server: add fetching pool stats

libs/live-fetcher.js

@@ -1,30 +1,29 @@
-const waitings = {} // Cache ongoing fetching, prevent redundant request
+// Cache ongoing fetching, prevent redundant request
+const { waitings } = require('./live-pool.js')
 
 module.exports = async (scope, fn, paramsPath) => {
   const fetchKey = `#${scope} ${paramsPath}`
   if (waitings[fetchKey]) return waitings[fetchKey]
 
   console.time(fetchKey)
-  waitings[fetchKey] = fn(...paramsPath.split('/')).catch(e => {
-    let status = 'unknown'
+  waitings[fetchKey] = fn(...paramsPath.split('/')).then(
+    result => typeof result === 'object' ? result : { failed: true },
+    err => {
+      let status = 'unknown'
 
-    if (e.response && e.response.status === 404) {
-      status = 'not found'
-    } else if (e.code === 'ECONNABORTED') {
-      status = 'timeout'
-    }
+      if (err.response && err.response.status === 404) {
+        status = 'not found'
+      } else if (err.code === 'ECONNABORTED') {
+        status = 'timeout'
+      }
 
-    const info = status === 'unknown' ? e.stack : e.message
-    console.error(fetchKey, `LIVEFN_ERR<${status}>`, info)
-    return { status, failed: true }
-  }).then(result => {
+      const info = status === 'unknown' ? err.stack : err.message
+      console.error(fetchKey, `LIVEFN_ERR<${status}>`, info)
+
+      return { status, failed: true }
+    }).finally(() => {
     console.timeEnd(fetchKey)
     waitings[fetchKey] = undefined
-    if (typeof result === 'object') {
-      return result
-    } else {
-      return { failed: true }
-    }
   })
 
   return waitings[fetchKey]

libs/live-pool.js

@@ -0,0 +1,10 @@
+const waitings = {}
+
+const list = () => {
+  return waitings
+}
+
+module.exports = {
+  waitings,
+  list
+}

libs/serve-stats.js

@@ -1,10 +1,12 @@
 const axios = require('axios')
 const { send } = require('micro')
+const livePool = require('./live-pool.js')
 
 module.exports = async (req, res) => {
   const [githubRateLimit] = await Promise.all([getGithubRateLimit()])
+  const fetching = Object.values(livePool.list()).filter(Boolean).length
 
-  send(res, 200, { githubRateLimit })
+  send(res, 200, { githubRateLimit, fetching })
 }
 
 const getGithubRateLimit = () => {