1 files changed, 263 insertions, 0 deletions
diff --git a/toolkit/components/asyncshutdown/nsAsyncShutdown.jsm b/toolkit/components/asyncshutdown/nsAsyncShutdown.jsm
new file mode 100644
index 0000000000..0483824ccb
--- /dev/null
+++ b/toolkit/components/asyncshutdown/nsAsyncShutdown.jsm
@@ -0,0 +1,263 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * An implementation of nsIAsyncShutdown* based on AsyncShutdown.jsm
+ */
+
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "AsyncShutdown",
+  "resource://gre/modules/AsyncShutdown.jsm"
+);
+
+/**
+ * Conversion between nsIPropertyBag and JS object
+ */
+var PropertyBagConverter = {
+  // From nsIPropertyBag to JS
+  toObject(bag) {
+    if (!(bag instanceof Ci.nsIPropertyBag)) {
+      throw new TypeError("Not a property bag");
+    }
+    let result = {};
+    for (let { name, value: property } of bag.enumerator) {
+      let value = this.toValue(property);
+      result[name] = value;
+    }
+    return result;
+  },
+  toValue(property) {
+    if (typeof property != "object") {
+      return property;
+    }
+    if (Array.isArray(property)) {
+      return property.map(this.toValue, this);
+    }
+    if (property && property instanceof Ci.nsIPropertyBag) {
+      return this.toObject(property);
+    }
+    return property;
+  },
+
+  // From JS to nsIPropertyBag
+  fromObject(obj) {
+    if (obj == null || typeof obj != "object") {
+      throw new TypeError("Invalid object: " + obj);
+    }
+    let bag = Cc["@mozilla.org/hash-property-bag;1"].createInstance(
+      Ci.nsIWritablePropertyBag
+    );
+    for (let k of Object.keys(obj)) {
+      let value = this.fromValue(obj[k]);
+      bag.setProperty(k, value);
+    }
+    return bag;
+  },
+  fromValue(value) {
+    if (typeof value == "function") {
+      return null; // Emulating the behavior of JSON.stringify with functions
+    }
+    if (Array.isArray(value)) {
+      return value.map(this.fromValue, this);
+    }
+    if (value == null || typeof value != "object") {
+      // Auto-converted to nsIVariant
+      return value;
+    }
+    return this.fromObject(value);
+  },
+};
+
+/**
+ * Construct an instance of nsIAsyncShutdownClient from a
+ * AsyncShutdown.Barrier client.
+ *
+ * @param {object} moduleClient A client, as returned from the `client`
+ * property of an instance of `AsyncShutdown.Barrier`. This client will
+ * serve as back-end for methods `addBlocker` and `removeBlocker`.
+ * @constructor
+ */
+function nsAsyncShutdownClient(moduleClient) {
+  if (!moduleClient) {
+    throw new TypeError("nsAsyncShutdownClient expects one argument");
+  }
+  this._moduleClient = moduleClient;
+  this._byName = new Map();
+}
+nsAsyncShutdownClient.prototype = {
+  _getPromisified(xpcomBlocker) {
+    let candidate = this._byName.get(xpcomBlocker.name);
+    if (!candidate) {
+      return null;
+    }
+    if (candidate.xpcom === xpcomBlocker) {
+      return candidate.jsm;
+    }
+    return null;
+  },
+  _setPromisified(xpcomBlocker, moduleBlocker) {
+    let candidate = this._byName.get(xpcomBlocker.name);
+    if (!candidate) {
+      this._byName.set(xpcomBlocker.name, {
+        xpcom: xpcomBlocker,
+        jsm: moduleBlocker,
+      });
+      return;
+    }
+    if (candidate.xpcom === xpcomBlocker) {
+      return;
+    }
+    throw new Error(
+      "We have already registered a distinct blocker with the same name: " +
+        xpcomBlocker.name
+    );
+  },
+  _deletePromisified(xpcomBlocker) {
+    let candidate = this._byName.get(xpcomBlocker.name);
+    if (!candidate || candidate.xpcom !== xpcomBlocker) {
+      return false;
+    }
+    this._byName.delete(xpcomBlocker.name);
+    return true;
+  },
+  get jsclient() {
+    return this._moduleClient;
+  },
+  get name() {
+    return this._moduleClient.name;
+  },
+  addBlocker(
+    /* nsIAsyncShutdownBlocker*/ xpcomBlocker,
+    fileName,
+    lineNumber,
+    stack
+  ) {
+    // We need a Promise-based function with the same behavior as
+    // `xpcomBlocker`. Furthermore, to support `removeBlocker`, we
+    // need to ensure that we always get the same Promise-based
+    // function if we call several `addBlocker`/`removeBlocker` several
+    // times with the same `xpcomBlocker`.
+    //
+    // Ideally, this should be done with a WeakMap() with xpcomBlocker
+    // as a key, but XPConnect NativeWrapped objects cannot serve as
+    // WeakMap keys.
+    //
+    let moduleBlocker = this._getPromisified(xpcomBlocker);
+    if (!moduleBlocker) {
+      moduleBlocker = () =>
+        new Promise(
+          // This promise is never resolved. By opposition to AsyncShutdown
+          // blockers, `nsIAsyncShutdownBlocker`s are always lifted by calling
+          // `removeBlocker`.
+          () => xpcomBlocker.blockShutdown(this)
+        );
+
+      this._setPromisified(xpcomBlocker, moduleBlocker);
+    }
+
+    this._moduleClient.addBlocker(xpcomBlocker.name, moduleBlocker, {
+      fetchState: () => {
+        let state = xpcomBlocker.state;
+        if (state) {
+          return PropertyBagConverter.toValue(state);
+        }
+        return null;
+      },
+      filename: fileName,
+      lineNumber,
+      stack,
+    });
+  },
+
+  removeBlocker(xpcomBlocker) {
+    let moduleBlocker = this._getPromisified(xpcomBlocker);
+    if (!moduleBlocker) {
+      return false;
+    }
+    this._deletePromisified(xpcomBlocker);
+    return this._moduleClient.removeBlocker(moduleBlocker);
+  },
+
+  QueryInterface: ChromeUtils.generateQI(["nsIAsyncShutdownBarrier"]),
+};
+
+/**
+ * Construct an instance of nsIAsyncShutdownBarrier from an instance
+ * of AsyncShutdown.Barrier.
+ *
+ * @param {object} moduleBarrier an instance if
+ * `AsyncShutdown.Barrier`. This instance will serve as back-end for
+ * all methods.
+ * @constructor
+ */
+function nsAsyncShutdownBarrier(moduleBarrier) {
+  this._client = new nsAsyncShutdownClient(moduleBarrier.client);
+  this._moduleBarrier = moduleBarrier;
+}
+nsAsyncShutdownBarrier.prototype = {
+  get state() {
+    return PropertyBagConverter.fromValue(this._moduleBarrier.state);
+  },
+  get client() {
+    return this._client;
+  },
+  wait(onReady) {
+    this._moduleBarrier.wait().then(() => {
+      onReady.done();
+    });
+    // By specification, _moduleBarrier.wait() cannot reject.
+  },
+
+  QueryInterface: ChromeUtils.generateQI(["nsIAsyncShutdownBarrier"]),
+};
+
+function nsAsyncShutdownService() {
+  // Cache for the getters
+
+  for (let _k of [
+    // Parent process
+    "profileBeforeChange",
+    "profileChangeTeardown",
+    "quitApplicationGranted",
+    "sendTelemetry",
+
+    // Child processes
+    "contentChildShutdown",
+
+    // All processes
+    "webWorkersShutdown",
+    "xpcomWillShutdown",
+  ]) {
+    let k = _k;
+    Object.defineProperty(this, k, {
+      configurable: true,
+      get() {
+        delete this[k];
+        let wrapped = AsyncShutdown[k]; // May be undefined, if we're on the wrong process.
+        let result = wrapped ? new nsAsyncShutdownClient(wrapped) : undefined;
+        Object.defineProperty(this, k, {
+          value: result,
+        });
+        return result;
+      },
+    });
+  }
+
+  // Hooks for testing purpose
+  this.wrappedJSObject = {
+    _propertyBagConverter: PropertyBagConverter,
+  };
+}
+nsAsyncShutdownService.prototype = {
+  makeBarrier(name) {
+    return new nsAsyncShutdownBarrier(new AsyncShutdown.Barrier(name));
+  },
+
+  QueryInterface: ChromeUtils.generateQI(["nsIAsyncShutdownService"]),
+};
+
+var EXPORTED_SYMBOLS = ["nsAsyncShutdownService"];