GUI implementation of GamaServer: the play command doesn't wait before returning the `CommandExecutedSuccessfully` message

[AlexisDrogoul]

I noticed another problem specific to the GUI implementation: the play command doesn't wait for everything to be initialized before returning the CommandExecutedSuccessfully message which leads to errors in client programs that do not exist in purely server mode.

Here is an example python client program:

import asyncio
from pathlib import Path
from typing import Dict

from gama_client.sync_client import GamaSyncClient
from gama_client.message_types import MessageTypes

async def async_command_answer_handler(message: Dict):
    print("Here is the answer to an async command: ", message)

async def gama_server_message_handler(message: Dict):
    print("I just received a message from Gama-server and it's not an answer to a command!")
    print("Here it is:", message)

async def main():

    # Experiment and Gama-server constants
    server_url = "localhost"
    server_port = 1000
    gaml_file_path = str(Path(__file__).parents[0] / "predatorPrey.gaml")
    exp_name = "prey_predator"
    exp_parameters = [{"type": "int", "name": "nb_preys_init", "value": 100}]

    client = GamaSyncClient(server_url, server_port, async_command_answer_handler, gama_server_message_handler)

    print("connecting to Gama server")
    await client.connect()

    print("initialize a gaml model")
    gama_response = client.sync_load(gaml_file_path, exp_name, True, True, True, True, parameters=exp_parameters)
    try:
        experiment_id = gama_response["content"]
    except Exception as e:
        print("error while initializing", gama_response, e)
        return

    print("initialization successful, running the model")
    gama_response = client.sync_play(experiment_id)
    if gama_response["type"] != MessageTypes.CommandExecutedSuccessfully.value:
        print("error while trying to run the experiment", gama_response)
        return

    print("wait 10sec")
    await asyncio.sleep(10)

    print("pausing the model")
    gama_response = client.sync_pause(experiment_id)
    if gama_response["type"] != MessageTypes.CommandExecutedSuccessfully.value:
        print("Unable to pause the experiment", gama_response)
        return

    gama_response = client.sync_expression(experiment_id, r"cycle")
    print("asking simulation the value of: cycle=", gama_response["content"])

    gama_response = client.sync_expression(experiment_id, r"nb_preys/nb_preys_init")
    print("asking simulation the value of: nb_preys/nb_preys_init=",  gama_response["content"])

    print("asking gama to run 10 more steps of the experiment")
    gama_response = client.sync_step(experiment_id, 100, True)
    if gama_response["type"] != MessageTypes.CommandExecutedSuccessfully.value:
        print("Unable to execute 10 new steps in the experiment", gama_response)
        return

    gama_response = client.sync_expression(experiment_id, r"cycle")
    print("asking simulation the value of: cycle=", gama_response["content"])

    print("making async calls (non-blocking)")
    print("asking to execute 500 steps async")
    await client.step(experiment_id, 500, False)
    print("waiting 2sec")
    await asyncio.sleep(2)
    print("asking current cycle (async)")
    await client.expression(experiment_id, "cycle")

    print("everything done, waiting 20sec to simulate some other process running")
    await asyncio.sleep(20)

    print("killing the simulation")
    gama_response = client.sync_stop(experiment_id)
    if gama_response["type"] != MessageTypes.CommandExecutedSuccessfully.value:
        print("Unable to stop the experiment", gama_response)
        return

    print("closing socket just to be sure")
    client.sync_close_connection()

if __name__ == "__main__":
    asyncio.run(main())

if you comment out the wait 10sec line and the following, it breaks the rest of the program when interacting with GUI

Originally posted by @lesquoyb in https://github.com/gama-platform/gama/issues/3910#issuecomment-1774593894

[AlexisDrogoul]

@hqnghi88 @lesquoyb I have committed a refactoring of IExperimentController (and its subclasses), which only exposes methods that explicitly require an argument telling to run it synchronously or asynchronously. This will allow to test which ones should be synced or not. I have changed also the corresponding GAMA methods and made the "play"/"pause"/"reload" commands in GUI call the synchronous versions. Thanks for testing this !

[AlexisDrogoul]

I introduced a bug when dealing with this issue: reloading a simulation does not reopen its parameters view (actually it seems to be an on/off state, as it is reopened if one reloads it one more time...).

[AlexisDrogoul]

This one has been tested and seems to work well.