refactor: refactor getVersions logic

Author: yyx990803

packages/@vue/cli/lib/util/getVersions.js

@@ -1,57 +1,61 @@
 const fs = require('fs-extra')
 const path = require('path')
+const semver = require('semver')
 const fsCachePath = path.resolve(__dirname, '.version')
 
+let sessionCached
+
 module.exports = async function getVersions () {
+  if (sessionCached) {
+    return sessionCached
+  }
+
   let latest
-  const current = require(`../../package.json`).version
+  const local = require(`../../package.json`).version
   if (process.env.VUE_CLI_TEST || process.env.VUE_CLI_DEBUG) {
-    return {
-      latest: current,
-      current
-    }
+    return (sessionCached = {
+      current: local,
+      latest: local
+    })
   }
 
   if (fs.existsSync(fsCachePath)) {
-    // if we haven't check for a new version in a week, force a full check
-    // before proceeding.
+    const cached = await fs.readFile(fsCachePath, 'utf-8')
     const lastChecked = (await fs.stat(fsCachePath)).mtimeMs
     const daysPassed = (Date.now() - lastChecked) / (60 * 60 * 1000 * 24)
-    if (daysPassed > 7) {
-      const cachedCurrent = await fs.readFile(fsCachePath, 'utf-8')
-      await getAndCacheLatestVersion(cachedCurrent)
+    if (daysPassed > 1) {
+      // if we haven't check for a new version in a day, wait for the check
+      // before proceeding
+      latest = await getAndCacheLatestVersion(cached)
+    } else {
+      // Otherwise, do a check in the background. If the result was updated,
+      // it will be used for the next 24 hours.
+      getAndCacheLatestVersion(cached)
+      latest = cached
     }
-    latest = await fs.readFile(fsCachePath, 'utf-8')
   } else {
     // if the cache file doesn't exist, this is likely a fresh install
     // so no need to check
-    latest = current
+    latest = local
   }
 
-  // Do a check in the background. The cached file will be used for the next
-  // startup within a week.
-  getAndCacheLatestVersion(current)
-
-  return {
-    current,
+  return (sessionCached = {
+    current: local,
     latest
-  }
+  })
 }
 
 // fetch the latest version and save it on disk
 // so that it is available immediately next time
-let sentCheckRequest = false
-async function getAndCacheLatestVersion (current) {
-  if (sentCheckRequest) {
-    return
-  }
-  sentCheckRequest = true
+async function getAndCacheLatestVersion (cached) {
   const getPackageVersion = require('./getPackageVersion')
   const res = await getPackageVersion('vue-cli-version-marker', 'latest')
   if (res.statusCode === 200) {
     const { version } = res.body
-    if (version !== current) {
+    if (semver.valid(version) && version !== cached) {
       await fs.writeFile(fsCachePath, version)
+      return version
     }
   }
+  return cached
 }