Fix merging bug in 6.1.0 that resulted in sessions being deleted. (#348)

`deepmerge` is fairly battle tested and handles the many edge cases
when it comes to merging objects deeply in JS.

#346

lib/connect-redis.js

@@ -4,12 +4,15 @@
  * MIT Licensed
  */
 
+const deepmerge = require("deepmerge")
+
 module.exports = function (session) {
   const Store = session.Store
 
   // All callbacks should have a noop if none provided for compatibility
   // with the most Redis clients.
   const noop = () => {}
+  const TOMBSTONE = "TOMBSTONE"
 
   class RedisStore extends Store {
     constructor(options = {}) {
@@ -27,12 +30,13 @@ module.exports = function (session) {
       this.disableTouch = options.disableTouch || false
     }
 
-    get(sid, cb = noop) {
+    get(sid, cb = noop, showTombs = false) {
       let key = this.prefix + sid
 
       this.client.get(key, (err, data) => {
         if (err) return cb(err)
         if (!data) return cb()
+        if (data === TOMBSTONE) return cb(null, showTombs ? data : undefined)
 
         let result
         try {
@@ -45,28 +49,40 @@ module.exports = function (session) {
     }
 
     set(sid, sess, cb = noop) {
-      let args = [this.prefix + sid]
-
-      let value
-      try {
-        value = this.serializer.stringify(sess)
-      } catch (er) {
-        return cb(er)
-      }
-      args.push(value)
+      this.get(
+        sid,
+        (err, oldSess) => {
+          if (oldSess === TOMBSTONE) {
+            return cb()
+          } else if (oldSess && oldSess.lastModified !== sess.lastModified) {
+            sess = deepmerge(oldSess, sess)
+          }
+          let args = [this.prefix + sid]
+          let value
+          sess.lastModified = Date.now()
+          try {
+            value = this.serializer.stringify(sess)
+          } catch (er) {
+            return cb(er)
+          }
+          args.push(value)
+          args.push("EX", this._getTTL(sess))
 
-      let ttl = 1
-      if (!this.disableTTL) {
-        ttl = this._getTTL(sess)
-        args.push("EX", ttl)
-      }
+          let ttl = 1
+          if (!this.disableTTL) {
+            ttl = this._getTTL(sess)
+            args.push("EX", ttl)
+          }
 
-      if (ttl > 0) {
-        this.client.set(args, cb)
-      } else {
-        // If the resulting TTL is negative we can delete / destroy the key
-        this.destroy(sid, cb)
-      }
+          if (ttl > 0) {
+            this.client.set(args, cb)
+          } else {
+            // If the resulting TTL is negative we can delete / destroy the key
+            this.destroy(sid, cb)
+          }
+        },
+        true
+      )
     }
 
     touch(sid, sess, cb = noop) {
@@ -81,7 +97,9 @@ module.exports = function (session) {
 
     destroy(sid, cb = noop) {
       let key = this.prefix + sid
-      this.client.del(key, cb)
+      this.client.set([key, TOMBSTONE, "EX", 300], (err) => {
+        cb(err, 1)
+      })
     }
 
     clear(cb = noop) {
@@ -92,9 +110,9 @@ module.exports = function (session) {
     }
 
     length(cb = noop) {
-      this._getAllKeys((err, keys) => {
+      this.all((err, result) => {
         if (err) return cb(err)
-        return cb(null, keys.length)
+        return cb(null, result.length)
       })
     }
 
@@ -121,7 +139,7 @@ module.exports = function (session) {
           let result
           try {
             result = sessions.reduce((accum, data, index) => {
-              if (!data) return accum
+              if (!data || data === TOMBSTONE) return accum
               data = this.serializer.parse(data)
               data.id = keys[index].substr(prefixLen)
               accum.push(data)

package.json

@@ -18,6 +18,7 @@
     "eslint-config-prettier": "^8.3.0",
     "express-session": "^1.17.0",
     "ioredis": "^4.17.1",
+    "mockdate": "^3.0.5",
     "nyc": "^15.0.1",
     "prettier": "^2.0.5",
     "redis-mock": "^0.56.3",
@@ -36,6 +37,9 @@
     "fmt": "prettier --write .",
     "fmt-check": "prettier --check ."
   },
+  "dependencies": {
+    "deepmerge": "^4.2.2"
+  },
   "keywords": [
     "connect",
     "redis",

test/connect-redis-test.js

@@ -5,8 +5,10 @@ const redisV3 = require("redis-v3")
 const redisV4 = require("redis-v4")
 const ioRedis = require("ioredis")
 const redisMock = require("redis-mock")
+const MockDate = require("mockdate")
 
 let RedisStore = require("../")(session)
+MockDate.set("2000-11-22")
 
 let p =
   (ctx, method) =>
@@ -70,11 +72,34 @@ test("redis-mock client", async (t) => {
 test("teardown", redisSrv.disconnect)
 
 async function lifecycleTest(store, t) {
-  let res = await p(store, "set")("123", { foo: "bar" })
+  await p(store, "set")("123", { foo: "bar3" })
+  let res = await p(store, "get")("123")
+  t.same(res, { foo: "bar3", lastModified: 974851200000 }, "get value 1")
+  await p(store, "set")("123", {
+    foo: "bar3",
+    luke: "skywalker",
+    obi: "wan",
+    lastModified: 974851000000,
+  })
+  await p(store, "set")("123", {
+    luke: "skywalker",
+    lastModified: 974851000000,
+  })
+  res = await p(store, "get")("123")
+  t.same(
+    res,
+    { foo: "bar3", luke: "skywalker", obi: "wan", lastModified: 974851200000 },
+    "get merged value"
+  )
+
+  res = await p(store, "clear")()
+  t.ok(res >= 1, "cleared key")
+
+  res = await p(store, "set")("123", { foo: "bar" })
   t.equal(res, "OK", "set value")
 
   res = await p(store, "get")("123")
-  t.same(res, { foo: "bar" }, "get value")
+  t.same(res, { foo: "bar", lastModified: 974851200000 }, "get value")
 
   res = await p(store.client, "ttl")("sess:123")
   t.ok(res >= 86399, "check one day ttl")
@@ -108,20 +133,29 @@ async function lifecycleTest(store, t) {
   t.same(
     res,
     [
-      { id: "123", foo: "bar" },
-      { id: "456", cookie: { expires } },
+      { id: "123", foo: "bar", lastModified: 974851200000 },
+      { id: "456", cookie: { expires }, lastModified: 974851200000 },
     ],
     "stored two keys data"
   )
 
   res = await p(store, "destroy")("456")
   t.equal(res, 1, "destroyed one")
 
+  res = await p(store, "get")("456")
+  t.equal(res, undefined, "tombstoned one")
+
+  res = await p(store, "set")("456", { a: "new hope" })
+  t.equal(res, undefined, "tombstoned set")
+
+  res = await p(store, "get")("456")
+  t.equal(res, undefined, "tombstoned two")
+
   res = await p(store, "length")()
   t.equal(res, 1, "one key remains")
 
   res = await p(store, "clear")()
-  t.equal(res, 1, "cleared remaining key")
+  t.equal(res, 2, "cleared remaining key")
 
   res = await p(store, "length")()
   t.equal(res, 0, "no key remains")