Merge pull request #481 from highcharts/health/moving-average-indicat…

…or-last-30-mins

health/moving-average-indicator

lib/chart.js

@@ -16,7 +16,7 @@ import { readFileSync, writeFileSync } from 'fs';
 
 import { getOptions, initExportSettings } from './config.js';
 import { log, logWithStack } from './logger.js';
-import { killPool, postWork } from './pool.js';
+import { killPool, postWork, stats } from './pool.js';
 import {
   fixType,
   handleResources,
@@ -59,7 +59,13 @@ export const startExport = async (settings, endCallback) => {
   if (options.payload?.svg && options.payload.svg !== '') {
     try {
       log(4, '[chart] Attempting to export from a SVG input.');
-      return exportAsString(options.payload.svg.trim(), options, endCallback);
+      const result = exportAsString(
+        options.payload.svg.trim(),
+        options,
+        endCallback
+      );
+      ++stats.exportFromSvgAttempts;
+      return result;
     } catch (error) {
       return endCallback(
         new ExportError('[chart] Error loading SVG input.').setError(error)

lib/pool.js

@@ -27,11 +27,16 @@ import { measureTime } from './utils.js';
 
 import ExportError from './errors/ExportError.js';
 
-let performedExports = 0;
-let exportAttempts = 0;
-let timeSpent = 0;
-let droppedExports = 0;
-let spentAverage = 0;
+// Pool statistics
+export const stats = {
+  performedExports: 0,
+  exportAttempts: 0,
+  exportFromSvgAttempts: 0,
+  timeSpent: 0,
+  droppedExports: 0,
+  spentAverage: 0
+};
+
 let poolConfig = {};
 
 // The pool instance
@@ -299,7 +304,7 @@ export const postWork = async (chart, options) => {
   try {
     log(4, '[pool] Work received, starting to process.');
 
-    ++exportAttempts;
+    ++stats.exportAttempts;
     if (poolConfig.benchmarking) {
       getPoolInfo();
     }
@@ -377,8 +382,8 @@ export const postWork = async (chart, options) => {
     // in turn is used by the /health route.
     const workEnd = new Date().getTime();
     const exportTime = workEnd - workStart;
-    timeSpent += exportTime;
-    spentAverage = timeSpent / ++performedExports;
+    stats.timeSpent += exportTime;
+    stats.spentAverage = stats.timeSpent / ++stats.performedExports;
 
     log(4, `[pool] Work completed in ${exportTime} ms.`);
 
@@ -388,7 +393,7 @@ export const postWork = async (chart, options) => {
       options
     };
   } catch (error) {
-    ++droppedExports;
+    ++stats.droppedExports;
 
     if (workerHandle) {
       pool.release(workerHandle);
@@ -455,8 +460,5 @@ export default {
   getPool,
   getPoolInfo,
   getPoolInfoJSON,
-  workAttempts: () => exportAttempts,
-  droppedWork: () => droppedExports,
-  averageTime: () => spentAverage,
-  processedWorkCount: () => performedExports
+  getStats: () => stats
 };

lib/server/routes/health.js

@@ -14,6 +14,7 @@ See LICENSE file in root for details.
 
 import { readFileSync } from 'fs';
 import { join as pather } from 'path';
+import { log } from '../../logger.js';
 
 import cache from '../../cache.js';
 import pool from '../../pool.js';
@@ -23,28 +24,71 @@ const pkgFile = JSON.parse(readFileSync(pather(__dirname, 'package.json')));
 
 const serverStartTime = new Date();
 
+const successRates = [];
+const recordInterval = 60 * 1000; // record every minute
+const windowSize = 30; // 30 minutes
+
+function recordSuccessRate() {
+  const stats = pool.getStats();
+  const successRatio =
+    stats.exportAttempts === 0
+      ? 1
+      : (stats.performedExports / stats.exportAttempts) * 100;
+
+  successRates.push(successRatio);
+  if (successRates.length > windowSize) {
+    successRates.shift();
+  }
+}
+
+function calculateMovingAverage() {
+  const sum = successRates.reduce((a, b) => a + b, 0);
+  return sum / successRates.length;
+}
+
+setInterval(recordSuccessRate, recordInterval);
+
 /**
- * Adds the GET /health route, which outputs basic stats for the server.
+ * Adds the /health and /success-moving-average routes
+ * which output basic stats for the server.
  */
-export default (app) =>
-  !app
-    ? false
-    : app.get('/health', (request, response) => {
-        response.send({
-          status: 'OK',
-          bootTime: serverStartTime,
-          uptime:
-            Math.floor(
-              (new Date().getTime() - serverStartTime.getTime()) / 1000 / 60
-            ) + ' minutes',
-          version: pkgFile.version,
-          highchartsVersion: cache.version(),
-          averageProcessingTime: pool.averageTime(),
-          performedExports: pool.processedWorkCount(),
-          failedExports: pool.droppedWork(),
-          exportAttempts: pool.workAttempts(),
-          sucessRatio: (pool.processedWorkCount() / pool.workAttempts()) * 100,
-          // eslint-disable-next-line import/no-named-as-default-member
-          pool: pool.getPoolInfoJSON()
-        });
-      });
+export default function addHealthRoutes(app) {
+  if (!app) {
+    return false;
+  }
+
+  app.get('/health', (_, res) => {
+    const stats = pool.getStats();
+    const period = successRates.length;
+    const movingAverage = calculateMovingAverage();
+
+    log(4, '[health.js] GET /health [200] - returning server health.');
+
+    res.send({
+      status: 'OK',
+      bootTime: serverStartTime,
+      uptime:
+        Math.floor(
+          (new Date().getTime() - serverStartTime.getTime()) / 1000 / 60
+        ) + ' minutes',
+      version: pkgFile.version,
+      highchartsVersion: cache.version(),
+      averageProcessingTime: stats.spentAverage,
+      performedExports: stats.performedExports,
+      failedExports: stats.droppedExports,
+      exportAttempts: stats.exportAttempts,
+      sucessRatio: (stats.performedExports / stats.exportAttempts) * 100,
+      // eslint-disable-next-line import/no-named-as-default-member
+      pool: pool.getPoolInfoJSON(),
+
+      // Moving average
+      period,
+      movingAverage,
+      message: `Last ${period} minutes had a success rate of ${movingAverage.toFixed(2)}%.`,
+
+      // SVG/JSON attempts
+      svgExportAttempts: stats.exportFromSvgAttempts,
+      jsonExportAttempts: stats.performedExports - stats.exportFromSvgAttempts
+    });
+  });
+}