commit 15e281d2bf92669f79cc97fec267a5de0d2278b0
author Pier Luigi <pierventre@hotmail.com> Sun Mar 04 14:30:43 2018 +0100
committer Charles Chan <rascov@gmail.com> Tue Mar 06 11:35:40 2018 -0800
tree 6db07d5b93f3d4ee25cf6c5186e2c2dff69bf31f
parent 8d16304fe80709e4879fadd398970418ac362897

[CORD-2801] Fix NPE in FlowStatsCollector

java.lang.NullPointerException
  at org.onosproject.provider.of.flow.impl.FlowStatsCollector.stop(FlowStatsCollector.java:96)[180:org.onosproject.onos-providers-openflow-flow:1.12.1.SNAPSHOT]
  at org.onosproject.provider.of.flow.impl.OpenFlowRuleProvider.stopCollectorIfNeeded(OpenFlowRuleProvider.java:263)[180:org.onosproject.onos-providers-openflow-flow:1.12.1.SNAPSHOT]
  at org.onosproject.provider.of.flow.impl.OpenFlowRuleProvider.access$400(OpenFlowRuleProvider.java:112)[180:org.onosproject.onos-providers-openflow-flow:1.12.1.SNAPSHOT]
  at org.onosproject.provider.of.flow.impl.OpenFlowRuleProvider$InternalFlowProvider.switchRemoved(OpenFlowRuleProvider.java:417)[180:org.onosproject.onos-providers-openflow-flow:1.12.1.SNAPSHOT]
  at org.onosproject.openflow.controller.impl.OpenFlowControllerImpl$OpenFlowSwitchAgent.removeConnectedSwitch(OpenFlowControllerImpl.java:783)[177:org.onosproject.onos-protocols-openflow-ctl:1.12.1.SNAPSHOT]
  at org.onosproject.openflow.controller.driver.AbstractOpenFlowSwitch.removeConnectedSwitch(AbstractOpenFlowSwitch.java:344)[164:org.onosproject.onos-protocols-openflow-api:1.12.1.SNAPSHOT]
  at org.onosproject.openflow.controller.impl.OFChannelHandler.channelInactive(OFChannelHandler.java:1288)[177:org.onosproject.onos-protocols-openflow-ctl:1.12.1.SNAPSHOT]

Change-Id: Iae3150f9eb3767c4b579d6b287dededb2da76997

providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowStatsCollector.java

diff --git a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowStatsCollector.java b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowStatsCollector.java
index 0f2ed27..1aabf24 100644
--- a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowStatsCollector.java
+++ b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowStatsCollector.java
@@ -92,9 +92,11 @@
     }
 
     public synchronized void stop() {
-        log.debug("Stopping Stats collection thread for {}", sw.getStringId());
-        task.cancel();
-        task = null;
+        if (task != null) {
+            log.debug("Stopping Stats collection thread for {}", sw.getStringId());
+            task.cancel();
+            task = null;
+        }
     }
 
 }