Replace far-too-clever decorator LRU cache with something simpler

libmproxy/console/common.py

@@ -327,11 +327,7 @@ def ask_save_body(part, master, state, flow):
         signals.status_message.send(message="No content to save.")
 
 
-class FlowCache:
-    @utils.LRUCache(200)
-    def format_flow(self, *args):
-        return raw_format_flow(*args)
-flowcache = FlowCache()
+flowcache = utils.LRUCache(800)
 
 
 def format_flow(f, focus, extended=False, hostheader=False, padding=2):
@@ -370,6 +366,7 @@ def format_flow(f, focus, extended=False, hostheader=False, padding=2):
             d["resp_ctype"] = t[0].split(";")[0]
         else:
             d["resp_ctype"] = ""
-    return flowcache.format_flow(
+    return flowcache.get(
+        raw_format_flow,
         tuple(sorted(d.items())), focus, extended, padding
     )

libmproxy/console/flowview.py

@@ -107,16 +107,7 @@ class FlowViewHeader(urwid.WidgetWrap):
             )
 
 
-class CallbackCache:
-    @utils.LRUCache(200)
-    def _callback(self, method, *args, **kwargs):
-        return getattr(self.obj, method)(*args, **kwargs)
-
-    def callback(self, obj, method, *args, **kwargs):
-        # obj varies!
-        self.obj = obj
-        return self._callback(method, *args, **kwargs)
-cache = CallbackCache()
+cache = utils.LRUCache(200)
 
 
 class FlowView(urwid.WidgetWrap):
@@ -158,8 +149,8 @@ class FlowView(urwid.WidgetWrap):
             limit = sys.maxint
         else:
             limit = contentview.VIEW_CUTOFF
-        description, text_objects = cache.callback(
-                    self, "_cached_content_view",
+        description, text_objects = cache.get(
+                    self._cached_content_view,
                     viewmode,
                     tuple(tuple(i) for i in conn.headers.lst),
                     conn.content,

libmproxy/utils.py

@@ -119,40 +119,33 @@ pkg_data = Data(__name__)
 
 class LRUCache:
     """
-        A decorator that implements a self-expiring LRU cache for class
-        methods (not functions!).
-
-        Cache data is tracked as attributes on the object itself. There is
-        therefore a separate cache for each object instance.
+        A simple LRU cache for generated values.
     """
     def __init__(self, size=100):
         self.size = size
+        self.cache = {}
+        self.cacheList  = []
 
-    def __call__(self, f):
-        cacheName = "_cached_%s"%f.__name__
-        cacheListName = "_cachelist_%s"%f.__name__
-        size = self.size
-
-        @functools.wraps(f)
-        def wrap(self, *args):
-            if not hasattr(self, cacheName):
-                setattr(self, cacheName, {})
-                setattr(self, cacheListName, [])
-            cache = getattr(self, cacheName)
-            cacheList = getattr(self, cacheListName)
-            if cache.has_key(args):
-                cacheList.remove(args)
-                cacheList.insert(0, args)
-                return cache[args]
+    def get(self, gen, *args):
+        """
+            gen: A (presumably expensive) generator function. The identity of
+            gen is NOT taken into account by the cache.
+            *args: A list of immutable arguments, used to establish identiy by
+            *the cache, and passed to gen to generate values.
+        """
+        if self.cache.has_key(args):
+            self.cacheList.remove(args)
+            self.cacheList.insert(0, args)
+            return self.cache[args]
         else:
-                ret = f(self, *args)
-                cacheList.insert(0, args)
-                cache[args] = ret
-                if len(cacheList) > size:
-                    d = cacheList.pop()
-                    cache.pop(d)
+            ret = gen(*args)
+            self.cacheList.insert(0, args)
+            self.cache[args] = ret
+            if len(self.cacheList) > self.size:
+                d = self.cacheList.pop()
+                self.cache.pop(d)
             return ret
-        return wrap
+
 
 def parse_content_type(c):
     """

test/test_utils.py

@@ -67,33 +67,34 @@ def test_pretty_duration():
     assert utils.pretty_duration(0.123) == "123ms"
 
 def test_LRUCache():
+    cache = utils.LRUCache(2)
     class Foo:
         ran = False
-        @utils.LRUCache(2)
-        def one(self, x):
+        def gen(self, x):
             self.ran = True
             return x
-
     f = Foo()
-    assert f.one(1) == 1
+
+    assert not f.ran
+    assert cache.get(f.gen, 1) == 1
     assert f.ran
     f.ran = False
-    assert f.one(1) == 1
+    assert cache.get(f.gen, 1) == 1
     assert not f.ran
 
     f.ran = False
-    assert f.one(1) == 1
+    assert cache.get(f.gen, 1) == 1
     assert not f.ran
-    assert f.one(2) == 2
-    assert f.one(3) == 3
+    assert cache.get(f.gen, 2) == 2
+    assert cache.get(f.gen, 3) == 3
     assert f.ran
 
     f.ran = False
-    assert f.one(1) == 1
+    assert cache.get(f.gen, 1) == 1
     assert f.ran
 
-    assert len(f._cached_one) == 2
-    assert len(f._cachelist_one) == 2
+    assert len(cache.cacheList) == 2
+    assert len(cache.cache) == 2
 
 
 def test_unparse_url():
@@ -128,4 +129,3 @@ def test_safe_subn():
 
 def test_urlencode():
     assert utils.urlencode([('foo','bar')])
-

test/tools/testpatt

@@ -2,8 +2,8 @@
 
 # Generate a test pattern with pathoc
 PATHOD=http://localhost:9999
-pathoc localhost:8080 "get:'$PATHOD/p/200:p0,1:b@200b':b@200b"
-pathoc localhost:8080 "get:'$PATHOD/p/300:p0,1:b@200b':b@200b"
-pathoc localhost:8080 "get:'$PATHOD/p/400:p0,1:b@200b':b@200b"
-pathoc localhost:8080 "get:'$PATHOD/p/500:p0,1:b@200b':b@200b"
-pathoc localhost:8080 "get:'$PATHOD/p/600:p0,1:b@200b':b@200b"
+pathoc localhost:8080 "get:'$PATHOD/p/200:p0,1:b@2048b':b@2048b"
+pathoc localhost:8080 "get:'$PATHOD/p/300:p0,1:b@2048b':b@2048b"
+pathoc localhost:8080 "get:'$PATHOD/p/400:p0,1:b@2048b':b@2048b"
+pathoc localhost:8080 "get:'$PATHOD/p/500:p0,1:b@2048b':b@2048b"
+pathoc localhost:8080 "get:'$PATHOD/p/600:p0,1:b@2048b':b@2048b"