WIP instead of having one function that can handle both async and callback signatures, let's implement a new Async suite of functions, and use callbackify to shim the old interface

lib/datastore.js

@@ -1,4 +1,5 @@
 const { EventEmitter } = require('events')
+const { callbackify } = require('util')
 const async = require('async')
 const Cursor = require('./cursor.js')
 const customUtils = require('./customUtils.js')
@@ -267,17 +268,52 @@ class Datastore extends EventEmitter {
    * @param {Boolean} dontExpireStaleDocs Optional, defaults to false, if true don't remove stale docs. Useful for the remove function which shouldn't be impacted by expirations
    * @param {Function} callback Signature err, candidates
    */
-  async getCandidates (query, dontExpireStaleDocs, callback) {
-    const validDocs = []
-
+  getCandidates (query, dontExpireStaleDocs, callback) {
     if (typeof dontExpireStaleDocs === 'function') {
       callback = dontExpireStaleDocs
       dontExpireStaleDocs = false
     }
 
-    try {
+    callbackify(this.getCandidatesAsync.bind(this))(query, dontExpireStaleDocs, callback)
+  }
+
+  async getCandidatesAsync (query, dontExpireStaleDocs = false) {
+    const indexNames = Object.keys(this.indexes)
+    const validDocs = []
+
+    const _getCandidates = query => {
       // STEP 1: get candidates list by checking indexes from most to least frequent usecase
-      const docs = this._getCandidates(query)
+      // For a basic match
+      let usableQuery
+      usableQuery = Object.entries(query)
+        .filter(([k, v]) =>
+          !!(typeof v === 'string' || typeof v === 'number' || typeof v === 'boolean' || isDate(v) || v === null) &&
+          indexNames.includes(k)
+        )
+        .pop()
+      if (usableQuery) return this.indexes[usableQuery[0]].getMatching(usableQuery[1])
+      // For a $in match
+      usableQuery = Object.entries(query)
+        .filter(([k, v]) =>
+          !!(query[k] && Object.prototype.hasOwnProperty.call(query[k], '$in')) &&
+          indexNames.includes(k)
+        )
+        .pop()
+      if (usableQuery) return this.indexes[usableQuery[0]].getMatching(usableQuery[1].$in)
+      // For a comparison match
+      usableQuery = Object.entries(query)
+        .filter(([k, v]) =>
+          !!(query[k] && (Object.prototype.hasOwnProperty.call(query[k], '$lt') || Object.prototype.hasOwnProperty.call(query[k], '$lte') || Object.prototype.hasOwnProperty.call(query[k], '$gt') || Object.prototype.hasOwnProperty.call(query[k], '$gte'))) &&
+          indexNames.includes(k)
+        )
+        .pop()
+      if (usableQuery) return this.indexes[usableQuery[0]].getBetweenBounds(usableQuery[1])
+      // By default, return all the DB data
+      return this.getAllData()
+    }
+
+    // STEP 1: get candidates list by checking indexes from most to least frequent usecase
+    const docs = _getCandidates(query)
     // STEP 2: remove all expired documents
       if (!dontExpireStaleDocs) {
       const expiredDocsIds = []
@@ -296,12 +332,7 @@ class Datastore extends EventEmitter {
           })
       }
     } else validDocs.push(...docs)
-    } catch (error) {
-      if (typeof callback === 'function') callback(error, null)
-      else throw error
-    }
-    if (typeof callback === 'function') callback(null, validDocs)
-    else return validDocs
+    return validDocs
   }
 
   /**
@@ -509,19 +540,30 @@ class Datastore extends EventEmitter {
       options = {}
     }
     const callback = cb || (() => {})
+
+    const _callback = (err, res = {}) => {
+      callback(err, res.numAffected, res.affectedDocuments, res.upsert)
+    }
+    callbackify(this._updateAsync.bind(this))(query, updateQuery, options, _callback)
+  }
+
+  async _updateAsync (query, updateQuery, options = {}) {
     const multi = options.multi !== undefined ? options.multi : false
     const upsert = options.upsert !== undefined ? options.upsert : false
 
-    async.waterfall([
-      cb => { // If upsert option is set, check whether we need to insert the doc
-        if (!upsert) return cb()
-
+    // If upsert option is set, check whether we need to insert the doc
+    if (upsert) {
       // Need to use an internal function not tied to the executor to avoid deadlock
       const cursor = new Cursor(this, query)
+
+      const docs = await new Promise((resolve, reject) => {
         cursor.limit(1)._exec((err, docs) => {
-          if (err) return callback(err)
-          if (docs.length === 1) return cb()
-          else {
+          if (err) reject(err)
+          else resolve(docs)
+        })
+      })
+
+      if (docs.length !== 1) {
         let toBeInserted
 
         try {
@@ -531,32 +573,26 @@ class Datastore extends EventEmitter {
         } catch (e) {
           // updateQuery contains modifiers, use the find query as the base,
           // strip it from all operators and update it according to updateQuery
-              try {
           toBeInserted = model.modify(model.deepCopy(query, true), updateQuery)
-              } catch (err) {
-                return callback(err)
-              }
         }
 
-            return this._insert(toBeInserted, (err, newDoc) => {
-              if (err) return callback(err)
-              return callback(null, 1, newDoc, true)
+        return new Promise((resolve, reject) => {
+          this._insert(toBeInserted, (err, newDoc) => {
+            if (err) return reject(err)
+            return resolve({ numAffected: 1, affectedDocuments: newDoc, upsert: true })
           })
-          }
         })
-      },
-      () => { // Perform the update
+      }
+    }
+    // Perform the update
     let numReplaced = 0
     let modifiedDoc
     const modifications = []
     let createdAt
 
-        this.getCandidates(query, (err, candidates) => {
-          if (err) return callback(err)
-
+    const candidates = await this.getCandidatesAsync(query)
     // Preparing update (if an error is thrown here neither the datafile nor
     // the in-memory indexes are affected)
-          try {
     for (const candidate of candidates) {
       if (model.match(candidate, query) && (multi || numReplaced === 0)) {
         numReplaced += 1
@@ -569,32 +605,25 @@ class Datastore extends EventEmitter {
         modifications.push({ oldDoc: candidate, newDoc: modifiedDoc })
       }
     }
-          } catch (err) {
-            return callback(err)
-          }
 
     // Change the docs in memory
-          try {
     this.updateIndexes(modifications)
-          } catch (err) {
-            return callback(err)
-          }
 
     // Update the datafile
     const updatedDocs = modifications.map(x => x.newDoc)
+    await new Promise((resolve, reject) => {
       this.persistence.persistNewState(updatedDocs, err => {
-            if (err) return callback(err)
-            if (!options.returnUpdatedDocs) {
-              return callback(null, numReplaced)
-            } else {
+        if (err) return reject(err)
+        else resolve()
+      })
+    })
+    if (!options.returnUpdatedDocs) return { numAffected: numReplaced }
+    else {
       let updatedDocsDC = []
       updatedDocs.forEach(doc => { updatedDocsDC.push(model.deepCopy(doc)) })
       if (!multi) updatedDocsDC = updatedDocsDC[0]
-              return callback(null, numReplaced, updatedDocsDC)
+      return { numAffected: numReplaced, affectedDocuments: updatedDocsDC }
     }
-          })
-        })
-      }])
   }
 
   update () {