DeltaPatcher: better support for the new Delta format

Summary: Adds support for the `deleted` key to remove modules from the bundle. Without this, source maps would break after removing a module, since it would still end up in the patched bundle but not in the source map.

Reviewed By: mjesun

Differential Revision: D12874011

fbshipit-source-id: 79239756854cb2c02f14ec8b0bb2b649766393fe

Author: Alexandre Kirszenberg

local-cli/server/util/debugger-ui/DeltaPatcher.js

@@ -63,24 +63,33 @@
 
       // Reset the current bundle when we receive a base bundle.
       if (bundle.base) {
+        this._lastNumModifiedFiles = bundle.modules.length;
+
         this._lastBundle = {
-          revisionId: undefined,
+          revisionId: bundle.revisionId,
           pre: bundle.pre,
           post: bundle.post,
-          modules: new Map(),
+          modules: new Map(bundle.modules),
         };
-      }
+      } else {
+        this._lastNumModifiedFiles =
+          bundle.modules.length + bundle.deleted.length;
 
-      this._lastNumModifiedFiles = bundle.modules.size;
+        this._lastBundle.revisionId = bundle.revisionId;
+
+        for (const [key, value] of bundle.modules) {
+          this._lastBundle.modules.set(key, value);
+        }
+
+        for (const id of bundle.deleted) {
+          this._lastBundle.modules.delete(id);
+        }
+      }
 
       if (this._lastNumModifiedFiles > 0) {
         this._lastModifiedDate = new Date();
       }
 
-      this._patchMap(this._lastBundle.modules, bundle.modules);
-
-      this._lastBundle.revisionId = bundle.revisionId;
-
       return this;
     }
 
@@ -104,21 +113,11 @@
 
     getAllModules() {
       return [].concat(
-        this._lastBundle.pre,
+        [this._lastBundle.pre],
         Array.from(this._lastBundle.modules.values()),
-        this._lastBundle.post,
+        [this._lastBundle.post],
       );
     }
-
-    _patchMap(original, patch) {
-      for (const [key, value] of patch.entries()) {
-        if (value == null) {
-          original.delete(key);
-        } else {
-          original.set(key, value);
-        }
-      }
-    }
   }
 
   DeltaPatcher._deltaPatchers = new Map();

local-cli/server/util/debugger-ui/__tests__/DeltaPatcher-test.js

@@ -0,0 +1,111 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @emails oncall+javascript_foundation
+ */
+
+'use strict';
+
+describe('DeltaPatcher', () => {
+  const window = (global.window = {});
+  require('../DeltaPatcher');
+
+  it('should initialize to an empty bundle', () => {
+    global.Date = jest.fn();
+    const dp = new window.DeltaPatcher();
+    expect(dp.getLastRevisionId()).toBe(undefined);
+    expect(dp.getLastModifiedDate()).toBe(global.Date.mock.instances[0]);
+    expect(dp.getLastNumModifiedFiles()).toBe(0);
+    // Empty pre and post.
+    expect(dp.getAllModules()).toEqual(['', '']);
+  });
+
+  it('should expect a base bundle at initialization', () => {
+    const dp = new window.DeltaPatcher();
+    expect(() => {
+      dp.applyDelta({
+        base: false,
+        revisionId: 'hello',
+        modules: [],
+        deleted: [],
+      });
+    }).toThrow();
+  });
+
+  it('should accept a base bundle at initialization', () => {
+    const dp = new window.DeltaPatcher();
+    global.Date = jest.fn();
+    dp.applyDelta({
+      base: true,
+      revisionId: 'rev0',
+      pre: 'pre0',
+      post: 'post0',
+      modules: [[0, '__d(0);']],
+    });
+    expect(dp.getLastRevisionId()).toBe('rev0');
+    expect(dp.getLastModifiedDate()).toBe(global.Date.mock.instances[0]);
+    expect(dp.getLastNumModifiedFiles()).toBe(1);
+    expect(dp.getAllModules()).toEqual(['pre0', '__d(0);', 'post0']);
+  });
+
+  it('should accept a delta bundle after a base bundle', () => {
+    const dp = new window.DeltaPatcher();
+    dp.applyDelta({
+      base: true,
+      revisionId: 'rev0',
+      pre: 'pre0',
+      post: 'post0',
+      modules: [[0, '__d(0);'], [1, '__d(1);'], [2, '__d(2);']],
+    });
+    global.Date = jest.fn();
+    dp.applyDelta({
+      base: false,
+      revisionId: 'rev1',
+      modules: [[1, '__d(1.1);'], [3, '__d(3);']],
+      deleted: [0],
+    });
+    expect(dp.getLastRevisionId()).toBe('rev1');
+    expect(dp.getLastModifiedDate()).toBe(global.Date.mock.instances[0]);
+    expect(dp.getLastNumModifiedFiles()).toBe(3);
+    expect(dp.getAllModules()).toEqual([
+      'pre0',
+      '__d(1.1);',
+      '__d(2);',
+      '__d(3);',
+      'post0',
+    ]);
+  });
+
+  it('should accept a base bundle after initialization', () => {
+    const dp = new window.DeltaPatcher();
+    dp.applyDelta({
+      base: true,
+      revisionId: 'rev0',
+      pre: 'pre0',
+      post: 'post0',
+      modules: [[0, '__d(0);'], [1, '__d(1);'], [2, '__d(2);']],
+    });
+    dp.applyDelta({
+      base: false,
+      revisionId: 'rev1',
+      modules: [[1, '__d(1.1);'], [3, '__d(3);']],
+      deleted: [0],
+    });
+    global.Date = jest.fn();
+    dp.applyDelta({
+      base: true,
+      revisionId: 'rev2',
+      pre: 'pre2',
+      post: 'post2',
+      modules: [[4, '__d(4);'], [5, '__d(5);']],
+    });
+    expect(dp.getLastRevisionId()).toBe('rev2');
+    expect(dp.getLastModifiedDate()).toBe(global.Date.mock.instances[0]);
+    expect(dp.getLastNumModifiedFiles()).toBe(2);
+    expect(dp.getAllModules()).toEqual(['pre2', '__d(4);', '__d(5);', 'post2']);
+  });
+});

local-cli/server/util/debugger-ui/deltaUrlToBlobUrl.js

@@ -29,13 +29,7 @@
     const data = await fetch(deltaUrl + revisionId);
     const bundle = await data.json();
 
-    const deltaPatcher = client.applyDelta({
-      base: bundle.base,
-      revisionId: bundle.revisionId,
-      pre: bundle.pre,
-      post: bundle.post,
-      modules: new Map(bundle.modules),
-    });
+    const deltaPatcher = client.applyDelta(bundle);
 
     let cachedBundle = cachedBundleUrls.get(deltaUrl);