Reuse builds in the toolcache when they exist

ruby-builder.js

@@ -1,6 +1,5 @@
 const os = require('os')
 const path = require('path')
-const core = require('@actions/core')
 const exec = require('@actions/exec')
 const io = require('@actions/io')
 const tc = require('@actions/tool-cache')
@@ -17,24 +16,33 @@ export function getAvailableVersions(platform, engine) {
 }
 
 export async function install(platform, engine, version) {
-  return await downloadAndExtract(platform, engine, version)
-}
-
-async function downloadAndExtract(platform, engine, version) {
-  let rubyPrefix
-  if (common.shouldExtractInToolCache(engine, version)) {
-    rubyPrefix = common.getToolCacheRubyPrefix(platform, version)
+  let rubyPrefix, inToolCache
+  if (common.shouldUseToolCache(engine, version)) {
+    inToolCache = tc.find('Ruby', version)
+    if (inToolCache) {
+      rubyPrefix = inToolCache
+    } else {
+      rubyPrefix = common.getToolCacheRubyPrefix(platform, version)
+    }
   } else if (windows) {
     rubyPrefix = path.join(`${common.drive}:`, `${engine}-${version}`)
   } else {
     rubyPrefix = path.join(os.homedir(), '.rubies', `${engine}-${version}`)
   }
 
-  const parentDir = path.dirname(rubyPrefix)
-
   // Set the PATH now, so the MSYS2 'tar' is in Path on Windows
   common.setupPath([path.join(rubyPrefix, 'bin')])
 
+  if (!inToolCache) {
+    await downloadAndExtract(platform, engine, version, rubyPrefix);
+  }
+
+  return rubyPrefix
+}
+
+async function downloadAndExtract(platform, engine, version, rubyPrefix) {
+  const parentDir = path.dirname(rubyPrefix)
+
   await io.rmRF(rubyPrefix)
   await io.mkdirP(parentDir)
 
@@ -47,13 +55,11 @@ async function downloadAndExtract(platform, engine, version) {
   await common.measure('Extracting Ruby', async () => {
     if (windows) {
       // Windows 2016 doesn't have system tar, use MSYS2's, it needs unix style paths
-      await exec.exec('tar', [ '-xz', '-C', common.win2nix(parentDir), '-f', common.win2nix(downloadPath) ])
+      await exec.exec('tar', ['-xz', '-C', common.win2nix(parentDir), '-f', common.win2nix(downloadPath)])
     } else {
-      await exec.exec('tar', [ '-xz', '-C', parentDir, '-f',  downloadPath ])
+      await exec.exec('tar', ['-xz', '-C', parentDir, '-f', downloadPath])
     }
   })
-
-  return rubyPrefix
 }
 
 function getDownloadURL(platform, engine, version) {