refactor(clustering/sync): improve error handling

kong/clustering/services/sync/rpc.lua

@@ -177,7 +177,16 @@ local function is_rpc_ready()
 end
 
 
-local function do_sync()
+local do_sync
+
+
+local function error_handler(err)
+  ngx_log(ngx_ERR, err)
+  return nil, err
+end
+
+
+function do_sync()
   if not is_rpc_ready() then
     return nil, "rpc is not ready"
   end
@@ -195,13 +204,14 @@ local function do_sync()
 
   local ns_delta = ns_deltas.default
   if not ns_delta then
-    return nil, "default namespace does not exist inside params"
+    return error_handler("default namespace does not exist inside params")
   end
 
   local deltas = ns_delta.deltas
+  local is_full_sync = ns_delta.wipe
 
   if not deltas then
-    return nil, "sync get_delta error: deltas is null"
+    return error_handler("sync get_delta error: deltas is null")
   end
 
   if isempty(deltas) then
@@ -225,8 +235,7 @@ local function do_sync()
 
   local t = txn.begin(512)
 
-  local wipe = ns_delta.wipe
-  if wipe then
+  if is_full_sync then
     ngx_log(ngx_INFO, "[kong.sync.v2] full sync begins")
 
     t:db_drop(false)
@@ -257,20 +266,20 @@ local function do_sync()
       -- does the entity already exists?
       local old_entity, err = db[delta_type]:select(delta_entity)
       if err then
-        return nil, err
+        return error_handler(err)
       end
 
       -- If we will wipe lmdb, we don't need to delete it from lmdb.
-      if old_entity and not wipe then
+      if old_entity and not is_full_sync then
         local res, err = delete_entity_for_txn(t, delta_type, old_entity, opts)
         if not res then
-          return nil, err
+          return error_handler(err)
         end
       end
 
       local res, err = insert_entity_for_txn(t, delta_type, delta_entity, opts)
       if not res then
-        return nil, err
+        return error_handler(err)
       end
 
       ngx_log(ngx_DEBUG,
@@ -279,22 +288,22 @@ local function do_sync()
               ", type: ", delta_type)
 
       -- wipe the whole lmdb, should not have events
-      if not wipe then
+      if not is_full_sync then
         ev = { delta_type, old_entity and "update" or "create", delta_entity, old_entity, }
       end
 
     else
       -- delete the entity, opts for getting correct lmdb key
       local old_entity, err = db[delta_type]:select(delta.pk, opts) -- composite key
       if err then
-        return nil, err
+        return error_handler(err)
       end
 
       -- If we will wipe lmdb, we don't need to delete it from lmdb.
-      if old_entity and not wipe then
+      if old_entity and not is_full_sync then
         local res, err = delete_entity_for_txn(t, delta_type, old_entity, opts)
         if not res then
-          return nil, err
+          return error_handler(err)
         end
       end
 
@@ -304,13 +313,13 @@ local function do_sync()
               ", type: ", delta_type)
 
       -- wipe the whole lmdb, should not have events
-      if not wipe then
+      if not is_full_sync then
         ev = { delta_type, "delete", old_entity, }
       end
     end -- if delta_entity ~= nil and delta_entity ~= ngx_null
 
     -- wipe the whole lmdb, should not have events
-    if not wipe then
+    if not is_full_sync then
       crud_events_n = crud_events_n + 1
       crud_events[crud_events_n] = ev
     end
@@ -329,16 +338,16 @@ local function do_sync()
   -- record the default workspace into LMDB for any of the following case:
   -- * wipe is false, but the default workspace has been changed
   -- * wipe is true (full sync)
-  if default_ws_changed or wipe then
+  if default_ws_changed or is_full_sync then
     t:set(DECLARATIVE_DEFAULT_WORKSPACE_KEY, kong.default_workspace)
   end
 
   local ok, err = t:commit()
   if not ok then
-    return nil, err
+    return error_handler("failure on commiting to LMDB: " .. err)
   end
 
-  if wipe then
+  if is_full_sync then
     ngx_log(ngx_INFO, "[kong.sync.v2] full sync ends")
 
     kong.core_cache:purge()
@@ -351,7 +360,7 @@ local function do_sync()
     local reconfigure_data = { kong.default_workspace, nil, nil, nil, }
     local ok, err = events.declarative_reconfigure_notify(reconfigure_data)
     if not ok then
-      return nil, err
+      return error_handler(err)
     end
 
   else