Cache intermediate NJK template compiles

src/Eleventy.js

@@ -18,6 +18,7 @@ const deleteRequireCache = require("./Util/DeleteRequireCache");
 const config = require("./Config");
 const bench = require("./BenchmarkManager");
 const debug = require("debug")("Eleventy");
+const eventBus = require("./EventBus");
 
 /**
  * @module 11ty/eleventy/Eleventy
@@ -449,7 +450,7 @@ Arguments:
    * @param {String} changedFilePath - File that triggered a re-run (added or modified)
    */
   async _addFileToWatchQueue(changedFilePath) {
-    TemplateContent.deleteCached(changedFilePath);
+    eventBus.emit("resourceModified", changedFilePath);
     this.watchManager.addToPendingQueue(changedFilePath);
   }
 

src/Engines/Nunjucks.js

@@ -3,9 +3,10 @@ const TemplateEngine = require("./TemplateEngine");
 const TemplatePath = require("../TemplatePath");
 const EleventyErrorUtil = require("../EleventyErrorUtil");
 const EleventyBaseError = require("../EleventyBaseError");
+const eventBus = require("../EventBus");
 
 /*
- * This IFFE applies a monkey-patch to Nunjucks internals to cache
+ * The IFFE below apply a monkey-patch to Nunjucks internals to cache
  * compiled templates and re-use them where possible.
  */
 (function () {
@@ -24,6 +25,17 @@ const EleventyBaseError = require("../EleventyBaseError");
     ].join(" :: ");
   };
 
+  let evictByPath = (path) => {
+    let keys = templateCache.keys();
+    // Likely to be slow; do we care?
+    for (let k of keys) {
+      if (k.indexOf(path) >= 0) {
+        templateCache.delete(k);
+      }
+    }
+  };
+  eventBus.on("resourceModified", evictByPath);
+
   let _compile = NunjucksLib.Template.prototype._compile;
   NunjucksLib.Template.prototype._compile = function _wrap_compile(...args) {
     if (!this.compiled && !this.tmplProps && templateCache.has(getKey(this))) {
@@ -109,16 +121,17 @@ class Nunjucks extends TemplateEngine {
   }
 
   setLibrary(env) {
-    this.njkEnv =
-      env ||
-      new NunjucksLib.Environment(
-        new NunjucksLib.FileSystemLoader(
-          [super.getIncludesDir(), TemplatePath.getWorkingDir()],
-          {
-            noCache: true,
-          }
-        )
-      );
+    let fsLoader = new NunjucksLib.FileSystemLoader([
+      super.getIncludesDir(),
+      TemplatePath.getWorkingDir(),
+    ]);
+    this.njkEnv = env || new NunjucksLib.Environment(fsLoader);
+    // Correct, but overbroad. Better would be to evict more granularly, but
+    // resolution from paths isn't straightforward.
+    eventBus.on("resourceModified", (path) => {
+      this.njkEnv.invalidateCache();
+    });
+
     this.setEngineLib(this.njkEnv);
 
     this.addFilters(this.config.nunjucksFilters);

src/EventBus.js

@@ -0,0 +1,17 @@
+const EventEmitter = require("./Util/AsyncEventEmitter");
+const debug = require("debug")("Eleventy:EventBus");
+
+/**
+ * @module 11ty/eleventy/EventBus
+ */
+
+debug("Setting up global EventBus.");
+/**
+ * Provides a global event bus that modules deep down in the stack can
+ * subscribe to from a global singleton for decoupled pub/sub.
+ * @type * {module:11ty/eleventy/Util/AsyncEventEmitter~AsyncEventEmitter}
+ */
+let bus = new EventEmitter();
+bus.setMaxListeners(100);
+
+module.exports = bus;

src/TemplateContent.js

@@ -14,6 +14,7 @@ const config = require("./Config");
 const debug = require("debug")("Eleventy:TemplateContent");
 const debugDev = require("debug")("Dev:Eleventy:TemplateContent");
 const bench = require("./BenchmarkManager").get("Aggregate");
+const eventBus = require("./EventBus");
 
 class TemplateContentFrontMatterError extends EleventyBaseError {}
 class TemplateContentCompileError extends EleventyBaseError {}
@@ -277,5 +278,8 @@ class TemplateContent {
 
 TemplateContent._inputCache = new Map();
 TemplateContent._compileEngineCache = new Map();
+eventBus.on("resourceModified", (path) => {
+  TemplateContent.deleteCached(path);
+});
 
 module.exports = TemplateContent;

test/TemplateTest.js

@@ -2049,11 +2049,9 @@ test("Engine Singletons", async (t) => {
 });
 
 test("Make sure layout cache takes new changes during watch (nunjucks)", async (t) => {
-  await fsp.writeFile(
-    "./test/stubs-layout-cache/_includes/include-script-1.js",
-    `alert("hi");`,
-    { encoding: "utf8" }
-  );
+  let filePath = "./test/stubs-layout-cache/_includes/include-script-1.js";
+
+  await fsp.writeFile(filePath, `alert("hi");`, { encoding: "utf8" });
 
   let tmpl = getNewTemplate(
     "./test/stubs-layout-cache/test.njk",
@@ -2065,13 +2063,23 @@ test("Make sure layout cache takes new changes during watch (nunjucks)", async (
 
   t.is((await tmpl.render(data)).trim(), '<script>alert("hi");</script>');
 
-  await fsp.writeFile(
-    "./test/stubs-layout-cache/_includes/include-script-1.js",
-    `alert("bye");`,
-    { encoding: "utf8" }
-  );
+  let eventBus = require("../src/EventBus");
+  let chokidar = require("chokidar");
+  let watcher = chokidar.watch(filePath, { interval: 10, persistent: true });
+  watcher.on("change", (path, stats) => {
+    eventBus.emit("resourceModified", path);
+  });
+
+  await fsp.writeFile(filePath, `alert("bye");`, { encoding: "utf8" });
+
+  // Give Chokidar time to see the change;
+  await new Promise((res, rej) => {
+    setTimeout(res, 200);
+  });
 
   t.is((await tmpl.render(data)).trim(), '<script>alert("bye");</script>');
+
+  await watcher.close();
 });
 
 test("Make sure layout cache takes new changes during watch (liquid)", async (t) => {