Refactor rates API to use time cache

bitcash/network/rates.py

@@ -1,11 +1,9 @@
 from collections import OrderedDict
 from decimal import ROUND_DOWN
-from functools import wraps
-from time import time
 
 import requests
 from bitcash.network.http import session
-from bitcash.utils import Decimal
+from bitcash.utils import Decimal, time_cache
 
 DEFAULT_CACHE_TIME = 60
 
@@ -651,42 +649,9 @@ def currency_to_satoshi(amount, currency):
     return int(satoshis * Decimal(amount))
 
 
-class CachedRate:
-    __slots__ = ("satoshis", "last_update")
-
-    def __init__(self, satoshis, last_update):
-        self.satoshis = satoshis
-        self.last_update = last_update
-
-
-def currency_to_satoshi_local_cache(f):
-    start_time = time()
-
-    cached_rates = dict(
-        [(currency, CachedRate(None, start_time)) for currency in EXCHANGE_RATES.keys()]
-    )
-
-    @wraps(f)
-    def wrapper(amount, currency):
-        now = time()
-
-        cached_rate = cached_rates[currency]
-
-        if (
-            not cached_rate.satoshis
-            or now - cached_rate.last_update > DEFAULT_CACHE_TIME
-        ):
-            cached_rate.satoshis = EXCHANGE_RATES[currency]()
-            cached_rate.last_update = now
-
-        return int(cached_rate.satoshis * Decimal(amount))
-
-    return wrapper
-
-
-@currency_to_satoshi_local_cache
-def currency_to_satoshi_local_cached():
-    pass  # pragma: no cover
+@time_cache(max_age=DEFAULT_CACHE_TIME, cache_size=len(EXCHANGE_RATES))
+def _currency_to_satoshi_cached(currency):
+    return EXCHANGE_RATES[currency]()
 
 
 def currency_to_satoshi_cached(amount, currency):
@@ -700,7 +665,8 @@ def currency_to_satoshi_cached(amount, currency):
     :type currency: ``str``
     :rtype: ``int``
     """
-    return currency_to_satoshi_local_cached(amount, currency)
+    satoshis = _currency_to_satoshi_cached(currency)
+    return int(satoshis * Decimal(amount))
 
 
 def satoshi_to_currency(num, currency):

tests/network/test_rates.py

@@ -1,11 +1,14 @@
 from time import sleep, time
 
+from _pytest.monkeypatch import MonkeyPatch
 import bitcash
+from bitcash.network import rates as _rates
 from bitcash.network.rates import (
     RatesAPI,
     bch_to_satoshi,
     currency_to_satoshi,
     currency_to_satoshi_cached,
+    EXCHANGE_RATES,
     mbch_to_satoshi,
     satoshi_to_currency,
     satoshi_to_currency_cached,
@@ -73,38 +76,45 @@ def test_rates_close():
     assert rates[-1] / rates[0] < 1.1 and rates[-1] / rates[0] > 0.9
 
 
+def _dummy_usd_to_satoshi():
+    sleep(1)
+    return 1
+
+
+DUMMY_EXCHANGE_RATES = {"usd": _dummy_usd_to_satoshi}
+
+
 class TestRateCache:
-    def test_cache(self):
-        sleep(0.2)
+    def setup_method(self):
+        self.monkeypatch = MonkeyPatch()
 
+    def test_cache(self):
+        self.monkeypatch.setattr(_rates, "EXCHANGE_RATES", DUMMY_EXCHANGE_RATES)
         start_time = time()
-        set_rate_cache_time(0)
         currency_to_satoshi_cached(1, "usd")
         initial_time = time() - start_time
 
         start_time = time()
-        set_rate_cache_time(60)
-        currency_to_satoshi_cached(1, "usd")
+        currency_to_satoshi_cached(2, "usd")
         cached_time = time() - start_time
 
         assert initial_time > cached_time
+        self.monkeypatch.setattr(_rates, "EXCHANGE_RATES", EXCHANGE_RATES)
 
     def test_expires(self):
-        sleep(0.2)
-
-        set_rate_cache_time(0)
+        self.monkeypatch.setattr(_rates, "EXCHANGE_RATES", DUMMY_EXCHANGE_RATES)
+        set_rate_cache_time(1.2)
         currency_to_satoshi_cached(1, "usd")
 
         start_time = time()
-        set_rate_cache_time(60)
-        currency_to_satoshi_cached(1, "usd")
+        currency_to_satoshi_cached(2, "usd")
         cached_time = time() - start_time
 
         sleep(0.2)
 
         start_time = time()
-        set_rate_cache_time(0.1)
-        currency_to_satoshi_cached(1, "usd")
+        currency_to_satoshi_cached(3, "usd")
         update_time = time() - start_time
 
         assert update_time > cached_time
+        self.monkeypatch.setattr(_rates, "EXCHANGE_RATES", EXCHANGE_RATES)