how can I figure out how much time it takes to send a message from one node to the other? is there a function or a c++ node example to use as a test scenario for this ?
It depends on your application and on the accuracy you want to achieve: it could vary as a stochastic process in multi-thread environment.
However, you can have a rough estimation using pre_publish_time_ = ros::Time::now() just before the publish() call and computes the elapsed time in the subscriber callback as ros::Time elapsed_time = ros::Time::now() - pre_publish_time_, where pre_publish_time_ is a ros::Time member variable.
If publisher and subscriber lay in different classes you can add the std_msgs/Header in you message and use the header.stamp field as pre_publish_time_ (properly filled just before the publish() method as said above).
geometry_msgs/Vector3Stamped Example:
void publishFcn() {
// ...
geometry_msgs::Vector3Stamped msg;
msg.vector.x = 0;
msg.vector.y = 0;
msg.vector.z = 1;
msg.header.stamp = ros::Time::now();
publisher_.publish(msg);
}
void msgCallback(const geometry_msgs::Vector3Stamped &msg) {
ros::Time elapsed_time = ros::Time::now() - msg.header.stamp;
// ...
}
Related
How do I make an action occur with a delay, but after a timeout?
The setTimeout() function doesn’t work in Decentraland scenes, so is there an alternative?
For example, I want an entity to wait 300 milliseconds after it’s clicked before I remove it from the engine.
To implement this you’ll have to create:
A custom component to keep track of time
A component group to keep track of all the entities with a delay in the scene
A system that updates the timers con all these
components on each frame.
It sounds rather complicated, but once you created one delay, implementing another delay only takes one line.
The component:
#Component("timerDelay")
export class Delay implements ITimerComponent{
elapsedTime: number;
targetTime: number;
onTargetTimeReached: (ownerEntity: IEntity) => void;
private onTimeReachedCallback?: ()=> void
/**
* #param millisecs amount of time in milliseconds
* #param onTimeReachedCallback callback for when time is reached
*/
constructor(millisecs: number, onTimeReachedCallback?: ()=> void){
this.elapsedTime = 0
this.targetTime = millisecs / 1000
this.onTimeReachedCallback = onTimeReachedCallback
this.onTargetTimeReached = (entity)=>{
if (this.onTimeReachedCallback) this.onTimeReachedCallback()
entity.removeComponent(this)
}
}
}
The component group:
export const delayedEntities = engine.getComponentGroup(Delay)
The system:
// define system
class TimerSystem implements ISystem {
update(dt: number){
for (let entity of delayedEntities.entities) {
let timerComponent = entity.getComponent(component)
timerComponent.elapsedTime += dt
if (timerComponent.elapsedTime >= timerComponent.targetTime){
timerComponent.onTargetTimeReached(entity)
}
})
}
}
// instance system
engine.addSystem(new TimerSystem())
Once all these parts are in place, you can simply do the following to delay an execution in your scene:
const myEntity = new Entity()
myEntity.addComponent(new Delay(1000, () => {
log("time ran out")
}))
engine.addEntity(myEntity)
A few years late, but the OP's selected answer is kind of deprecated because you can accomplish a delay doing:
import { Delay } from "node_modules/decentraland-ecs-utils/timer/component/delay"
const ent = new Entity
ent.addComponent(new Delay(3 * 1000, () => {
// this code will run when time is up
}))
Read the docs.
Use the utils.Delay() function in the utils library.
This function just takes the delay time in milliseconds, and the function you want to execute.
Here's the full documentation, explaining how to add the library + how to use this function, including example code:
https://www.npmjs.com/package/decentraland-ecs-utils
I want to know this start time in code.
I found this Mircosoft document about ITask.
It provides some methods to get the task's information such as application name, max run time and working directory ... but doesn't have what I need - start time.
The task start time is associated with the task trigger, not the task itself.
In the following code you need to initialize IRegisteredTask with the task that you are looking for.
Notice that a task may have more than one trigger and each could have a different type.
void GetStartTime(IRegisteredTask* pTask)
{
ITaskTrigger *pTT = NULL;
TASK_TRIGGER Trigger;
ITaskDefinition *pDefinition = NULL;
ITriggerCollection *pTriggers = NULL;
pTask->get_Definition(&pDefinition);
pDefinition->get_Triggers(&pTriggers);
LONG cTriggers = 0;
pTriggers->get_Count(&cTriggers);
while (cTriggers > 0)
{
ITrigger *pT = NULL;
pTriggers->get_Item(cTriggers, &pT);
cTriggers--;
BSTR bStart;
pT->get_StartBoundary(&bStart);
/*
bStart will be some thing like L"2013-08-01T12:05:00"
*/
::SysFreeString(bStart);
pT->Release();
}
pTriggers->Release();
}
I have a set of Akka Actors and I give about a couple of hundreds of messages to each one of them. I want to track how much time each instance of that Actor took to process all the messages that it received. What I'm doing currently is to have a state in the Actor instance as:
var startTime
var firstCall
I set both the variables when the Actor instance is first called. Is there another way that I could use to track the processing time for my Actor instances? I want to avoid having a local state in my Actor instance.
This is a good use case for context.become.
Remember than a receive block in an Akka actor is just a PartialFunction[Any, Unit], so we can wrap that in another partial function. This is the same approach taken by Akka's builtin LoggingReceive.
class TimingReceive(r: Receive, totalTime: Long)(implicit ctx: ActorContext) extends Receive {
def isDefinedAt(o: Any): Boolean = {
r.isDefinedAt(o)
}
def apply(o: Any): Unit = {
val startTime = System.nanoTime
r(o)
val newTotal = totalTime + (System.nanoTime - startTime)
log.debug("Total time so far: " + totalTime + " nanoseconds")
ctx.become(new TimingReceive(r, newTotal))
}
}
object TimingReceive {
def apply(r: Receive)(implicit ctx: ActorContext): Receive = new TimingReceive(r, 0)
}
Then you can use it like this:
class FooActor extends Actor {
def receive = TimingReceive {
case x: String => println("got " + x)
}
}
After each message, the actor will log the time taken so far. Of course, if you want to do something else with that variable, you'll have to adapt this.
This approach doesn't measure the time the actor is alive of course, only the time taken to actually process messages. Nor will it be accurate if your receive function creates a future.
This thread was useful in finding out the next run-time for a scheduled task.
How do I find out the next run time for a Scheduled Task?
But, is there also a way to simply get the next scheduled task due to run?
If I can get the date and name of the next task due to run, I can plug that date into a jQuery countdown timer, which will display a countdown to the next scheduled task, something like:
TaskABC due to run in:
12 03 20
hrs min sec
. This is for an admin interface in case you're wondering how geeky can people get:-)
EDIT
I had the same thought as Bill. But was curious if there was another way.
I poked around and apparently the internal Scheduler class maintains a list of upcoming tasks. The list is private, but you can use the same reflection technique to access it. Interestingly the list also includes system tasks like the mail spooler, session/application trackers, watchers, etecetera. So you must iterate through it until you find a "scheduled task" ie CronTabEntry
Below is a very lightly tested function that seems to do the trick in CF9. (Note, includes the CreateTimeStruct function from http://www.cflib.org).
Rules:
Returns a structure containing the name and time remaining until the next task. If no tasks were found, result.task is an empty string.
Excludes paused tasks
Usage:
result = new TaskUtil().getNextTask();
WriteDump(result);
CFC
component {
public struct function getNextTask() {
// get list of upcoming tasks from factory (UNDOCUMENTED)
local.scheduler = createObject("java", "coldfusion.server.ServiceFactory").getSchedulerService();
local.taskField = local.scheduler.getClass().getDeclaredField("_tasks");
local.taskField.setAccessible( true );
local.taskList = local.taskField.get(local.scheduler);
// taskList contains system jobs too, so we must iterate
// through the tasks to find the next "scheduled task"
local.nextTask = "";
local.tasks = local.taskList.iterator();
while ( local.tasks.hasNext() ) {
local.currTask = local.tasks.next();
local.className = local.currTask.getRunnable().getClass().name;
// exit as soon as we find a scheduled task that is NOT paused
if (local.className eq "coldfusion.scheduling.CronTabEntry"
&& !local.currTask.getRunnable().paused) {
local.nextTask = local.currTask;
break;
}
}
// if we found a task, calculate how many days, hours, etcetera
// until its next run time
local.details = { task="", remaining={} };
if ( isObject(local.nextTask) ) {
local.secondsToGo = (local.nextTask.getWhen() - now().getTime()) / 1000;
local.details.task = local.nextTask.getRunnable().task;
local.details.remaining = createTimeStruct(local.secondsToGo);
local.details.nextDate = dateAdd("s", local.nextTask.getWhen() / 1000
, "January 1 1970 00:00:00" );
}
return local.details;
}
/**
* Abbreviated version of CreateTimeStruct by Dave Pomerance
* See http://www.cflib.org/index.cfm?event=page.udfbyid&udfid=421
*
* #param timespan The timespan to convert.
* #return Returns a structure.
* #author Dave Pomerance
* #version 1, January 7, 2002
*/
public struct function CreateTimeStruct(required numeric timespan) {
var timestruct = StructNew();
var mask = "s";
// only 4 allowed values for mask - if not one of those, return blank struct
if (ListFind("d,h,m,s", mask)) {
// compute seconds
if (mask eq "s") {
timestruct.s = (timespan mod 60) + (timespan - Int(timespan));
timespan = int(timespan/60);
mask = "m";
} else timestruct.s = 0;
// compute minutes
if (mask eq "m") {
timestruct.m = timespan mod 60;
timespan = int(timespan/60);
mask = "h";
} else timestruct.m = 0;
// compute hours, days
if (mask eq "h") {
timestruct.h = timespan mod 24;
timestruct.d = int(timespan/24);
} else {
timestruct.h = 0;
timestruct.d = timespan;
}
}
return timestruct;
}
}
My first thought is to iterate Leigh's getNextRunTime(string taskName) function over the collection of tasks. You can get an array of structs containing the details of all scheduled tasks using taskArray = createobject("java","coldfusion.server.ServiceFactory").getCronService().listAll();
The key in the struct containing the task name is "task". So you can extract all the task names as an array for example, run Leigh's function on each element and determine which one will run next.
I have a C++ program that sends out various events, e.g. StatusEvent and DetectionEvent with different proto message definitions to a message service (currently Active MQ, via activemq-cpp APU). I want to write a message listener that receives these messages, parses them and writes them to cout, for debugging purposes. The listener has status_event_pb.h and detection_event_pb.h linked.
My question is: How can I parse the received event without knowing its type? I want to do something like (in pseudo code)
receive event
type = parseEventType(event);
if( type == events::StatusEventType) {
events::StatusEvent se = parseEvent(event);
// do stuff with se
}
else {
// handle the case when the event is a DetectionEvent
}
I looked at this question but I'm not sure if extensions are the right way to go here. A short code snippet pointing the way will be much appreciated. Examples on protobuf are so rare!
Thanks!
It seems extensions are indeed the way to go but I've got one last point to clear up. Here's the proto definition that I have so far:
// A general event, can be thought as base Event class for other event types.
message Event {
required int64 task_id = 1;
required string module_name = 2; // module that sent the event
extensions 100 to 199; // for different event types
}
// Extend the base Event with additional types of events.
extend Event {
optional StatusEvent statusEvent = 100;
optional DetectionEvent detectionEvent = 101;
}
// Contains one bounding box detected in a video frame,
// representing a region of interest.
message DetectionEvent {
optional int64 frame = 2;
optional int64 time = 4;
optional string label = 6;
}
// Indicate status change of current module to other modules in same service.
// In addition, parameter information that is to be used to other modules can
// be passed, e.g. the video frame dimensions.
message StatusEvent {
enum EventType {
MODULE_START = 1;
MODULE_END = 2;
MODULE_FATAL = 3;
}
required EventType type = 1;
required string module_name = 2; // module that sent the event
// Optional key-value pairs for data to be passed on.
message Data {
required string key = 1;
required string value = 2;
}
repeated Data data = 3;
}
My problem now is (1) how to know which specific event that the Event message contains and (2) make sure that it contains only one such event (according to the definition, it can contain both a StatusEvent and a DetectionEvent).
I would not use Protocol Buffers for that, but that's perhaps a combination of little use and other habits.
Anyway, I think I would use an abstract class here, to ease general handling and to contain routing information. Class that would not be defined using protobuf, and would contain a protobuf message.
class Message
{
public:
Type const& GetType() const;
Origin const& GetOrigin() const;
Destination const& GetDestination() const;
// ... other informations
template <class T>
void GetContent(T& proto) const
{
proto.ParseFromIstream(&mContent); // perhaps a try/catch ?
}
private:
// ...
std::stringstream mContent;
};
With this structure, you have both general and specific handling at the tip of your fingers:
void receive(Message const& message)
{
LOG("receive - " << message.GetType() << " from " << message.GetOrigin()
<< " to " << message.GetDestination());
if (message.GetType() == "StatusEvent")
{
StatusEvent statusEvent;
message.Decode(statusEvent);
// do something
}
else if (message.GetType() == "DetectionEvent")
{
DetectionEvent detectionEvent;
message.Decode(detectionEvent);
// do something
}
else
{
LOG("receive - Unhandled type");
}
}
Of course, it would be prettier if you used a std::unordered_map<Type,Handler> instead of a hardcoded if / else if + / else chain, but the principle remains identical:
Encode the type of message sent in the header
Decode only the header upon reception and dispatch based on this type
Decode the protobuf message in a part of the code where the type is known statically