implement a core logic to cache dependnecies

src/cache.ts

@@ -0,0 +1,110 @@
+/**
+ * @fileoverview this file provides methods handling dependency cache
+ */
+
+import { join } from 'path';
+import os from 'os';
+import * as cache from '@actions/cache';
+import * as core from '@actions/core';
+import * as glob from '@actions/glob';
+
+const STATE_CACHE_PRIMARY_KEY = 'cache-primary-key';
+const CACHE_MATCHED_KEY = 'cache-matched-key';
+
+interface PackageManager {
+  id: 'maven' | 'gradle';
+  /**
+   * Paths of the file that specify the files to cache.
+   */
+  path: string[];
+  pattern: string[];
+}
+const supportedPackageManager: PackageManager[] = [
+  {
+    id: 'maven',
+    path: [join(os.homedir(), '.m2', 'repository')],
+    // https://github.com/actions/cache/blob/0638051e9af2c23d10bb70fa9beffcad6cff9ce3/examples.md#java---maven
+    pattern: ['**/pom.xml']
+  },
+  {
+    id: 'gradle',
+    path: [join(os.homedir(), '.gradle', 'caches'), join(os.homedir(), '.gradle', 'wrapper')],
+    // https://github.com/actions/cache/blob/0638051e9af2c23d10bb70fa9beffcad6cff9ce3/examples.md#java---gradle
+    pattern: ['**/*.gradle*', '**/gradle-wrapper.properties']
+  }
+];
+
+function findPackageManager(id: string): PackageManager {
+  const packageManager = supportedPackageManager.find(packageManager => packageManager.id === id);
+  if (packageManager === undefined) {
+    throw new Error(`unknown package manager specified: ${id}`);
+  }
+  return packageManager;
+}
+
+/**
+ * A function that generates a cache key to use.
+ * Format of the generated key will be "${{ platform }}-${{ id }}-${{ fileHash }}"".
+ * If there is no file matched to {@link PackageManager.path}, the generated key ends with a dash (-).
+ * @see {@link https://docs.github.com/en/actions/guides/caching-dependencies-to-speed-up-workflows#matching-a-cache-key|spec of cache key}
+ */
+async function computeCacheKey(packageManager: PackageManager) {
+  return `${process.env['RUNNER_OS']}-${packageManager.id}-${await glob.hashFiles(
+    packageManager.pattern.join('\n')
+  )}`;
+}
+
+/**
+ * Restore the dependency cache
+ * @param id ID of the package manager, should be "maven" or "gradle"
+ */
+export async function restore(id: string) {
+  const packageManager = findPackageManager(id);
+  const primaryKey = await computeCacheKey(packageManager);
+
+  core.debug(`primary key is ${primaryKey}`);
+  core.saveState(STATE_CACHE_PRIMARY_KEY, primaryKey);
+  if (primaryKey.endsWith('-')) {
+    core.warning(
+      `No file in ${process.cwd()} matched to [${
+        packageManager.pattern
+      }], make sure you have checked out the target repository`
+    );
+    return;
+  }
+
+  const matchedKey = await cache.restoreCache(packageManager.path, primaryKey, [
+    `${process.env['RUNNER_OS']}-${id}`
+  ]);
+  if (matchedKey) {
+    core.saveState(CACHE_MATCHED_KEY, matchedKey);
+    core.info(`Cache restored from key: ${matchedKey}`);
+  } else {
+    core.info(`${packageManager.id} cache is not found`);
+  }
+}
+
+/**
+ * Save the dependency cache
+ * @param id ID of the package manager, should be "maven" or "gradle"
+ */
+export async function save(id: string) {
+  const packageManager = findPackageManager(id);
+  const primaryKey = await computeCacheKey(packageManager);
+  const matchedKey = core.getState(CACHE_MATCHED_KEY);
+  if (matchedKey === primaryKey) {
+    // no change in target directories
+    core.info(`Cache hit occurred on the primary key ${primaryKey}, not saving cache.`);
+    return;
+  }
+  try {
+    await cache.saveCache(packageManager.path, primaryKey);
+    core.info(`Cache saved with the key: ${primaryKey}`);
+  } catch (error) {
+    if (error.name === cache.ReserveCacheError.name) {
+      core.info(error.message);
+    } else {
+      throw error;
+    }
+  }
+}