Feature/tz cache lazy load

tests/utils.py

@@ -20,9 +20,7 @@
 import os
 
 
-class TestUtils(unittest.TestCase):
-    session = None
-
+class TestCache(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
         cls.tempCacheDir = tempfile.TemporaryDirectory()
@@ -51,9 +49,41 @@ def test_setTzCacheLocation(self):
 
         self.assertTrue(os.path.exists(os.path.join(self.tempCacheDir.name, "tkr-tz.db")))
 
+
+class TestCacheNoPermission(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        yf.set_tz_cache_location("/root/yf-cache")
+
+    def test_tzCacheRootStore(self):
+        # Test that if cache path in read-only filesystem, no exception.
+        tkr = 'AMZN'
+        tz1 = "America/New_York"
+
+        # During attempt to store, will discover cannot write
+        yf.utils.get_tz_cache().store(tkr, tz1)
+
+        # Handling the store failure replaces cache with a dummy
+        cache = yf.utils.get_tz_cache()
+        self.assertTrue(cache.dummy)
+        cache.store(tkr, tz1)
+
+    def test_tzCacheRootLookup(self):
+        # Test that if cache path in read-only filesystem, no exception.
+        tkr = 'AMZN'
+        # During attempt to lookup, will discover cannot write
+        yf.utils.get_tz_cache().lookup(tkr)
+
+        # Handling the lookup failure replaces cache with a dummy
+        cache = yf.utils.get_tz_cache()
+        self.assertTrue(cache.dummy)
+        cache.lookup(tkr)
+
+
 def suite():
     suite = unittest.TestSuite()
-    suite.addTest(TestUtils('Test utils'))
+    suite.addTest(TestCache('Test cache'))
+    suite.addTest(TestCacheNoPermission('Test cache no permission'))
     return suite
 
 

yfinance/utils.py

@@ -934,21 +934,15 @@ class _TzCacheManager:
     _tz_cache = None
 
     @classmethod
-    def get_tz(cls):
+    def get_tz_cache(cls):
         if cls._tz_cache is None:
             with _cache_init_lock:
                 cls._initialise()
         return cls._tz_cache
 
     @classmethod
     def _initialise(cls, cache_dir=None):
-        try:
-            cls._tz_cache = _TzCache()
-        except _TzCacheException as err:
-            get_yf_logger().info(f"Failed to create TzCache, reason: {err}. "
-                                 "TzCache will not be used. "
-                                 "Tip: You can direct cache to use a different location with 'set_tz_cache_location(mylocation)'")
-            cls._tz_cache = _TzCacheDummy()
+        cls._tz_cache = _TzCache()
 
 
 class _DBManager:
@@ -1008,34 +1002,78 @@ def get_location(cls):
 _atexit.register(_DBManager.close_db)
 
 
+db_proxy = _peewee.Proxy()
 class _KV(_peewee.Model):
     key = _peewee.CharField(primary_key=True)
     value = _peewee.CharField(null=True)
 
     class Meta:
-        try:
-            database = _DBManager.get_database()
-        except Exception:
-            # This code runs at import, so Logger won't be ready yet, so must discard exception.
-            database = None
+        database = db_proxy
         without_rowid = True
 
 
 class _TzCache:
     def __init__(self):
-        db = _DBManager.get_database()
+        self.initialised = -1
+        self.db = None
+        self.dummy = False
+
+    def get_db(self):
+        if self.db is not None:
+            return self.db
+
+        try:
+            self.db = _DBManager.get_database()
+        except _TzCacheException as err:
+            get_yf_logger().info(f"Failed to create TzCache, reason: {err}. "
+                                 "TzCache will not be used. "
+                                 "Tip: You can direct cache to use a different location with 'set_tz_cache_location(mylocation)'")
+            self.dummy = True
+            return None
+        return self.db
+
+    def initialise(self):
+        if self.initialised != -1:
+            return
+
+        db = self.get_db()
+        if db is None:
+            self.initialised = 0  # failure
+            return
+
         db.connect()
+        db_proxy.initialize(db)
         db.create_tables([_KV])
-
+        self.initialised = 1  # success
 
     def lookup(self, key):
+        if self.dummy:
+            return None
+
+        if self.initialised == -1:
+            self.initialise()
+
+        if self.initialised == 0:  # failure
+            return None
+
         try:
             return _KV.get(_KV.key == key).value
         except _KV.DoesNotExist:
             return None
 
     def store(self, key, value):
-        db = _DBManager.get_database()
+        if self.dummy:
+            return
+
+        if self.initialised == -1:
+            self.initialise()
+
+        if self.initialised == 0:  # failure
+            return
+
+        db = self.get_db()
+        if db is None:
+            return
         try:
             if value is None:
                 q = _KV.delete().where(_KV.key == key)
@@ -1054,13 +1092,7 @@ def store(self, key, value):
 
 
 def get_tz_cache():
-    """
-    Get the timezone cache, initializes it and creates cache folder if needed on first call.
-    If folder cannot be created for some reason it will fall back to initialize a
-    dummy cache with same interface as real cash.
-    """
-    # as this can be called from multiple threads, protect it.
-    return _TzCacheManager.get_tz()
+    return _TzCacheManager.get_tz_cache()
 
 
 def set_tz_cache_location(cache_dir: str):