Add destruction function to sub manager middleware

package.json

@@ -1,6 +1,6 @@
 {
   "name": "eth-json-rpc-filters",
-  "version": "4.1.0",
+  "version": "4.1.1",
   "description": "[json-rpc-engine](https://github.com/kumavis/json-rpc-engine) middleware implementing ethereum filter methods. Backed by an [eth-block-tracker](https://github.com/MetaMask/eth-block-tracker) and web3 provider interface (`web3.currentProvider`).",
   "main": "index.js",
   "scripts": {

subscriptionManager.js

@@ -13,15 +13,24 @@ function createSubscriptionMiddleware({ blockTracker, provider }) {
   const subscriptions = {}
   const filterManager = createFilterMiddleware({ blockTracker, provider })
 
+  // internal flag
+  let isDestroyed = false
+
   // create subscriptionManager api object
   const events = new SafeEventEmitter()
   const middleware = createScaffoldMiddleware({
     eth_subscribe: createAsyncMiddleware(subscribe),
     eth_unsubscribe: createAsyncMiddleware(unsubscribe),
   })
+  middleware.destroy = destroy
   return { events, middleware }
 
   async function subscribe(req, res) {
+
+    if (isDestroyed) throw new Error(
+      'SubscriptionManager - attempting to use after destroying'
+    )
+
     const subscriptionType = req.params[0]
     // subId is 16 byte hex string
     const subId = unsafeRandomBytes(16)
@@ -81,6 +90,11 @@ function createSubscriptionMiddleware({ blockTracker, provider }) {
   }
 
   async function unsubscribe(req, res) {
+
+    if (isDestroyed) throw new Error(
+      'SubscriptionManager - attempting to use after destroying'
+    )
+
     const id = req.params[0]
     const subscription = subscriptions[id]
     // if missing, return "false" to indicate it was not removed
@@ -105,6 +119,14 @@ function createSubscriptionMiddleware({ blockTracker, provider }) {
     })
   }
 
+  function destroy () {
+    events.removeAllListeners()
+    for (const id in subscriptions) {
+      subscriptions[id].destroy()
+      delete subscriptions[id]
+    }
+    isDestroyed = true
+  }
 }
 
 function normalizeBlock(block) {

test/ganache.js

@@ -1,13 +1,7 @@
 const test = require('tape')
-const clone = require('deep-clone')
-const JsonRpcEngine = require('json-rpc-engine')
-const asMiddleware = require('json-rpc-engine/src/asMiddleware')
-const createScaffoldMiddleware = require('eth-json-rpc-middleware/scaffold')
-const providerFromEngine = require('eth-json-rpc-middleware/providerFromEngine')
 const ethUtil = require('ethereumjs-util')
 const {
   createTestSetup,
-  createPayload,
   asyncTest,
   deployLogEchoContract,
 } = require('./util')

tx-filter.js

@@ -5,13 +5,13 @@ const { incrementHexInt } = require('./hexUtils')
 
 class TxFilter extends BaseFilter {
 
-  constructor ({ provider, params }) {
+  constructor ({ provider }) {
     super()
     this.type = 'tx'
     this.provider = provider
   }
 
-  async update ({ oldBlock, newBlock }) {
+  async update ({ oldBlock }) {
     const toBlock = oldBlock
     const fromBlock = incrementHexInt(oldBlock)
     const blocks = await getBlocksForRange({ provider: this.provider, fromBlock, toBlock })