feat: add cancellation function

lib/shameimaru.js

@@ -1,5 +1,6 @@
 "use strict";
 
+const { CancellationError } = require("bluebird");
 const fs = require("fs");
 const path = require("path");
 
@@ -11,14 +12,32 @@ class Shameimaru {
         this.projDir = projDir;
         this.nodeModuleDir = path.resolve(process.cwd(), projDir, "node_modules");
         this.package = JSON.parse(fs.readFileSync(path.join(projDir, "package.json"), "utf8"));
+        this.traversePromise = null;
     }
 
     async traverse() {
-        const ret = await traverse(
+        this.traversePromise = traverse(
             utils.extraDependenciesFromPackage(this.package),
             this.nodeModuleDir);
+
+        const ret = await new Promise((resolve, reject) => {
+            this.traversePromise.then(resolve, reject).finally(() => {
+                // onFulfilled & onFailure won't be called if the promise was cancelled, so we need to handle cancellation mannually
+                if (this.traversePromise.isCancelled()) {
+                    reject(new CancellationError());
+                }
+            });
+        });
         return ret;
     }
+
+    cancel() {
+        if (!this.traversePromise) {
+            return;
+        }
+
+        this.traversePromise.cancel();
+    }
 }
 
 module.exports = Shameimaru;

lib/traverse.js

@@ -6,6 +6,9 @@ const fs = require("mz/fs");
 const Linklist = require("algorithmjs").ds.Linklist;
 const npa = require("npm-package-arg");
 const uuid = require("uuid/v4");
+const Bluebird = require("bluebird");
+
+Bluebird.config({ cancellation: true });
 
 const utils = require("./utils");
 
@@ -192,7 +195,7 @@ async function scanDir(q, node, ancestors, refs) {
     }
 }
 
-async function traverse(rootDependencies, rootDir) {
+function traverse(rootDependencies, rootDir) {
     const q = new Linklist();
     const rootTree = {};
     const ancestors = {};
@@ -205,12 +208,25 @@ async function traverse(rootDependencies, rootDir) {
         dummyFolder: "/"
     });
 
-    while(q.length) {
+    let isCanceled = false;
+    const run = async () => {
+        // when cancelled or the queue is empty, stop and return
+        if (isCanceled || !q.length) {
+            return rootTree;
+        }
+
         const node = q.popFront();
         await scanDir(q, node, ancestors, refs);
+        return run();
     }
 
-    return rootTree;
+    return new Bluebird((resolve, reject, onCancel) => {
+        onCancel(() => {
+            isCanceled = true;
+        });
+
+        run().then(resolve, reject);
+    }) ;
 }
 
 module.exports = traverse;

package.json

@@ -4,6 +4,7 @@
   "description": "Shameimaru Aya likes to traverse node_modules and capture the tree",
   "dependencies": {
     "algorithmjs": "^1.0.0",
+    "bluebird": "^3.7.2",
     "mz": "^2.7.0",
     "npm-package-arg": "^6.1.0",
     "uuid": "^3.2.1"

test/app1.test.js

@@ -2,6 +2,7 @@
 
 require("should");
 
+const { CancellationError } = require("bluebird");
 const Shameimaru = require("../");
 const utils = require("./utils");
 
@@ -20,6 +21,17 @@ describe("app1.test.js", () => {
 
             // require("fs").writeFileSync("./test/fixtures/apps/app1/target.npm.json", JSON.stringify(tree, 0, 2));
         });
+
+        it("#traverse canncel", async function() {
+            const shameimaru = new Shameimaru("./test/fixtures/apps/app1");
+            console.time("app1#npm");
+            const promise = shameimaru.traverse();
+            setTimeout(() => {
+                shameimaru.cancel();
+            }, 0);
+            console.timeEnd("app1#npm");
+            promise.should.rejectedWith(CancellationError);
+        })
     });
 
     describe("cnpm 6", () => {