Implement declare alarms

src/apps/ipv4/arp.lua

@@ -19,7 +19,6 @@ local lib      = require("core.lib")
 local datagram = require("lib.protocol.datagram")
 local ethernet = require("lib.protocol.ethernet")
 local ipv4     = require("lib.protocol.ipv4")
-local alarm_codec = require("apps.config.alarm_codec")
 local alarms = require("lib.yang.alarms")
 
 alarms.add_to_inventory {
@@ -29,6 +28,16 @@ alarms.add_to_inventory {
     description='Raise up if ARP app cannot resolve IP address'
   }
 }
+local resolve_alarm = alarms.declare_alarm {
+   [{resource='external-interface', alarm_type_id='arp-resolution', alarm_type_qualifier=''}] = {
+      perceived_severity = 'critical',
+      alarm_text =
+         'Make sure you can resolve external-interface.next-hop.ip address '..
+         'manually.  If it cannot be resolved, consider setting the MAC '..
+         'address of the next-hop directly.  To do it so, set '..
+         'external-interface.next-hop.mac to the value of the MAC address.',
+   },
+}
 
 local C = ffi.C
 local receive, transmit = link.receive, link.transmit
@@ -158,8 +167,7 @@ end
 function ARP:arp_resolving (ip)
    print(("ARP: Resolving '%s'"):format(ipv4:ntop(self.next_ip)))
    if self.alarm_notification then
-      local key = {resource='external-interface', alarm_type_id='arp-resolution'}
-      alarm_codec.raise_alarm(key)
+      resolve_alarm:raise()
    end
 end
 
@@ -180,8 +188,7 @@ end
 function ARP:arp_resolved (ip, mac)
    print(("ARP: '%s' resolved (%s)"):format(ipv4:ntop(ip), ethernet:ntop(mac)))
    if self.alarm_notification then
-      local key = {resource='external-interface', alarm_type_id='arp-resolution'}
-      alarm_codec.clear_alarm(key)
+      resolve_alarm:clear()
    end
 end
 

src/lib/yang/alarms.lua

@@ -2,6 +2,7 @@ module(..., package.seeall)
 
 local data = require('lib.yang.data')
 local util = require('lib.yang.util')
+local alarm_codec = require('apps.config.alarm_codec')
 
 local state = {
    alarm_inventory = {
@@ -43,6 +44,63 @@ function add_to_inventory (alarm_types)
    end
 end
 
+-- Single point to access alarm keys.
+alarm_keys = {}
+
+function alarm_keys:fetch (...)
+   self.cache = self.cache or {}
+   local function lookup (resource, alarm_type_id, alarm_type_qualifier)
+      if not self.cache[resource] then
+         self.cache[resource] = {}
+      end
+      if not self.cache[resource][alarm_type_id] then
+         self.cache[resource][alarm_type_id] = {}
+      end
+      return self.cache[resource][alarm_type_id][alarm_type_qualifier]
+   end
+   local resource, alarm_type_id, alarm_type_qualifier = unpack({...})
+   assert(resource and alarm_type_id)
+   alarm_type_qualifier = alarm_type_qualifier or ''
+   local key = lookup(resource, alarm_type_id, alarm_type_qualifier)
+   if not key then
+      key = {resource=resource, alarm_type_id=alarm_type_id,
+             alarm_type_qualifier=alarm_type_qualifier}
+      self.cache[resource][alarm_type_id][alarm_type_qualifier] = key
+   end
+   return key
+end
+function alarm_keys:normalize (key)
+   local resource = assert(key.resource)
+   local alarm_type_id = assert(key.alarm_type_id)
+   local alarm_type_qualifier = key.alarm_type_qualifier or ''
+   return self:fetch(resource, alarm_type_id, alarm_type_qualifier)
+end
+
+local function table_size (t)
+   local size = 0
+   for _ in pairs(t) do size = size + 1 end
+   return size
+end
+
+-- Contains a table with all the declared alarms.
+local alarm_list = {}
+
+function declare_alarm (alarm)
+   assert(table_size(alarm) == 1)
+   local key
+   for k, v in pairs(alarm) do
+      key = alarm_keys:normalize(k)
+      alarm_list[key] = v
+   end
+   function alarm:raise (args)
+      alarm_codec.raise_alarm(key, args)
+   end
+   function alarm:clear ()
+      alarm_codec.clear_alarm(key)
+   end
+   return alarm
+end
+
 ---
 
 function raise_alarm (key, args)
@@ -60,11 +118,6 @@ end
 
 function selftest ()
    print("selftest: alarms")
-   local function table_size (t)
-      local size = 0
-      for _ in pairs(t) do size = size + 1 end
-      return size
-   end
 
    require("apps.ipv4.arp")
    assert(table_size(state.alarm_inventory.alarm_type) > 0)