lazily load graphql static json files (github#25981)

Author: peterbe

lib/read-json-file.js

@@ -30,3 +30,34 @@ export function readCompressedJsonFileFallback(xpath) {
     }
   }
 }
+
+// Wrapper on readCompressedJsonFileFallback that initially only checks
+// if the file exists but doesn't read the content till you call it.
+export function readCompressedJsonFileFallbackLazily(xpath) {
+  const cache = new Map()
+  // This will throw if the file isn't accessible at all, e.g. ENOENT
+  // But, the file might have been replaced by one called `SAMENAME.json.br`
+  // because in staging, we ship these files compressed to make the
+  // deployment faster. So, in our file-presence check, we need to
+  // account for that.
+  try {
+    fs.accessSync(xpath)
+  } catch (err) {
+    if (err.code === 'ENOENT') {
+      try {
+        fs.accessSync(xpath + '.br')
+      } catch (err) {
+        if (err.code === 'ENOENT') {
+          throw new Error(`Neither ${xpath} nor ${xpath}.br is accessible`)
+        }
+        throw err
+      }
+    } else {
+      throw err
+    }
+  }
+  return () => {
+    if (!cache.has(xpath)) cache.set(xpath, readCompressedJsonFileFallback(xpath))
+    return cache.get(xpath)
+  }
+}

middleware/archived-enterprise-versions.js

@@ -1,4 +1,3 @@
-import fs from 'fs'
 import path from 'path'
 import slash from 'slash'
 import statsd from '../lib/statsd.js'
@@ -11,7 +10,7 @@ import versionSatisfiesRange from '../lib/version-satisfies-range.js'
 import isArchivedVersion from '../lib/is-archived-version.js'
 import { setFastlySurrogateKey, SURROGATE_ENUMS } from './set-fastly-surrogate-key.js'
 import got from 'got'
-import { readCompressedJsonFileFallback } from '../lib/read-json-file.js'
+import { readCompressedJsonFileFallbackLazily } from '../lib/read-json-file.js'
 import { cacheControlFactory } from './cache-control.js'
 import { pathLanguagePrefixed, languagePrefixPathRegex } from '../lib/languages.js'
 
@@ -25,42 +24,13 @@ function splitByLanguage(uri) {
   return [language, withoutLanguage]
 }
 
-function readJsonFileLazily(xpath) {
-  const cache = new Map()
-  // This will throw if the file isn't accessible at all, e.g. ENOENT
-  // But, the file might have been replaced by one called `SAMENAME.json.br`
-  // because in staging, we ship these files compressed to make the
-  // deployment faster. So, in our file-presence check, we need to
-  // account for that.
-  try {
-    fs.accessSync(xpath)
-  } catch (err) {
-    if (err.code === 'ENOENT') {
-      try {
-        fs.accessSync(xpath + '.br')
-      } catch (err) {
-        if (err.code === 'ENOENT') {
-          throw new Error(`Neither ${xpath} nor ${xpath}.br is accessible`)
-        }
-        throw err
-      }
-    } else {
-      throw err
-    }
-  }
-  return () => {
-    if (!cache.has(xpath)) cache.set(xpath, readCompressedJsonFileFallback(xpath))
-    return cache.get(xpath)
-  }
-}
-
 // These files are huge so lazy-load them. But note that the
 // `readJsonFileLazily()` function will, at import-time, check that
 // the path does exist.
-const archivedRedirects = readJsonFileLazily(
+const archivedRedirects = readCompressedJsonFileFallbackLazily(
   './lib/redirects/static/archived-redirects-from-213-to-217.json'
 )
-const archivedFrontmatterFallbacks = readJsonFileLazily(
+const archivedFrontmatterFallbacks = readCompressedJsonFileFallbackLazily(
   './lib/redirects/static/archived-frontmatter-fallbacks.json'
 )
 

middleware/contextualizers/graphql.js

@@ -1,15 +1,17 @@
-import { readCompressedJsonFileFallback } from '../../lib/read-json-file.js'
+import { readCompressedJsonFileFallbackLazily } from '../../lib/read-json-file.js'
 import { allVersions } from '../../lib/all-versions.js'
-const previews = readCompressedJsonFileFallback('./lib/graphql/static/previews.json')
-const upcomingChanges = readCompressedJsonFileFallback('./lib/graphql/static/upcoming-changes.json')
-const changelog = readCompressedJsonFileFallback('./lib/graphql/static/changelog.json')
-const prerenderedObjects = readCompressedJsonFileFallback(
+const previews = readCompressedJsonFileFallbackLazily('./lib/graphql/static/previews.json')
+const upcomingChanges = readCompressedJsonFileFallbackLazily(
+  './lib/graphql/static/upcoming-changes.json'
+)
+const changelog = readCompressedJsonFileFallbackLazily('./lib/graphql/static/changelog.json')
+const prerenderedObjects = readCompressedJsonFileFallbackLazily(
   './lib/graphql/static/prerendered-objects.json'
 )
-const prerenderedInputObjects = readCompressedJsonFileFallback(
+const prerenderedInputObjects = readCompressedJsonFileFallbackLazily(
   './lib/graphql/static/prerendered-input-objects.json'
 )
-const prerenderedMutations = readCompressedJsonFileFallback(
+const prerenderedMutations = readCompressedJsonFileFallbackLazily(
   './lib/graphql/static/prerendered-mutations.json'
 )
 
@@ -32,16 +34,16 @@ export default function graphqlContext(req, res, next) {
   const graphqlVersion = currentVersionObj.miscVersionName
 
   req.context.graphql = {
-    schemaForCurrentVersion: readCompressedJsonFileFallback(
+    schemaForCurrentVersion: readCompressedJsonFileFallbackLazily(
       `lib/graphql/static/schema-${graphqlVersion}.json`
-    ),
-    previewsForCurrentVersion: previews[graphqlVersion],
-    upcomingChangesForCurrentVersion: upcomingChanges[graphqlVersion],
-    prerenderedObjectsForCurrentVersion: prerenderedObjects[graphqlVersion],
-    prerenderedInputObjectsForCurrentVersion: prerenderedInputObjects[graphqlVersion],
-    prerenderedMutationsForCurrentVersion: prerenderedMutations[graphqlVersion],
+    )(),
+    previewsForCurrentVersion: previews()[graphqlVersion],
+    upcomingChangesForCurrentVersion: upcomingChanges()[graphqlVersion],
+    prerenderedObjectsForCurrentVersion: prerenderedObjects()[graphqlVersion],
+    prerenderedInputObjectsForCurrentVersion: prerenderedInputObjects()[graphqlVersion],
+    prerenderedMutationsForCurrentVersion: prerenderedMutations()[graphqlVersion],
     explorerUrl,
-    changelog,
+    changelog: changelog(),
   }
 
   return next()