add support for ring buffers for debugging, this lets you more easily

keep state on what has happened recently w/o having to spam the log
as much...  we default to 50 entries...

add comment to make sure you update the global line when adding new
functions otherwise when you try to overwrite them, it won't...

[git-p4: depot-paths = "//depot/": change = 844]

debug.py

@@ -2,27 +2,44 @@
 
 from twisted.internet import reactor
 
-__all__ = [ 'appendnamespace', 'insertnamespace', ]
+# Make sure to update the global line when adding a new function
+__all__ = [ 'appendnamespace', 'insertnamespace', 'insertringbuf' ]
+
+DEFAULTRINGSIZE = 50
 
 appendnamespace = lambda k, v: []
 insertnamespace = lambda k, v: None
+insertringbuf = lambda k, l = DEFAULTRINGSIZE: None
+
+# This code from: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/68429
+class RingBuffer:
+	def __init__(self,size_max):
+		self.max = size_max
+		self.data = []
+	def append(self,x):
+		"""append an element at the end of the buffer"""
+		self.data.append(x)
+		if len(self.data) == self.max:
+			self.cur=0
+			self.__class__ = RingBufferFull
+	def get(self):
+  		""" return a list of elements from the oldest to the newest"""
+		return self.data
+
+class RingBufferFull:
+	def __init__(self,n):
+		raise "you should use RingBuffer"
+	def append(self,x):		
+		self.data[self.cur]=x
+		self.cur=(self.cur+1) % self.max
+	def get(self):
+		return self.data[self.cur:]+self.data[:self.cur]
 
 def doDebugging(opt):
 	if not opt:
 		return
 
-	from twisted.manhole import telnet
-
-	class Debug(telnet.Shell):
-		def welcomeMessage(self):
-			data = [ '', 'PyMedS Debugging Console', '', '' ]
-			return '\r\n'.join(data)
-		
-	sf = telnet.ShellFactory()
-	sf.protocol = Debug
-	reactor.listenTCP(56283, sf)
-
-	global insertnamespace, appendnamespace
+	global insertnamespace, appendnamespace, insertringbuf
 
 	def insertnamespace(k, v):
 		assert isinstance(k, basestring)
@@ -33,3 +50,17 @@ def doDebugging(opt):
 			sf.namespace[k].append(v)
 		except KeyError:
 			sf.namespace[k] = [ v ]
+
+	def insertringbuf(k, l = DEFAULTRINGSIZE):
+		insertnamespace(k, RingBuffer(l))
+
+	from twisted.manhole import telnet
+
+	class Debug(telnet.Shell):
+		def welcomeMessage(self):
+			data = [ '', 'PyMedS Debugging Console', '', '' ]
+			return '\r\n'.join(data)
+		
+	sf = telnet.ShellFactory()
+	sf.protocol = Debug
+	reactor.listenTCP(56283, sf)