neo4j
diff --git a/‎packages/bolt-connection/src/connection-provider/connection-provider-routing.js
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+12-13Lines changed: 12 additions & 13 deletions b/‎packages/bolt-connection/src/connection-provider/connection-provider-routing.js
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+12-13Lines changed: 12 additions & 13 deletions
diff --git a/‎packages/bolt-connection/src/lang/functional.js
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+28Lines changed: 28 additions & 0 deletions b/‎packages/bolt-connection/src/lang/functional.js
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+28Lines changed: 28 additions & 0 deletions
diff --git a/‎packages/bolt-connection/test/lang/functional.test.js
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+170Lines changed: 170 additions & 0 deletions b/‎packages/bolt-connection/test/lang/functional.test.js
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+170Lines changed: 170 additions & 0 deletions
@@ -28,6 +28,7 @@ import {
   ConnectionErrorHandler,
   DelegateConnection
 } from '../connection'
+import { functional } from '../lang'
 
 const { SERVICE_UNAVAILABLE, SESSION_EXPIRED } = error
 const {
@@ -97,6 +98,8 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
         ? int(routingTablePurgeDelay)
         : DEFAULT_ROUTING_TABLE_PURGE_DELAY
     )
+
+    this._refreshRoutingTable = functional.reuseOngoingRequest(this._refreshRoutingTable, this)
   }
 
   _createConnectionErrorHandler () {
@@ -357,10 +360,14 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     this._log.info(
       `Routing table is stale for database: "${database}" and access mode: "${accessMode}": ${currentRoutingTable}`
     )
-    return this._refreshRoutingTable(currentRoutingTable, bookmarks, impersonatedUser, onDatabaseNameResolved, auth)
+    return this._refreshRoutingTable(currentRoutingTable, bookmarks, impersonatedUser, auth)
+      .then(newRoutingTable => {
+        onDatabaseNameResolved(newRoutingTable.database)
+        return newRoutingTable
+      })
   }
 
-  _refreshRoutingTable (currentRoutingTable, bookmarks, impersonatedUser, onDatabaseNameResolved, auth) {
+  _refreshRoutingTable (currentRoutingTable, bookmarks, impersonatedUser, auth) {
     const knownRouters = currentRoutingTable.routers
 
     if (this._useSeedRouter) {
@@ -369,7 +376,6 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
         currentRoutingTable,
         bookmarks,
         impersonatedUser,
-        onDatabaseNameResolved,
         auth
       )
     }
@@ -378,7 +384,6 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
       currentRoutingTable,
       bookmarks,
       impersonatedUser,
-      onDatabaseNameResolved,
       auth
     )
   }
@@ -388,7 +393,6 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     currentRoutingTable,
     bookmarks,
     impersonatedUser,
-    onDatabaseNameResolved,
     auth
   ) {
     // we start with seed router, no routers were probed before
@@ -420,7 +424,6 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     return await this._applyRoutingTableIfPossible(
       currentRoutingTable,
       newRoutingTable,
-      onDatabaseNameResolved,
       error
     )
   }
@@ -430,7 +433,6 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     currentRoutingTable,
     bookmarks,
     impersonatedUser,
-    onDatabaseNameResolved,
     auth
   ) {
     let [newRoutingTable, error] = await this._fetchRoutingTableUsingKnownRouters(
@@ -456,7 +458,6 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     return await this._applyRoutingTableIfPossible(
       currentRoutingTable,
       newRoutingTable,
-      onDatabaseNameResolved,
       error
     )
   }
@@ -630,7 +631,7 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
     return [null, error]
   }
 
-  async _applyRoutingTableIfPossible (currentRoutingTable, newRoutingTable, onDatabaseNameResolved, error) {
+  async _applyRoutingTableIfPossible (currentRoutingTable, newRoutingTable, error) {
     if (!newRoutingTable) {
       // none of routing servers returned valid routing table, throw exception
       throw newError(
@@ -646,21 +647,19 @@ export default class RoutingConnectionProvider extends PooledConnectionProvider
       this._useSeedRouter = true
     }
 
-    await this._updateRoutingTable(newRoutingTable, onDatabaseNameResolved)
+    await this._updateRoutingTable(newRoutingTable)
 
     return newRoutingTable
   }
 
-  async _updateRoutingTable (newRoutingTable, onDatabaseNameResolved) {
+  async _updateRoutingTable (newRoutingTable) {
     // close old connections to servers not present in the new routing table
     await this._connectionPool.keepAll(newRoutingTable.allServers())
     this._routingTableRegistry.removeExpired()
     this._routingTableRegistry.register(
       newRoutingTable
     )
 
-    onDatabaseNameResolved(newRoutingTable.database)
-
     this._log.info(`Updated routing table ${newRoutingTable}`)
   }
 
 
@@ -17,6 +17,8 @@
  * limitations under the License.
  */
 
+import { json } from 'neo4j-driver-core'
+
 /**
  * Identity function.
  *
@@ -28,3 +30,29 @@
 export function identity (x) {
   return x
 }
+
+/**
+ * Makes the function able to share ongoing requests
+ *
+ * @param {function(...args): Promise} func The function to be decorated
+ * @param {any} thisArg The `this` which should be used in the function call
+ * @return {function(...args): Promise} The decorated function
+ */
+export function reuseOngoingRequest (func, thisArg = null) {
+  const ongoingRequests = new Map()
+
+  return function (...args) {
+    const key = json.stringify(args)
+    if (ongoingRequests.has(key)) {
+      return ongoingRequests.get(key)
+    }
+
+    const promise = func.apply(thisArg, args)
+
+    ongoingRequests.set(key, promise)
+
+    return promise.finally(() => {
+      ongoingRequests.delete(key)
+    })
+  }
+}
@@ -0,0 +1,170 @@
+import { reuseOngoingRequest } from '../../src/lang/functional.js'
+
+describe('functional', () => {
+  describe('reuseOnGoingRequest', () => {
+    it('should call supplied function with the params', async () => {
+      const expectedParams = ['a', 1, { a: 'a' }]
+      const func = jest.fn(() => Promise.resolve())
+
+      const decoratedFunction = reuseOngoingRequest(func)
+      await decoratedFunction(...expectedParams)
+
+      expect(func).toHaveBeenCalledWith(...expectedParams)
+    })
+
+    it('should call supplied function with this', async () => {
+      const expectedParams = ['a', 1, { a: 'a' }]
+      const thisArg = { t: 'his' }
+      const func = jest.fn(async function () {
+        return this
+      })
+
+      const decoratedFunction = reuseOngoingRequest(func, thisArg)
+      const receivedThis = await decoratedFunction(...expectedParams)
+
+      expect(receivedThis).toBe(thisArg)
+    })
+
+    it('should return values returned by the supplied function', async () => {
+      const expectedResult = { a: 'abc' }
+      const func = jest.fn(() => Promise.resolve(expectedResult))
+
+      const decoratedFunction = reuseOngoingRequest(func)
+      const result = await decoratedFunction()
+
+      expect(result).toBe(expectedResult)
+    })
+
+    it('should throw value thrown by supplied function', async () => {
+      const error = new Error('Oops, I did it again!')
+      const func = jest.fn(() => Promise.reject(error))
+
+      const decoratedFunction = reuseOngoingRequest(func)
+      const promise = decoratedFunction()
+      expect(promise).rejects.toThrow(error)
+    })
+
+    it('should share ongoing request with same params', async () => {
+      const expectedParams = ['a', 1, [3]]
+      const expectedResult = { a: 'abc' }
+      const { promises, func } = mockPromiseFunction()
+
+      const decoratedFunction = reuseOngoingRequest(func)
+
+      const resultPromises = [
+        decoratedFunction(...expectedParams),
+        decoratedFunction(...expectedParams),
+        decoratedFunction(...expectedParams)
+      ]
+
+      expect(func).toBeCalledTimes(1)
+      expect(promises.length).toBe(1)
+
+      promises[0].resolve(expectedResult) // closing ongoing request
+
+      const results = await Promise.all(resultPromises)
+
+      expect(results).toEqual([expectedResult, expectedResult, expectedResult])
+    })
+
+    it('should not share ongoing request with different params', async () => {
+      const expectedParams1 = ['a', 1, [3]]
+      const expectedResult1 = { a: 'abc' }
+      const expectedParams2 = [4, 'a', []]
+      const expectedResult2 = { k: 'bbk' }
+      const { promises, func } = mockPromiseFunction()
+
+      const decoratedFunction = reuseOngoingRequest(func)
+
+      const resultPromises = [
+        decoratedFunction(...expectedParams1),
+        decoratedFunction(...expectedParams2)
+      ]
+
+      expect(func).toBeCalledTimes(2)
+      expect(func).toBeCalledWith(...expectedParams1)
+      expect(func).toBeCalledWith(...expectedParams2)
+
+      expect(promises.length).toBe(2)
+
+      promises[0].resolve(expectedResult1) // closing ongoing request 1
+      promises[1].resolve(expectedResult2) // closing ongoing request 2
+
+      const results = await Promise.all(resultPromises)
+
+      expect(results).toEqual([expectedResult1, expectedResult2])
+    })
+
+    it('should not share resolved requests with same params', async () => {
+      const expectedParams = ['a', 1, [3]]
+      const expectedResult1 = { a: 'abc' }
+      const expectedResult2 = { k: 'bbk' }
+      const { promises, func } = mockPromiseFunction()
+
+      const decoratedFunction = reuseOngoingRequest(func)
+
+      const resultPromises = [
+        decoratedFunction(...expectedParams)
+      ]
+
+      expect(func).toBeCalledTimes(1)
+      expect(promises.length).toBe(1)
+
+      promises[0].resolve(expectedResult1) // closing ongoing request
+
+      const results = await Promise.all(resultPromises)
+
+      resultPromises.push(decoratedFunction(...expectedParams))
+
+      expect(func).toBeCalledTimes(2)
+      expect(promises.length).toBe(2)
+
+      promises[1].resolve(expectedResult2) // closing ongoing request
+
+      results.push(await resultPromises[1])
+
+      expect(results).toEqual([expectedResult1, expectedResult2])
+    })
+
+    it('should not share rejected requests with same params', async () => {
+      const expectedParams = ['a', 1, [3]]
+      const expectedResult1 = new Error('Ops, I did it again!')
+      const expectedResult2 = { k: 'bbk' }
+      const { promises, func } = mockPromiseFunction()
+
+      const decoratedFunction = reuseOngoingRequest(func)
+
+      const resultPromises = [
+        decoratedFunction(...expectedParams)
+      ]
+
+      expect(func).toBeCalledTimes(1)
+      expect(promises.length).toBe(1)
+
+      promises[0].reject(expectedResult1) // closing ongoing request
+
+      const results = await Promise.all(
+        resultPromises.map(promise => promise.catch(error => error))
+      )
+
+      resultPromises.push(decoratedFunction(...expectedParams))
+
+      expect(func).toBeCalledTimes(2)
+      expect(promises.length).toBe(2)
+
+      promises[1].resolve(expectedResult2) // closing ongoing request
+
+      results.push(await resultPromises[1])
+
+      expect(results).toEqual([expectedResult1, expectedResult2])
+    })
+
+    function mockPromiseFunction () {
+      const promises = []
+      const func = jest.fn(() => new Promise((resolve, reject) => {
+        promises.push({ resolve, reject })
+      }))
+      return { promises, func }
+    }
+  })
+})