IO-3051 canvas-handler optimization

Signed-off-by: Allan Carr <allan.carr@thinkimex.com>

server/middleware/validateCanvasRequestMiddleware.js

@@ -0,0 +1,20 @@
+const { isObject } = require("lodash");
+
+const validateCanvasRequestMiddleware = (req, res, next) => {
+  const { w, h, values, keys, override } = req.body;
+  if (!values || !keys) {
+    return res.status(400).send("Missing required data");
+  }
+  if (override && !isObject(override)) {
+    return res.status(400).send("Override must be an object");
+  }
+  if (w && (!Number.isFinite(w) || w <= 0)) {
+    return res.status(400).send("Width must be a positive number");
+  }
+  if (h && (!Number.isFinite(h) || h <= 0)) {
+    return res.status(400).send("Height must be a positive number");
+  }
+  next();
+};
+
+module.exports = validateCanvasRequestMiddleware;

server/render/canvas-handler.js

@@ -5,89 +5,120 @@ const logger = require("../utils/logger");
 const { backgroundColors, borderColors } = require("./canvas-colors");
 const { isObject, defaultsDeep, isNumber } = require("lodash");
 
+let isProcessing = false;
+const requestQueue = [];
+
+const processCanvasRequest = async (req, res) => {
+  try {
+    const { w, h, values, keys, override } = req.body;
+    logger.log("inbound-canvas-creation", "debug", "jsr", null, { w, h, values, keys, override });
+
+    // Set dimensions with defaults
+    const width = isNumber(w) ? w : 500;
+    const height = isNumber(h) ? h : 275;
+
+    const configuration = {
+      type: "doughnut",
+      data: {
+        labels: keys,
+        datasets: [
+          {
+            data: values,
+            backgroundColor: backgroundColors,
+            borderColor: borderColors,
+            borderWidth: 1
+          }
+        ]
+      },
+      options: {
+        animation: false,
+        devicePixelRatio: 4,
+        responsive: false,
+        maintainAspectRatio: true,
+        circumference: 180,
+        rotation: -90,
+        plugins: {
+          legend: {
+            labels: {
+              boxWidth: 20,
+              font: {
+                family: "'Montserrat'",
+                size: 10,
+                style: "normal",
+                weight: "normal"
+              }
+            },
+            position: "left"
+          }
+        }
+      }
+    };
+
+    // If we have a valid override object, merge it with the default configuration object.
+    // This allows for you to override the default configuration with a custom one.
+    const defaults = () => {
+      if (!override || !isObject(override)) {
+        return configuration;
+      }
+      return defaultsDeep(override, configuration);
+    };
+
+    // Generate chart
+    let canvas = createCanvas(width, height);
+    let ctx = canvas.getContext("2d");
+    let chart = new Chart(ctx, defaults());
+    const result = canvas.toDataURL();
+
+    chart.destroy();
+    canvas.width = 0;
+    canvas.height = 0;
+    ctx = null;
+    canvas = null;
+    chart = null;
+
+    res.status(200).send(result);
+  } catch (error) {
+    if (chart) chart.destroy();
+    if (canvas) {
+      canvas.width = 0;
+      canvas.height = 0;
+    }
+    ctx = null;
+    canvas = null;
+    chart = null;
+
+    logger.log("inbound-canvas-creation", "error", "jsr", null, { error: error.message, stack: error.stack });
+    res.status(500).send("Error generating canvas");
+  }
+};
+
+const processNextInQueue = async () => {
+  if (requestQueue.length === 0) {
+    isProcessing = false;
+    return;
+  }
+
+  const { req, res } = requestQueue.shift();
+  await processCanvasRequest(req, res);
+  processNextInQueue();
+};
+
 exports.canvastest = function (req, res) {
-  //console.log("Incoming test request.", req);
   res.status(200).send("OK");
 };
 
-exports.canvas = function (req, res) {
-  const { w, h, values, keys, override } = req.body;
-  //console.log("Incoming Canvas Request:", w, h, values, keys, override);
-  logger.log("inbound-canvas-creation", "debug", "jsr", null, { w, h, values, keys, override });
-  // Gate required values
-  if (!values || !keys) {
-    res.status(400).send("Missing required data");
+exports.canvas = async function (req, res) {
+  if (isProcessing) {
+    if (requestQueue.length >= 100) {
+      // Set a maximum queue size
+      return res.status(503).send("Server is busy. Please try again later.");
+    }
+    requestQueue.push({ req, res });
+    logger.log("inbound-canvas-creation-queue", "debug", "jsr", null, { queue: requestQueue.length });
     return;
   }
 
-  // Override must be an object if it exists
-  if (override && !isObject(override)) {
-    res.status(400).send("Override must be an object");
-    return;
-  }
-
-  // Set the default Width and Height
-  let [width, height] = [500, 275];
-
-  // Allow for custom width and height
-  if (isNumber(w)) {
-    width = w;
-  }
-  if (isNumber(h)) {
-    height = h;
-  }
-
-  const configuration = {
-    type: "doughnut",
-    data: {
-      labels: keys,
-      datasets: [
-        {
-          data: values,
-          backgroundColor: backgroundColors,
-          borderColor: borderColors,
-          borderWidth: 1
-        }
-      ]
-    },
-    options: {
-      devicePixelRatio: 4,
-      responsive: false,
-      maintainAspectRatio: true,
-      circumference: 180,
-      rotation: -90,
-      plugins: {
-        legend: {
-          labels: {
-            boxWidth: 20,
-            font: {
-              family: "'Montserrat'",
-              size: 10,
-              style: "normal",
-              weight: "normal"
-            }
-          },
-          position: "left"
-        }
-      }
-    }
-  };
-
-  // If we have a valid override object, merge it with the default configuration object.
-  // This allows for you to override the default configuration with a custom one.
-  const defaults = () => {
-    if (!override || !isObject(override)) {
-      return configuration;
-    }
-    return defaultsDeep(override, configuration);
-  };
-
-  res.status(200).send(
-    (() => {
-      const canvas = createCanvas(width, height);
-      const ctx = canvas.getContext("2d");
-      new Chart(ctx, defaults());
-      return canvas.toDataURL();
-    })()
-  );
+  isProcessing = true;
+  await processCanvasRequest(req, res);
+  processNextInQueue();
 };

server/routes/renderRoutes.js

@@ -2,10 +2,11 @@ const express = require("express");
 const router = express.Router();
 const { inlinecss } = require("../render/inlinecss");
 const validateFirebaseIdTokenMiddleware = require("../middleware/validateFirebaseIdTokenMiddleware");
+const validateCanvasRequestMiddleware = require("../middleware/validateCanvasRequestMiddleware");
 const { canvas } = require("../render/canvas-handler");
 
 // Define the route for inline CSS rendering
 router.post("/inlinecss", validateFirebaseIdTokenMiddleware, inlinecss);
-router.post("/canvas", validateFirebaseIdTokenMiddleware, canvas);
+router.post("/canvas", [validateFirebaseIdTokenMiddleware, validateCanvasRequestMiddleware], canvas);
 
 module.exports = router;