fix: avoid downloading package when local cache exists (#123)

* fix: avoid downloading package when local cache exists

As mentioned in
#107,
`setup` function didn't use `find` function even though it uses
`cacheDir` to store downloaded files, which leads to redundant download.

It is not significant on GitHub-hosted runners because
`cacheDir` stores files in local file system, which is ephemeral.
However, it wastes time on self-hosted runners.

This commit adds a step to search local file system cache for sccache as
well as splitting download procedure to a dedicated function.

* fix: explicit comparison for boolean-like value

src/setup.ts

@@ -17,7 +17,8 @@ import {
  downloadTool,
  extractTar,
  extractZip,
- cacheDir
+ cacheDir,
+ find
 } from '@actions/tool-cache';
 import {getOctokit} from '@actions/github';
 
@@ -39,8 +40,45 @@ async function setup() {
  }
  core.info(`try to setup sccache version: ${version}`);
 
+ // Search local file system cache for sccache.
+ // This is useful when actions run on a self-hosted runner.
+ let sccacheHome = find('sccache', version);
+ if (sccacheHome === '') {
+ const sccachePath = await downloadSCCache(version);
+ if (sccachePath instanceof Error) {
+ core.setFailed(sccachePath.message);
+ return;
+ } else {
+ const dirname = getDirname(version);
+ // Cache sccache.
+ sccacheHome = await cacheDir(
+ `${sccachePath}/${dirname}`,
+ 'sccache',
+ version
+ );
+ core.info(`sccache cached to: ${sccacheHome}`);
+ }
+ } else {
+ core.info(`find sccache at: ${sccacheHome}`);
+ }
+ // Add sccache into path.
+ core.addPath(`${sccacheHome}`);
+ // Expose the sccache path as env.
+ core.exportVariable('SCCACHE_PATH', `${sccacheHome}/sccache`);
+
+ // Expose the gha cache related variable to make it easier for users to
+ // integrate with gha support.
+ core.exportVariable('ACTIONS_CACHE_URL', process.env.ACTIONS_CACHE_URL || '');
+ core.exportVariable(
+ 'ACTIONS_RUNTIME_TOKEN',
+ process.env.ACTIONS_RUNTIME_TOKEN || ''
+ );
+}
+/**
+ * @param version sccache version
+ * @returns Path to sccache on success. Error on checksum verification failure. */
+async function downloadSCCache(version: string): Promise<Error | string> {
  const filename = getFilename(version);
- const dirname = getDirname(version);
 
  const downloadUrl = `https://github.com/mozilla/sccache/releases/download/${version}/${filename}`;
  const sha256Url = `${downloadUrl}.sha256`;
@@ -63,8 +101,7 @@ async function setup() {
 
  // Compare the checksums.
  if (calculatedChecksum !== providedChecksum) {
- core.setFailed('Checksum verification failed');
- return;
+ return Error('Checksum verification failed');
  }
  core.info(`Correct checksum: ${calculatedChecksum}`);
 
@@ -75,27 +112,7 @@ async function setup() {
  sccachePath = await extractTar(sccachePackage);
  }
  core.info(`sccache extracted to: ${sccachePath}`);
-
- // Cache sccache.
- const sccacheHome = await cacheDir(
- `${sccachePath}/${dirname}`,
- 'sccache',
- version
- );
- core.info(`sccache cached to: ${sccacheHome}`);
-
- // Add cached sccache into path.
- core.addPath(`${sccacheHome}`);
- // Expose the sccache path as env.
- core.exportVariable('SCCACHE_PATH', `${sccacheHome}/sccache`);
-
- // Expose the gha cache related variable to make it easier for users to
- // integrate with gha support.
- core.exportVariable('ACTIONS_CACHE_URL', process.env.ACTIONS_CACHE_URL || '');
- core.exportVariable(
- 'ACTIONS_RUNTIME_TOKEN',
- process.env.ACTIONS_RUNTIME_TOKEN || ''
- );
+ return sccachePath;
 }
 
 function getFilename(version: string): Error | string {