Improve responsiveness of request and response viewing.

- Computing the view of a large body is expensive, so we introduce an LRU cache
to hold the latest 20 results.

- Use ListView more correctly, passing it individual urwid.Text snippets,
rather than a single large one. This hugely improves render time.

3 files changed, 104 insertions, 57 deletions

diff --git a/libmproxy/console.py b/libmproxy/console.py
index f05b27e7..b7e8f879 100644
--- a/libmproxy/console.py
+++ b/libmproxy/console.py
@@ -289,71 +289,31 @@ class ConnectionView(WWrap):
                 )
         return f
 
-    def _view_normal(self, conn, txt):
-        for i in conn.content.splitlines():
-            txt.append(
-                ("text", i),
-            )
-            txt.append(
-                ("text", "\n"),
-            )
-
-    def _view_binary(self, conn, txt):
-        for offset, hex, s in utils.hexdump(conn.content):
-            txt.extend([
-                ("offset", offset),
-                " ",
-                ("text", hex),
-                "   ",
-                ("text", s),
-                "\n"
-            ])
-
-    def _view_pretty(self, conn, txt):
-        for i in utils.pretty_xmlish(conn.content):
-            txt.append(
-                ("text", i),
-            )
-            txt.append(
-                ("text", "\n"),
-            )
-
-    def _conn_text(self, conn):
+    def _conn_text(self, conn, viewmode):
         if conn:
-            txt = []
-            txt.extend(
-                format_keyvals(
-                    [(h+":", v) for (h, v) in sorted(conn.headers.itemPairs())],
-                    key = "header",
-                    val = "text"
-                )
-            )
-            txt.append("\n\n")
-            if conn.content:
-                if self.state.view_body_mode == VIEW_BODY_BINARY:
-                    self._view_binary(conn, txt)
-                elif self.state.view_body_mode == VIEW_BODY_INDENT:
-                    self.master.statusbar.update("Calculating pretty mode...")
-                    self._view_pretty(conn, txt)
-                    self.master.statusbar.update("")
-                else:
-                    if utils.isBin(conn.content):
-                        self._view_binary(conn, txt)
-                    else:
-                        self._view_normal(conn, txt)
-            return urwid.ListBox([urwid.Text(txt)])
+            return self.master._cached_conn_text(conn.content, tuple(conn.headers.itemPairs()), viewmode)
         else:
             return urwid.ListBox([])
 
     def view_request(self):
         self.state.view_flow_mode = VIEW_FLOW_REQUEST
-        body = self._conn_text(self.flow.request)
+        self.master.statusbar.update("Calculating view...")
+        body = self._conn_text(
+            self.flow.request,
+            self.state.view_body_mode
+        )
         self.w = self.wrap_body(VIEW_FLOW_REQUEST, body)
+        self.master.statusbar.update("")
 
     def view_response(self):
         self.state.view_flow_mode = VIEW_FLOW_RESPONSE
-        body = self._conn_text(self.flow.response)
+        self.master.statusbar.update("Calculating view...")
+        body = self._conn_text(
+            self.flow.response,
+            self.state.view_body_mode
+        )
         self.w = self.wrap_body(VIEW_FLOW_RESPONSE, body)
+        self.master.statusbar.update("")
 
     def refresh_connection(self, c=None):
         if c == self.flow:
@@ -729,11 +689,11 @@ class StatusBar(WWrap):
             ),
         ]), "statusbar")
         self.ib.set_w(status)
-        self.master.drawscreen()
 
     def update(self, text):
         self.helptext = text
         self.redraw()
+        self.master.drawscreen()
 
     def selectable(self):
         return True
@@ -896,6 +856,52 @@ class ConsoleMaster(flow.FlowMaster):
         if options.server_replay:
             self.server_playback_path(options.server_replay)
 
+    def _view_conn_normal(self, content, txt):
+        for i in content.splitlines():
+            txt.append(
+                urwid.Text(("text", i))
+            )
+
+    def _view_conn_binary(self, content, txt):
+        for offset, hex, s in utils.hexdump(content):
+            txt.append(urwid.Text([
+                ("offset", offset),
+                " ",
+                ("text", hex),
+                "   ",
+                ("text", s),
+            ]))
+
+    def _view_conn_pretty(self, content, txt):
+        for i in utils.pretty_xmlish(content):
+            txt.append(
+                urwid.Text(("text", i)),
+            )
+
+    @utils.LRUCache(20)
+    def _cached_conn_text(self, content, hdrItems, viewmode):
+        hdr = []
+        hdr.extend(
+            format_keyvals(
+                [(h+":", v) for (h, v) in sorted(hdrItems)],
+                key = "header",
+                val = "text"
+            )
+        )
+        hdr.append("\n")
+
+        txt = [urwid.Text(hdr)]
+        if content:
+            if viewmode == VIEW_BODY_BINARY:
+                self._view_conn_binary(content, txt)
+            elif viewmode == VIEW_BODY_INDENT:
+                self._view_conn_pretty(content, txt)
+            else:
+                if utils.isBin(content):
+                    self._view_conn_binary(content, txt)
+                else:
+                    self._view_conn_normal(content, txt)
+        return urwid.ListBox(txt)
 
     def _readflow(self, path):
         path = os.path.expanduser(path)
@@ -1272,8 +1278,8 @@ class ConsoleMaster(flow.FlowMaster):
         slave.start()
         try:
             while not self._shutdown:
-                size = self.drawscreen()
                 self.statusbar.redraw()
+                size = self.drawscreen()
                 self.tick(q)
                 self.ui.set_input_timeouts(max_wait=0.1)
                 keys = self.ui.get_input()
diff --git a/libmproxy/proxy.py b/libmproxy/proxy.py
index 5ec167d6..80040a03 100644
--- a/libmproxy/proxy.py
+++ b/libmproxy/proxy.py
@@ -303,6 +303,9 @@ class Response(controller.Msg):
                     del i["expires"]
         return c.output(header="").strip()
 
+    def __hash__(self):
+        return id(self)
+
     def refresh(self, now=None):
         """
             This fairly complex and heuristic function refreshes a server
diff --git a/libmproxy/utils.py b/libmproxy/utils.py
index a64eca4e..34c49e14 100644
--- a/libmproxy/utils.py
+++ b/libmproxy/utils.py
@@ -12,7 +12,7 @@
 # 
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-import re, os, subprocess, datetime, textwrap, errno, sys, time
+import re, os, subprocess, datetime, textwrap, errno, sys, time, functools
 
 
 def timestamp():
@@ -444,3 +444,41 @@ def dummy_cert(certdir, ca, commonname):
         )
         if ret: return None
     return certpath
+
+
+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.
+    """
+    def __init__(self, size=100):
+        self.size = size
+
+    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]
+            else:
+                ret = f(self, *args)
+                cacheList.insert(0, args)
+                cache[args] = ret
+                if len(cacheList) > size:
+                    d = cacheList.pop()
+                    cache.pop(d)
+                return ret
+        return wrap