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-rw-r--r--components/promiseworker/PromiseWorker.jsm390
-rw-r--r--components/promiseworker/moz.build8
-rw-r--r--components/promiseworker/worker/PromiseWorker.js206
-rw-r--r--components/promiseworker/worker/moz.build8
4 files changed, 612 insertions, 0 deletions
diff --git a/components/promiseworker/PromiseWorker.jsm b/components/promiseworker/PromiseWorker.jsm
new file mode 100644
index 000000000..0c6e054a2
--- /dev/null
+++ b/components/promiseworker/PromiseWorker.jsm
@@ -0,0 +1,390 @@
+/* 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/. */
+
+/**
+ * A wrapper around ChromeWorker with extended capabilities designed
+ * to simplify main thread-to-worker thread asynchronous function calls.
+ *
+ * This wrapper:
+ * - groups requests and responses as a method `post` that returns a `Promise`;
+ * - ensures that exceptions thrown on the worker thread are correctly deserialized;
+ * - provides some utilities for benchmarking various operations.
+ *
+ * Generally, you should use PromiseWorker.jsm along with its worker-side
+ * counterpart PromiseWorker.js.
+ */
+
+"use strict";
+
+this.EXPORTED_SYMBOLS = ["BasePromiseWorker"];
+
+const Cu = Components.utils;
+const Ci = Components.interfaces;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
+
+XPCOMUtils.defineLazyModuleGetter(this, "Promise",
+ "resource://gre/modules/Promise.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "Task",
+ "resource://gre/modules/Task.jsm");
+
+/**
+ * An implementation of queues (FIFO).
+ *
+ * The current implementation uses one array, runs in O(n ^ 2), and is optimized
+ * for the case in which queues are generally short.
+ */
+function Queue() {
+ this._array = [];
+}
+Queue.prototype = {
+ pop: function pop() {
+ return this._array.shift();
+ },
+ push: function push(x) {
+ return this._array.push(x);
+ },
+ isEmpty: function isEmpty() {
+ return this._array.length == 0;
+ }
+};
+
+/**
+ * Constructors for decoding standard exceptions received from the
+ * worker.
+ */
+const EXCEPTION_CONSTRUCTORS = {
+ EvalError: function(error) {
+ let result = new EvalError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ InternalError: function(error) {
+ let result = new InternalError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ RangeError: function(error) {
+ let result = new RangeError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ ReferenceError: function(error) {
+ let result = new ReferenceError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ SyntaxError: function(error) {
+ let result = new SyntaxError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ TypeError: function(error) {
+ let result = new TypeError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ URIError: function(error) {
+ let result = new URIError(error.message, error.fileName, error.lineNumber);
+ result.stack = error.stack;
+ return result;
+ },
+ StopIteration: function() {
+ return StopIteration;
+ }
+};
+
+/**
+ * An object responsible for dispatching messages to a chrome worker
+ * and routing the responses.
+ *
+ * Instances of this constructor who need logging may provide a method
+ * `log: function(...args) { ... }` in charge of printing out (or
+ * discarding) logs.
+ *
+ * Instances of this constructor may add exception handlers to
+ * `this.ExceptionHandlers`, if they need to handle custom exceptions.
+ *
+ * @param {string} url The url containing the source code for this worker,
+ * as in constructor ChromeWorker.
+ *
+ * @constructor
+ */
+this.BasePromiseWorker = function(url) {
+ if (typeof url != "string") {
+ throw new TypeError("Expecting a string");
+ }
+ this._url = url;
+
+ /**
+ * A set of methods, with the following
+ *
+ * ConstructorName: function({message, fileName, lineNumber}) {
+ * // Construct a new instance of ConstructorName based on
+ * // `message`, `fileName`, `lineNumber`
+ * }
+ *
+ * By default, this covers EvalError, InternalError, RangeError,
+ * ReferenceError, SyntaxError, TypeError, URIError, StopIteration.
+ */
+ this.ExceptionHandlers = Object.create(EXCEPTION_CONSTRUCTORS);
+
+ /**
+ * The queue of deferred, waiting for the completion of their
+ * respective job by the worker.
+ *
+ * Each item in the list may contain an additional field |closure|,
+ * used to store strong references to value that must not be
+ * garbage-collected before the reply has been received (e.g.
+ * arrays).
+ *
+ * @type {Queue<{deferred:deferred, closure:*=}>}
+ */
+ this._queue = new Queue();
+
+ /**
+ * The number of the current message.
+ *
+ * Used for debugging purposes.
+ */
+ this._id = 0;
+
+ /**
+ * The instant at which the worker was launched.
+ */
+ this.launchTimeStamp = null;
+
+ /**
+ * Timestamps provided by the worker for statistics purposes.
+ */
+ this.workerTimeStamps = null;
+};
+this.BasePromiseWorker.prototype = {
+ log: function() {
+ // By Default, ignore all logs.
+ },
+
+ /**
+ * Instantiate the worker lazily.
+ */
+ get _worker() {
+ delete this._worker;
+ let worker = new ChromeWorker(this._url);
+ Object.defineProperty(this, "_worker", {value:
+ worker
+ });
+
+ // We assume that we call to _worker for the purpose of calling
+ // postMessage().
+ this.launchTimeStamp = Date.now();
+
+ /**
+ * Receive errors that have been serialized by the built-in mechanism
+ * of DOM/Chrome Workers.
+ *
+ * PromiseWorker.js knows how to serialize a number of errors
+ * without losing information. These are treated by
+ * |worker.onmessage|. However, for other errors, we rely on
+ * DOM's mechanism for serializing errors, which transmits these
+ * errors through |worker.onerror|.
+ *
+ * @param {Error} error Some JS error.
+ */
+ worker.onerror = error => {
+ this.log("Received uncaught error from worker", error.message, error.filename, error.lineno);
+ error.preventDefault();
+ let {deferred} = this._queue.pop();
+ deferred.reject(error);
+ };
+
+ /**
+ * Receive messages from the worker, propagate them to the listeners.
+ *
+ * Messages must have one of the following shapes:
+ * - {ok: some_value} in case of success
+ * - {fail: some_error} in case of error, where
+ * some_error is an instance of |PromiseWorker.WorkerError|
+ *
+ * Messages may also contain a field |id| to help
+ * with debugging.
+ *
+ * Messages may also optionally contain a field |durationMs|, holding
+ * the duration of the function call in milliseconds.
+ *
+ * @param {*} msg The message received from the worker.
+ */
+ worker.onmessage = msg => {
+ this.log("Received message from worker", msg.data);
+ let handler = this._queue.pop();
+ let deferred = handler.deferred;
+ let data = msg.data;
+ if (data.id != handler.id) {
+ throw new Error("Internal error: expecting msg " + handler.id + ", " +
+ " got " + data.id + ": " + JSON.stringify(msg.data));
+ }
+ if ("timeStamps" in data) {
+ this.workerTimeStamps = data.timeStamps;
+ }
+ if ("ok" in data) {
+ // Pass the data to the listeners.
+ deferred.resolve(data);
+ } else if ("fail" in data) {
+ // We have received an error that was serialized by the
+ // worker.
+ deferred.reject(new WorkerError(data.fail));
+ }
+ };
+ return worker;
+ },
+
+ /**
+ * Post a message to a worker.
+ *
+ * @param {string} fun The name of the function to call.
+ * @param {Array} args The arguments to pass to `fun`. If any
+ * of the arguments is a Promise, it is resolved before posting the
+ * message. If any of the arguments needs to be transfered instead
+ * of copied, this may be specified by making the argument an instance
+ * of `BasePromiseWorker.Meta` or by using the `transfers` argument.
+ * By convention, the last argument may be an object `options`
+ * with some of the following fields:
+ * - {number|null} outExecutionDuration A parameter to be filled with the
+ * duration of the off main thread execution for this call.
+ * @param {*=} closure An object holding references that should not be
+ * garbage-collected before the message treatment is complete.
+ * @param {Array=} transfers An array of objects that should be transfered
+ * to the worker instead of being copied. If any of the objects is a Promise,
+ * it is resolved before posting the message.
+ *
+ * @return {promise}
+ */
+ post: function(fun, args, closure, transfers) {
+ return Task.spawn(function* postMessage() {
+ // Normalize in case any of the arguments is a promise
+ if (args) {
+ args = yield Promise.resolve(Promise.all(args));
+ }
+ if (transfers) {
+ transfers = yield Promise.resolve(Promise.all(transfers));
+ } else {
+ transfers = [];
+ }
+
+ if (args) {
+ // Extract `Meta` data
+ args = args.map(arg => {
+ if (arg instanceof BasePromiseWorker.Meta) {
+ if (arg.meta && "transfers" in arg.meta) {
+ transfers.push(...arg.meta.transfers);
+ }
+ return arg.data;
+ }
+ return arg;
+ });
+ }
+
+ let id = ++this._id;
+ let message = {fun: fun, args: args, id: id};
+ this.log("Posting message", message);
+ try {
+ this._worker.postMessage(message, ...[transfers]);
+ } catch (ex) {
+ if (typeof ex == "number") {
+ this.log("Could not post message", message, "due to xpcom error", ex);
+ // handle raw xpcom errors (see eg bug 961317)
+ throw new Components.Exception("Error in postMessage", ex);
+ }
+
+ this.log("Could not post message", message, "due to error", ex);
+ throw ex;
+ }
+
+ let deferred = Promise.defer();
+ this._queue.push({deferred:deferred, closure: closure, id: id});
+ this.log("Message posted");
+
+ let reply;
+ try {
+ this.log("Expecting reply");
+ reply = yield deferred.promise;
+ } catch (error) {
+ this.log("Got error", error);
+ reply = error;
+
+ if (error instanceof WorkerError) {
+ // We know how to deserialize most well-known errors
+ throw this.ExceptionHandlers[error.data.exn](error.data);
+ }
+
+ if (error instanceof ErrorEvent) {
+ // Other errors get propagated as instances of ErrorEvent
+ this.log("Error serialized by DOM", error.message, error.filename, error.lineno);
+ throw new Error(error.message, error.filename, error.lineno);
+ }
+
+ // We don't know about this kind of error
+ throw error;
+ }
+
+ // By convention, the last argument may be an object `options`.
+ let options = null;
+ if (args) {
+ options = args[args.length - 1];
+ }
+
+ // Check for duration and return result.
+ if (!options ||
+ typeof options !== "object" ||
+ !("outExecutionDuration" in options)) {
+ return reply.ok;
+ }
+ // If reply.durationMs is not present, just return the result,
+ // without updating durations (there was an error in the method
+ // dispatch).
+ if (!("durationMs" in reply)) {
+ return reply.ok;
+ }
+ // Bug 874425 demonstrates that two successive calls to Date.now()
+ // can actually produce an interval with negative duration.
+ // We assume that this is due to an operation that is so short
+ // that Date.now() is not monotonic, so we round this up to 0.
+ let durationMs = Math.max(0, reply.durationMs);
+ // Accumulate (or initialize) outExecutionDuration
+ if (typeof options.outExecutionDuration == "number") {
+ options.outExecutionDuration += durationMs;
+ } else {
+ options.outExecutionDuration = durationMs;
+ }
+ return reply.ok;
+
+ }.bind(this));
+ }
+};
+
+/**
+ * An error that has been serialized by the worker.
+ *
+ * @constructor
+ */
+function WorkerError(data) {
+ this.data = data;
+}
+
+/**
+ * A constructor used to send data to the worker thread while
+ * with special treatment (e.g. transmitting data instead of
+ * copying it).
+ *
+ * @param {object=} data The data to send to the caller thread.
+ * @param {object=} meta Additional instructions, as an object
+ * that may contain the following fields:
+ * - {Array} transfers An array of objects that should be transferred
+ * instead of being copied.
+ *
+ * @constructor
+ */
+this.BasePromiseWorker.Meta = function(data, meta) {
+ this.data = data;
+ this.meta = meta;
+};
diff --git a/components/promiseworker/moz.build b/components/promiseworker/moz.build
new file mode 100644
index 000000000..f14062b63
--- /dev/null
+++ b/components/promiseworker/moz.build
@@ -0,0 +1,8 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# 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/.
+
+DIRS += ['worker']
+
+EXTRA_JS_MODULES += ['PromiseWorker.jsm']
diff --git a/components/promiseworker/worker/PromiseWorker.js b/components/promiseworker/worker/PromiseWorker.js
new file mode 100644
index 000000000..ba4408c1a
--- /dev/null
+++ b/components/promiseworker/worker/PromiseWorker.js
@@ -0,0 +1,206 @@
+/* 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/. */
+
+/**
+ * A wrapper around `self` with extended capabilities designed
+ * to simplify main thread-to-worker thread asynchronous function calls.
+ *
+ * This wrapper:
+ * - groups requests and responses as a method `post` that returns a `Promise`;
+ * - ensures that exceptions thrown on the worker thread are correctly serialized;
+ * - provides some utilities for benchmarking various operations.
+ *
+ * Generally, you should use PromiseWorker.js along with its main thread-side
+ * counterpart PromiseWorker.jsm.
+ */
+
+"use strict";
+
+if (typeof Components != "undefined") {
+ throw new Error("This module is meant to be used from the worker thread");
+}
+if (typeof require == "undefined" || typeof module == "undefined") {
+ throw new Error("this module is meant to be imported using the implementation of require() at resource://gre/modules/workers/require.js");
+}
+
+importScripts("resource://gre/modules/workers/require.js");
+
+/**
+ * Built-in JavaScript exceptions that may be serialized without
+ * loss of information.
+ */
+const EXCEPTION_NAMES = {
+ EvalError: "EvalError",
+ InternalError: "InternalError",
+ RangeError: "RangeError",
+ ReferenceError: "ReferenceError",
+ SyntaxError: "SyntaxError",
+ TypeError: "TypeError",
+ URIError: "URIError",
+};
+
+/**
+ * A constructor used to return data to the caller thread while
+ * also executing some specific treatment (e.g. shutting down
+ * the current thread, transmitting data instead of copying it).
+ *
+ * @param {object=} data The data to return to the caller thread.
+ * @param {object=} meta Additional instructions, as an object
+ * that may contain the following fields:
+ * - {bool} shutdown If |true|, shut down the current thread after
+ * having sent the result.
+ * - {Array} transfers An array of objects that should be transferred
+ * instead of being copied.
+ *
+ * @constructor
+ */
+function Meta(data, meta) {
+ this.data = data;
+ this.meta = meta;
+}
+exports.Meta = Meta;
+
+/**
+ * Base class for a worker.
+ *
+ * Derived classes are expected to provide the following methods:
+ * {
+ * dispatch: function(method, args) {
+ * // Dispatch a call to method `method` with args `args`
+ * },
+ * log: function(...msg) {
+ * // Log (or discard) messages (optional)
+ * },
+ * postMessage: function(message, ...transfers) {
+ * // Post a message to the main thread
+ * },
+ * close: function() {
+ * // Close the worker
+ * }
+ * }
+ *
+ * By default, the AbstractWorker is not connected to a message port,
+ * hence will not receive anything.
+ *
+ * To connect it, use `onmessage`, as follows:
+ * self.addEventListener("message", msg => myWorkerInstance.handleMessage(msg));
+ */
+function AbstractWorker(agent) {
+ this._agent = agent;
+}
+AbstractWorker.prototype = {
+ // Default logger: discard all messages
+ log: function() {
+ },
+
+ /**
+ * Handle a message.
+ */
+ handleMessage: function(msg) {
+ let data = msg.data;
+ this.log("Received message", data);
+ let id = data.id;
+
+ let start;
+ let options;
+ if (data.args) {
+ options = data.args[data.args.length - 1];
+ }
+ // If |outExecutionDuration| option was supplied, start measuring the
+ // duration of the operation.
+ if (options && typeof options === "object" && "outExecutionDuration" in options) {
+ start = Date.now();
+ }
+
+ let result;
+ let exn;
+ let durationMs;
+ let method = data.fun;
+ try {
+ this.log("Calling method", method);
+ result = this.dispatch(method, data.args);
+ this.log("Method", method, "succeeded");
+ } catch (ex) {
+ exn = ex;
+ this.log("Error while calling agent method", method, exn, exn.moduleStack || exn.stack || "");
+ }
+
+ if (start) {
+ // Record duration
+ durationMs = Date.now() - start;
+ this.log("Method took", durationMs, "ms");
+ }
+
+ // Now, post a reply, possibly as an uncaught error.
+ // We post this message from outside the |try ... catch| block
+ // to avoid capturing errors that take place during |postMessage| and
+ // built-in serialization.
+ if (!exn) {
+ this.log("Sending positive reply", result, "id is", id);
+ if (result instanceof Meta) {
+ if ("transfers" in result.meta) {
+ // Take advantage of zero-copy transfers
+ this.postMessage({ok: result.data, id: id, durationMs: durationMs},
+ result.meta.transfers);
+ } else {
+ this.postMessage({ok: result.data, id:id, durationMs: durationMs});
+ }
+ if (result.meta.shutdown || false) {
+ // Time to close the worker
+ this.close();
+ }
+ } else {
+ this.postMessage({ok: result, id:id, durationMs: durationMs});
+ }
+ } else if (exn.constructor.name in EXCEPTION_NAMES) {
+ // Rather than letting the DOM mechanism [de]serialize built-in
+ // JS errors, which loses lots of information (in particular,
+ // the constructor name, the moduleName and the moduleStack),
+ // we [de]serialize them manually with a little more care.
+ this.log("Sending back exception", exn.constructor.name, "id is", id);
+ let error = {
+ exn: exn.constructor.name,
+ message: exn.message,
+ fileName: exn.moduleName || exn.fileName,
+ lineNumber: exn.lineNumber,
+ stack: exn.moduleStack
+ };
+ this.postMessage({fail: error, id: id, durationMs: durationMs});
+ } else if (exn == StopIteration) {
+ // StopIteration is a well-known singleton, and requires a
+ // slightly different treatment.
+ this.log("Sending back StopIteration, id is", id);
+ let error = {
+ exn: "StopIteration"
+ };
+ this.postMessage({fail: error, id: id, durationMs: durationMs});
+ } else if ("toMsg" in exn) {
+ // Extension mechanism for exception [de]serialization. We
+ // assume that any exception with a method `toMsg()` knows how
+ // to serialize itself. The other side is expected to have
+ // registered a deserializer using the `ExceptionHandlers`
+ // object.
+ this.log("Sending back an error that knows how to serialize itself", exn, "id is", id);
+ let msg = exn.toMsg();
+ this.postMessage({fail: msg, id:id, durationMs: durationMs});
+ } else {
+ // If we encounter an exception for which we have no
+ // serialization mechanism in place, we have no choice but to
+ // let the DOM handle said [de]serialization. We can just
+ // attempt to mitigate the data loss by injecting `moduleName` and
+ // `moduleStack`.
+ this.log("Sending back regular error", exn, exn.moduleStack || exn.stack, "id is", id);
+
+ try {
+ // Attempt to introduce human-readable filename and stack
+ exn.filename = exn.moduleName;
+ exn.stack = exn.moduleStack;
+ } catch (_) {
+ // Nothing we can do
+ }
+ throw exn;
+ }
+ }
+};
+exports.AbstractWorker = AbstractWorker;
diff --git a/components/promiseworker/worker/moz.build b/components/promiseworker/worker/moz.build
new file mode 100644
index 000000000..abac4be46
--- /dev/null
+++ b/components/promiseworker/worker/moz.build
@@ -0,0 +1,8 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# 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/.
+
+EXTRA_JS_MODULES.workers = [
+ 'PromiseWorker.js',
+]
generated by cgit v1.2.3 (git 2.26.2) at 2024-11-10 13:51:02 +0000