Remove PGs from an administratively down port. (sonic-net#1677)

- What I did
Bug fixes: Remove PGs from an administratively down port.

- Why I did it
To fix bugs

- How I verified it
Run regression and vs test

- Details if related
Remove PGs from an administratively down port.
Introduce a new state: PORT_ADMIN_DOWN which represents the port is administratively down.
Remove all PGs when the port is shut down and re-add all configured PGs when port is started up.
Only record the new value but don't touch BUFFER_PG_TABLE if the following events come when a port is administratively down a port's MTU, speed, or cable length is updated a new PG is added to a port or an existing PG is removed from a port.
Optimize the port event handling flow since refreshPriorityGroupsForPort should be called only once in case more than one fields are updated.
Adjust the Lua plugin which calculates the buffer pool size accordingly

Signed-off-by: Stephen Sun <stephens@nvidia.com>

cfgmgr/buffer_pool_mellanox.lua

@@ -12,7 +12,7 @@ local lossypg_400g = 0
 local result = {}
 local profiles = {}
 
-local count_up_port = 0
+local total_port = 0
 
 local mgmt_pool_size = 256 * 1024
 local egress_mirror_headroom = 10 * 1024
@@ -30,56 +30,46 @@ end
 
 local function iterate_all_items(all_items)
     table.sort(all_items)
-    local prev_port = "None"
     local port
-    local is_up
     local fvpairs
-    local status
-    local admin_down_ports = 0
     for i = 1, #all_items, 1 do
-        -- Check whether the port on which pg or tc hosts is admin down
+        -- Count the number of priorities or queues in each BUFFER_PG or BUFFER_QUEUE item
+        -- For example, there are:
+        --     3 queues in 'BUFFER_QUEUE_TABLE:Ethernet0:0-2'
+        --     2 priorities in 'BUFFER_PG_TABLE:Ethernet0:3-4'
         port = string.match(all_items[i], "Ethernet%d+")
         if port ~= nil then
-            if prev_port ~= port then
-                status = redis.call('HGET', 'PORT_TABLE:'..port, 'admin_status')
-                prev_port = port
-                if status == "down" then
-                    is_up = false
-                else
-                    is_up = true
-                end
+            local range = string.match(all_items[i], "Ethernet%d+:([^%s]+)$")
+            local profile = redis.call('HGET', all_items[i], 'profile')
+            local index = find_profile(profile)
+            if index == 0 then
+                -- Indicate an error in case the referenced profile hasn't been inserted or has been removed
+                -- It's possible when the orchagent is busy
+                -- The buffermgrd will take care of it and retry later
+                return 1
             end
-            if is_up == true then
-                local range = string.match(all_items[i], "Ethernet%d+:([^%s]+)$")
-                local profile = redis.call('HGET', all_items[i], 'profile')
-                local index = find_profile(profile)
-                local size
-                if string.len(range) == 1 then
-                    size = 1
-                else
-                    size = 1 + tonumber(string.sub(range, -1)) - tonumber(string.sub(range, 1, 1))
-                end
-                profiles[index][2] = profiles[index][2] + size
-                local speed = redis.call('HGET', 'PORT_TABLE:'..port, 'speed')
-                if speed == '400000' and profile == '[BUFFER_PROFILE_TABLE:ingress_lossy_profile]' then
-                    lossypg_400g = lossypg_400g + size
-                end
+            local size
+            if string.len(range) == 1 then
+                size = 1
+            else
+                size = 1 + tonumber(string.sub(range, -1)) - tonumber(string.sub(range, 1, 1))
+            end
+            profiles[index][2] = profiles[index][2] + size
+            local speed = redis.call('HGET', 'PORT_TABLE:'..port, 'speed')
+            if speed == '400000' and profile == '[BUFFER_PROFILE_TABLE:ingress_lossy_profile]' then
+                lossypg_400g = lossypg_400g + size
             end
         end
     end
+    return 0
 end
 
 -- Connect to CONFIG_DB
 redis.call('SELECT', config_db)
 
 local ports_table = redis.call('KEYS', 'PORT|*')
 
-for i = 1, #ports_table do
-    local status = redis.call('HGET', ports_table[i], 'admin_status')
-    if status == "up" then
-        count_up_port = count_up_port + 1
-    end
-end
+total_port = #ports_table
 
 local egress_lossless_pool_size = redis.call('HGET', 'BUFFER_POOL|egress_lossless_pool', 'size')
 
@@ -114,8 +104,12 @@ end
 local all_pgs = redis.call('KEYS', 'BUFFER_PG*')
 local all_tcs = redis.call('KEYS', 'BUFFER_QUEUE*')
 
-iterate_all_items(all_pgs)
-iterate_all_items(all_tcs)
+local fail_count = 0
+fail_count = fail_count + iterate_all_items(all_pgs)
+fail_count = fail_count + iterate_all_items(all_tcs)
+if fail_count > 0 then
+    return {}
+end
 
 local statistics = {}
 
@@ -130,7 +124,7 @@ for i = 1, #profiles, 1 do
                 size = size + lossypg_reserved
             end
             if profiles[i][1] == "BUFFER_PROFILE_TABLE:egress_lossy_profile" then
-                profiles[i][2] = count_up_port
+                profiles[i][2] = total_port
             end
             if size ~= 0 then
                 if shp_enabled and shp_size == 0 then
@@ -152,7 +146,7 @@ local lossypg_extra_for_400g = (lossypg_reserved_400g - lossypg_reserved) * loss
 accumulative_occupied_buffer = accumulative_occupied_buffer + lossypg_extra_for_400g
 
 -- Accumulate sizes for egress mirror and management pool
-local accumulative_egress_mirror_overhead = count_up_port * egress_mirror_headroom
+local accumulative_egress_mirror_overhead = total_port * egress_mirror_headroom
 accumulative_occupied_buffer = accumulative_occupied_buffer + accumulative_egress_mirror_overhead + mgmt_pool_size
 
 -- Fetch mmu_size
@@ -240,5 +234,6 @@ table.insert(result, "debug:egress_mirror:" .. accumulative_egress_mirror_overhe
 table.insert(result, "debug:shp_enabled:" .. tostring(shp_enabled))
 table.insert(result, "debug:shp_size:" .. shp_size)
 table.insert(result, "debug:accumulative xoff:" .. accumulative_xoff)
+table.insert(result, "debug:total port:" .. total_port)
 
 return result