Fix wsproxy CPU usage without affecting latency.

Instead of selecting on everything every time, only select the writers
that we have items queued for. Most of the time the writers are ready
so if we select on them even when we don't have anything to send we
will fall into a tight loop.

wsproxy.py

@@ -9,7 +9,7 @@ as taken from http://docs.python.org/dev/library/ssl.html#certificates
 
 '''
 
-import sys, socket, ssl, time
+import sys, socket, ssl
 from select import select
 from websocket import *
 
@@ -32,15 +32,16 @@ def do_proxy(client, target):
     cqueue = []
     cpartial = ""
     tqueue = []
-    socks = [client, target]
+    rlist = [client, target]
 
     while True:
-        time.sleep(0.01) # 10ms
-
-        ins, outs, excepts = select(socks, socks, socks, 1)
+        wlist = []
+        if tqueue: wlist.append(target)
+        if cqueue: wlist.append(client)
+        ins, outs, excepts = select(rlist, wlist, [], 1)
         if excepts: raise Exception("Socket exception")
 
-        if tqueue and target in outs:
+        if target in outs:
             dat = tqueue.pop(0)
             sent = target.send(dat)
             if sent == len(dat):
@@ -50,7 +51,7 @@ def do_proxy(client, target):
                 traffic(".>")
             ##log.write("Target send: %s\n" % map(ord, dat))
 
-        if cqueue and client in outs:
+        if client in outs:
             dat = cqueue.pop(0)
             sent = client.send(dat)
             if sent == len(dat):