sobjectizer VS so5extra

Message Delivery Tracing aims to debug an application built on top of SObjectizer. In essence, it logs the primary stages of the message delivery process, allowing visibility into whether there is a suitable subscriber with the corresponding event handler.

An additional rationale for structuring cooperations in hierarchies is to facilitate the sharing and propagation of dispatchers. A recent update of SObjectizer includes new functionalities that allow access to both agent and cooperation dispatchers. This enhancement was prompted by feedback provided by a user and myself.

If a stop signal arrives, it will be enqueued at the end as a demand for image_producer_callback. This means, it will be processed after the other 6 demands currently in the queue. Maybe this is not an issue but in some cases it might be. At this point, another feature of SObjectizer is to consider: agent priorities. Essentially, this feature allows for the demands to be handled in different orders based on the priorities of agents. In this context, if we assign image_producer_callback a higher priority than others, the “stop signal” would be processed before the rest of the requests.

The real solution consists in using another slick feature of SObjectizer: mutable messages.

However, this kind of filtering is inefficient and might result in a significant run-time cost. Indeed, every empty cv::Mat follows all the message handling workflow, only to be thrown out. Although we expect that empty images will be sporadic, a more idiomatic approach exists: delivery filters.

SObjectizer’s agent states are quite sophisticated and provide some utilities that might be useful for developing a working solution. First of all, image_viewer can be modeled as a two-state agent:

An alternative way is using SObjectizer’s timers.

Those who came looking for actor model examples should check out sobjectizer

In sobjectizer the ownership is held by "environment" , while in rotor each thread must held appropriate context, when actor environment is running.

May be actor frameworks like caf, sobjectizer or rotor is something, that you are looking for.

In this case, it’s possible that we need to craft and use a custom dispatcher for the purpose. This might be not an easy task in general but we know where to start as we learnt in this previous post. For example, in calico we have discussed and crafted a do_gui_message_loop() function to guarantee the OpenCV drawing happens on the calling thread – and we call this function from the main thread. An alternative solution consists in developing a customized dispatcher. Just to share another example, SObjectizer’s companion project so5extra, provides some battle-tested dispatchers tailored for boost ASIO.

Have you ever tried to cancel a timer on Alexa…while it was about to ring?! In SObjectizer, message cancellation is not strictly guaranteed. Indeed, a delayed message won’t be revoked if it left the timer thread already. This happens if you try cancelling the message too late, in that case there are good chances it will be delivered anyway. For example, if you send a message with delay 100ms and you try cancelling after 100ms then it might have left the timer thread already. There are ways to prevent this problem but won’t be discussed here. If you are interested, have a look at this.