refactor(settings): make HathorSettings always return the same instance

hathor/builder/cli_builder.py

@@ -55,7 +55,7 @@ def check_or_raise(self, condition: bool, message: str) -> None:
     def create_manager(self, reactor: PosixReactorBase, args: Namespace) -> HathorManager:
         import hathor
         from hathor.conf import HathorSettings
-        from hathor.conf.get_settings import get_settings_filepath, get_settings_module
+        from hathor.conf.get_settings import get_settings_source
         from hathor.daa import TestMode, _set_test_mode
         from hathor.event.storage import EventMemoryStorage, EventRocksDBStorage, EventStorage
         from hathor.event.websocket.factory import EventWebsocketFactory
@@ -74,8 +74,7 @@ def create_manager(self, reactor: PosixReactorBase, args: Namespace) -> HathorMa
         settings = HathorSettings()
 
         # only used for logging its location
-        settings_module = get_settings_module()
-        settings_source = settings_module.__file__ if settings_module is not None else get_settings_filepath()
+        settings_source = get_settings_source()
 
         self.log = logger.new()
         self.reactor = reactor

hathor/conf/get_settings.py

@@ -14,8 +14,7 @@
 
 import importlib
 import os
-from types import ModuleType
-from typing import Optional
+from typing import NamedTuple, Optional
 
 from structlog import get_logger
 
@@ -24,8 +23,14 @@
 
 logger = get_logger()
 
-_settings_filepath: Optional[str] = None
-_config_file: Optional[str] = None
+
+class _SettingsMetadata(NamedTuple):
+    source: str
+    is_yaml: bool
+    settings: Settings
+
+
+_settings_singleton: Optional[_SettingsMetadata] = None
 
 
 def HathorSettings() -> Settings:
@@ -37,52 +42,57 @@ def HathorSettings() -> Settings:
 
     If neither is set, or if the module import fails, the mainnet configuration is returned.
     """
-    settings_module = get_settings_module()
 
-    if settings_module is not None:
-        log = logger.new()
-        log.warn(
-            "Setting a config module via the 'HATHOR_CONFIG_FILE' env var will be deprecated soon. "
-            "Use the '--config-yaml' CLI option or the 'HATHOR_CONFIG_YAML' env var to set a yaml filepath instead."
-        )
-        settings = getattr(settings_module, 'SETTINGS')
-        assert isinstance(settings, Settings)
-        return settings
+    settings_module_filepath = os.environ.get('HATHOR_CONFIG_FILE')
+    if settings_module_filepath is not None:
+        return _load_settings_singleton(settings_module_filepath, is_yaml=False)
 
-    settings_filepath = get_settings_filepath()
+    settings_yaml_filepath = os.environ.get('HATHOR_CONFIG_YAML', conf.MAINNET_SETTINGS_FILEPATH)
+    return _load_settings_singleton(settings_yaml_filepath, is_yaml=True)
 
-    return Settings.from_yaml(filepath=settings_filepath)
 
+def get_settings_source() -> str:
+    """ Returns the path of the settings module or YAML file that was loaded.
+
+    XXX: Will raise an assertion error if HathorSettings() wasn't used before.
+    """
+    global _settings_singleton
+    assert _settings_singleton is not None, 'HathorSettings() not called before'
+    return _settings_singleton.source
 
-def get_settings_module() -> Optional[ModuleType]:
-    global _config_file
-    # Import config file for network
-    config_file = os.environ.get('HATHOR_CONFIG_FILE')
-    if _config_file is None:
-        _config_file = config_file
-    elif _config_file != config_file:
-        raise Exception('loading config twice with a different file')
 
-    if not config_file:
-        return None
+def _load_settings_singleton(source: str, *, is_yaml: bool) -> Settings:
+    global _settings_singleton
 
-    try:
-        module = importlib.import_module(config_file)
-    except ModuleNotFoundError:
-        default_file = 'hathor.conf.mainnet'
-        module = importlib.import_module(default_file)
+    if _settings_singleton is not None:
+        if _settings_singleton.is_yaml != is_yaml:
+            raise Exception('loading config twice with a different file type')
+        if _settings_singleton.source != source:
+            raise Exception('loading config twice with a different file')
 
-    return module
+        return _settings_singleton.settings
 
+    settings_loader = _load_yaml_settings if is_yaml else _load_module_settings
+    _settings_singleton = _SettingsMetadata(
+        source=source,
+        is_yaml=is_yaml,
+        settings=settings_loader(source)
+    )
 
-def get_settings_filepath() -> str:
-    global _settings_filepath
+    return _settings_singleton.settings
 
-    new_settings_filepath = os.environ.get('HATHOR_CONFIG_YAML', conf.MAINNET_SETTINGS_FILEPATH)
 
-    if _settings_filepath is not None and _settings_filepath != new_settings_filepath:
-        raise Exception('loading config twice with a different file')
+def _load_module_settings(module_path: str) -> Settings:
+    log = logger.new()
+    log.warn(
+        "Setting a config module via the 'HATHOR_CONFIG_FILE' env var will be deprecated soon. "
+        "Use the '--config-yaml' CLI option or the 'HATHOR_CONFIG_YAML' env var to set a yaml filepath instead."
+    )
+    settings_module = importlib.import_module(module_path)
+    settings = getattr(settings_module, 'SETTINGS')
+    assert isinstance(settings, Settings)
+    return settings
 
-    _settings_filepath = new_settings_filepath
 
-    return new_settings_filepath
+def _load_yaml_settings(filepath: str) -> Settings:
+    return Settings.from_yaml(filepath=filepath)