From 539d3478c8f15dffd15037a051f545aa2f6b3a7d Mon Sep 17 00:00:00 2001
From: Jeff Hill <johill@lanl.gov>
Date: Wed, 11 Sep 2002 23:30:12 +0000
Subject: [PATCH] fixed beacon detect logic does not detect reconnected servers

---
 src/ca/bhe.cpp    | 25 +++++++++++++++++++++----
 src/ca/bhe.h      |  6 +++---
 src/ca/caProto.h  |  2 ++
 src/ca/cac.cpp    |  2 +-
 src/ca/cac.h      |  2 +-
 src/ca/casw.cpp   |  2 +-
 src/ca/udpiiu.cpp |  2 +-
 7 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/src/ca/bhe.cpp b/src/ca/bhe.cpp
index 094444ff7..c7aae430e 100644
--- a/src/ca/bhe.cpp
+++ b/src/ca/bhe.cpp
@@ -89,7 +89,7 @@ void bhe::beaconAnomalyNotify ()
  * updates beacon period, and looks for beacon anomalies
  */
 bool bhe::updatePeriod ( const epicsTime & programBeginTime, 
-    const epicsTime & currentTime, unsigned beaconNumber, 
+    const epicsTime & currentTime, ca_uint32_t beaconNumber, 
     unsigned protocolRevision )
 {
     //
@@ -115,11 +115,28 @@ bool bhe::updatePeriod ( const epicsTime & programBeginTime,
         return false;
     }
 
-    // detect beacon duplications due to IP redundant packet routes
+    // 1) detect beacon duplications due to redundant routes
+    // 2) detect lost beacons due to input queue overrun or damage
     if ( CA_V410 ( protocolRevision ) ) {
-        unsigned lastBeaconNumberSave = this->lastBeaconNumber;
+        unsigned beaconSeqAdvance;
+        if ( beaconNumber > this->lastBeaconNumber ) {
+            beaconSeqAdvance = beaconNumber - this->lastBeaconNumber;
+        }
+        else {
+            beaconSeqAdvance = ( ca_uint32_max - this->lastBeaconNumber ) + beaconNumber;
+        }
         this->lastBeaconNumber = beaconNumber;
-        if ( beaconNumber != lastBeaconNumberSave + 1 ) {
+
+        // throw out sequence numbers just prior to, or the same as, the last one received 
+        // (this situation is probably caused by a temporary duplicate route )
+        if ( beaconSeqAdvance == 0 ||  beaconSeqAdvance > ca_uint32_max - 256 ) {
+            return false;
+        }
+
+        // throw out sequence numbers that jump forward by only a few numbers 
+        // (this situation is probably caused by a duplicate route 
+        // or a beacon due to input queue overun)
+        if ( beaconSeqAdvance > 1 &&  beaconSeqAdvance < 4 ) {
             return false;
         }
     }
diff --git a/src/ca/bhe.h b/src/ca/bhe.h
index f57823fa6..33591e71f 100644
--- a/src/ca/bhe.h
+++ b/src/ca/bhe.h
@@ -39,7 +39,7 @@
 #endif
 
 #include "inetAddrID.h"
-
+#include "caProto.h"
 
 class tcpiiu;
 
@@ -50,7 +50,7 @@ public:
     epicsShareFunc ~bhe (); 
     epicsShareFunc void destroy ();
     epicsShareFunc bool updatePeriod ( const epicsTime & programBeginTime, 
-                        const epicsTime & currentTime, unsigned beaconNumber, 
+                        const epicsTime & currentTime, ca_uint32_t beaconNumber, 
                         unsigned protocolRevision );
     epicsShareFunc double period () const;
     epicsShareFunc epicsTime updateTime () const;
@@ -63,7 +63,7 @@ private:
     tsDLList < tcpiiu > iiuList;
     epicsTime timeStamp;
     double averagePeriod;
-    unsigned lastBeaconNumber;
+    ca_uint32_t lastBeaconNumber;
     void beaconAnomalyNotify ();
     static epicsSingleton < tsFreeList < class bhe, 1024 > > pFreeList;
 	bhe ( const bhe & );
diff --git a/src/ca/caProto.h b/src/ca/caProto.h
index b051b50b0..f750e0acc 100644
--- a/src/ca/caProto.h
+++ b/src/ca/caProto.h
@@ -101,6 +101,8 @@ typedef unsigned int    ca_uint32_t;
 typedef float           ca_float32_t;
 typedef ca_uint32_t     caResId;
 
+#define ca_uint32_max 0xffffffff
+
         /* values for m_cmmd */
 #define CA_PROTO_VERSION        0u  /* set minor version and priority (used to be NOOP cmd) */
 #define CA_PROTO_EVENT_ADD      1u  /* add an event */
diff --git a/src/ca/cac.cpp b/src/ca/cac.cpp
index 9384c285e..28c3f616b 100644
--- a/src/ca/cac.cpp
+++ b/src/ca/cac.cpp
@@ -372,7 +372,7 @@ void cac::show ( unsigned level ) const
  *  cac::beaconNotify
  */
 void cac::beaconNotify ( const inetAddrID & addr, const epicsTime & currentTime,
-                        unsigned beaconNumber, unsigned protocolRevision  )
+                        ca_uint32_t beaconNumber, unsigned protocolRevision  )
 {
     epicsGuard < cacMutex > guard ( this->mutex );
 
diff --git a/src/ca/cac.h b/src/ca/cac.h
index 5da51062e..bd87fcbc8 100644
--- a/src/ca/cac.h
+++ b/src/ca/cac.h
@@ -108,7 +108,7 @@ public:
 
     // beacon management
     void beaconNotify ( const inetAddrID & addr, const epicsTime & currentTime, 
-        unsigned beaconNumber, unsigned protocolRevision );
+        ca_uint32_t beaconNumber, unsigned protocolRevision );
     void repeaterSubscribeConfirmNotify ();
 
     // IO management
diff --git a/src/ca/casw.cpp b/src/ca/casw.cpp
index 60ba22b93..e719bbce4 100644
--- a/src/ca/casw.cpp
+++ b/src/ca/casw.cpp
@@ -195,7 +195,7 @@ int main ( int argc, char ** argv )
                     ina.sin_port = epicsNTOH16 ( serverPort );
                 }
 
-                unsigned beaconNumber = ntohl ( pCurMsg->m_cid );
+                ca_uint32_t beaconNumber = ntohl ( pCurMsg->m_cid );
                 unsigned protocolRevision = ntohs ( pCurMsg->m_dataType );
 
                 epicsTime currentTime = epicsTime::getCurrent();
diff --git a/src/ca/udpiiu.cpp b/src/ca/udpiiu.cpp
index 4a7951fee..6f360edcf 100644
--- a/src/ca/udpiiu.cpp
+++ b/src/ca/udpiiu.cpp
@@ -684,7 +684,7 @@ bool udpiiu::beaconAction ( epicsGuard < callbackMutex > &, const caHdr &msg,
         ina.sin_port = epicsHTON16 ( this->serverPort );
     }
     unsigned protocolRevision = msg.m_dataType;
-    unsigned beaconNumber = msg.m_cid;
+    ca_uint32_t beaconNumber = msg.m_cid;
 
     this->cacRef.beaconNotify ( ina, currentTime, 
         beaconNumber, protocolRevision );