#353 Cache aliases in a temporary file

tests/conftest.py

@@ -10,3 +10,8 @@ def no_memoize(monkeypatch):
 @pytest.fixture
 def settings():
     return Mock(debug=False, no_colors=True)
+
+
+@pytest.fixture(autouse=True)
+def no_cache(monkeypatch):
+    monkeypatch.setattr('thefuck.utils.cache.disabled', True)

tests/test_utils.py

@@ -1,8 +1,9 @@
+from contextlib import contextmanager
 import pytest
 from mock import Mock
-from thefuck.utils import wrap_settings,\
+from thefuck.utils import wrap_settings, \
     memoize, get_closest, get_all_executables, replace_argument, \
-    get_all_matched_commands, is_app, for_app
+    get_all_matched_commands, is_app, for_app, cache
 from thefuck.types import Settings
 from tests.utils import Command
 
@@ -34,7 +35,6 @@ def test_no_memoize():
 
 
 class TestGetClosest(object):
-
     def test_when_can_match(self):
         assert 'branch' == get_closest('brnch', ['branch', 'status'])
 
@@ -116,3 +116,56 @@ def test_for_app(script, names, result):
         return True
 
     assert match(Command(script), None) == result
+
+
+class TestCache(object):
+    @pytest.fixture(autouse=True)
+    def enable_cache(self, monkeypatch):
+        monkeypatch.setattr('thefuck.utils.cache.disabled', False)
+
+    @pytest.fixture
+    def shelve(self, mocker):
+        value = {}
+
+        @contextmanager
+        def _shelve(path):
+            yield value
+
+        mocker.patch('thefuck.utils.shelve.open', new_callable=lambda: _shelve)
+        return value
+
+    @pytest.fixture(autouse=True)
+    def mtime(self, mocker):
+        mocker.patch('thefuck.utils.os.path.getmtime', return_value=0)
+
+    @pytest.fixture
+    def fn(self):
+        @cache('~/.bashrc')
+        def fn():
+            return 'test'
+
+        return fn
+
+    def test_with_blank_cache(self, shelve, fn):
+        assert shelve == {}
+        assert fn() == 'test'
+        assert shelve == {
+            'tests.test_utils.<function TestCache.fn.<locals>.fn ': {
+                'etag': '0', 'value': 'test'}}
+
+    def test_with_filled_cache(self, shelve, fn):
+        cache_value = {
+            'tests.test_utils.<function TestCache.fn.<locals>.fn ': {
+                'etag': '0', 'value': 'new-value'}}
+        shelve.update(cache_value)
+        assert fn() == 'new-value'
+        assert shelve == cache_value
+
+    def test_when_etag_changed(self, shelve, fn):
+        shelve.update({
+            'tests.test_utils.<function TestCache.fn.<locals>.fn ': {
+                'etag': '-1', 'value': 'old-value'}})
+        assert fn() == 'test'
+        assert shelve == {
+            'tests.test_utils.<function TestCache.fn.<locals>.fn ': {
+                'etag': '0', 'value': 'test'}}

thefuck/shells.py

@@ -9,7 +9,7 @@ from subprocess import Popen, PIPE
 from time import time
 import io
 import os
-from .utils import DEVNULL, memoize
+from .utils import DEVNULL, memoize, cache
 
 
 class Generic(object):
@@ -85,6 +85,7 @@ class Bash(Generic):
         return name, value
 
     @memoize
+    @cache('.bashrc', '.bash_profile')
     def get_aliases(self):
         proc = Popen(['bash', '-ic', 'alias'], stdout=PIPE, stderr=DEVNULL)
         return dict(
@@ -169,6 +170,7 @@ class Zsh(Generic):
         return name, value
 
     @memoize
+    @cache('.zshrc')
     def get_aliases(self):
         proc = Popen(['zsh', '-ic', 'alias'], stdout=PIPE, stderr=DEVNULL)
         return dict(

thefuck/utils.py

@@ -1,6 +1,8 @@
 from difflib import get_close_matches
 from functools import wraps
+import shelve
 from decorator import decorator
+import tempfile
 
 import os
 import pickle
@@ -150,3 +152,40 @@ def for_app(*app_names):
             return False
 
     return decorator(_for_app)
+
+
+def cache(*depends_on):
+    """Caches function result in temporary file.
+
+    Cache will be expired when modification date of files from `depends_on`
+    will be changed.
+
+    Function wrapped in `cache` should be arguments agnostic.
+
+    """
+    def _get_mtime(name):
+        path = os.path.join(os.path.expanduser('~'), name)
+        try:
+            return str(os.path.getmtime(path))
+        except OSError:
+            return '0'
+
+    @decorator
+    def _cache(fn, *args, **kwargs):
+        if cache.disabled:
+            return fn(*args, **kwargs)
+
+        cache_path = os.path.join(tempfile.gettempdir(), '.thefuck-cache')
+        key = '{}.{}'.format(fn.__module__, repr(fn).split('at')[0])
+
+        etag = '.'.join(_get_mtime(name) for name in depends_on)
+
+        with shelve.open(cache_path) as db:
+            if db.get(key, {}).get('etag') == etag:
+                return db[key]['value']
+            else:
+                value = fn(*args, **kwargs)
+                db[key] = {'etag': etag, 'value': value}
+                return value
+    return _cache
+cache.disabled = False