config: enforce that SimpleConfig is singleton

related: #5629

electrum/__init__.py

@@ -5,7 +5,7 @@ from .storage import WalletStorage
 from .coinchooser import COIN_CHOOSERS
 from .network import Network, pick_random_server
 from .interface import Interface
-from .simple_config import SimpleConfig, get_config, set_config
+from .simple_config import SimpleConfig
 from . import bitcoin
 from . import transaction
 from . import daemon

electrum/gui/qt/qrcodewidget.py

@@ -9,6 +9,8 @@ from PyQt5.QtWidgets import (
 
 import electrum
 from electrum.i18n import _
+from electrum.simple_config import SimpleConfig
+
 from .util import WindowModalDialog
 
 
@@ -105,7 +107,7 @@ class QRDialog(WindowModalDialog):
         hbox = QHBoxLayout()
         hbox.addStretch(1)
 
-        config = electrum.get_config()
+        config = SimpleConfig.get_instance()
         if config:
             filename = os.path.join(config.path, "qrcode.png")
 

electrum/gui/qt/qrtextedit.py

@@ -2,6 +2,7 @@ from PyQt5.QtWidgets import QFileDialog
 
 from electrum.i18n import _
 from electrum.plugin import run_hook
+from electrum.simple_config import SimpleConfig
 
 from .util import ButtonsTextEdit, MessageBoxMixin, ColorScheme
 
@@ -54,9 +55,9 @@ class ScanQRTextEdit(ButtonsTextEdit, MessageBoxMixin):
             self.setText(data)
 
     def qr_input(self):
-        from electrum import qrscanner, get_config
+        from electrum import qrscanner
         try:
-            data = qrscanner.scan_barcode(get_config().get_video_device())
+            data = qrscanner.scan_barcode(SimpleConfig.get_instance().get_video_device())
         except BaseException as e:
             self.show_error(repr(e))
             data = ''

electrum/lnchannel.py

@@ -35,7 +35,6 @@ from .util import bfh, bh2u, PR_PAID, PR_FAILED
 from .bitcoin import TYPE_SCRIPT, TYPE_ADDRESS
 from .bitcoin import redeem_script_to_address
 from .crypto import sha256, sha256d
-from .simple_config import get_config
 from .transaction import Transaction
 from .logging import Logger
 

electrum/lnpeer.py

@@ -18,7 +18,6 @@ from datetime import datetime
 
 import aiorpcx
 
-from .simple_config import get_config
 from .crypto import sha256, sha256d
 from . import bitcoin
 from . import ecc

electrum/network.py

@@ -224,7 +224,7 @@ class UntrustedServerReturnedError(NetworkException):
         return f"<UntrustedServerReturnedError original_exception: {repr(self.original_exception)}>"
 
 
-INSTANCE = None
+_INSTANCE = None
 
 
 class Network(Logger):
@@ -235,8 +235,9 @@ class Network(Logger):
     LOGGING_SHORTCUT = 'n'
 
     def __init__(self, config: SimpleConfig):
-        global INSTANCE
-        INSTANCE = self
+        global _INSTANCE
+        assert _INSTANCE is None, "Network is a singleton!"
+        _INSTANCE = self
 
         Logger.__init__(self)
 
@@ -322,7 +323,7 @@ class Network(Logger):
 
     @staticmethod
     def get_instance() -> Optional["Network"]:
-        return INSTANCE
+        return _INSTANCE
 
     def with_recent_servers_lock(func):
         def func_wrapper(self, *args, **kwargs):

electrum/simple_config.py

@@ -31,19 +31,9 @@ FEERATE_STATIC_VALUES = [1000, 2000, 5000, 10000, 20000, 30000,
 FEERATE_REGTEST_HARDCODED = 180000  # for eclair compat
 
 
-config = {}
 _logger = get_logger(__name__)
 
 
-def get_config():
-    global config
-    return config
-
-
-def set_config(c):
-    global config
-    config = c
-
 def estimate_fee(tx_size_bytes: int) -> int:
     def use_fallback_feerate():
         fee_per_kb = FEERATE_FALLBACK_STATIC_FEE
@@ -61,6 +51,10 @@ def estimate_fee(tx_size_bytes: int) -> int:
 FINAL_CONFIG_VERSION = 3
 
 
+_INSTANCE = None
+_ENFORCE_SIMPLECONFIG_SINGLETON = True  # disabled in tests
+
+
 class SimpleConfig(Logger):
     """
     The SimpleConfig class is responsible for handling operations involving
@@ -74,6 +68,12 @@ class SimpleConfig(Logger):
 
     def __init__(self, options=None, read_user_config_function=None,
                  read_user_dir_function=None):
+        # note: To be honest, singletons are bad design... :/
+        #       However currently we somewhat rely on config being one.
+        global _INSTANCE
+        if _ENFORCE_SIMPLECONFIG_SINGLETON:
+            assert _INSTANCE is None, "SimpleConfig is a singleton!"
+        _INSTANCE = self
 
         if options is None:
             options = {}
@@ -120,8 +120,9 @@ class SimpleConfig(Logger):
         if self.requires_upgrade():
             self.upgrade()
 
-        # Make a singleton instance of 'self'
-        set_config(self)
+    @staticmethod
+    def get_instance() -> Optional["SimpleConfig"]:
+        return _INSTANCE
 
     def electrum_path(self):
         # Read electrum_path from command line

electrum/tests/__init__.py

@@ -2,6 +2,7 @@ import unittest
 import threading
 
 from electrum import constants
+from electrum import simple_config
 
 
 # Set this locally to make the test suite run faster.
@@ -11,6 +12,9 @@ from electrum import constants
 FAST_TESTS = False
 
 
+simple_config._ENFORCE_SIMPLECONFIG_SINGLETON = False
+
+
 # some unit tests are modifying globals; sorry.
 class SequentialTestCase(unittest.TestCase):
 

electrum/wallet.py

@@ -47,7 +47,7 @@ from .util import (NotEnoughFunds, UserCancelled, profiler,
                    InvalidPassword, format_time, timestamp_to_datetime, Satoshis,
                    Fiat, bfh, bh2u, TxMinedInfo, quantize_feerate, create_bip21_uri, OrderedDictWithIndex)
 from .util import PR_TYPE_ADDRESS, PR_TYPE_BIP70, PR_TYPE_LN
-from .simple_config import get_config
+from .simple_config import SimpleConfig
 from .bitcoin import (COIN, TYPE_ADDRESS, is_address, address_to_script,
                       is_minikey, relayfee, dust_threshold)
 from .crypto import sha256d
@@ -71,7 +71,6 @@ from .paymentrequest import PaymentRequest
 
 if TYPE_CHECKING:
     from .network import Network
-    from .simple_config import SimpleConfig
 
 
 _logger = get_logger(__name__)
@@ -236,7 +235,9 @@ class Abstract_Wallet(AddressSynchronizer):
 
         self.contacts = Contacts(self.storage)
         self._coin_price_cache = {}
-        self.config = get_config()
+        # TODO config should be passed as a param instead? SimpleConfig should not be a singleton.
+        self.config = SimpleConfig.get_instance()
+        assert self.config is not None, "config must not be None"
         self.lnworker = LNWallet(self) if self.config.get('lightning') else None
 
     def stop_threads(self):