Add check for file existance before fetching from the server
What is it about?
Addresses #2 (closed)
Currently vv fetches all the files it needs without checking if those files already exist. This wastes bandwidth, time and puts unnecessary load on swpc-noaa servers. This MR tries to fix that.
How do I test?
Till the logging MR is merged (hopefully before this one), you can run the following script in the terminal and try to see a time difference.
Note that the files will be downloaded to the current working directory. So it is advisable to run the program in an empty directory.
# First run: runtime is 32.6 s
❯ time python sample_script.py
python sample_script.py 0.70s user 0.23s system 2% cpu 32.602 total
# Second run: runtime is 0.4 s
❯ time python sample_script.py
python sample_script.py 0.53s user 0.21s system 166% cpu 0.442 total
Signed-off-by: Adithya Venkateswaran adithyav1511@gmail.com