[6.7] [intepreter][Canvas] Dedupe server functions in batched requests (#32712) (#32833)

* [intepreter][Canvas] Dedupe server functions in batched requests (#32712)

* [intepreter][Canvas] Dedupe server functions in batched requests

* Add and correct tests

* Update interpreter.test.js

Fix merge error

* Delete batched_fetch.test.js

This file was not present in the branch and is failing.

packages/kbn-interpreter/src/public/batched_fetch.js

@@ -18,6 +18,7 @@
  */
 
 import { FUNCTIONS_URL } from './consts';
+import _ from 'lodash';
 
 /**
  * Create a function which executes an Expression function on the
@@ -51,12 +52,30 @@ export function batchedFetch({ kfetch, serialize, ms = 10 }) {
       timeout = setTimeout(runBatch, ms);
     }
 
-    const id = nextId();
+    const request = {
+      functionName,
+      args,
+      context: serialize(context),
+    };
+
+    // Check to see if this is a duplicate server function.
+    const duplicate = Object.values(batch).find(batchedRequest =>
+      _.isMatch(batchedRequest.request, request)
+    );
+
+    // If it is, just return the promise of the duplicated request.
+    if (duplicate) {
+      return duplicate.future.promise;
+    }
+
+    // If not, create a new promise, id, and add it to the batched collection.
     const future = createFuture();
+    const id = nextId();
+    request.id = id;
 
     batch[id] = {
       future,
-      request: { id, functionName, args, context: serialize(context) },
+      request,
     };
 
     return future.promise;

packages/kbn-interpreter/src/public/interpreter.test.js

@@ -67,7 +67,7 @@ describe('kbn-interpreter/interpreter', () => {
 
     expect(register).toHaveBeenCalledTimes(2);
 
-    const [ hello, world ] = register.mock.calls.map(([fn]) => fn());
+    const [hello, world] = register.mock.calls.map(([fn]) => fn());
 
     expect(hello.name).toEqual('hello');
     expect(typeof hello.fn).toEqual('function');
@@ -85,14 +85,15 @@ describe('kbn-interpreter/interpreter', () => {
       pathname: FUNCTIONS_URL,
       method: 'POST',
       body: JSON.stringify({
-        functions: [{
-          id: 1,
-          functionName: 'hello',
-          args,
-          context,
-        }]
+        functions: [
+          {
+            functionName: 'hello',
+            args,
+            context,
+            id: 1,
+          },
+        ],
       }),
     });
   });
-
 });