Revert "lwaftr: keep full config in worker setup"

This reverts commit d4a1083.

Instead we attach instance device/queue_id meta-data to the
worker configs using a setmetatable, and ensure that all
config manipulation based on the worker queue id is performed
within the manager process.

Specifically, this means moving select_instance() from
apps.lwaftr.lwaftr to apps.lwaftr.lwutil and calling it from
program.lwaftr.setup. (I also took the liberty to make this
function pure to avoid future confusion on my end.)

src/apps/lwaftr/lwaftr.lua

@@ -339,21 +339,6 @@ local function drop(pkt)
    packet.free(pkt)
 end
 
-local function select_instance(conf)
-   local function table_merge(t1, t2)
-      local ret = {}
-      for k,v in pairs(t1) do ret[k] = v end
-      for k,v in pairs(t2) do ret[k] = v end
-      return ret
-   end
-   local device, id, queue = lwutil.parse_instance(conf)
-   conf.softwire_config.external_interface = table_merge(
-      conf.softwire_config.external_interface, queue.external_interface)
-   conf.softwire_config.internal_interface = table_merge(
-      conf.softwire_config.internal_interface, queue.internal_interface)
-   return conf
-end
-
 LwAftr = { yang_schema = 'snabb-softwire-v2' }
 -- Fields:
 --   - direction: "in", "out", "hairpin", "drop";
@@ -420,9 +405,8 @@ LwAftr.shm = {
 function LwAftr:new(conf)
    if conf.debug then debug = true end
    local o = setmetatable({}, {__index=LwAftr})
-   conf = select_instance(conf).softwire_config
+   conf = conf.softwire_config
    o.conf = conf
-
    o.binding_table = bt.load(conf.binding_table)
    o.inet_lookup_queue = bt.BTLookupQueue.new(o.binding_table)
    o.hairpin_lookup_queue = bt.BTLookupQueue.new(o.binding_table)

src/apps/lwaftr/lwutil.lua

@@ -21,6 +21,7 @@ local ntohs = lib.ntohs
 
 -- Return device PCI address, queue ID, and queue configuration.
 function parse_instance(conf)
+   assert(conf.worker_config, "conf missing instance/queue metadata.")
    local device = conf.worker_config.device
    local id = conf.worker_config.queue_id
    local queue = conf.softwire_config.instance[device].queue[id]
@@ -49,6 +50,25 @@ function num_queues(conf)
    return n
 end
 
+function select_instance(conf)
+   local function table_merge(t1, t2)
+      local ret = {}
+      for k,v in pairs(t1) do ret[k] = v end
+      for k,v in pairs(t2) do ret[k] = v end
+      return ret
+   end
+   local device, id, queue = parse_instance(conf)
+   local copy = {softwire_config={}}
+   for k,v in pairs(conf.softwire_config) do
+      copy.softwire_config[k] = v
+   end
+   copy.softwire_config.external_interface = table_merge(
+      conf.softwire_config.external_interface, queue.external_interface)
+   copy.softwire_config.internal_interface = table_merge(
+      conf.softwire_config.internal_interface, queue.internal_interface)
+   return copy
+end
+
 function get_ihl_from_offset(pkt, offset)
    local ver_and_ihl = pkt.data[offset]
    return band(ver_and_ihl, 0xf) * 4

src/lib/yang/snabb-softwire-v2.yang

@@ -886,18 +886,5 @@ module snabb-softwire-v2 {
     }
   }
 
-  container worker-config {
-    description
-    "Worker process configuration state. The contained leaves are used only
-     internally. Setting them has no effect.";
-
-    leaf device {
-      type string;
-    }
-    leaf queue-id {
-      type uint8;
-    }
-  }
-
   uses state-counters;
 }

src/program/lwaftr/setup.lua

@@ -87,7 +87,7 @@ function lwaftr_app(c, conf)
               { address = convert_ipv4(iexternal_interface.ip) })
    config.app(c, "icmpechov6", ipv6_echo.ICMPEcho,
               { address = iinternal_interface.ip })
-   config.app(c, "lwaftr", lwaftr.LwAftr, conf)
+   config.app(c, "lwaftr", lwaftr.LwAftr, lwutil.select_instance(conf))
    config.app(c, "fragmenterv4", ipv4_fragment.Fragmenter,
               { mtu=gexternal_interface.mtu })
    config.app(c, "fragmenterv6", ipv6_fragment.Fragmenter,
@@ -827,8 +827,8 @@ local function compute_worker_configs(conf)
       for id, _ in pairs(queues.queue) do
          local worker_id = string.format('%s/%s', device, id)
          local worker_config = make_copy()
-         worker_config.worker_config = {device=device, queue_id=id}
-         ret[worker_id] = worker_config
+         local meta = {worker_config = {device=device, queue_id=id}}
+         ret[worker_id] = setmetatable(worker_config, {__index=meta})
       end
    end
    return ret