1 files changed, 116 insertions, 0 deletions
diff --git a/lib/internal/loader/ModuleJob.js b/lib/internal/loader/ModuleJob.js
new file mode 100644
index 00000000000..db4cb6ae5c5
--- /dev/null
+++ b/lib/internal/loader/ModuleJob.js
@@ -0,0 +1,116 @@
+'use strict';
+
+const { SafeSet, SafePromise } = require('internal/safe_globals');
+const resolvedPromise = SafePromise.resolve();
+const resolvedArrayPromise = SafePromise.resolve([]);
+const { ModuleWrap } = require('internal/loader/ModuleWrap');
+
+const NOOP = () => { /* No-op */ };
+class ModuleJob {
+  /**
+   * @param {module: ModuleWrap?, compiled: Promise} moduleProvider
+   */
+  constructor(loader, moduleProvider, url) {
+    this.url = `${moduleProvider.url}`;
+    this.moduleProvider = moduleProvider;
+    this.loader = loader;
+    this.error = null;
+    this.hadError = false;
+
+    if (moduleProvider instanceof ModuleWrap !== true) {
+      // linked == promise for dependency jobs, with module populated,
+      // module wrapper linked
+      this.modulePromise = this.moduleProvider.createModule();
+      this.module = undefined;
+      const linked = async () => {
+        const dependencyJobs = [];
+        this.module = await this.modulePromise;
+        this.module.link(async (dependencySpecifier) => {
+          const dependencyJobPromise =
+            this.loader.getModuleJob(this, dependencySpecifier);
+          dependencyJobs.push(dependencyJobPromise);
+          const dependencyJob = await dependencyJobPromise;
+          return dependencyJob.modulePromise;
+        });
+        return SafePromise.all(dependencyJobs);
+      };
+      this.linked = linked();
+
+      // instantiated == deep dependency jobs wrappers instantiated,
+      //module wrapper instantiated
+      this.instantiated = undefined;
+    } else {
+      const getModuleProvider = async () => moduleProvider;
+      this.modulePromise = getModuleProvider();
+      this.moduleProvider = { finish: NOOP };
+      this.module = moduleProvider;
+      this.linked = resolvedArrayPromise;
+      this.instantiated = this.modulePromise;
+    }
+  }
+
+  instantiate() {
+    if (this.instantiated) {
+      return this.instantiated;
+    }
+    return this.instantiated = new Promise(async (resolve, reject) => {
+      const jobsInGraph = new SafeSet();
+      let jobsReadyToInstantiate = 0;
+      // (this must be sync for counter to work)
+      const queueJob = (moduleJob) => {
+        if (jobsInGraph.has(moduleJob)) {
+          return;
+        }
+        jobsInGraph.add(moduleJob);
+        moduleJob.linked.then((dependencyJobs) => {
+          for (const dependencyJob of dependencyJobs) {
+            queueJob(dependencyJob);
+          }
+          checkComplete();
+        }, (e) => {
+          if (!this.hadError) {
+            this.error = e;
+            this.hadError = true;
+          }
+          checkComplete();
+        });
+      };
+      const checkComplete = () => {
+        if (++jobsReadyToInstantiate === jobsInGraph.size) {
+          // I believe we only throw once the whole tree is finished loading?
+          // or should the error bail early, leaving entire tree to still load?
+          if (this.hadError) {
+            reject(this.error);
+          } else {
+            try {
+              this.module.instantiate();
+              for (const dependencyJob of jobsInGraph) {
+                dependencyJob.instantiated = resolvedPromise;
+              }
+              resolve(this.module);
+            } catch (e) {
+              e.stack;
+              reject(e);
+            }
+          }
+        }
+      };
+      queueJob(this);
+    });
+  }
+
+  async run() {
+    const module = await this.instantiate();
+    try {
+      module.evaluate();
+    } catch (e) {
+      e.stack;
+      this.hadError = true;
+      this.error = e;
+      throw e;
+    }
+    return module;
+  }
+}
+Object.setPrototypeOf(ModuleJob.prototype, null);
+module.exports = ModuleJob;