Feature/tz cache lazy load

[ValueRaider]

The initial singleton design pattern for database access meant that lazy-loading was broken,
due to structure of '_KV' class. So errors were blocking import.
Fix = use 'peewee' proxy database and initialise when needed.

[rickturner2001]

Lazy loading is working correctly but execution will fail on read-only file systems. Were you expecting this?

[ValueRaider]

No didn't expect that. Should be fixed now plus added some unit tests.

[rickturner2001]

There are still some issues with this

import yfinance as yf

# this works
ticker = yf.Ticker("MSFT")

# This returns an empty dataframe when the code is executed in Read only fs
df = yf.download("MSFT")

print(ticker.info)
print(df.tail())

output

[*********************100%%**********************]  1 of 1 completed
1 Failed download:
['MSFT']: _TzCacheException("Error creating TzCache folder: '/root/.cache/py-yfinance' reason: [Errno 30] Read-only file system: '/root/.cache/py-yfinance'")

'address1': 'One Microsoft Way', 'city': 'Redmond', 'state': 'WA', 'zip': '98052-6399', 'country': 'United States', 'phone': '425 882 8080', 'website': 'https://www.microsoft.com', 'industry': 'Software—Infrastructure', 'industryKey':

...

Empty DataFrame
Columns: [Open, High, Low, Close, Adj Close, Volume]
Index: []

[ValueRaider]

I can't reproduce with little effort, so can you re-run after yf.enable_debug_mode()

[rickturner2001]

DEBUG    Entering download()
DEBUG     Disabling multithreading because DEBUG logging enabled
DEBUG     Entering history()
ERROR     
          1 Failed download:
ERROR     ['MSFT']: _TzCacheException("Error creating TzCache folder: '/root/.cache/py-yfinance' reason: [Errno 30] Read-only file system: '/root/.cache/py-yfinance'")
DEBUG     ['MSFT']: Traceback (most recent call last):
            File "/yfinance/utils.py", line 981, in _initialise
              _os.makedirs(cls._cache_dir)
            File "<frozen os>", line 225, in makedirs
          OSError: [Errno 30] Read-only file system: '/root/.cache/py-yfinance'
          
          During handling of the above exception, another exception occurred:
          
          Traceback (most recent call last):
            File "/yfinance/multi.py", line 275, in _download_one
              data = Ticker(ticker, session=session).history(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            File "/yfinance/utils.py", line 114, in wrapper
              result = func(*args, **kwargs)
                       ^^^^^^^^^^^^^^^^^^^^^
            File "/yfinance/base.py", line 148, in history
              tz = self._get_ticker_tz(proxy, timeout)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
            File "/yfinance/base.py", line 1645, in _get_ticker_tz
              tz = cache.lookup(self.ticker)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
            File "/yfinance/utils.py", line 1035, in lookup
              self.initialise()
            File "/yfinance/utils.py", line 1028, in initialise
              db = _DBManager.get_database()
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
            File "/yfinance/utils.py", line 961, in get_database
              cls._initialise()
            File "/yfinance/utils.py", line 983, in _initialise
              raise _TzCacheException(f"Error creating TzCache folder: '{cls._cache_dir}' reason: {err}")
          yfinance.utils._TzCacheException: Error creating TzCache folder: '/root/.cache/py-yfinance' reason: [Errno 30] Read-only file system: '/root/.cache/py-yfinance'

Reproduce locally

Dockerfile

FROM python:3.11

COPY . .
RUN pip install -r requirements.txt

CMD ["python", "your_test_script.py"]

Build the container

docker build -t yfinance-test .

Run the container in a read-only env

docker run --read-only yfinance-test

[ValueRaider]

Line numbers don't match code. Did you git pull ? It should be impossible for a _TzCacheException to propagate up, because it only has 1 route where it is caught.

[rickturner2001]

Nope, you were right, I wasn't up to date. Everything works perfectly. Can you make a beta release?