patch for issue sonic-net#1971 - enable Rx Drop handling for cisco-8000 (sonic-net#2041)

What I did

Enables support for Rx traffic drop for a port/tc by applying the zero buffer profile
Changed class hierarchy so that default getHwCounters() function is used (since the Rx counter support is enabled)
Fixes a pfc-wd off by 1 detection in case of PFC-WD detection without traffic
Why I did it

enabling a missing functionality
leveraging sonic code as our sdk now implements the missing counter
fixes a bug
How I verified it
on a cisco-8000 router:

detected pfc-wd detection and restore happens within the (detection/restore-time + 1 poll interval) duration and that the changeset passes MSFT tests
Verified that when PFC-WD is detected, both Rx and Tx traffic for a port/tc is dropped and no forwarding happens
Details if related

this patch will need to be double committed to the 202012 branch along with sonic-net#1942 , sonic-net#1748 and sonic-net#1962

Signed-off-by: Alpesh S Patel <alpesh@cisco.com>

Author: alpeshspatel

orchagent/pfc_restore_cisco-8000.lua

@@ -44,7 +44,7 @@ for i = n, 1, -1 do
         and (debug_storm ~= "enabled")
         -- DEBUG CODE END.
         then
-            if time_left <= 0 then
+            if time_left <= poll_time then
                 redis.call('PUBLISH', 'PFC_WD_ACTION', '["' .. KEYS[i] .. '","restore"]')
                 time_left = restoration_time
             else

orchagent/pfcactionhandler.cpp

@@ -221,7 +221,7 @@ void PfcWdActionHandler::updateWdCounters(const string& queueIdStr, const PfcWdQ
 
 PfcWdSaiDlrInitHandler::PfcWdSaiDlrInitHandler(sai_object_id_t port, sai_object_id_t queue,
                                                uint8_t queueId, shared_ptr<Table> countersTable):
-    PfcWdActionHandler(port, queue, queueId, countersTable)
+    PfcWdZeroBufferHandler(port, queue, queueId, countersTable)
 {
     SWSS_LOG_ENTER();
 
@@ -262,39 +262,6 @@ PfcWdSaiDlrInitHandler::~PfcWdSaiDlrInitHandler(void)
     }
 }
 
-bool PfcWdSaiDlrInitHandler::getHwCounters(PfcWdHwStats& counters)
-{
-    SWSS_LOG_ENTER();
-
-    static const vector<sai_stat_id_t> queueStatIds =
-    {
-        SAI_QUEUE_STAT_PACKETS,
-        SAI_QUEUE_STAT_DROPPED_PACKETS,
-    };
-
-    vector<uint64_t> queueStats;
-    queueStats.resize(queueStatIds.size());
-
-    sai_status_t status = sai_queue_api->get_queue_stats(
-            getQueue(),
-            static_cast<uint32_t>(queueStatIds.size()),
-            queueStatIds.data(),
-            queueStats.data());
-
-    if (status != SAI_STATUS_SUCCESS)
-    {
-        SWSS_LOG_ERROR("Failed to fetch queue 0x%" PRIx64 " stats: %d", getQueue(), status);
-        return false;
-    }
-
-    counters.txPkt = queueStats[0];
-    counters.txDropPkt = queueStats[1];
-    counters.rxPkt = 0;
-    counters.rxDropPkt = 0;
-
-    return true;
-}
-
 PfcWdAclHandler::PfcWdAclHandler(sai_object_id_t port, sai_object_id_t queue,
         uint8_t queueId, shared_ptr<Table> countersTable):
     PfcWdLossyHandler(port, queue, queueId, countersTable)
@@ -472,6 +439,14 @@ PfcWdLossyHandler::PfcWdLossyHandler(sai_object_id_t port, sai_object_id_t queue
 {
     SWSS_LOG_ENTER();
 
+    string platform = getenv("platform") ? getenv("platform") : "";
+    if (platform == CISCO_8000_PLATFORM_SUBSTRING)
+    {
+        SWSS_LOG_DEBUG("Skipping in constructor PfcWdLossyHandler for platform %s on port 0x%" PRIx64,
+                       platform.c_str(), port);
+        return;
+    }
+
     uint8_t pfcMask = 0;
 
     if (!gPortsOrch->getPortPfc(port, &pfcMask))
@@ -491,6 +466,14 @@ PfcWdLossyHandler::~PfcWdLossyHandler(void)
 {
     SWSS_LOG_ENTER();
 
+    string platform = getenv("platform") ? getenv("platform") : "";
+    if (platform == CISCO_8000_PLATFORM_SUBSTRING)
+    {
+        SWSS_LOG_DEBUG("Skipping in destructor PfcWdLossyHandler for platform %s on port 0x%" PRIx64,
+                       platform.c_str(), getPort());
+        return;
+    }
+
     uint8_t pfcMask = 0;
 
     if (!gPortsOrch->getPortPfc(getPort(), &pfcMask))

orchagent/pfcactionhandler.h

@@ -165,13 +165,12 @@ class PfcWdZeroBufferHandler: public PfcWdLossyHandler
 
 // PFC queue that implements drop action by draining queue via SAI
 // attribute SAI_QUEUE_ATTR_PFC_DLR_INIT.
-class PfcWdSaiDlrInitHandler: public PfcWdActionHandler
+class PfcWdSaiDlrInitHandler: public PfcWdZeroBufferHandler
 {
     public:
         PfcWdSaiDlrInitHandler(sai_object_id_t port, sai_object_id_t queue,
                 uint8_t queueId, shared_ptr<Table> countersTable);
         virtual ~PfcWdSaiDlrInitHandler(void);
-        virtual bool getHwCounters(PfcWdHwStats& counters);
 };
 
 #endif