fix(gatsby): [loki] sync db autosaves (#10212)

This PR orchestrates the saving of db state for both loki and redux into one place. Previously, loki would use its `autosave` feature and save to disk every 1000ms. Whereas now, it uses the same style as `gatsby/redux` where a debounced save is triggered for each new event. 

Note that both database save asynchronously (redux's write to disk is async) so this isn't a perfect "Stop the world" synchronized save. However it's better than it was before.

packages/gatsby/src/bootstrap/index.js

@@ -21,6 +21,7 @@ const getConfigFile = require(`./get-config-file`)
 const tracer = require(`opentracing`).globalTracer()
 const preferDefault = require(`./prefer-default`)
 const nodeTracking = require(`../db/node-tracking`)
+require(`../db`).startAutosave()
 
 // Show stack trace on unhandled promises.
 process.on(`unhandledRejection`, (reason, p) => {

packages/gatsby/src/db/index.js

@@ -0,0 +1,50 @@
+const _ = require(`lodash`)
+const redux = require(`../redux`)
+const { emitter } = redux
+
+// Even if we are using loki, we still include redux in the list of
+// dbs since it still has pages, config, etc.
+const dbs = [redux]
+if (process.env.GATSBY_DB_NODES === `loki`) {
+ dbs.push(require(`./loki`))
+}
+
+// calls `saveState()` on all DBs
+function saveState() {
+ for (const db of dbs) {
+ db.saveState()
+ }
+}
+const saveStateDebounced = _.debounce(saveState, 1000)
+
+/**
+ * Sets up listeners so that once bootstrap has finished, all
+ * databases save their state to disk. If we're in `develop` mode,
+ * then any new event triggers a debounced save as well.
+ */
+function startAutosave() {
+ // During development, once bootstrap is finished, persist state on changes.
+ let bootstrapFinished = false
+ if (process.env.gatsby_executing_command === `develop`) {
+ emitter.on(`BOOTSTRAP_FINISHED`, () => {
+ bootstrapFinished = true
+ saveState()
+ })
+ emitter.on(`*`, () => {
+ if (bootstrapFinished) {
+ saveStateDebounced()
+ }
+ })
+ }
+
+ // During builds, persist state once bootstrap has finished.
+ if (process.env.gatsby_executing_command === `build`) {
+ emitter.on(`BOOTSTRAP_FINISHED`, () => {
+ saveState()
+ })
+ }
+}
+
+module.exports = {
+ startAutosave,
+}

packages/gatsby/src/db/loki/index.js

@@ -71,8 +71,6 @@ function startFileDb(saveFile) {
  resolve()
  }
  },
- autosave: true,
- autosaveInterval: 1000,
  }
  db = new loki(saveFile, dbOptions)
  })
@@ -109,6 +107,24 @@ async function start({ saveFile } = {}) {
  ensureNodeCollections(db)
 }
 
+// Saves the database to disk and returns a promise that will be
+// resolved once the save has finished
+function saveState() {
+ return new Promise((resolve, reject) => {
+ if (db) {
+ db.saveDatabase(err => {
+ if (err) {
+ console.log(`error saving loki DB`)
+ console.log(err)
+ reject(err)
+ } else {
+ resolve()
+ }
+ })
+ }
+ })
+}
+
 /**
  * Returns a reference to the database. If undefined, the db has not been
  * initalized yet. Call `start()`
@@ -123,4 +139,5 @@ module.exports = {
  start,
  getDb,
  colls,
+ saveState,
 }

packages/gatsby/src/redux/index.js

@@ -63,7 +63,8 @@ const store = Redux.createStore(
 )
 
 // Persist state.
-const saveState = state => {
+function saveState() {
+ const state = store.getState()
  const pickedState = _.pick(state, [
  `nodes`,
  `status`,
@@ -85,34 +86,14 @@ const saveState = state => {
  () => {}
  )
 }
-const saveStateDebounced = _.debounce(saveState, 1000)
+
+exports.saveState = saveState
 
 store.subscribe(() => {
  const lastAction = store.getState().lastAction
  emitter.emit(lastAction.type, lastAction)
 })
 
-// During development, once bootstrap is finished, persist state on changes.
-let bootstrapFinished = false
-if (process.env.gatsby_executing_command === `develop`) {
- emitter.on(`BOOTSTRAP_FINISHED`, () => {
- bootstrapFinished = true
- saveState(store.getState())
- })
- emitter.on(`*`, () => {
- if (bootstrapFinished) {
- saveStateDebounced(store.getState())
- }
- })
-}
-
-// During builds, persist state once bootstrap has finished.
-if (process.env.gatsby_executing_command === `build`) {
- emitter.on(`BOOTSTRAP_FINISHED`, () => {
- saveState(store.getState())
- })
-}
-
 /** Event emitter */
 exports.emitter = emitter