transport dispatcher now provides its own time expressed in

fractions of second. SNMP engine uses this notion of time for
handling requests timeout to make packet flow time bound

5 files changed, 47 insertions, 16 deletions

diff --git a/pysnmp/carrier/base.py b/pysnmp/carrier/base.py
index 5701043..cc0fdd7 100644
--- a/pysnmp/carrier/base.py
+++ b/pysnmp/carrier/base.py
@@ -25,7 +25,10 @@ class AbstractTransportDispatcher:
         self.__jobs = {}
         self.__recvCbFun = None
         self.__timerCallables = []
-
+        self.__ticks = 0
+        self.__timerResolution = 0.5
+        self.__lastTime = 0
+        
     def _cbFun(self, incomingTransport, transportAddress, incomingMessage):
         for name, transport in self.__transports.items():
             if transport is incomingTransport:
@@ -96,7 +99,22 @@ class AbstractTransportDispatcher:
                 'No suitable transport domain for %s' % (transportDomain,)
                 )
 
+    def getTimerResolution(self):
+        return self.__timerResolution
+    def setTimerResolution(self, timerResolution):
+        if timerResolution < 0.01 or timerResolution > 10:
+            raise error.CarrierError('Impossible timer resolution')
+        self.__timerResolution = timerResolution
+    
+    def getTimerTicks(self): return self.__ticks
+    
     def handleTimerTick(self, timeNow):
+        if self.__lastTime + self.__timerResolution > timeNow:
+            return
+        
+        self.__ticks += 1
+        self.__lastTime = timeNow
+
         for timerCallable in self.__timerCallables:
             timerCallable(timeNow)
 
diff --git a/pysnmp/carrier/twisted/dispatch.py b/pysnmp/carrier/twisted/dispatch.py
index 89e1629..7304e95 100644
--- a/pysnmp/carrier/twisted/dispatch.py
+++ b/pysnmp/carrier/twisted/dispatch.py
@@ -19,9 +19,9 @@ class TwistedDispatcher(AbstractTransportDispatcher):
         AbstractTransportDispatcher.__init__(self)
         self.__transportCount = 0
         if 'timeout' in kwargs:
-            self.timeout = kwargs['timeout']
+            self.setTimerResolution(kwargs['timeout'])
         else:
-            self.timeout = 1.0
+            self.setTimerResolution(1.0)            
         self.loopingcall = task.LoopingCall(self.handleTimeout)
 
     def handleTimeout(self):
@@ -37,8 +37,8 @@ class TwistedDispatcher(AbstractTransportDispatcher):
     # jobstarted/jobfinished might be okay as-is
 
     def registerTransport(self, tDomain, transport):
-        if not self.loopingcall.running and self.timeout > 0:
-            self.loopingcall.start(self.timeout, now = False)
+        if not self.loopingcall.running and self.getTimerResolution() > 0:
+            self.loopingcall.start(self.getTimerResolution(), now = False)
         AbstractTransportDispatcher.registerTransport(
             self, tDomain, transport
             )
diff --git a/pysnmp/entity/rfc3413/cmdgen.py b/pysnmp/entity/rfc3413/cmdgen.py
index d9666d1..478e2cc 100644
--- a/pysnmp/entity/rfc3413/cmdgen.py
+++ b/pysnmp/entity/rfc3413/cmdgen.py
@@ -180,6 +180,10 @@ class CommandGeneratorBase:
         cbInfo
         ):
         (processResponsePdu, cbCtx) = cbInfo
+
+        # Convert timeout in seconds into timeout in timer ticks
+        timeoutInTicks = float(timeout)/100/snmpEngine.transportDispatcher.getTimerResolution()
+
         # 3.1
         sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
             snmpEngine,
@@ -193,8 +197,8 @@ class CommandGeneratorBase:
             contextName,
             pduVersion,
             reqPDU,
-            1,                                 # expectResponse
-            float(timeout)/100 + time.time(),  # timeout
+            1,                          # expectResponse
+            timeoutInTicks,
             processResponsePdu,
             cbCtx
             )
diff --git a/pysnmp/entity/rfc3413/ntforg.py b/pysnmp/entity/rfc3413/ntforg.py
index fb5599f..ec18e96 100644
--- a/pysnmp/entity/rfc3413/ntforg.py
+++ b/pysnmp/entity/rfc3413/ntforg.py
@@ -61,7 +61,10 @@ class NotificationOriginator:
                     cbFun,
                     cbCtx)
                 return
-               
+
+            # Convert timeout in seconds into timeout in timer ticks
+            timeoutInTicks = float(origTimeout)/100/snmpEngine.transportDispatcher.getTimerResolution()
+        
             # 3.3.6a
             sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
                 snmpEngine,
@@ -75,8 +78,8 @@ class NotificationOriginator:
                 origContextName,
                 origPduVersion,
                 origPdu,
-                1,                                     # expectResponse
-                float(origTimeout)/100 + time.time(),  # timeout
+                1,                              # expectResponse
+                timeoutInTicks,
                 self.processResponsePdu,
                 (cbFun, cbCtx)
                 )
@@ -235,6 +238,9 @@ class NotificationOriginator:
                     None
                     )
             else:
+                # Convert timeout in seconds into timeout in timer ticks
+                timeoutInTicks = float(timeout)/100/snmpEngine.transportDispatcher.getTimerResolution()
+
                 # 3.3.6a
                 sendPduHandle = snmpEngine.msgAndPduDsp.sendPdu(
                     snmpEngine,
@@ -248,8 +254,8 @@ class NotificationOriginator:
                     contextName,
                     pduVersion,
                     pdu,
-                    1,                                     # expectResponse
-                    float(timeout)/100 + time.time(),      # timeout
+                    1,                      # expectResponse
+                    timeoutInTicks,
                     self.processResponsePdu,
                     (cbFun, cbCtx)
                     )
diff --git a/pysnmp/proto/rfc3412.py b/pysnmp/proto/rfc3412.py
index b940847..11c7233 100644
--- a/pysnmp/proto/rfc3412.py
+++ b/pysnmp/proto/rfc3412.py
@@ -1,5 +1,5 @@
 """SNMP v3 Message Processing and Dispatching (RFC3412)"""
-import time, sys
+import sys
 from pyasn1.compat.octets import null
 from pysnmp.smi import builder, instrum
 from pysnmp.proto import errind, error, cache
@@ -104,7 +104,7 @@ class MsgAndPduDispatcher:
         pduVersion,
         PDU,
         expectResponse,
-        timeout=0,    # response items
+        timeout=0,    # timeout expressed in dispatcher ticks
         cbFun=None,
         cbCtx=None
         ):
@@ -127,10 +127,11 @@ class MsgAndPduDispatcher:
                 sendPduHandle,
                 messageProcessingModel=messageProcessingModel,
                 sendPduHandle=sendPduHandle,
-                timeout=timeout,
+                timeout=timeout+snmpEngine.transportDispatcher.getTimerTicks(),
                 cbFun=cbFun,
                 cbCtx=cbCtx
                 )
+            debug.logger & debug.flagDsp and debug.logger('sendPdu: current time in ticks %d' % (snmpEngine.transportDispatcher.getTimerTicks(),))
 
         debug.logger & debug.flagDsp and debug.logger('sendPdu: new sendPduHandle %s, timeout %s, cbFun %s' % (sendPduHandle, timeout, cbFun))
 
@@ -456,8 +457,10 @@ class MsgAndPduDispatcher:
 
     def __expireRequest(self, cacheKey, cachedParams, snmpEngine,
                         statusInformation=None):
+        timeNow = snmpEngine.transportDispatcher.getTimerTicks()
         timeoutAt = cachedParams['timeout']
-        if statusInformation is None and time.time() < timeoutAt:
+
+        if statusInformation is None and timeNow < timeoutAt:
             return
 
         processResponsePdu = cachedParams['cbFun']