),
+      path.join(cargoHome, ".crates2.json"),
+      path.join(cargoHome, ".crates.toml"),
+      paths.git,
+      paths.cache,
+      paths.index,
+      paths.target,
+    ],
+    key: `${key}-${lockHash}`,
+    restoreKeys: [key],
   };
 }
 
+export async function getCargoBins(): Promise<Set<string>> {
+  try {
+    const { installs }: { installs: { [key: string]: { bins: Array<string> } } } = JSON.parse(
+      await fs.promises.readFile(path.join(paths.cargoHome, ".crates2.json"), "utf8"),
+    );
+    const bins = new Set<string>();
+    for (const pkg of Object.values(installs)) {
+      for (const bin of pkg.bins) {
+        bins.add(bin);
+      }
+    }
+    return bins;
+  } catch {
+    return new Set<string>();
+  }
+}
+
 async function getRustKey(): Promise<string> {
   const rustc = await getRustVersion();
-  return `${rustc.release}-${rustc.host}-${rustc["commit-hash"]}`;
+  return `${rustc.release}-${rustc.host}-${rustc["commit-hash"].slice(0, 12)}`;
 }
 
 interface RustVersion {
@@ -115,22 +141,10 @@ export async function getCmdOutput(
   return stdout;
 }
 
-export async function getRegistryName() {
-  const globber = await glob.create(`${paths.index}/**/.last-updated`, { followSymbolicLinks: false });
-  const files = await globber.glob();
-  if (files.length > 1) {
-    core.debug(`got multiple registries: "${files.join('", "')}"`);
-  }
-
-  const first = files.shift();
-  if (!first) {
-    return;
-  }
-  return path.basename(path.dirname(first));
-}
-
-async function getLockfileHash() {
-  const globber = await glob.create("**/Cargo.toml\n**/Cargo.lock", { followSymbolicLinks: false });
+async function getLockfileHash(): Promise<string> {
+  const globber = await glob.create("**/Cargo.toml\n**/Cargo.lock\nrust-toolchain\nrust-toolchain.toml", {
+    followSymbolicLinks: false,
+  });
   const files = await globber.glob();
   files.sort((a, b) => a.localeCompare(b));
 
@@ -140,5 +154,97 @@ async function getLockfileHash() {
       hasher.update(chunk);
     }
   }
-  return hasher.digest("hex");
+  return hasher.digest("hex").slice(0, 20);
+}
+
+export interface PackageDefinition {
+  name: string;
+  version: string;
+  path: string;
+  targets: Array<string>;
+}
+
+export type Packages = Array<PackageDefinition>;
+
+interface Meta {
+  packages: Array<{
+    name: string;
+    version: string;
+    manifest_path: string;
+    targets: Array<{ kind: Array<string>; name: string }>;
+  }>;
+}
+
+export async function getPackages(): Promise<Packages> {
+  const cwd = process.cwd();
+  const meta: Meta = JSON.parse(await getCmdOutput("cargo", ["metadata", "--all-features", "--format-version", "1"]));
+
+  return meta.packages
+    .filter((p) => !p.manifest_path.startsWith(cwd))
+    .map((p) => {
+      const targets = p.targets.filter((t) => t.kind[0] === "lib").map((t) => t.name);
+      return { name: p.name, version: p.version, targets, path: path.dirname(p.manifest_path) };
+    });
+}
+
+export async function cleanTarget(packages: Packages) {
+  await fs.promises.unlink(path.join(targetDir, "./.rustc_info.json"));
+  await io.rmRF(path.join(targetDir, "./debug/examples"));
+  await io.rmRF(path.join(targetDir, "./debug/incremental"));
+
+  let dir: fs.Dir;
+  // remove all *files* from debug
+  dir = await fs.promises.opendir(path.join(targetDir, "./debug"));
+  for await (const dirent of dir) {
+    if (dirent.isFile()) {
+      await rm(dir.path, dirent);
+    }
+  }
+
+  const keepPkg = new Set(packages.map((p) => p.name));
+  await rmExcept(path.join(targetDir, "./debug/build"), keepPkg);
+  await rmExcept(path.join(targetDir, "./debug/.fingerprint"), keepPkg);
+
+  const keepDeps = new Set(
+    packages.flatMap((p) => {
+      const names = [];
+      for (const n of [p.name, ...p.targets]) {
+        const name = n.replace(/-/g, "_");
+        names.push(name, `lib${name}`);
+      }
+      return names;
+    }),
+  );
+  await rmExcept(path.join(targetDir, "./debug/deps"), keepDeps);
+}
+
+const oneWeek = 7 * 24 * 3600 * 1000;
+
+export async function rmExcept(dirName: string, keepPrefix: Set<string>) {
+  const dir = await fs.promises.opendir(dirName);
+  for await (const dirent of dir) {
+    let name = dirent.name;
+    const idx = name.lastIndexOf("-");
+    if (idx !== -1) {
+      name = name.slice(0, idx);
+    }
+    const fileName = path.join(dir.path, dirent.name);
+    const { mtime } = await fs.promises.stat(fileName);
+    // we don’t really know
+    if (!keepPrefix.has(name) || Date.now() - mtime.getTime() > oneWeek) {
+      await rm(dir.path, dirent);
+    }
+  }
+}
+
+export async function rm(parent: string, dirent: fs.Dirent) {
+  try {
+    const fileName = path.join(parent, dirent.name);
+    core.debug(`deleting "${fileName}"`);
+    if (dirent.isFile()) {
+      await fs.promises.unlink(fileName);
+    } else if (dirent.isDirectory()) {
+      await io.rmRF(fileName);
+    }
+  } catch {}
 }

src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}

src/restore.ts

@@ -1,41 +1,46 @@
 import * as cache from "@actions/cache";
 import * as core from "@actions/core";
-import { getCaches, isValidEvent } from "./common";
+import { cleanTarget, getCacheConfig, getCargoBins, getPackages, stateBins, stateKey } from "./common";
 
 async function run() {
-  if (!isValidEvent()) {
-    return;
-  }
-
   try {
     core.exportVariable("CARGO_INCREMENTAL", 0);
 
-    const caches = await getCaches();
-    for (const [type, { name, path, key, restoreKeys }] of Object.entries(caches)) {
-      const start = Date.now();
-      core.startGroup(`Restoring ${name}…`);
-      core.info(`Restoring to path "${path}".`);
-      core.info(`Using keys:\n    ${[key, ...restoreKeys].join("\n    ")}`);
-      try {
-        const restoreKey = await cache.restoreCache([path], key, restoreKeys);
-        if (restoreKey) {
-          core.info(`Restored from cache key "${restoreKey}".`);
-          core.saveState(type, restoreKey);
-        } else {
-          core.info("No cache found.");
-        }
-      } catch (e) {
-        core.info(`[warning] ${e.message}`);
+    const { paths, key, restoreKeys } = await getCacheConfig();
+
+    const bins = await getCargoBins();
+    core.saveState(stateBins, JSON.stringify([...bins]));
+
+    core.info(`Restoring paths:\n    ${paths.join("\n    ")}`);
+    core.info(`In directory:\n    ${process.cwd()}`);
+    core.info(`Using keys:\n    ${[key, ...restoreKeys].join("\n    ")}`);
+    const restoreKey = await cache.restoreCache(paths, key, restoreKeys);
+    if (restoreKey) {
+      core.info(`Restored from cache key "${restoreKey}".`);
+      core.saveState(stateKey, restoreKey);
+
+      if (restoreKey !== key) {
+        // pre-clean the target directory on cache mismatch
+        const packages = await getPackages();
+
+        await cleanTarget(packages);
       }
-      const duration = Math.round((Date.now() - start) / 1000);
-      if (duration) {
-        core.info(`Took ${duration}s.`);
-      }
-      core.endGroup();
+
+      setCacheHitOutput(restoreKey === key);
+    } else {
+      core.info("No cache found.");
+
+      setCacheHitOutput(false);
     }
   } catch (e) {
+    setCacheHitOutput(false);
+
     core.info(`[warning] ${e.message}`);
   }
 }
 
+function setCacheHitOutput(cacheHit: boolean): void {
+  core.setOutput("cache-hit", cacheHit.toString());
+}
+
 run();

src/save.ts

@@ -1,58 +1,57 @@
 import * as cache from "@actions/cache";
 import * as core from "@actions/core";
 import * as exec from "@actions/exec";
+import * as glob from "@actions/glob";
 import * as io from "@actions/io";
 import fs from "fs";
 import path from "path";
-import { getCaches, getCmdOutput, getRegistryName, isValidEvent, paths } from "./common";
+import {
+  cleanTarget,
+  getCacheConfig,
+  getCargoBins,
+  getPackages,
+  Packages,
+  paths,
+  rm,
+  stateBins,
+  stateKey,
+} from "./common";
 
 async function run() {
-  if (!isValidEvent()) {
-    return;
-  }
-
   try {
-    const caches = await getCaches();
-    const registryName = await getRegistryName();
-    const packages = await getPackages();
+    const { paths: savePaths, key } = await getCacheConfig();
+
+    if (core.getState(stateKey) === key) {
+      core.info(`Cache up-to-date.`);
+      return;
+    }
 
     // TODO: remove this once https://github.com/actions/toolkit/pull/553 lands
     await macOsWorkaround();
 
-    await pruneTarget(packages);
+    const registryName = await getRegistryName();
+    const packages = await getPackages();
 
-    if (registryName) {
-      // save the index based on its revision
-      const indexRef = await getIndexRef(registryName);
-      caches.index.key += indexRef;
-      await io.rmRF(path.join(paths.index, registryName, ".cache"));
+    try {
+      await cleanRegistry(registryName, packages);
+    } catch {}
 
-      await pruneRegistryCache(registryName, packages);
-    } else {
-      delete (caches as any).index;
-      delete (caches as any).cache;
-    }
+    try {
+      await cleanBin();
+    } catch {}
 
-    for (const [type, { name, path, key }] of Object.entries(caches)) {
-      if (core.getState(type) === key) {
-        core.info(`${name} up-to-date.`);
-        continue;
-      }
-      const start = Date.now();
-      core.startGroup(`Saving ${name}…`);
-      core.info(`Saving path "${path}".`);
-      core.info(`Using key "${key}".`);
-      try {
-        await cache.saveCache([path], key);
-      } catch (e) {
-        core.info(`[warning] ${e.message}`);
-      }
-      const duration = Math.round((Date.now() - start) / 1000);
-      if (duration) {
-        core.info(`Took ${duration}s.`);
-      }
-      core.endGroup();
-    }
+    try {
+      await cleanGit(packages);
+    } catch {}
+
+    try {
+      await cleanTarget(packages);
+    } catch {}
+
+    core.info(`Saving paths:\n    ${savePaths.join("\n    ")}`);
+    core.info(`In directory:\n    ${process.cwd()}`);
+    core.info(`Using key:\n    ${key}`);
+    await cache.saveCache(savePaths, key);
   } catch (e) {
     core.info(`[warning] ${e.message}`);
   }
@@ -60,82 +59,90 @@ async function run() {
 
 run();
 
-async function getIndexRef(registryName: string) {
-  const cwd = path.join(paths.index, registryName);
-  return (await getCmdOutput("git", ["rev-parse", "--short", "origin/master"], { cwd })).trim();
+async function getRegistryName(): Promise<string> {
+  const globber = await glob.create(`${paths.index}/**/.last-updated`, { followSymbolicLinks: false });
+  const files = await globber.glob();
+  if (files.length > 1) {
+    core.warning(`got multiple registries: "${files.join('", "')}"`);
+  }
+
+  const first = files.shift()!;
+  return path.basename(path.dirname(first));
 }
 
-interface PackageDefinition {
-  name: string;
-  version: string;
+async function cleanBin() {
+  const bins = await getCargoBins();
+  const oldBins = JSON.parse(core.getState(stateBins));
+
+  for (const bin of oldBins) {
+    bins.delete(bin);
+  }
+
+  const dir = await fs.promises.opendir(path.join(paths.cargoHome, "bin"));
+  for await (const dirent of dir) {
+    if (dirent.isFile() && !bins.has(dirent.name)) {
+      await rm(dir.path, dirent);
+    }
+  }
 }
 
-type Packages = Array<PackageDefinition>;
+async function cleanRegistry(registryName: string, packages: Packages) {
+  await io.rmRF(path.join(paths.index, registryName, ".cache"));
 
-async function getPackages(): Promise<Packages> {
-  const meta = JSON.parse(await getCmdOutput("cargo", ["metadata", "--all-features", "--format-version", "1"]));
-  return meta.packages.map(({ name, version }: any) => ({ name, version }));
-}
-
-async function pruneRegistryCache(registryName: string, packages: Packages) {
   const pkgSet = new Set(packages.map((p) => `${p.name}-${p.version}.crate`));
 
   const dir = await fs.promises.opendir(path.join(paths.cache, registryName));
   for await (const dirent of dir) {
     if (dirent.isFile() && !pkgSet.has(dirent.name)) {
-      const fileName = path.join(dir.path, dirent.name);
-      await fs.promises.unlink(fileName);
-      core.debug(`deleting "${fileName}"`);
+      await rm(dir.path, dirent);
     }
   }
 }
 
-async function pruneTarget(packages: Packages) {
-  await fs.promises.unlink("./target/.rustc_info.json");
-  await io.rmRF("./target/debug/examples");
-  await io.rmRF("./target/debug/incremental");
+async function cleanGit(packages: Packages) {
+  const coPath = path.join(paths.git, "checkouts");
+  const dbPath = path.join(paths.git, "db");
+  const repos = new Map<string, Set<string>>();
+  for (const p of packages) {
+    if (!p.path.startsWith(coPath)) {
+      continue;
+    }
+    const [repo, ref] = p.path.slice(coPath.length + 1).split(path.sep);
+    const refs = repos.get(repo);
+    if (refs) {
+      refs.add(ref);
+    } else {
+      repos.set(repo, new Set([ref]));
+    }
+  }
+
+  // we have to keep both the clone, and the checkout, removing either will
+  // trigger a rebuild
+
   let dir: fs.Dir;
-
-  // remove all *files* from debug
-  dir = await fs.promises.opendir("./target/debug");
+  // clean the db
+  dir = await fs.promises.opendir(dbPath);
   for await (const dirent of dir) {
-    if (dirent.isFile()) {
-      const fileName = path.join(dir.path, dirent.name);
-      await fs.promises.unlink(fileName);
+    if (!repos.has(dirent.name)) {
+      await rm(dir.path, dirent);
     }
   }
 
-  const keepPkg = new Set(packages.map((p) => p.name));
-  await rmExcept("./target/debug/build", keepPkg);
-  await rmExcept("./target/debug/.fingerprint", keepPkg);
-
-  const keepDeps = new Set(
-    packages.flatMap((p) => {
-      const name = p.name.replace(/-/g, "_");
-      return [name, `lib${name}`];
-    }),
-  );
-  await rmExcept("./target/debug/deps", keepDeps);
-}
-
-const twoWeeks = 14 * 24 * 3600 * 1000;
-
-async function rmExcept(dirName: string, keepPrefix: Set<string>) {
-  const dir = await fs.promises.opendir(dirName);
+  // clean the checkouts
+  dir = await fs.promises.opendir(coPath);
   for await (const dirent of dir) {
-    let name = dirent.name;
-    const idx = name.lastIndexOf("-");
-    if (idx !== -1) {
-      name = name.slice(0, idx);
+    const refs = repos.get(dirent.name);
+    if (!refs) {
+      await rm(dir.path, dirent);
+      continue;
     }
-    const fileName = path.join(dir.path, dirent.name);
-    const { mtime } = await fs.promises.stat(fileName);
-    if (!keepPrefix.has(name) || Date.now() - mtime.getTime() > twoWeeks) {
-      core.debug(`deleting "${fileName}"`);
-      if (dirent.isFile()) {
-        await fs.promises.unlink(fileName);
-      } else if (dirent.isDirectory()) {
-        await io.rmRF(fileName);
+    if (!dirent.isDirectory()) {
+      continue;
+    }
+    const refsDir = await fs.promises.opendir(path.join(dir.path, dirent.name));
+    for await (const dirent of refsDir) {
+      if (!refs.has(dirent.name)) {
+        await rm(refsDir.path, dirent);
       }
     }
   }

tsconfig.json

@@ -4,7 +4,7 @@
     "diagnostics": true,
     "lib": ["esnext"],
 
-    "target": "es2017",
+    "target": "es2020",
 
     "resolveJsonModule": true,
     "moduleResolution": "node",