Optimize Canvas REST calls via batching (#29847) (#30380)

Optimize the expression interpreter by introducing batching of remote function calls.

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

@@ -0,0 +1,111 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { FUNCTIONS_URL } from './consts';
+
+/**
+ * Create a function which executes an Expression function on the
+ * server as part of a larger batch of executions.
+ */
+export function batchedFetch({ kfetch, serialize, ms = 10 }) {
+  // Uniquely identifies each function call in a batch operation
+  // so that the appropriate promise can be resolved / rejected later.
+  let id = 0;
+
+  // A map like { id: { future, request } }, which is used to
+  // track all of the function calls in a batch operation.
+  let batch = {};
+  let timeout;
+
+  const nextId = () => ++id;
+
+  const reset = () => {
+    id = 0;
+    batch = {};
+    timeout = undefined;
+  };
+
+  const runBatch = () => {
+    processBatch(kfetch, batch);
+    reset();
+  };
+
+  return ({ functionName, context, args }) => {
+    if (!timeout) {
+      timeout = setTimeout(runBatch, ms);
+    }
+
+    const id = nextId();
+    const future = createFuture();
+
+    batch[id] = {
+      future,
+      request: { id, functionName, args, context: serialize(context) },
+    };
+
+    return future.promise;
+  };
+}
+
+/**
+ * An externally resolvable / rejectable promise, used to make sure
+ * individual batch responses go to the correct caller.
+ */
+function createFuture() {
+  let resolve;
+  let reject;
+
+  return {
+    resolve(val) { return resolve(val); },
+    reject(val) { return reject(val); },
+    promise: new Promise((res, rej) => {
+      resolve = res;
+      reject = rej;
+    }),
+  };
+}
+
+/**
+ * Runs the specified batch of functions on the server, then resolves
+ * the related promises.
+ */
+async function processBatch(kfetch, batch) {
+  try {
+    const { results } = await kfetch({
+      pathname: FUNCTIONS_URL,
+      method: 'POST',
+      body: JSON.stringify({
+        functions: Object.values(batch).map(({ request }) => request),
+      }),
+    });
+
+    results.forEach(({ id, result }) => {
+      const { future } = batch[id];
+      if (result.statusCode && result.err) {
+        future.reject(result);
+      } else {
+        future.resolve(result);
+      }
+    });
+  } catch (err) {
+    Object.values(batch).forEach(({ future }) => {
+      future.reject(err);
+    });
+  }
+}

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

@@ -0,0 +1,21 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+// The server endpoint for retrieiving and running Canvas functions.
+export const FUNCTIONS_URL = '/api/canvas/fns';

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

@@ -20,11 +20,14 @@
 import { interpreterProvider } from '../common/interpreter/interpret';
 import { serializeProvider } from '../common/lib/serialize';
 import { createHandlers } from './create_handlers';
-
-export const FUNCTIONS_URL = '/api/canvas/fns';
+import { batchedFetch } from './batched_fetch';
+import { FUNCTIONS_URL } from './consts';
 
 export async function initializeInterpreter(kfetch, typesRegistry, functionsRegistry) {
   const serverFunctionList = await kfetch({ pathname: FUNCTIONS_URL });
+  const types = typesRegistry.toJS();
+  const { serialize } = serializeProvider(types);
+  const batch = batchedFetch({ kfetch, serialize });
 
   // For every sever-side function, register a client-side
   // function that matches its definition, but which simply
@@ -32,20 +35,7 @@ export async function initializeInterpreter(kfetch, typesRegistry, functionsRegi
   Object.keys(serverFunctionList).forEach(functionName => {
     functionsRegistry.register(() => ({
       ...serverFunctionList[functionName],
-      async fn(context, args) {
-        const types = typesRegistry.toJS();
-        const { serialize } = serializeProvider(types);
-        const result = await kfetch({
-          pathname: `${FUNCTIONS_URL}/${functionName}`,
-          method: 'POST',
-          body: JSON.stringify({
-            args,
-            context: serialize(context),
-          }),
-        });
-
-        return result;
-      },
+      fn: (context, args) => batch({ functionName, args, context }),
     }));
   });
 

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

@@ -17,7 +17,8 @@
  * under the License.
  */
 
-import { initializeInterpreter, FUNCTIONS_URL } from './interpreter';
+import { FUNCTIONS_URL } from './consts';
+import { initializeInterpreter } from './interpreter';
 
 jest.mock('../common/interpreter/interpret', () => ({
   interpreterProvider: () => () => ({}),
@@ -42,10 +43,23 @@ describe('kbn-interpreter/interpreter', () => {
   });
 
   it('registers client-side functions that pass through to the server', async () => {
-    const kfetch = jest.fn(async () => ({
-      hello: { name: 'hello' },
-      world: { name: 'world' },
-    }));
+    const kfetch = jest.fn(async ({ method }) => {
+      if (method === 'POST') {
+        return {
+          results: [{
+            id: 1,
+            result: {
+              hello: 'world',
+            },
+          }],
+        };
+      }
+
+      return {
+        hello: { name: 'hello' },
+        world: { name: 'world' },
+      };
+    });
 
     const register = jest.fn();
 
@@ -63,12 +77,21 @@ describe('kbn-interpreter/interpreter', () => {
     const context = {};
     const args = { quote: 'All we have to decide is what to do with the time that is given us.' };
 
-    await hello.fn(context, args);
+    const result = await hello.fn(context, args);
+
+    expect(result).toEqual({ hello: 'world' });
 
     expect(kfetch).toHaveBeenCalledWith({
-      pathname: `${FUNCTIONS_URL}/hello`,
+      pathname: FUNCTIONS_URL,
       method: 'POST',
-      body: JSON.stringify({ args, context }),
+      body: JSON.stringify({
+        functions: [{
+          id: 1,
+          functionName: 'hello',
+          args,
+          context,
+        }]
+      }),
     });
   });
 

src/dev/license_checker/config.js

@@ -74,7 +74,6 @@ export const DEV_ONLY_LICENSE_WHITELIST = [
 
 // Globally overrides a license for a given package@version
 export const LICENSE_OVERRIDES = {
-  'scriptjs@2.5.8': ['MIT'], // license header appended in the dist
   'react-lib-adler32@1.0.1': ['BSD'], // adler32 extracted from react source,
   'cycle@1.0.3': ['CC0-1.0'], // conversion to a public-domain like license
   'jsts@1.1.2': ['Eclipse Distribution License - v 1.0'], //cf. https://github.com/bjornharrtell/jsts

src/legacy/core_plugins/interpreter/server/routes/server_functions.js

@@ -21,31 +21,69 @@ import Boom from 'boom';
 import { serializeProvider } from '@kbn/interpreter/common';
 import { API_ROUTE } from '../../common/constants';
 import { createHandlers } from '../lib/create_handlers';
+import Joi from 'joi';
 
+/**
+ * Register the Canvas function endopints.
+ *
+ * @param {*} server - The Kibana server
+ */
 export function registerServerFunctions(server) {
-  // Execute functions, kind of RPC like.
+  getServerFunctions(server);
+  runServerFunctions(server);
+}
+
+/**
+ * Register the endpoint that executes a batch of functions, and sends the result back as a single response.
+ *
+ * @param {*} server - The Kibana server
+ */
+function runServerFunctions(server) {
   server.route({
     method: 'POST',
-    path: `${API_ROUTE}/fns/{functionName}`,
+    path: `${API_ROUTE}/fns`,
+    options: {
+      validate: {
+        payload: Joi.object({
+          functions: Joi.array().items(
+            Joi.object()
+              .keys({
+                id: Joi.number().required(),
+                functionName: Joi.string().required(),
+                args: Joi.object().default({}),
+                context: Joi.object().default({}),
+              }),
+          ).required(),
+        }).required(),
+      },
+    },
     async handler(req) {
-      const types = server.plugins.interpreter.types.toJS();
-      const { deserialize } = serializeProvider(types);
-      const { functionName } = req.params;
-      const { args, context } = req.payload;
-      const fnDef = server.plugins.interpreter.serverFunctions.toJS()[functionName];
-
-      if (!fnDef) {
-        throw Boom.notFound(`Function "${functionName}" could not be found.`);
-      }
-
       const handlers = await createHandlers(req, server);
-      const result = await fnDef.fn(deserialize(context), args, handlers);
+      const { functions } = req.payload;
 
-      return result;
+      // Process each function individually, and bundle up respones / errors into
+      // the format expected by the front-end batcher.
+      const results = await Promise.all(functions.map(async ({ id, ...fnCall }) => {
+        const result = await runFunction(server, handlers, fnCall)
+          .catch(err => {
+            if (Boom.isBoom(err)) {
+              return { err, statusCode: err.statusCode, message: err.output.payload };
+            }
+            return {  err: 'Internal Server Error', statusCode: 500, message: 'See server logs for details.' };
+          });
+        return { id, result };
+      }));
+
+      return { results };
     },
   });
+}
 
-  // Give the client the list of server-functions.
+/**
+ * Register the endpoint that returns the list of server-only functions.
+ * @param {*} server - The Kibana server
+ */
+function getServerFunctions(server) {
   server.route({
     method: 'GET',
     path: `${API_ROUTE}/fns`,
@@ -54,3 +92,23 @@ export function registerServerFunctions(server) {
     },
   });
 }
+
+/**
+ * Run a single Canvas function.
+ *
+ * @param {*} server - The Kibana server object
+ * @param {*} handlers - The Canvas handlers
+ * @param {*} fnCall - Describes the function being run `{ functionName, args, context }`
+ */
+async function runFunction(server, handlers, fnCall) {
+  const { functionName, args, context } = fnCall;
+  const types = server.plugins.interpreter.types.toJS();
+  const { deserialize } = serializeProvider(types);
+  const fnDef = server.plugins.interpreter.serverFunctions.toJS()[functionName];
+
+  if (!fnDef) {
+    throw Boom.notFound(`Function "${functionName}" could not be found.`);
+  }
+
+  return fnDef.fn(deserialize(context), args, handlers);
+}