better halflife support, fix some minor bugs..

ui/medashare/tags.py

@@ -38,12 +38,16 @@ class TagCache:
 	'''
 
 	def __init__(self, tags=(), count=10, **kwargs):
-		self._cache = collections.OrderedDict((x, None) for x in tags)
+		values = kwargs.pop('values', None)
+		if values is None:
+			values = itertools.repeat((0, 0))
+		self._cache = collections.OrderedDict(zip(tags, values))
 		self._count = count
 		self._modified = False
 
 		# λ = ln(2) / t1/2
 		hl = kwargs.pop('half_life', None)
+		self._half_life = hl
 		self._lambda = None if not hl else math.log(2) / hl
 		self._limit = kwargs.pop('limit', self._count)
 
@@ -88,6 +92,10 @@ class TagCache:
 
 		return self._modified
 
+	def _new_values(self, t, oldval, oldtime, addnl):
+		return (t, oldval * math.exp(-self._lambda * (t -
+		    oldtime)) + addnl)
+
 	def add(self, tag):
 		'''Add a tag (tuple) to the cache, possibly dropping ann older
 		tag if necessary.'''
@@ -100,8 +108,7 @@ class TagCache:
 
 		# N(t) = N0 e^(-λt)
 		if self._lambda:
-			v = (t, oldval * math.exp(-self._lambda * (t -
-			    oldtime)) + 1)
+			v = self._new_values(t, oldval, oldtime, 1)
 		else:
 			v = 0, 0
 
@@ -115,8 +122,7 @@ class TagCache:
 		t = time.time()
 
 		for k, (oldtime, oldval) in self._cache.items():
-			v = (t, oldval * math.exp(-self._lambda * (t -
-			    oldtime)) + 1)
+			v = self._new_values(t, oldval, oldtime, 0)
 			self._cache[k] = v
 
 	def tags(self):
@@ -128,7 +134,8 @@ class TagCache:
 			    self._cache[x][1], reverse=True)[:self._count])
 		else:
 			return sorted(itertools.islice(self._cache.keys(),
-			    len(self._cache) - self._count, len(self._cache)))
+			    max(0, len(self._cache) - self._count),
+			    len(self._cache)))
 
 	def __repr__(self):
 		return 'TagCache(tags=%s, count=%d, limit=%d)' % \
@@ -151,13 +158,24 @@ class TagCache:
 
 		return cls(**cache)
 
+	def _to_dict(self):
+		tags=list(self._cache.keys())
+
+		values = None
+		if self._half_life:
+			values = [ self._cache[x] for x in tags ]
+
+		return dict(tags=tags, count=self._count,
+		    limit=self._limit, half_life=self._half_life,
+		    values=values)
+
 	def store(self, fname):
 		'''Store the cache to fname.  The modified property will
 		be cleared after this.'''
 
 		self._modified = False
 
-		cache = dict(tags=list(self._cache.keys()), count=self._count)
+		cache = self._to_dict()
 
 		with open(fname, 'wb') as fp:
 			fp.write(_asn1coder.dumps(cache))
@@ -179,6 +197,30 @@ class _TestTagCache(unittest.TestCase):
 		with self.assertRaises(TypeError):
 			TagCache(randomkwargs=True)
 
+	@unittest.mock.patch('time.time', return_value=5)
+	def test_multipletagscalls(self, tt):
+		# that a half_life tc.
+
+		tcdict = dict(tags=[('foo', 'foo')], half_life=10,
+		    values=[( 5, 102.3 )], count=5, limit=5)
+
+		tc = TagCache(**tcdict)
+
+		# when tags is called multiple times
+		tc.tags()
+		tc.tags()
+		tc.tags()
+		tc.tags()
+
+		# that it doesn't change
+		self.assertEqual(tc._to_dict(), tcdict)
+
+	@unittest.mock.patch('time.time', side_effect=lambda cnt=
+	    itertools.count(): next(cnt) * 1.)
+	def test_timebackwards(self, tt):
+		# test for if/when time goes backwards
+		pass
+
 	@unittest.mock.patch('time.time', side_effect=lambda cnt=
 	    itertools.count(): next(cnt) * 1.)
 	def test_halflife(self, tt):
@@ -198,6 +240,29 @@ class _TestTagCache(unittest.TestCase):
 		# XXX - deal with limit better, that is, drop the small value,
 		# not the last
 
+	@unittest.mock.patch('time.time', side_effect=lambda cnt=
+	    itertools.count(): next(cnt) * 1.)
+	def test_halflife(self, tt):
+		tc = TagCache(count=2, limit=10, half_life=10)
+
+		# that when it is added twice
+		tc.add(('foo', 'foo'))
+		tc.add(('foo', 'foo'))
+
+		# and saved/reloaded
+		cachefile = self.tempdir / 'somecache'
+		tc.store(cachefile)
+
+		# that it can be loaded
+		tc = TagCache.load(cachefile)
+
+		# and two others are added
+		tc.add(('bar', 'bar'))
+		tc.add(('baz', 'baz'))
+
+		# it will have preference
+		self.assertEqual(tc.tags(), [ ('baz', 'baz'), ('foo', 'foo'), ])
+
 	def test_limit(self):
 		tc = TagCache(count=2, limit=3)
 
@@ -237,6 +302,8 @@ class _TestTagCache(unittest.TestCase):
 
 		tc.add(('foo', 'foo'))
 
+		self.assertEqual(tc.tags(), [ ('foo', 'foo') ])
+
 		tc.add(('bar', 'bar'))
 
 		tc.add(('baz', 'baz'))