The Tor Browser: comparison js/src/v8/richards.js

comparison: js/src/v8/richards.js

js/src/v8/richards.js

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+// Copyright 2006-2008 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// This is a JavaScript implementation of the Richards
+// benchmark from:
+//
+//    http://www.cl.cam.ac.uk/~mr10/Bench.html
+//
+// The benchmark was originally implemented in BCPL by
+// Martin Richards.
+var Richards = new BenchmarkSuite('Richards', 35302, [
+new Benchmark("Richards", runRichards)
+]);
+/**
+* The Richards benchmark simulates the task dispatcher of an
+* operating system.
+**/
+function runRichards() {
+var scheduler = new Scheduler();
+scheduler.addIdleTask(ID_IDLE, 0, null, COUNT);
+var queue = new Packet(null, ID_WORKER, KIND_WORK);
+queue = new Packet(queue,  ID_WORKER, KIND_WORK);
+scheduler.addWorkerTask(ID_WORKER, 1000, queue);
+queue = new Packet(null, ID_DEVICE_A, KIND_DEVICE);
+queue = new Packet(queue,  ID_DEVICE_A, KIND_DEVICE);
+queue = new Packet(queue,  ID_DEVICE_A, KIND_DEVICE);
+scheduler.addHandlerTask(ID_HANDLER_A, 2000, queue);
+queue = new Packet(null, ID_DEVICE_B, KIND_DEVICE);
+queue = new Packet(queue,  ID_DEVICE_B, KIND_DEVICE);
+queue = new Packet(queue,  ID_DEVICE_B, KIND_DEVICE);
+scheduler.addHandlerTask(ID_HANDLER_B, 3000, queue);
+scheduler.addDeviceTask(ID_DEVICE_A, 4000, null);
+scheduler.addDeviceTask(ID_DEVICE_B, 5000, null);
+scheduler.schedule();
+if (scheduler.queueCount != EXPECTED_QUEUE_COUNT ||
+scheduler.holdCount != EXPECTED_HOLD_COUNT) {
+var msg =
+"Error during execution: queueCount = " + scheduler.queueCount +
+", holdCount = " + scheduler.holdCount + ".";
+throw new Error(msg);
+}
+}
+var COUNT = 1000;
+/**
+* These two constants specify how many times a packet is queued and
+* how many times a task is put on hold in a correct run of richards.
+* They don't have any meaning a such but are characteristic of a
+* correct run so if the actual queue or hold count is different from
+* the expected there must be a bug in the implementation.
+**/
+var EXPECTED_QUEUE_COUNT = 2322;
+var EXPECTED_HOLD_COUNT = 928;
+/**
+* A scheduler can be used to schedule a set of tasks based on their relative
+* priorities.  Scheduling is done by maintaining a list of task control blocks
+* which holds tasks and the data queue they are processing.
+* @constructor
+*/
+function Scheduler() {
+this.queueCount = 0;
+this.holdCount = 0;
+this.blocks = new Array(NUMBER_OF_IDS);
+this.list = null;
+this.currentTcb = null;
+this.currentId = null;
+}
+var ID_IDLE       = 0;
+var ID_WORKER     = 1;
+var ID_HANDLER_A  = 2;
+var ID_HANDLER_B  = 3;
+var ID_DEVICE_A   = 4;
+var ID_DEVICE_B   = 5;
+var NUMBER_OF_IDS = 6;
+var KIND_DEVICE   = 0;
+var KIND_WORK     = 1;
+/**
+* Add an idle task to this scheduler.
+* @param {int} id the identity of the task
+* @param {int} priority the task's priority
+* @param {Packet} queue the queue of work to be processed by the task
+* @param {int} count the number of times to schedule the task
+*/
+Scheduler.prototype.addIdleTask = function (id, priority, queue, count) {
+this.addRunningTask(id, priority, queue, new IdleTask(this, 1, count));
+};
+/**
+* Add a work task to this scheduler.
+* @param {int} id the identity of the task
+* @param {int} priority the task's priority
+* @param {Packet} queue the queue of work to be processed by the task
+*/
+Scheduler.prototype.addWorkerTask = function (id, priority, queue) {
+this.addTask(id, priority, queue, new WorkerTask(this, ID_HANDLER_A, 0));
+};
+/**
+* Add a handler task to this scheduler.
+* @param {int} id the identity of the task
+* @param {int} priority the task's priority
+* @param {Packet} queue the queue of work to be processed by the task
+*/
+Scheduler.prototype.addHandlerTask = function (id, priority, queue) {
+this.addTask(id, priority, queue, new HandlerTask(this));
+};
+/**
+* Add a handler task to this scheduler.
+* @param {int} id the identity of the task
+* @param {int} priority the task's priority
+* @param {Packet} queue the queue of work to be processed by the task
+*/
+Scheduler.prototype.addDeviceTask = function (id, priority, queue) {
+this.addTask(id, priority, queue, new DeviceTask(this))
+};
+/**
+* Add the specified task and mark it as running.
+* @param {int} id the identity of the task
+* @param {int} priority the task's priority
+* @param {Packet} queue the queue of work to be processed by the task
+* @param {Task} task the task to add
+*/
+Scheduler.prototype.addRunningTask = function (id, priority, queue, task) {
+this.addTask(id, priority, queue, task);
+this.currentTcb.setRunning();
+};
+/**
+* Add the specified task to this scheduler.
+* @param {int} id the identity of the task
+* @param {int} priority the task's priority
+* @param {Packet} queue the queue of work to be processed by the task
+* @param {Task} task the task to add
+*/
+Scheduler.prototype.addTask = function (id, priority, queue, task) {
+this.currentTcb = new TaskControlBlock(this.list, id, priority, queue, task);
+this.list = this.currentTcb;
+this.blocks[id] = this.currentTcb;
+};
+/**
+* Execute the tasks managed by this scheduler.
+*/
+Scheduler.prototype.schedule = function () {
+this.currentTcb = this.list;
+while (this.currentTcb != null) {
+if (this.currentTcb.isHeldOrSuspended()) {
+this.currentTcb = this.currentTcb.link;
+} else {
+this.currentId = this.currentTcb.id;
+this.currentTcb = this.currentTcb.run();
+}
+}
+};
+/**
+* Release a task that is currently blocked and return the next block to run.
+* @param {int} id the id of the task to suspend
+*/
+Scheduler.prototype.release = function (id) {
+var tcb = this.blocks[id];
+if (tcb == null) return tcb;
+tcb.markAsNotHeld();
+if (tcb.priority > this.currentTcb.priority) {
+return tcb;
+} else {
+return this.currentTcb;
+}
+};
+/**
+* Block the currently executing task and return the next task control block
+* to run.  The blocked task will not be made runnable until it is explicitly
+* released, even if new work is added to it.
+*/
+Scheduler.prototype.holdCurrent = function () {
+this.holdCount++;
+this.currentTcb.markAsHeld();
+return this.currentTcb.link;
+};
+/**
+* Suspend the currently executing task and return the next task control block
+* to run.  If new work is added to the suspended task it will be made runnable.
+*/
+Scheduler.prototype.suspendCurrent = function () {
+this.currentTcb.markAsSuspended();
+return this.currentTcb;
+};
+/**
+* Add the specified packet to the end of the worklist used by the task
+* associated with the packet and make the task runnable if it is currently
+* suspended.
+* @param {Packet} packet the packet to add
+*/
+Scheduler.prototype.queue = function (packet) {
+var t = this.blocks[packet.id];
+if (t == null) return t;
+this.queueCount++;
+packet.link = null;
+packet.id = this.currentId;
+return t.checkPriorityAdd(this.currentTcb, packet);
+};
+/**
+* A task control block manages a task and the queue of work packages associated
+* with it.
+* @param {TaskControlBlock} link the preceding block in the linked block list
+* @param {int} id the id of this block
+* @param {int} priority the priority of this block
+* @param {Packet} queue the queue of packages to be processed by the task
+* @param {Task} task the task
+* @constructor
+*/
+function TaskControlBlock(link, id, priority, queue, task) {
+this.link = link;
+this.id = id;
+this.priority = priority;
+this.queue = queue;
+this.task = task;
+if (queue == null) {
+this.state = STATE_SUSPENDED;
+} else {
+this.state = STATE_SUSPENDED_RUNNABLE;
+}
+}
+/**
+* The task is running and is currently scheduled.
+*/
+var STATE_RUNNING = 0;
+/**
+* The task has packets left to process.
+*/
+var STATE_RUNNABLE = 1;
+/**
+* The task is not currently running.  The task is not blocked as such and may
+* be started by the scheduler.
+*/
+var STATE_SUSPENDED = 2;
+/**
+* The task is blocked and cannot be run until it is explicitly released.
+*/
+var STATE_HELD = 4;
+var STATE_SUSPENDED_RUNNABLE = STATE_SUSPENDED | STATE_RUNNABLE;
+var STATE_NOT_HELD = ~STATE_HELD;
+TaskControlBlock.prototype.setRunning = function () {
+this.state = STATE_RUNNING;
+};
+TaskControlBlock.prototype.markAsNotHeld = function () {
+this.state = this.state & STATE_NOT_HELD;
+};
+TaskControlBlock.prototype.markAsHeld = function () {
+this.state = this.state | STATE_HELD;
+};
+TaskControlBlock.prototype.isHeldOrSuspended = function () {
+return (this.state & STATE_HELD) != 0 || (this.state == STATE_SUSPENDED);
+};
+TaskControlBlock.prototype.markAsSuspended = function () {
+this.state = this.state | STATE_SUSPENDED;
+};
+TaskControlBlock.prototype.markAsRunnable = function () {
+this.state = this.state | STATE_RUNNABLE;
+};
+/**
+* Runs this task, if it is ready to be run, and returns the next task to run.
+*/
+TaskControlBlock.prototype.run = function () {
+var packet;
+if (this.state == STATE_SUSPENDED_RUNNABLE) {
+packet = this.queue;
+this.queue = packet.link;
+if (this.queue == null) {
+this.state = STATE_RUNNING;
+} else {
+this.state = STATE_RUNNABLE;
+}
+} else {
+packet = null;
+}
+return this.task.run(packet);
+};
+/**
+* Adds a packet to the worklist of this block's task, marks this as runnable if
+* necessary, and returns the next runnable object to run (the one
+* with the highest priority).
+*/
+TaskControlBlock.prototype.checkPriorityAdd = function (task, packet) {
+if (this.queue == null) {
+this.queue = packet;
+this.markAsRunnable();
+if (this.priority > task.priority) return this;
+} else {
+this.queue = packet.addTo(this.queue);
+}
+return task;
+};
+TaskControlBlock.prototype.toString = function () {
+return "tcb { " + this.task + "@" + this.state + " }";
+};
+/**
+* An idle task doesn't do any work itself but cycles control between the two
+* device tasks.
+* @param {Scheduler} scheduler the scheduler that manages this task
+* @param {int} v1 a seed value that controls how the device tasks are scheduled
+* @param {int} count the number of times this task should be scheduled
+* @constructor
+*/
+function IdleTask(scheduler, v1, count) {
+this.scheduler = scheduler;
+this.v1 = v1;
+this.count = count;
+}
+IdleTask.prototype.run = function (packet) {
+this.count--;
+if (this.count == 0) return this.scheduler.holdCurrent();
+if ((this.v1 & 1) == 0) {
+this.v1 = this.v1 >> 1;
+return this.scheduler.release(ID_DEVICE_A);
+} else {
+this.v1 = (this.v1 >> 1) ^ 0xD008;
+return this.scheduler.release(ID_DEVICE_B);
+}
+};
+IdleTask.prototype.toString = function () {
+return "IdleTask"
+};
+/**
+* A task that suspends itself after each time it has been run to simulate
+* waiting for data from an external device.
+* @param {Scheduler} scheduler the scheduler that manages this task
+* @constructor
+*/
+function DeviceTask(scheduler) {
+this.scheduler = scheduler;
+this.v1 = null;
+}
+DeviceTask.prototype.run = function (packet) {
+if (packet == null) {
+if (this.v1 == null) return this.scheduler.suspendCurrent();
+var v = this.v1;
+this.v1 = null;
+return this.scheduler.queue(v);
+} else {
+this.v1 = packet;
+return this.scheduler.holdCurrent();
+}
+};
+DeviceTask.prototype.toString = function () {
+return "DeviceTask";
+};
+/**
+* A task that manipulates work packets.
+* @param {Scheduler} scheduler the scheduler that manages this task
+* @param {int} v1 a seed used to specify how work packets are manipulated
+* @param {int} v2 another seed used to specify how work packets are manipulated
+* @constructor
+*/
+function WorkerTask(scheduler, v1, v2) {
+this.scheduler = scheduler;
+this.v1 = v1;
+this.v2 = v2;
+}
+WorkerTask.prototype.run = function (packet) {
+if (packet == null) {
+return this.scheduler.suspendCurrent();
+} else {
+if (this.v1 == ID_HANDLER_A) {
+this.v1 = ID_HANDLER_B;
+} else {
+this.v1 = ID_HANDLER_A;
+}
+packet.id = this.v1;
+packet.a1 = 0;
+for (var i = 0; i < DATA_SIZE; i++) {
+this.v2++;
+if (this.v2 > 26) this.v2 = 1;
+packet.a2[i] = this.v2;
+}
+return this.scheduler.queue(packet);
+}
+};
+WorkerTask.prototype.toString = function () {
+return "WorkerTask";
+};
+/**
+* A task that manipulates work packets and then suspends itself.
+* @param {Scheduler} scheduler the scheduler that manages this task
+* @constructor
+*/
+function HandlerTask(scheduler) {
+this.scheduler = scheduler;
+this.v1 = null;
+this.v2 = null;
+}
+HandlerTask.prototype.run = function (packet) {
+if (packet != null) {
+if (packet.kind == KIND_WORK) {
+this.v1 = packet.addTo(this.v1);
+} else {
+this.v2 = packet.addTo(this.v2);
+}
+}
+if (this.v1 != null) {
+var count = this.v1.a1;
+var v;
+if (count < DATA_SIZE) {
+if (this.v2 != null) {
+v = this.v2;
+this.v2 = this.v2.link;
+v.a1 = this.v1.a2[count];
+this.v1.a1 = count + 1;
+return this.scheduler.queue(v);
+}
+} else {
+v = this.v1;
+this.v1 = this.v1.link;
+return this.scheduler.queue(v);
+}
+}
+return this.scheduler.suspendCurrent();
+};
+HandlerTask.prototype.toString = function () {
+return "HandlerTask";
+};
+/* --- *
+* P a c k e t
+* --- */
+var DATA_SIZE = 4;
+/**
+* A simple package of data that is manipulated by the tasks.  The exact layout
+* of the payload data carried by a packet is not importaint, and neither is the
+* nature of the work performed on packets by the tasks.
+*
+* Besides carrying data, packets form linked lists and are hence used both as
+* data and worklists.
+* @param {Packet} link the tail of the linked list of packets
+* @param {int} id an ID for this packet
+* @param {int} kind the type of this packet
+* @constructor
+*/
+function Packet(link, id, kind) {
+this.link = link;
+this.id = id;
+this.kind = kind;
+this.a1 = 0;
+this.a2 = new Array(DATA_SIZE);
+}
+/**
+* Add this packet to the end of a worklist, and return the worklist.
+* @param {Packet} queue the worklist to add this packet to
+*/
+Packet.prototype.addTo = function (queue) {
+this.link = null;
+if (queue == null) return this;
+var peek, next = queue;
+while ((peek = next.link) != null)
+next = peek;
+next.link = this;
+return queue;
+};
+Packet.prototype.toString = function () {
+return "Packet";
+};