// 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,
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// 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.
/**
* 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";
};
for (var i = 0; i < 350; ++i)
runRichards();
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