Test server before returning it in ansys.dpf.core.server.connect_to_server

[PProfizi]

Before submitting the issue

• I have checked for Compatibility issues
• I have searched among the existing issues
• I am using a Python virtual environment

Description of the bug

When using ansys-dpf-core 0.5.2 with InProcess by default and starting a DPF server on a docker, then trying to connect to it from outside, the connect_to_server method might finish and return a GrpcServer, however consequent commands can fail due to the server actually not being ready.

The connect_to_server method should further test the connection before returning the DpfServer object.
One should also make a GrpcServer method available to test the status of the server, much like what is done in check_ansys_grpc_dpf_version function. This could also be done for the LegacyGrpcServer.

A trick used by @janvonrickenbach to check the server is finally ready is:

timeout = 5
import time

tstart = time.time()
while ((time.time() - tstart) < timeout):
    time.sleep(0.001)
    try:
        server.version
        break
    except Exception as e:
        pass
server.version

For information this can take up to 3 seconds depending on the docker environment.

Steps To Reproduce

Run DPF on docker
Then connect to it
server = connect_to_server(...)
Then ask for its version
version = server.version

Which Operating System are you using?

Linux

Which Python version are you using?

3.7

Installed packages

NA

[PProfizi]

Hi @janvonrickenbach is this still an ongoing request?
When looking at the current state of the connect_to_server method, I think one can only connect to an already running DPF server. I do not see a case where we start a remote server.
To clarify, is the need for a check due to having previously started a server, then trying to connect to it too quickly?

[janvonrickenbach]

Hi @PProfizi

Yes it looks like the connect method now ensures that the server is always in a valid state before it returns (in _check_first_call). Closing.