feat: initial version

Author: Simon Grondin

lib/index.js

@@ -0,0 +1,55 @@
+module.exports = throttlingPlugin
+
+const Bottleneck = require('bottleneck/light')
+const wrapRequest = require('./wrap-request')
+
+const triggersNotificationRoutes = [
+  '/repos/:owner/:repo/issues',
+  '/repos/:owner/:repo/issues/:number/comments',
+  '/orgs/:org/invitations',
+  '/repos/:owner/:repo/pulls',
+  '/repos/:owner/:repo/pulls',
+  '/repos/:owner/:repo/pulls/:number/merge',
+  '/repos/:owner/:repo/pulls/:number/reviews',
+  '/repos/:owner/:repo/pulls/:number/comments',
+  '/repos/:owner/:repo/pulls/:number/comments',
+  '/repos/:owner/:repo/pulls/:number/requested_reviewers',
+  '/repos/:owner/:repo/collaborators/:username',
+  '/repos/:owner/:repo/commits/:sha/comments',
+  '/repos/:owner/:repo/releases',
+  '/teams/:team_id/discussions',
+  '/teams/:team_id/discussions/:discussion_number/comments'
+]
+
+function buildLookup (arr) {
+  return arr.reduce(function (acc, elem) {
+    acc[elem] = true
+    return acc
+  }, {})
+}
+
+function throttlingPlugin (octokit) {
+  const state = {
+    triggersNotification: buildLookup(triggersNotificationRoutes),
+    minimumAbuseRetryAfter: 5,
+    maxRetries: 1,
+    globalLimiter: new Bottleneck({
+      maxConcurrent: 1
+    }),
+    writeLimiter: new Bottleneck({
+      maxConcurrent: 1,
+      minTime: 1000
+    }),
+    triggersNotificationLimiter: new Bottleneck({
+      maxConcurrent: 1,
+      minTime: 3000
+    })
+  }
+
+  octokit.throttle = {
+    options: (options = {}) => Object.assign(state, options)
+  }
+  const emitter = new Bottleneck.Events(octokit.throttle)
+
+  octokit.hook.wrap('request', wrapRequest.bind(null, state, emitter))
+}

lib/wrap-request.js

@@ -0,0 +1,61 @@
+/* eslint padded-blocks: 0 */
+module.exports = wrapRequest
+
+const noop = () => Promise.resolve()
+
+async function wrapRequest (state, emitter, request, options) {
+  const retryRequest = function (after) {
+    return new Promise(resolve => setTimeout(resolve, after * 1000))
+      .then(() => wrapRequest(state, emitter, request, options))
+  }
+  const isWrite = options.method !== 'GET' && options.method !== 'HEAD'
+  const retryCount = ~~options.request.retryCount
+  const jobOptions = retryCount > 0 ? { priority: 0, weight: 0 } : {}
+
+  // Guarantee at least 1000ms between writes
+  if (isWrite) {
+    await state.writeLimiter.schedule(noop)
+  }
+
+  // Guarantee at least 3000ms between requests that trigger notifications
+  if (isWrite && state.triggersNotification[options.url]) {
+    await state.triggersNotificationLimiter.schedule(noop)
+  }
+
+  return state.globalLimiter.schedule(jobOptions, async function () {
+    try {
+      // Execute request
+      return await request(options)
+    } catch (error) {
+      if (error.status === 403 && /\babuse\b/i.test(error.message)) {
+        // The user has hit the abuse rate limit.
+        // https://developer.github.com/v3/#abuse-rate-limits
+
+        // The Retry-After header can sometimes be blank when hitting an abuse limit,
+        // but is always present after 2-3s, so make sure to set `retryAfter` to at least 5s by default.
+        const retryAfter = Math.max(~~error.headers['retry-after'], state.minimumAbuseRetryAfter)
+        emitter.trigger('abuse-limit', retryAfter)
+
+        if (state.maxRetries > retryCount) {
+          options.request.retryCount = retryCount + 1
+          return retryRequest(retryAfter)
+        }
+
+      } else if (error.status === 403 && error.headers['x-ratelimit-remaining'] === '0') {
+        // The user has used all their allowed calls for the current time period
+        // https://developer.github.com/v3/#rate-limiting
+
+        const rateLimitReset = new Date(~~error.headers['x-ratelimit-reset'] * 1000).getTime()
+        const retryAfter = Math.max(Math.ceil((rateLimitReset - Date.now()) / 1000), 0)
+        emitter.trigger('rate-limit', retryAfter)
+
+        if (state.maxRetries > retryCount) {
+          options.request.retryCount = retryCount + 1
+          return retryRequest(retryAfter)
+        }
+      }
+
+      throw error
+    }
+  })
+}