Updating writethrough cache a bit to make sure it implements the PouchDB API properly.

packages/backend-core/cache.js

@@ -3,5 +3,6 @@ const generic = require("./src/cache/generic")
 module.exports = {
   user: require("./src/cache/user"),
   app: require("./src/cache/appMetadata"),
+  writethrough: require("./src/cache/writethrough"),
   ...generic,
 }

packages/backend-core/src/cache/tests/writethrough.spec.js

@@ -9,30 +9,30 @@ tk.freeze(START_DATE)
 const DELAY = 5000
 
 const db = dangerousGetDB("test")
-const writethrough = new Writethrough(db)
+const writethrough = new Writethrough(db, DELAY)
 
 describe("writethrough", () => {
   describe("put", () => {
     let first
     it("should be able to store, will go to DB", async () => {
-      const response = await writethrough.put({ _id: "test", value: 1 }, DELAY)
-      const output = await db.get(response._id)
+      const response = await writethrough.put({ _id: "test", value: 1 })
+      const output = await db.get(response.id)
       first = output
       expect(output.value).toBe(1)
     })
 
     it("second put shouldn't update DB", async () => {
-      const response = await writethrough.put({ ...first, value: 2 }, DELAY)
-      const output = await db.get(response._id)
+      const response = await writethrough.put({ ...first, value: 2 })
+      const output = await db.get(response.id)
       expect(first._rev).toBe(output._rev)
       expect(output.value).toBe(1)
     })
 
     it("should put it again after delay period", async () => {
       tk.freeze(START_DATE + DELAY + 1)
-      const response = await writethrough.put({ ...first, value: 3 }, DELAY)
-      const output = await db.get(response._id)
-      expect(response._rev).not.toBe(first._rev)
+      const response = await writethrough.put({ ...first, value: 3 })
+      const output = await db.get(response.id)
+      expect(response.rev).not.toBe(first._rev)
       expect(output.value).toBe(3)
     })
   })

packages/backend-core/src/cache/writethrough.ts

@@ -5,7 +5,7 @@ const DEFAULT_WRITE_RATE_MS = 10000
 let CACHE: BaseCache | null = null
 
 interface CacheItem {
-  value: any
+  doc: any
   lastWrite: number
 }
 
@@ -17,57 +17,85 @@ async function getCache() {
   return CACHE
 }
 
-function makeCacheItem(value: any, lastWrite: number | null = null): CacheItem {
-  return { value, lastWrite: lastWrite || Date.now() }
+function makeCacheItem(doc: any, lastWrite: number | null = null): CacheItem {
+  return { doc, lastWrite: lastWrite || Date.now() }
 }
 
 export async function put(
   db: PouchDB.Database,
-  value: any,
+  doc: any,
   writeRateMs: number = DEFAULT_WRITE_RATE_MS
 ) {
   const cache = await getCache()
-  const key = value._id
+  const key = doc._id
   let cacheItem: CacheItem | undefined = await cache.get(key)
   const updateDb = !cacheItem || cacheItem.lastWrite < Date.now() - writeRateMs
-  let output = value
+  let output = doc
   if (updateDb) {
-    // value should contain the _id and _rev
-    const response = await db.put(value)
+    // doc should contain the _id and _rev
+    const response = await db.put(doc)
     output = {
-      ...value,
+      ...doc,
       _id: response.id,
       _rev: response.rev,
     }
   }
   // if we are updating the DB then need to set the lastWrite to now
-  cacheItem = makeCacheItem(value, updateDb ? null : cacheItem?.lastWrite)
+  cacheItem = makeCacheItem(output, updateDb ? null : cacheItem?.lastWrite)
   await cache.store(key, cacheItem)
-  return output
+  return { ok: true, id: output._id, rev: output._rev }
 }
 
 export async function get(db: PouchDB.Database, id: string): Promise<any> {
   const cache = await getCache()
   let cacheItem: CacheItem = await cache.get(id)
   if (!cacheItem) {
-    const value = await db.get(id)
-    cacheItem = makeCacheItem(value)
+    const doc = await db.get(id)
+    cacheItem = makeCacheItem(doc)
     await cache.store(id, cacheItem)
   }
-  return cacheItem.value
+  return cacheItem.doc
+}
+
+export async function remove(
+  db: PouchDB.Database,
+  docOrId: any,
+  rev?: any
+): Promise<void> {
+  const cache = await getCache()
+  if (!docOrId) {
+    throw new Error("No ID/Rev provided.")
+  }
+  const id = typeof docOrId === "string" ? docOrId : docOrId._id
+  rev = typeof docOrId === "string" ? rev : docOrId._rev
+  try {
+    await cache.delete(id)
+  } finally {
+    await db.remove(id, rev)
+  }
 }
 
 export class Writethrough {
   db: PouchDB.Database
-  constructor(db: PouchDB.Database) {
+  writeRateMs: number
+
+  constructor(
+    db: PouchDB.Database,
+    writeRateMs: number = DEFAULT_WRITE_RATE_MS
+  ) {
     this.db = db
+    this.writeRateMs = writeRateMs
   }
 
-  async put(value: any, writeRateMs: number = DEFAULT_WRITE_RATE_MS) {
-    return put(this.db, value, writeRateMs)
+  async put(doc: any) {
+    return put(this.db, doc, this.writeRateMs)
   }
 
   async get(id: string) {
     return get(this.db, id)
   }
+
+  async remove(docOrId: any, rev?: any) {
+    return remove(this.db, docOrId, rev)
+  }
 }